Pediococci

Biotechnol Appl Biochem . 2004 Dec 1; {Epub ahead of print}
Fed-batch pediocin production by Pediococcus acidilactici NRRL B-5627 on whey; Guerra NP et al.; Cell growth and pediocin production by Pediococcus acidilactici NRRL B-5627 on whey were compared by using batch and re-alkalized fed-batch fermentations . The batch fermentations were carried out on diluted whey (DW) supplemented with 1% (w/v) of glucose (DWG medium), DW medium supplemented with 2% (w/v) of yeast extract (DWYE medium) and DW medium was supplemented with 1% (w/v) of glucose (1%) plus 2% of yeast extract (DWGYE medium) . The fed-batch culture on DWYE medium was fed with a mixture of concentrated whey (48 g of total sugars/l) supplemented with a 2% (w/v) of yeast extract and a 400 g/l concentrated glucose . Re-alkalized and fed-batch culture was characterised with higher biomass (6.57 g/l) and pediocin (517.6 BU/ml) concentrations compared with the batch processes on MRS broth (1.76 g/l and 493.2 BU/ml), DW (0.17 g/l and 57.7 BU/ml), DWG (0.14 g/l and 53.6 BU/ml), DWYE (1.43 g/l and 187.6 BU/ml) and DWGYE (1.28 g/l and 167.3 BU/ml) . A mixed acid fermentation was observed during growth of Pediococcus acidilactici NRRL B-5627 in the fed-batch culture on DWYE medium, and other products (acetic acid and ethanol) in addition to lactic acid accumulated in the medium . Mathematical models were set up to describe both batch and fed-batch production of biomass and pediocin by Pediococcus acidilactici . The models developed offer a better fit and a more realistic description of the experimental biomass and pediocin production data than the logistic and Luedeking and Piret model.

Int J Food Microbiol, 2004 Dec 1, 97(1), 31 - 42
The pH-unrelated influence of salt, temperature and manganese on aroma formation by Staphylococcus xylosus and Staphylococcus carnosus in a fermented meat model system; Tjener K et al.; The influence of manganese (0.01-0.1-1.0 microg/g), temperature (15-24 degrees C) and salt (3-4% w/w) on volatile formation in model minces inoculated with Pediococcus pentosaceus and either Staphylococcus xylosus or Staphylococcus carnosus was studied in a full factorial experiment . In order to study the direct, pH-unrelated effect of the parameters, data were analysed by use of multiple linear regression and partial least-squares regression both before and after transformation of the volatile responses into pH-orthogonal (pH-unrelated) responses . By using the pH-orthogonalised data, the overall interpretability of the experiment was increased, and new cause-and-effect relations were suggested . Approximately 50% of the total variance in volatile levels was due to differences caused by S . xylosus and S . carnosus, and another 30% was related to differences in pH development . The remaining 20% covered pH-orthogonal effects of manganese, temperature and salt plus the experimental noise . From this, it was concluded that most of the variation in volatile profiles caused by manganese, temperature and salt was in fact directly or indirectly caused by changes in lactic acid bacterial activity and pH.

J Appl Microbiol, 2004, 97(5), 910 - 5
Detection and quantification of Brettanomyces bruxellensis and 'ropy' Pediococcus damnosus strains in wine by real-time polymerase chain reaction; Delaherche A et al.; AIMS: Brettanomyces bruxellensis is a well-known wine spoilage yeast that causes undesirable off-flavours . Likewise, glucan-producing strains of ropy Pediococcus damnosus are considered as spoilage micro-organisms because the synthesis of glucan leads to an unacceptable viscosity of wine . METHODS AND RESULTS: We developed a real-time PCR method to detect and quantify these two spoilage micro-organisms in wine . It is based on specific primer pairs for amplification of target DNA, and includes a melting-curve analysis of PCR products as a confirmatory test . CONCLUSIONS: The detection limit in wine was 10(4) CFU ml(-1) for B . bruxellensis and 40 CFU ml(-1) for ropy Pediococcus damnosus . The real-time PCR proved to be reliable for the early, sensitive detection and quantification of B . bruxellensis and ropy P . damnosus in wine . SIGNIFICANCE AND IMPACT OF THE STUDY: The real-time PCR-based method described in this study provides a new tool for monitoring spoilage micro-organisms in wine . Time-consuming culture and colony isolation steps are no longer needed, so winemakers can intervene before spoilage occurs.

Carbohydr Res, 2004 Oct 20, 339(15), 2499 - 506
Synthesis of an alpha-linked dimer of the trisaccharide repeating unit of the exopolysaccharide produced by Pediococcus damnosus 2.6; Li A et al.; A hexasaccharide, beta-D-Glcp-(1-->3)-{beta-D-Glcp-(1-->2)}-alpha-D-Glcp-(1-->3)-beta-D-Glcp-(1-->3)-{beta-D-Glcp-(1-->2)}-D-Glcp, the alpha-linked dimer of the trisaccharide repeating unit of the exopolysaccharide produced by Pediococcus damnosus 2.6, was synthesized as its methyl glycoside . Condensation of fully benzoylated alpha-D-glucopyranosyl trichloroacetimidate (1) with isopropyl 4,6-O-benzylidene-1-thio-beta-D-glucopyranoside (2) selectively furnished (1-->3)-linked disaccharide 3, and subsequent 2-O-acetylation, desulfation, and trichloroacetimidate formation afforded the disaccharide donor 6 . Meanwhile, selective 3-O-coupling of methyl 4,6-O-benzylidene-alpha-d-glucopyranoside (8) with 3-O-allyl-2,4,6-tri-O-benzoyl-alpha-D-glucopyranosyl trichloroacetimidate (7), followed by coupling with 1 gave the trisaccharide 10 . Removal of the benzylidene group of 10, benzoylation, and deallylation produced the trisaccharide acceptor 12 . Condensation of 12 with 6 yielded a pentasaccharide mixture 13 with beta and alpha isomers in a ratio of 2:1 . Removal of the benzylidene group of 13, followed by benzoylation gave the pentasaccharide mixture 14 . Selective 2'''-deacetylation of the isolated beta-linked 14beta with MeCOCl/MeOH/CH2Cl2 did not give the expected pentasaccharide acceptor, and serious decomposition occurred, indicating a large steric hindrance at C-2''' . Alternatively, 2,3-di-O-glycosylation of allyl 4,6-O-benzylidene-beta-D-glucopyranoside (21) with 1 gave 22, then deallylation and trichloroacetimidate formation afforded the trisaccharide donor 24 . Condensation of 12 with 24 furnished only the alpha-linked hexasaccharide 25, and its deprotection gave the free hexaoside 27.

Appl Microbiol Biotechnol, 2004 Sep, 65(4), 433 - 9 Epub 2004 Jun 16.
Isolation and partial characterization of bacteriocins from Pediococcus species; Jamuna M et al.; Lactic acid bacteria have received increased attention as a potential food preservative due to their strong antagonistic activity against many food-spoilage and pathogenic organisms . Three Pediococcus species, P . acidilactici NCIM 2292 , P . pentosaceous . NCIM 2296 and P . cervisiae NCIM 2171, were evaluated for bacteriocin production . Inhibitory substance were produced during the late growth phase and maximum production occurred at 37 degrees after 36-48 h of incubation . Bacteriocins partially purified from these species by cold-acetone precipitation at 0 degrees C and cell adsorption desorption techniques have a broad inhibitory spectrum against microorganisms, including gram-negative bacteria such as Escherichia coli and Pseudomonas . Proteolytic enzymes inactivated these peptides, but amylase and lipase did not show any effect . The bacteriocins were stable over a wide pH range (3-8) and apparently most active at pH 4.0-5.0 . They were heat-stable (1 h at approximately 80 degrees C and autoclaving) at pH 5.0 . No loss in activity was observed when stored under refrigeration (4-8 degrees C) . Tris-Tricine SDS-PAGE revealed the molecular masses of these peptides to be between 3.5 and 5.0 kDa.

J Agric Food Chem, 2004 Mar 10, 52(5), 1146 - 51
Purification and characterization of bacteriocin from Pediococcus pentosaceus ACCEL; Wu CW et al.; The Pediococcus pentosaceus ACCEL bacteriocin was purified to electrophoretical homogeneity by cell adsorption-desorption and Superose 12 fast performance liquid chromatography (FPLC) . The purified bacteriocin, with a molecular mass of 17.5 kDa and an N-terminal sequence of -KYYGNGVTXGKHSXXVDXG-, belongs to class IIa and is designated pediocin ACCEL . It was inactivated by various proteases and stable at pH 2.0-6.0 and <100 degrees C . More than 80% activity was left even after 15 min of heating at 121 degrees C and pH 2.0-4.0 . Gram-positive food-borne pathogens were inhibited by this bacteriocin, but Gram-negative ones were not . According to the storage stability study, the purified pediocin was stable at pH <6.0 and low temperature . No significant change in bactericidal activity was observed after freeze-drying and subsequent 1-month storage at room temperature.

Biotechnol Bioeng, 2004 Mar 20, 85(6), 676 - 82
Pediocin production by Pediococcus acidilactici in solid state culture on a waste medium: process simulation and experimental results; Vazquez Alvarez JA et al.; The production of pediocin by Pediococcus acidilactici was comparatively studied in submerged and solid-state culture, using polyurethane foam particles soaked in commercial (MRS) and waste media with various supplements, where product concentrations were 15 times higher in MRS medium . For the solid state analysis, cultures were treated by successive compression and refilling of tubular minireactors equipped with a piston, without the need for reinoculation . This method was found to be simple, reproducible, and easily controllable, allowing culture productivity to be maintained for long periods of time without alterations in the basic properties of the system . In addition, yields were found to be superior compared to those from submerged culture . The system kinetics were modeled on the basis of widely accepted assumptions with a good fit to the experimental results and observed biomass fluctuations less evident than those predicted by the kinetic model .

Int J Food Microbiol, 2004 Feb 1, 90(3), 283 - 93
A rapid turbidometric microplate bioassay for accurate quantification of lactic acid bacteria bacteriocins; Turcotte C et al.; A 1 day turbidometric microplate bioassay (TMB) was developed for the rapid, accurate and precise quantification of lactic acid bacteria (LAB) bacteriocins (nisin Z and pediocin PA-1) . Parameters such as the concentration of the indicator strains and the incubation time were optimized for each bacteriocin . A high correlation coefficient (r(2)=0.992+/-0.004) was obtained for the exponential regression in the nisin Z concentration range of 20-120 ng/ml with 1 x 10(7) CFU indicator strain (Pediococcus acidilactici UL5) and an incubation time of 3 h . Using these parameters, the detection limit was estimated at 80 ng/ml (3.2 IU/ml), compared to 300 ng/ml for the agar diffusion assay (ADA) . High precision (<7%) and accuracy (10%) were obtained for all nisin Z concentrations tested . Similar results were obtained with pediocin PA-1 with r(2)=0.993+/-0.005, a precision (8.2%) and an accuracy lower than 15%.

Lett Appl Microbiol, 2003, 37(5), 365 - 9
Substrate inhibition of Pediococcus acidilactici by glucose on a waste medium . Simulations and experimental results; Vazquez JA et al.; AIMS: The possibility of substrate inhibition by glucose on biomass and pediocin production was studied in cultures of Pediococcus acidilactici on a residual medium . METHODS AND RESULTS: Calculation of the substrate inhibition coefficient in the context of microbial growth is generally laborious, and very prone to experimental error . However, a simulation combining logistic and Monod kinetics equations demonstrates that quantitative evidence for this type of inhibition, without the possibility of misinterpretation, can be obtained through the comparison of punctual preasymptotic productions as a function of substrate concentration . SIGNIFICANCE AND IMPACT OF THE STUDY: It was concluded that glucose had an inhibitory effect on growth, but not on bacteriocin production.

Int J Food Microbiol, 2003 Oct 15, 87(1-2), 113 - 20
Exopolysaccharide production by Pediococcus damnosus 2.6 in a semidefined medium under different growth conditions; Duenas M et al.; Ropy Pediococcus damnosus (strain 2.6) was used for production of exopolysaccharide (EPS) in a semidefined medium . From a kinetic point of view, an experiment conducted in SMD medium containing 30 g l(-1) glucose and 5 g l(-1) Bacto casamino acids (Difco Laboratories, Detroit, MI), without pH control, showed that EPS production took place mainly during the growth phase . The viscosity of the cultures developed in parallel to the EPS synthesis until 94 h of incubation; after 200 h of fermentation, viscosity decreased . The effect of glucose, Bacto casamino acid concentrations and temperature on growth and EPS production was determined by using a full factorial design . Within the domain of experimental conditions considered, the concentration of glucose and Bacto casamino acids has a significant effect on the production of exopolysaccharide . The incubation at 12 degrees C produced a prolonged lag phase and due to the lower growth yield, higher specific EPS production was found at this temperature . At 25 degrees C the EPS production was mainly enhanced by the increase in glucose concentration . The increase in nitrogen concentration from 5 to 15 g l(-1) did not yield greater EPS production . However, at 12 degrees C optimal EPS production was obtained when both higher glucose and nitrogen concentrations were used.

Rheumatology (Oxford), 2003 Sep, 42(9), 1062 - 6 Epub 2003 Apr 16.
Concomitant septic and gouty arthritis--an analysis of 30 cases; Yu KH et al.; OBJECTIVES: To analyse the clinical features and outcomes of gouty patients with concomitant septic arthritis in a medical centre . METHODS: From the hospital database, we collected 30 hospitalized cases with concomitant septic arthritis and gouty arthritis from 1987 to 2001 . All patients had positive bacterial culture and monosodium urate crystals in the affected joints . Medical records of the patients were analysed in detail . RESULTS: The mean age of patients was 52.8+/-12.5 yr . One-third of patients were afebrile at presentation, 30% had a normal blood leucocyte count and 10% had a synovial fluid leucocyte count less than 6000/mm3 . The knee joint was the most common site of involvement, followed by the ankle, shoulder and wrist joints . Most patients had long-standing disease and subcutaneous tophi . Subcutaneous tophi rupture with secondary wound infection is the most common route of infection . Causative micro-organisms were Staphylococcus aureus (16 cases, 7 of whom were oxacillin-resistant), Streptococcus sp . (5 cases), Pediococcus sp . (1 case), and Gram-negative bacilli (9 cases) . Fourteen patients received surgical debridement, among them two patients had an arthrodesis owing to severe joint destruction and one received above-knee amputation . Two patients died . One died of septic complications and the other died of acute myocardial infarction . CONCLUSIONS: Septic arthritis coexistent with gout presented a diagnostic difficulty . An early diagnosis requires a high level of suspicion . Prompt aspiration and analysis of the synovial fluid is imperative, regardless of the absence of fever or leucocytosis . Culture of the aspirated synovial fluid is warranted in gouty attack, even when it has a low white cell count or the Gram stain reveals no organisms.

Can Vet J, 2003 Mar, 44(3), 212 - 6
Bacteriological evaluation of dog and cat diets that claim to contain probiotics; Weese JS et al.; Nineteen commercial pet foods claiming to contain probiotics were evaluated . Selective bacterial culture was performed to identify organisms that were claimed to be present . Twelve diets claimed only to contain specific bacterial fermentation products, which does not necessarily indicate that live growth would be expected, but these products also included the term "probiotic" somewhere on the package, suggesting that live, beneficial organisms were present . No products contained all of the listed organisms, while 1 or more of the listed contents were isolated from 10 out of 19 products (53%) . Eleven products contained additional, related organisms including Pediococcus spp, which was isolated from 4 products . No relevant growth was present in 5 (26%) products . Average bacterial growth ranged from 0 to 1.8 x 10(5) CFU/g . Overall, the actual contents of the diets were not accurately represented by the label descriptions.

Appl Environ Microbiol, 2003 Apr, 69(4), 2237 - 44
Functional replacement of the Escherichia coli D-(-)-lactate dehydrogenase gene (ldhA) with the L-(+)-lactate dehydrogenase gene (ldhL) from Pediococcus acidilactici; Zhou S et al.; The microbial production of L-(+)-lactic acid is rapidly expanding to allow increased production of polylactic acid (PLA), a renewable, biodegradable plastic . The physical properties of PLA can be tailored for specific applications by controlling the ratio of L-(+) and D-(-) isomers . For most uses of PLA, the L-(+) isomer is more abundant . As an approach to reduce costs associated with biocatalysis (complex nutrients, antibiotics, aeration, product purification, and waste disposal), a recombinant derivative of Escherichia coli W3110 was developed that contains five chromosomal deletions (focA-pflB frdBC adhE ackA ldhA) . This strain was constructed from a D-(-)-lactic acid-producing strain, SZ63 (focA-pflB frdBC adhE ackA), by replacing part of the chromosomal ldhA coding region with Pediococcus acidilactici ldhL encoding an L-lactate dehydrogenase . Although the initial strain (SZ79) grew and fermented poorly, a mutant (SZ85) was readily isolated by selecting for improved growth . SZ85 exhibited a 30-fold increase in L-lactate dehydrogenase activity in comparison to SZ79, functionally replacing the native D-lactate dehydrogenase activity . Sequencing revealed mutations in the upstream, coding, and terminator regions of ldhL in SZ85, which are presumed to be responsible for increased L-lactate dehydrogenase activity . SZ85 produced L-lactic acid in M9 mineral salts medium containing glucose or xylose with a yield of 93 to 95%, a purity of 98% (based on total fermentation products), and an optical purity greater than 99% . Unlike other recombinant biocatalysts for L-lactic acid, SZ85 remained prototrophic and is devoid of plasmids and antibiotic resistance genes.

J Agric Food Chem, 2003 Feb 12, 51(4), 1071 - 6
Bacteriocins from Pediococcus pentosaceus L and S from pork meat; Yin LJ et al.; Two strains of Pediococcus pentosaceus were isolated from refrigerated pork and found to produce antimicrobial substances that may inhibit foodborne pathogens and have potential as natural food preservatives . They were named P . pentosaceus L and S . The antimicrobial substances were purified to electrophoretical homogeneity by chloroform extraction and designated pentocins L and S with molecular masses (M) of 27 and 25 kDa, respectively . Both pentocins also had broad inhibition spectra and were thermostable . They inhibit the growth of tested spore-forming G+ and G- strains and the germination of Bacillus subtilis ATCC 10225, B . subtilis ATCC 10254, and Bacillus cereus ATCC 11778 spores . The inhibition activities decreased as the glucose in the medium decreased from 8.0 to 2.0%.

Int J Food Microbiol, 2003 Jan 26, 82(1), 25 - 31
Thermal inactivation of Pediococcus sp . in simulated apple cider during high-temperature short-time pasteurization; Piyasena P et al.; Prompted by concerns regarding outbreaks of food-borne illness which have occurred due to the consumption of commercial, nonpasteurized fruit juices contaminated with Escherichia coli O157:H7, the US Food and Drug Administration and Canadian Food Inspection Agency are considering several new safety standards to apply to fresh juices, including mandatory pasteurization of all apple cider . In support of these initiatives, a study was conducted to evaluate the pasteurization of simulated cider using a heat-resistant nonpathogenic test bacterium, Pediococcus sp . NRRL B-2354 . Thermal inactivation of the Pediococcus sp . was determined using a pilot scale high-temperature short-time (HTST) pasteurizer with a plate heat exchanger . The cumulative lethal effect, or pasteurization effect (PE), was obtained by converting times at different temperatures in the various sections of the pasteurizer to the equivalent time at the reference temperature (72 degrees C) . PE was then related by a simple linear function to the log(10) of the percentage of viable counts with a power transformation of the PE values to improve linear fit . r(2) values for the four Pediococcus sp . trials varied from 0.921 to 0.981 . Intertrial variation was incorporated into the model using @RISK simulation software . Output from simulations confirmed that treatment at 71 degrees C for 16 s can ensure a 5-log reduction of Pediococcus sp.

Int J Food Microbiol, 2002 Nov 15, 79(1-2), 99 - 104
The effect of temperature on the growth and persistence of Salmonella in fermented liquid pig feed; Beal JD et al.; Two studies were conducted to investigate the effect of temperature on the fate of Salmonella enterica subsp . enterica serovar typhimurium DT104:30 in fermented liquid pig feed . These were (1) by co-inoculation of feed with S . typhimurium DT104:30 and Pediococcus pentosaceus, as the fermenting organism, and (2) by fermenting feed for 48, 72 or 96 h prior to inoculation with S . typhimurium DT104:30 . In co-inoculated feed incubated at 20 degrees C, S . typhimurium DT104:30 persisted for at least 72 h . In contrast, in feed incubated at 30 degrees C, no S . typhimurium DT104:30 were detectable 48 h after inoculation . In prefermented feed, S . typhimurium DT104:30 died four to five times faster in feed maintained at 30 degrees C (D(value) 34-45 min) compared with feed maintained at 20 degrees C (D(value) 137-250 min) . This was not entirely due to differences in lactic acid concentration as feed fermented for 72 or 96 h at 20 degrees C and feed fermented for 48 h at 30 degrees C contained similar concentrations of lactic acid (160-170 mM) . Low numbers of S . typhimurium DT104:30 were still detectable in fermented feed 24 h after inoculation at 20 degrees C . In contrast, none were detectable 6-7 h after inoculation at 30 degrees C . The results of these studies indicate that it would be advisable for pig producers to control the temperature of liquid feed tanks to reduce the risk of Salmonella contamination.

J Appl Microbiol, 2002, 93(2), 288 - 94
Persistence of Escherichia coli O157:H7 in barley silage: effect of a bacterial inoculant; Bach SJ et al.; AIMS: The effect of a lactic acid producing bacterial (LAB) inoculant on the elimination of Escherichia coli O157:H7 from barley forage was assessed . METHODS AND RESULTS: Triplicate mini-silos were prepared for four treatments and six sampling times (1, 3, 7, 15, 30 and 42 d post-ensiling) . The treatments were (i) 10(5) cfu g(-1) Pediococcus pentosaceus and Propionibacterium jenzenii (P2); (ii) 10(5) cfu g(-1) E . coli O157:H7 strain 3081 and 10(5) cfu g(-1) E . coli Biotype 1 strains 719IE10, 719IE14 and 614ME49 (EC); (iii) P2 + EC; and (iv) the control (sterile distilled water) . Triplicate mini-silos were opened at each sampling time for pH, volatile fatty acid (VFA) and lactate determinations and E . coli, E . coli O157:H7 and LAB were enumerated . On d 3 and 7, numbers of E . coli O157:H7 in P2 + EC were significantly lower than in EC (P < 0;05) . Escherichia coli O157:H7 was not detected in P2 + EC and EC at 7 and 15 d post-ensiling, respectively . On d 15 through 42, E . coli Biotype 1 was not detected in P2 + EC or EC . Populations of LAB were higher in P2 and P2 + EC than in the control and EC on d 3 and 7 (P < 0.05) . After 3 d of ensiling, lactate levels were higher (P < 0.05) and pH was lower (P < 0.05) in P2 and P2 + EC as compared to the control and EC . Bacteriocins of P2 were not found to be inhibitory to E . coli O157:H7 using the agar-spot procedure . Escherichia coli O157:H7 inoculated into the control silage at a level of 10(3) cfu g(-1) and exposed to aerobic conditions at 22 degrees C was not detected after 1 d and remained undetectable for the 28 d exposure period . CONCLUSIONS: Silage inoculant P2 increased lactate levels and decreased pH more rapidly during ensiling, which appeared to hasten the elimination of E . coli O157:H7 from the silage . SIGNIFICANCE AND IMPACT OF THE STUDY: Results emphasize the importance of adequate ensiling since E . coli O157:H7 may be maintained and spread among cattle through feed.

Int J Food Microbiol, 2002 May 5, 75(1-2), 99 - 109
Growth and aroma production by Staphylococcus xylosus, S . carnosus and S . equorum--a comparative study in model systems; Sondergaard AK et al.; A laboratory medium inoculated with 20 different Staphylococcus strains was prepared in accordance with a full factorial experimental design investigating the effect of temperature, pH, NaCl and glucose on growth . The 12 strains most suited to growth in a fermented meat environment were inoculated in sausage minces together with Pediococcus pentosaceus, incubated at 25 degrees C for 1 week and the produced aroma compounds collected . The data were analysed by multiple linear regression and partial least squares regression analysis . The results showed that increasing pH and temperature from 4.6 to 6.0 and 10 to 26 degrees C, respectively, increased growth of all strains with strong synergy between temperature and pH . Increasing salt concentration from 5% to 15% w/v decreased growth of most strains, but the effect of pH and temperature was much stronger than the effect of salt . Strains of S . carnosus were more salt tolerant than strains of S . equorum and S . xylosus, especially at high pH and temperature . Addition of glucose up to 0.5% w/v had no significant influence on growth of any of the strains . With regard to aroma production, species characteristics were detected . S . carnosus and S . xylosus were quite different regarding the overall aroma profiles, whereas the profiles of S . equorum lied somewhere in-between . Contrary to S . carnosus, S . xylosus and S . equorum did not produce 2-methyl-1-butanol . On the other hand, in particular, S . xylosus produced more 3-methyl-1-butanol . Except for one of the strains of S . equorum, S . xylosus and S . equorum formed more diacetyl, 2-butanone and acetoin and also more of the methyl-branched ketones arising from degradation of leucine, isoleucine and valine . S . carnosus produced more methyl-branched aldehydes, acids and corresponding esters from leucine, isoleucine and valine compounds that have been correlated with fermented sausage maturity in former studies . S . equorum produced the least of the methyl-branched aldehydes.

J Appl Microbiol, 2001 Dec, 91(6), 1131 - 8
Growth optimization of Pediococcus damnosus NCFB 1832 and the influence of pH and nutrients on the production of pediocin PD-1; Nel HA et al.; AIMS: Optimization of the growth of Pediococcus damnosus NCFB 1832 and the production of pediocin PD-1 by traditional fermentation methods . METHODS AND RESULTS: Fermentation studies were conducted in De Man Rogosa and Sharpe (MRS) broth (Oxoid), preadjusted to specific pH values, and in MRS broth supplemented with various nitrogen sources, MnSO4, MgSO4 and Tween 80 . The production of pediocin PD-1 closely followed the growth curve of Ped . damnosus NCFB 1832 . Maximum levels of bacteriocin activity (3249 AU ml(-1)/O.D.max) were recorded in MRS broth with an initial pH of 6.7 . In media with an initial pH of 4.5 bacteriocin activity as low as 222 AU ml(-1)/O.D.max was recorded . The highest bacteriocin activity was recorded in growth conditions allowing the greatest pH variation (highest DeltapH) . The addition of bacteriological peptone (1.7%, w/v), MnSO4 (0.014%, w/v) and Tween 80 (3%, v/v) to MRS and adjustment of the medium pH to 6.7 resulted in a further increase in activity (from 3249 to 5078 AU ml(-1)/O.D.max) . The same medium, but with an initial pH of 6.2, resulted in an 82.5% decrease in bacteriocin activity . CONCLUSIONS: Pediocin PD-1 production is not only stimulated by the presence of specific growth factors (e.g., bacteriological peptone, MnSO4 or Tween 80), but may also be stimulated by the lowering in pH during growth (highest DeltapH), and thus also the amount of organic acids produced . SIGNIFICANCE AND IMPACT OF THE STUDY: The production of pediocin PD-1 by the wild-type producer strain was significantly improved by using a defined medium and traditional fermentation methods.

Appl Environ Microbiol, 2002 Feb, 68(2), 765 - 71
Genomic diversity within the genus Pediococcus as revealed by randomly amplified polymorphic DNA PCR and pulsed-field gel electrophoresis; Simpson PJ et al.; The genomic diversity of 33 previously assigned strains from six species within the genus Pediococcus was assessed by randomly amplified polymorphic DNA (RAPD) PCR and pulsed-field-gel electrophoresis (PFGE) . The RAPD PCR patterns produced by two separate random primers, termed P1 (ACGCGCCCT) and P2 (ATGTAACGCC), were compared by the Pearson correlation coefficient and the unweighted pair group method with arithmetic averages clustering algorithm . Pattern variations between repeat samples set a strain discrimination threshold of less than 70% similarity . P1 and P2 primers alone and in combination produced 14, 21, and 28 distinct patterns, respectively . When each strain was assigned with a type strain with which it shared the highest level of similarity, both primers grouped 17 of the 27 strains to their proposed species . PFGE following genomic digestion with the restriction enzymes ApaI, NotI, and AscI produced 30, 32, and 28 distinct macrorestriction patterns, respectively . Specific DNA fragments within the NotI and AscI macrorestriction patterns for each strain were observed that allowed 27 of the 33 strains to be assigned to their proposed species . For example, following digestion with AscI, all Pediococcus parvulus strains were characterized by two DNA fragments, one of approximately 220 kb and another between 700 and 800 kb . The exceptions correlated with those observed with both RAPD PCR primers and included three P . damnosus and two P . pentosaceus strains that grew at temperatures regarded as nonpermissive for their proposed species but not for those with which they grouped.

Curr Microbiol, 2002 Mar, 44(3), 155 - 60
Cloning of the L-lactate dehydrogenase gene from the ruminal bacterium Selenomonas ruminantium HD4; Evans JD et al.; A clone from a Selenomonas ruminantium HD4 Lambda ZAP II genomic library was isolated by its ability to complement the anaerobic growth deficiency of an Escherichia coli (pfl, ldh) double mutant . The 1.0-kb insert from the clone was sequenced and revealed a single open reading frame (ORF, 957-bp) which was preceded by a putative Shine-Dalgarno (SD) sequence (AGGGGG) . The potential SD sequence corresponded to 3' 16S rRNA sequences of various Selenomonas strains . The ORF was predicted to encode a protein of 318 amino acids with a calculated molecular mass of 34,975 Da and an isoelectric point of 5.54 . In addition, the ORF contained 51 mol % G + C and this is consistent with the average G + C content (54%) of the S . ruminantium chromosome . The cloned S . ruminantium gene exhibited 59% nucleotide identity and 61% deduced amino acid similarity with L-lactate dehydrogenases (L-LDH) of Pediococcus acidilactici and Bacillus megaterium, respectively . Incorporation of the cloned S . ruminantium gene into E . coli DC1368 (pfl, ldh) restored anaerobic growth on glucose and L-LDH activity was detected in cell extracts . Because lactate accumulation within the rumen can be detrimental to animal performance, characterizing the gene(s) involved in lactate production by predominant ruminal bacteria will lead to a better understanding of lactate metabolism within the rumen.

Curr Microbiol, 2002 Feb, 44(2), 77 - 80
Multilocus hybridization typing in Pediococcus acidilactici strains; Mora D et al.; In previous a study we demonstrated the presence of several genomic subpopulations within a collection of Pediococcus acidilactici strains isolated from different environments, through a multilocus typing analysis taking into consideration housekeeping conserved loci and protein coding genes of the primary metabolism . In this study, representative strains of five genomic subpopulations previously described (I, II, III, V, VII) were analyzed by restriction analysis of chromosomal DNA and subsequent hybridization assays using as probes amplified fragments obtained from five housekeeping genes (16S rDNA, rpoC, ldhD, ldhL, and metS) . A computer similarity and clustering analysis of hybridization data showed the subdivision of P . acidilactici strains in five distinct genotypes according to the grouping previously obtained confirming that pediocin AcH/PA-1 producer strains represent one genomic lineage within the species P . acidilactici.

Curr Microbiol, 2001 Oct, 43(4), 227 - 31
Characterization, production, and purification of carnocin H, a bacteriocin produced by Carnobacterium 377; Blom H et al.; Carnocin H, a bacteriocin produced by a Carnobacterium sp., inhibited lactic acid bacteria, clostridia, enterococci, and some Staphylococcus aureus strains . Some strains of Listeria and Pediococcus were also sensitive to carnocin H . The bacteriocin was produced during the late stationary growth phase . Carnocin H was purified by cation exchange chromatography and reverse phase chromatography . Amino acid sequence and composition indicate that carnocin H is a novel bacteriocin belonging to the class II bacteriocins . The bacteriocin consists of approximately 75 amino acid residues with a highly cationic N-terminal containing six succeeding lysines . Activity, as measured by agar diffusion zones, was reduced at increased pH values, levels of indicator bacteria, NaCl, agar, and soy oil.

Appl Microbiol Biotechnol, 2001 Jun, 55(6), 777 - 81
Flocculation and coflocculation of bacteria by yeasts; Peng X et al.; Biotransformations in natural environments frequently involve interactions between microorganisms . Although there are many reports on the interactions between bacteria, interactions between yeasts and bacteria have not been extensively studied . Previously we reported on the flocculation and coflocculation of Pediococcus damnosus by Saccharomyces cerevisiae . Now we report that several other yeasts, such as Candida utilis, Dekkera bruxellensis, Hanseniaspora guilliermondii, Kloeckera apiculata, and Schizosaccharomyces pombe, induce flocculation with several industrially or medically relevant bacteria, including Bacillus subtilis, Pseudomonas aeruginosa, and Staphylococcus aureus . Candida utilis was one of the best flocculation inducers . The results are discussed with respect to interactions between yeasts and bacteria and their applications in industry and medicine.

Appl Environ Microbiol, 2001 Aug, 67(8), 3753 - 5
Optimization of annealing temperature to reduce bias caused by a primer mismatch in multitemplate PCR; Ishii K et al.; To reduce PCR bias derived from a primer mismatch, the effect of the annealing temperature on the product ratio was investigated by denaturing gradient gel electrophoresis analysis of PCR products from a mixture of perfect-match and one-mismatch templates . These templates were generated by PCR from Pediococcus acidilactici for one mismatch and Micrococcus luteus for the perfect match . PCRs showed that the bias was reduced at lower temperatures . An environmental sample was also examined.

Appl Environ Microbiol, 2001 Aug, 67(8), 3413 - 7
Decrease in cell surface galactose residues of Schizosaccharomyces pombe enhances its coflocculation with Pediococcus damnosus; Peng X et al.; Pediococcus damnosus can coflocculate with Saccharomyces cerevisiae and cause beer acidification that may or may not be desired . Similar coflocculations occur with other yeasts except for Schizosaccharomyces pombe which has galactose-rich cell walls . We compared coflocculation rates of S . pombe wild-type species TP4-1D, having a mannose-to-galactose ratio (Man:Gal) of 5 to 6 in the cell wall, with its glycosylation mutants gms1-1 (Man:Gal = 5:1) and gms1Delta (Man:Gal = 1:0) . These mutants coflocculated at a much higher level (30 to 45%) than that of the wild type (5%) . Coflocculation of the mutants was inhibited by exogenous mannose but not by galactose . The S . cerevisiae mnn2 mutant, with a mannan content similar to that of gms1Delta, also showed high coflocculation (35%) and was sensitive to mannose inhibition . Coflocculation of P . damnosus and gms1Delta (or mnn2) also could be inhibited by gms1Delta mannan (with unbranched alpha-1,6-linked mannose residues), concanavalin A (mannose and glucose specific), or NPA lectin (specific for alpha-1,6-linked mannosyl units) . Protease treatment of the bacterial cells completely abolished coflocculation . From these results we conclude that mannose residues on the cell surface of S . pombe serve as receptors for a P . damnosus lectin but that these receptors are shielded by galactose residues in wild-type strains . Such interactions are important in the production of Belgian acid types of beers in which mixed cultures are used to improve flavor.

J Ind Microbiol Biotechnol, 2001 Apr, 26(4), 191 - 5
Effect of physical factors on the production of bacteriocin from Pediococcus acidilactici ITV 26; Calderon-Santoyo M et al.; The effect of pH, temperature and agitation on growth and bacteriocin production by Pediococcus acidilactici ITV 126 was investigated . Experiments were made in flasks containing MRS medium at 30 to 40 degrees C, pH 5 to 7 and agitation 0 to 200 rpm . Factor levels were arranged in a 2(3) factorial design with central and axial points . Anova and Tukey paired comparison tests showed that a temperature of 35 degrees C favored bacteriocin production, whereas 40 degrees C was best for cell growth . A statistical interaction of temperature and agitation was observed affecting microbial growth . pH 5 favored both cell growth and bacteriocin production.

Pediatrics, 2001 Apr, 107(4), 775 - 6
Bacteremic infection with Pediococcus: vancomycin-resistant opportunist; Barton LL et al.; Pediococci are recently recognized Gram-positive human pathogens, resistant to vancomycin and generally susceptible to penicillin . Infection in adults has been seen in patients with chronic underlying conditions as well as those with previous abdominal surgery . Two previous infants with congenital gastrointestinal malformations requiring surgical correction have been reported with sepsis attributable to Pediococcus sp . We report a third infant born with gastroschisis who developed Pediococcus bacteremia and meningitis 3 months after surgery, and speculate regarding the role of probiotics in the pathogenesis of this infection.

J Appl Microbiol, 2001 Apr, 90(4), 535 - 42
Direct polymerase chain reaction detection of ropy Pediococcus damnosus strains in wine; Gindreau E et al.; AIMS: Glucan-producing strains of Pediococcus damnosus are considered as spoilage micro-organisms because synthesis of glucan leads to an unacceptable viscosity of wine . In this report, we present a polymerase chain reaction (PCR) procedure to detect the presence of such strains in wines . METHODS AND RESULTS: We developed a direct DNA isolation method from the wine microflora using polyvinylpyrrolidone in order to decrease the polyphenolic concentration . The sequence of the plasmid involved in glucan production allowed the design of a primer pair usable for a specific and sensitive PCR procedure, leading to the amplification of a 563-bp fragment . CONCLUSION: The detection limit in wine was 102 cfu ml-1 . The detection sensitivity could be increased by using a second primer pair in nested PCR assays . SIGNIFICANCE AND IMPACT OF THE STUDY: The method proved to be efficient for the early and sensitive detection of ropy Ped . damnosus strains during wine-making . Time-consuming culture and colony isolation steps are no longer needed.

J Clin Microbiol, 2001 Apr, 39(4), 1241 - 6
Phenotypic and genotypic characterization of Pediococcus strains isolated from human clinical sources; Barros RR et al.; Seventy-two strains of pediococci isolated from human clinical sources were characterized by conventional physiological tests, chromogenic enzymatic tests, analysis of whole-cell protein profiles (WCPP) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and analysis of chromosomal DNA restriction profiles by pulsed-field gel electrophoresis (PFGE) . Conventional tests allowed identification of 67 isolates: 52 strains were identified as Pediococcus acidilactici, 15 strains were identified as Pediococcus pentosaceus, and 5 strains were not identified because of atypical reactions . Analysis of WCPP identified all isolates since each species had a unique WCPP . By the WCPP method, the atypical strains were identified as P . acidilactici (two strains) and P . pentosaceus (three strains) . The chromogenic substrate test with o-nitrophenyl-beta-D-glucopyranoside differentiated all 54 strains of P . acidilactici (negative reactions) and 13 (72%) of 18 strains of P . pentosaceus (positive reactions) . Isolates of both species were shown to be nonclonal as revealed by the genetic diversity when chromosomal DNA was analyzed by PFGE . Using WCPP as the definitive identification procedure, P . acidilactici (28 of 54 strains; 51.8%) was more likely than P . pentosaceus (4 of 18 strains; 22.3%) to be isolated from blood cultures.

Eur J Clin Microbiol Infect Dis, 2000 Dec, 19(12), 946 - 8
A case of septicemia with Pediococcus acidilactici after long-term antibiotic treatment; Heinz M et al.; Presented here is a case of septicemia caused by an uncommon, multiresistant, gram-positive microorganism (Pediococcus acidilactici) after long-term antibiotic treatment . Pediococcus spp . are rarely cultivated from clinical specimens, and species differentiation is difficult due to the paucity of phenotypic traits . In this case, a polyphasic approach consisting of phenotypic and molecular genetic analyses was used, and the identification of Pediococcus acidilactici was conclusive . Precise identification and antimicrobial susceptibility testing of rarely isolated bacteria are required in order to provide adequate treatment to infected patients and to determine the pathogenic role of these organisms.

Biosci Biotechnol Biochem, 2000 Nov, 64(11), 2420 - 8
A novel lantibiotic, nukacin ISK-1, of Staphylococcus warneri ISK-1: cloning of the structural gene and identification of the structure; Sashihara T et al.; Staphylococcus warneri ISK-1, which we had previously reported as Pediococcus sp . ISK-1, produces a novel bacteriocin, nukacin ISK-1 . Edman degradation of the chemically reduced nukacin ISK-1 produced a sequence of 27 amino acids, 7 of which were unidentified . Using single-specific-primer-PCR product as a probe, a 3.6-kb HindIII fragment containing the nukacin ISK-1 structural gene (nukA) was cloned and sequenced . The deduced amino acid sequence of nukacin ISK-1 had 57 amino acids, including a 30-amino acid leader region . The propeptide sequence showed significant similarity to those of lacticin-481 type lantibiotics . In the region upstream of nukA, a part of a long open reading frame (ORF), designated as nukM, encoding a putative modification enzyme was oriented in the opposite direction . In the region downstream of nukA, ORF1 was found in which the sequence of the putative translational product was similar to various response regulatory proteins.

Appl Environ Microbiol, 2001 Feb, 67(2), 553 - 60
Riboprinting and 16S rRNA gene sequencing for identification of brewery Pediococcus isolates; Barney M et al.; A total of 46 brewery and 15 ATCC Pediococcus isolates were ribotyped using a Qualicon RiboPrinter . Of these, 41 isolates were identified as Pediococcus damnosus using EcoRI digestion . Three ATCC reference strains had patterns similar to each other and matched 17 of the brewery isolates . Six other brewing isolates were similar to ATCC 25249 . The other 18 P . damnosus brewery isolates had unique patterns . Of the remaining brewing isolates, one was identified as P . parvulus, two were identified as P . acidilactici, and two were identified as unique Pediococcus species . The use of alternate restriction endonucleases indicated that PstI and PvuII could further differentiate some strains having identical EcoRI profiles . An acid-resistant P . damnosus isolate could be distinguished from non-acid-resistant varieties of the same species using PstI instead of EcoRI . 16S rRNA gene sequence analysis was compared to riboprinting for identifying pediococci . The complete 16S rRNA gene was PCR amplified and sequenced from seven brewery isolates and three ATCC references with distinctive riboprint patterns . The 16S rRNA gene sequences from six different brewery P . damnosus isolates were homologous with a high degree of similarity to the GenBank reference strain but were identical to each other and one ATCC strain with the exception of 1 bp in one strain . A slime-producing, beer spoilage isolate had 16S rRNA gene sequence homology to the P . acidilactici reference strain, in agreement with the riboprint data . Although 16S rRNA gene sequencing correctly identified the genus and species of the test Pediococcus isolates, riboprinting proved to be a better method for subspecies differentiation.

Syst Appl Microbiol, 2000 Oct, 23(3), 400 - 8
Development of molecular RAPD marker for the identification of Pediococcus acidilactici strains; Mora D et al.; A RAPD analysis performed using a single primer targeted to the pediocin AcH/PA-1 gene was carried out on several P . acidilactici strains and on some related species of lactic acid bacteria . The high degree of genetic variability detected in P . acidilactici strains did not allow the selection of a common RAPD fragment that could be chosen as a potential species-specific DNA marker . Nevertheless a 700 bp fragment, that was found to be peculiar of all potential pediocin producer strains analyzed, was cloned and sequenced with the aim to develop a species specific PCR marker . Sequence analysis of the cloned 700 bp fragment showed one putative small open reading frame (ORF1), with no significant homology with known genes, and a partial putative second coding region (ORF2) with a high degree of similarity with several methionyl tRNA synthesis (metS) genes . The two coding regions were separated by a short spacer region . Primers targeted to ORF2 plus part of the spacer region and primers designed for the amplification of the entire cloned RAPD fragment were found to be species-specific for the detection of P . acidilactici strains . Furthermore primers designed on the ORF1 sequence allowed the amplification of a 439 bp fragment only in some P . acidilactici strains, including pediocin producing strains.

Appl Environ Microbiol, 2000 Dec, 66(12), 5213 - 20
Biochemical and genetic characterization of coagulin, a new antilisterial bacteriocin in the pediocin family of bacteriocins, produced by Bacillus coagulans I(4); Le Marrec C et al.; A plasmid-linked antimicrobial peptide, named coagulin, produced by Bacillus coagulans I(4) has recently been reported (B . Hyronimus, C . Le Marrec and M . C . Urdaci, J . Appl . Microbiol . 85:42-50, 1998) . In the present study, the complete, unambiguous primary amino acid sequence of the peptide was obtained by a combination of both N-terminal sequencing of purified peptide and the complete sequence deduced from the structural gene harbored by plasmid I(4) . Data revealed that this peptide of 44 residues has an amino acid sequence similar to that described for pediocins AcH and PA-1, produced by different Pediococcus acidilactici strains and 100% identical . Coagulin and pediocin differed only by a single amino acid at their C terminus . Analysis of the genetic determinants revealed the presence, on the pI(4) DNA, of the entire 3.5-kb operon of four genes described for pediocin AcH and PA-1 production . No extended homology was observed between pSMB74 from P . acidilactici and pI(4) when analyzing the regions upstream and downstream of the operon . An oppositely oriented gene immediately dowstream of the bacteriocin operon specifies a 474-amino-acid protein which shows homology to Mob-Pre (plasmid recombination enzyme) proteins encoded by several small plasmids extracted from gram-positive bacteria . This is the first report of a pediocin-like peptide appearing naturally in a non-lactic acid bacterium genus.

J Food Prot, 2000 Nov, 63(11), 1492 - 5
Stimulation of starter culture for further reduction of foodborne pathogens during salami fermentation; Kang DH et al.; This study was conducted to determine if stimulated meat starter culture (MSC; Pediococcus acidilactici) would further control Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus during salami fermentation . Manganese ion (0.005% of MnSO4) was used as a stimulator for the growth and acid production of MSC . After 24-h salami fermentation, nonstimulated MSC and stimulated MSC reduced E . coli O157:H7 levels by 1.3 and 2.3 log10 units, respectively . Nonstimulated MSC reduced L . monocytogenes levels by 1.2 log10 units, whereas the stimulated MSC achieved a 2.2-log10 reduction after 24-h fermentation . In the case of S . aureus, nonstimulated MSC and stimulated MSC reduced S . aureus levels by 1.3 and 2.3 log10 units after 24-h fermentation, respectively . Stimulated MSC by MnSO4 reduced those foodborne pathogens more effectively compared with nonstimulated MSC (P < 0.05).

J Basic Microbiol, 2000, 40(4), 233 - 41
Analysis of the genetic determinant for production of the pediocin P of Pediococcus pentosaceus Pep1; Osmanagaoglu O et al.; Pediococcus pentosaceus Pep1 is a vacuum-packaged Turkish sausage isolate which produces a potentially novel bacteriocin of the pediocin (anti-Listeria) family of peptides designated as pediocin P . Curing experiments and plasmid profile analysis indicated that both bacteriocin immunity and production determinants were linked and encoded by 9.0 MDa plasmid, pHD1.0 . Attempts to transform purified plasmid pHD1.0 into recipient Escherichia coli JM109 cells by electroporation were successful but none of the E . coli JM109 cells were able to express and/or release pediocin P . However, P . pentosaceus PC, a plasmid-cured variant of P . pentosaceus Pep1 was successfully transformed with pHD1.0 by electroporation and Bac-Bacs P . pentosaceus PC cells restarted to express and/or release pediocin P again as indicated by the presence of zone of growth inhibition of L . plantarum NCDO 955 around colonies.

Microbiology, 2000 Aug, 146 ( Pt 8), 2027 - 38
Genomic subpopulations within the species Pediococcus acidilactici detected by multilocus typing analysis: relationships between pediocin AcH/PA-1 producing and non-producing strains; Mora D et al.; A high degree of genetic polymorphism among P . acidilactici strains was highlighted by a multilocus typing approach analysing several housekeeping genes and by sampling the whole genome using random amplified polymorphic DNA (RAPD) fingerprint analysis performed by using a single primer pedA gene targeted in low-stringency amplification conditions . Restriction fragment length polymorphism of the rpoC, ldhD/L and mle genes, and a modified RAPD analysis, permitted the grouping of Pediococcus acidilactici strains in seven genotypes (I-VII) . Genotypic results obtained by analysing housekeeping genes involved in the transcription/translation machinery and in primary metabolism were supported by phylogenetic analysis based on the partial 16S rDNA sequencing of a reference strain of each of the seven clusters obtained . Three of the seven genotypes detected showed relationships with pediocin AcH/PA-1 production and carbohydrate fermentation patterns: all pediocin-producing and sucrose-positive strains were grouped in genotype VII, melibiose-, sucrose- and raffinose-positive strains in genotype VI, and arabinose-positive strains in genotype V.

Syst Appl Microbiol, 1999 Dec, 22(4), 514 - 9
Induction and characterization of Pediococcus acidilactici temperate bacteriophage
Caldwell SL, McMahon DJ, Oberg CJ, Broadbent JR.
Mitomycin C was used to induce temperate bacteriophage from three strains of Pediococcus acidilactici . The new bacteriophage, designated pa97, pa40, and pa42, were characterized based on morphology, DNA homology, and major protein profiles . Morphological attributes (small isometric heads with non-contractile tails) place these bacteriophages within the B1 group of the family Siphovirdae . Restriction endonuclease digests suggested that the bacteriophage genomes were linear molecules without cohesive ends, and between 33 and 37 kilobases in length . All three bacteriophages possessed one major protein with an estimated mass of 30 to 35 kilodaltons . Bacteriophage pa42 also contained a second major protein of approximately 47 kilodaltons . DNA-DNA hybridization showed bacteriophages pa40 and pa42 were homologous to each other, but not to pa97, suggesting that Pediococcus acidilactici bacteriophage fall into at least two different species.

Int J Food Microbiol, 2000 Apr 10, 55(1-3), 255 - 8
Synergistic lethal combination of nitrite and acid pH on a verotoxin-negative strain of Escherichia coli O157; Casey P et al.; This study was concerned with the possible consequences of reducing the nitrite concentration of a fermented sausage environment on the survival of the pathogen E . coli O157:H45, a verotoxin-negative relative of E . coli O157:H7 . A liquid medium, FM, was constructed with a liquid phase, a(w) and pH similar to fermented sausage . Survival of E . coli O157:H45 in FM depended on both pH and nitrite concentration . In trials in which the pH was decreased by growing Pediococcus acidilactici in FM, survival of E . coli O157:H45 was clearly dependent on nitrite concentration; at least 100 ppm nitrite was required to inhibit growth and the number of survivors after 2 days with 200 ppm nitrite was 1000-fold less than in the absence of nitrite . In laboratory-scale sausage fermented with P . acidilactici, E . coli O157:H45 failed to grow in the absence of nitrite and the numbers slowly declined over 14 days . However, the rate of decline was much faster with nitrite present even at 50 ppm; at 200 ppm nitrite, the E . coli O157:H45 population declined 100 times faster than in the absence of nitrite.

J Basic Microbiol, 2000, 40(1), 41 - 9
Cloning and expression of a plasmid-linked pediocin determinant trait of Pediococcus acidilactici F; Osmanagaoglu O et al.; Plasmid DNA from Pediococcus acidilactici F was prepared by lysozyme-mutanolysin method and purified by cesium chloride-ethidium bromide (CsCl-EtBr) density gradient ultracentrifugation . Agarose gel electrophoresis of plasmid DNA and plasmid-curing experiments suggested that bacteriocin activity was harboured on a small plasmid of approximately 9.1 kb (kilobasepair) in Pediococcus acidilactici F . Plasmid encoding bacteriocin production in P . acidilactici F was examined for restriction enzyme cleavage patterns and its map has been constructed . An Escherichia coli strain transformed with the recombinant plasmid, pQE322, produced and, most probably, secreted pediocin F.

J Appl Microbiol, 2000 Feb, 88(2), 260 - 5
Identification of pediococci by ribotyping; Satokari R et al.; Pediococci are among the most prevalent microbial contaminants in breweries and they can cause ropiness and the accumulation of high levels of diacetyl in beer . The accurate identification of pediococci is important, because different species do not possess equal spoilage potential . In this study, 18 Pediococcus strains, mainly of brewery origin, were first identified using phenotypical characterization (API 50 CHL and SDS-PAGE profiling), and then ribotyped using a RiboPrinterR System . Six Pediococcus type strains and three other Pediococcus strains were used as references . Ribotyping showed higher discriminative capacity than phenotypical identification methods . Strains could be identified to species level and in many cases, differentiated even at strain level using this genetic fingerprinting method . The identifications performed by ribotyping were confirmed by 16S rDNA sequencing of selected strains . Automated ribotyping was found to be a rapid and reliable method for identifying pediococci, but requires the construction of a comprehensive fingerprint library.

Biotechnol Bioeng, 1999, 66(3), 180 - 8
Prolonging cell-free protein synthesis with a novel ATP regeneration system; Kim DM et al.; A new approach for the regeneration of adenosine triphosphate (ATP) during cell-free protein synthesis was developed to prolong the synthesis and also to avoid the accumulation of inorganic phosphate . This approach was demonstrated in a batch system derived from Escherichia coli . Contrary to the conventional methods in which exogenous energy sources contain high-energy phosphate bonds, the new system was designed to generate continuously the required high-energy phosphate bonds within the reaction mixture, thereby recycling the phosphate released during protein synthesis . If allowed to accumulate, phosphate inhibits protein synthesis, most likely by reducing the concentration of free magnesium ion . Pediococcus sp . pyruvate oxidase, when introduced in the reaction mixture along with thiamine pyrophosphate (TPP) and flavin adenine dinucleotide (FAD), catalyzed the generation of acetyl phosphate from pyruvate and inorganic phosphate . Acetyl kinase, already present with sufficient activity in Escherichia coli S30 extract, then catalyzed the regeneration of ATP . Oxygen is required for the generation of acetyl phosphate and the H(2)O(2) produced as a byproduct is sufficiently degraded by endogenous catalase activity . Through the continuous supply of chemical energy, and also through the prevention of inorganic phosphate accumulation, the duration of protein synthesis is extended up to 2 h . Protein accumulation levels also increase . The synthesis of human lymphotoxin receives greater benefit than than that of chloramphenicol acetyl transferase, because the former is more sensitive to phosphate inhibition . Finally, through repeated addition of pyruvate and amino acids during the reaction period, protein synthesis continued for 6 h in the new system, resulting in a final yield of 0.7 mg/mL .

Int J Food Microbiol, 1999 Oct 15, 51(2-3), 105 - 11
Exopolysaccharide-producing lactic acid bacteria strains from traditional Thai fermented foods: isolation, identification and exopolysaccharide characterization; Smitinont T et al.; Lactic Acid Bacteria (LAB) isolated from various traditional Thai fermented foods were screened for exopolysaccharides (EPS) production . From 104 isolates, two rod-shaped and five coccal-shaped LAB were able to produce EPS from sucrose on solid media . However, only the cocci were capable of producing EPS in liquid media and these were identified as Pediococcus pentosaceus . Pediococcus pentosaceus strains AP-1 and AP-3 produced EPS in high yield . In liquid media containing sucrose as carbon source, the amount of EPS produced by AP-1 and AP-3 strains was 6.0 and 2.5 g/L, respectively . The isolated and purified EPSs were chemically characterized . On the basis of sugar composition, methylation analysis and nuclear magnetic resonance spectroscopy, both the EPSs were shown to belong to the same dextran class . In particular, both EPSs differed from linear dextran by branching through 3,6-di-Osubstituted alpha-D-glucopyranosyl residues . The EPS from P . pentosaceus AP-3 was characterized by a relatively higher degree of branching and by a higher molecular weight than that from P . pentosaceus AP-1.

Microbiology, 1999 Oct, 145 ( Pt 10), 2777 - 87
Antibodies to a synthetic 1-9-N-terminal amino acid fragment of mature pediocin PA-1: sensitivity and specificity for pediocin PA-1 and cross-reactivity against Class IIa bacteriocins; Martinez JM et al.; Polyclonal antibodies specific for pediocin PA-1 (PedA1) were generated by immunization of rabbits with a chemically synthesized 1-9-N-terminal amino acid fragment of this bacteriocin (PH1) conjugated to the carrier protein keyhole limpet haemocyanin (KLH) . The PH1 fragment holds a highly conserved amino acid sequence with closely related Class IIa bacteriocins . The sensitivity and specificity of the PH1-KLH-generated rabbit polyclonal antibodies were evaluated by the development of various ELISAs, such as a non-competitive indirect ELISA (NCI-ELISA), a competitive indirect ELISA (CI-ELISA), a competitive direct ELISA (CD-ELISA) and a sandwich ELISA (S-ELISA), and by protein slot-blotting and Western blotting . NCI- and CI-ELISA were valuable for detecting the existence of PedA1-specific antibodies in the sera of immunized rabbits . The limit of detection of PedA1 in MRS medium was found to be 0.5 microg ml(-1) in NCI-ELISA, while CI-ELISA on plates coated with purified PedA1 increased the affinity of the PH1-KLH-generated antibodies for PedA1; the limit of detection of PedA1 was less than 0.01 microg ml(-1) and 50% binding inhibition was achieved with 0.1 microg PedA1 ml(-1) . Similarly, the limits of detection of PedA1 in MRS medium were found to be 5 microg ml(-1) by protein slot-blotting and 0.01 microg ml(-1) by Western blotting . Most importantly, PH1-KLH-generated polyclonal antibodies detected the presence of PedA1 in the supernatants of the producing strains of Pediococcus acidilactici 347, Z102, A172, X13 and P20, with no reactivity or negligible immunoreactivity with the supernatants of other lactic acid bacteria producing or not producing closely related or different bacteriocins . The approaches taken for the selection of the bacteriocin peptide fragment, the generation of antibodies and the development of immunoassays could prove useful for the generation and evaluation of antibodies of adequate specificity for other bacteriocins of interest in the food industry.

Lett Appl Microbiol, 1999 Sep, 29(3), 206 - 10
Reduction of Escherichia coli O157:H7 by stimulated Pediococcus acidilactici; Kang DH et al.; This study was conducted to determine if stimulating the growth of meat starter culture (Pediococcus acidilactici) in a laboratory medium (Brain Heart Infusion broth +2.3% NaCl + 1.5% sucrose; LBHI) and during meat fermentation would control Escherichia coli O157:H7 . In LBHI medium without P . acidilactici, the numbers of E . coli O157:H7 increased from 4.00 to 8.34 log10 cfu ml-1, whereas in the presence of P . acidilactici (approximately 6.0 log10 cfu ml-1) in LBHI, LBHIM (LBHI + 0.005% MnSO4), LBHIO (LBHI + 0.3 unit ml-1 Oxyrase), and LBHIMO (LBHI + M + O), the numbers of E . coli O157:H7 increased from 4.00 to 8.05, 7.50, 7.99, and 6.50 log10 cfu ml-1, respectively, after incubation at 40 degrees C for 15 h . During salami fermentation, the numbers of E . coli O157:H7 changed from 7.00 to 6.40 and 5.10 log10 cfu g-1 without and with P . acidilactici (approximately 7.0 log10 cfu g-1), respectively . Stimulated P . acidilactici by M, O, and MO further reduced the number of E . coli O157:H7 from 7.00 to 4.00, 4.80, and 3.65 log10 cfu g-1, respectively . The combination of MO was a better growth stimulator for P . acidilactici, which controlled E . coli O157:H7 in both systems (P < 0.05).

Can J Microbiol, 1999 Aug, 45(8), 670 - 7
Bacterial surface antigen-specific monoclonal antibodies used to detect beer spoilage pediococci; Whiting MS et al.; Fourteen monoclonal antibodies (Mabs) were isolated that react with surface antigens of Pediococcus beer spoilage organisms, including P . damnosus, P . pentosaceous, P . acidilactici, and unspeciated isolates . Immunoblotting, enzyme immunoassays (EIAs) of protease- and neuraminidase-treated surface antigen extracts, carbohydrate competition EIAs, and cardiolipin EIAs were used to characterize the bacterial antigens involved in Mab binding . Antigen stability in situ was tested by protease treatment or surface antigen extraction of washed bacteria . In most cases, the Mabs bind to Pediococcus surface antigens that appear to be covalently bound cell wall polymers resistant to alteration or removal from the bacterial surface . These bacterial surface antigen reactive Mabs show good potential for rapid, sensitive, and specific immunoassay detection of Pediococcus beer spoilage organisms.

J Food Prot, 1999 Sep, 62(9), 975 - 9
Effect of diacetyl on controlling Escherichia coli O157:H7 and Salmonella Typhimurium in the presence of starter culture in a laboratory medium and during meat fermentation; Kang DH et al.; Diacetyl is a flavor compound that possesses antimicrobial activity and is found in several dairy products . The effect of diacetyl on controlling the growth of two foodborne pathogens, Escherichia coli O157:H7 and Salmonella Typhimurium, when grown with Pediococcus acidilactici as a meat starter culture was evaluated in a laboratory medium and during salami fermentation . Diacetyl (50 ppm) added to each mixed culture system strongly inhibited the growth of E . coli O157:H7 and Salmonella Typhimurium in the laboratory medium (brain heart infusion, 2.3% of NaCl, 0.75% of dextrose) (P < 0.05) . During meat fermentation, the growth of E . coli O157:H7 and Salmonella Typhimurium was inhibited significantly by addition of diacetyl (300 ppm) (P < 0.05) after 24 h fermentation . However, the acid production and growth of P . acidilactici were not affected by the addition of diacetyl (P > 0.05) . After 24 h meat fermentation, about a 1.0-log CFU/g difference occurred in numbers of each foodborne pathogen mixed with P . acidilactici (P < 0.05) with and without 300 ppm diacetyl . Diacetyl and the acid produced by the meat starter culture reduced the growth of the two foodborne pathogens during salami fermentation . These results suggest that diacetyl can be used as a food ingredient during meat fermentation to control E . coli O157:H7 and Salmonella Typhimurium without harmful effects on the growth and acid production of P . acidilactici.

Yeast, 1999 Jun 15, 15(8), 647 - 56
The development of bactericidal yeast strains by expressing the Pediococcus acidilactici pediocin gene (pedA) in Saccharomyces cerevisiae; Schoeman H et al.; The excessive use of sulphur dioxide and other chemical preservatives in wine, beer and other fermented food and beverage products to prevent the growth of unwanted microbes holds various disadvantages for the quality of the end-products and is confronted by mounting consumer resistance . The objective of this study was to investigate the feasibility of controlling spoilage bacteria during yeast-based fermentations by engineering bactericidal strains of Saccharomyces cerevisiae . To test this novel concept, we have successfully expressed a bacteriocin gene in yeast . The pediocin operon of Pediococcus acidilactici PAC1.0 consists of four clustered genes, namely pedA (encoding a 62 amino acid precursor of the PA-1 pediocin), pedB (encoding an immunity factor), pedC (encoding a PA-1 transport protein) and pedD (encoding a protein involved in the transport and processing of PA-1) . The pedA gene was inserted into a yeast expression/secretion cassette and introduced as a multicopy episomal plasmid into a laboratory strain (Y294) of S . cerevisiae . Northern blot analysis confirmed that the pedA structural gene in this construct (ADH1P-MFa1S-pedA-ADH1T, designated PED1), was efficiently expressed under the control of the yeast alcohol dehydrogenase I gene promoter (ADH1P) and terminator (ADH1T) . Secretion of the PED1-encoded pediocin PA-1 was directed by the yeast mating pheromone alpha-factor's secretion signal (MFa1S) . The presence of biologically active antimicrobial peptides produced by the yeast transformants was indicated by agar diffusion assays against sensitive indicator bacteria (e.g . Listeria monocytogenes B73) . Protein analysis indicated the secreted heterologous peptide to be approximately 4.6 kDa, which conforms to the expected size . The heterologous peptide was present at relatively low levels in the yeast supernatant but pediocin activity was readily detected when intact yeast colonies were used in sensitive strain overlays . This study could lead to the development of bactericidal yeast strains where S . cerevisiae starter cultures not only conduct the fermentations in the wine, brewing and baking industries but also act as biological control agents to inhibit the growth of spoilage bacteria.

Appl Environ Microbiol, 1999 Jul, 65(7), 2857 - 62
Changes in membrane fatty acid composition of Pediococcus sp . strain NRRL B-2354 in response to growth conditions and its effect on thermal resistance; Annous BA et al.; Membrane fatty acid composition and thermal resistance (D value) of Pediococcus sp . were determined for mid-exponential-phase (ME) and stationary-phase (ST) cells grown in tryptic soy broth (TSB) and tryptone-glucose-yeast extract (TGY) at 28 and 37 degrees C . As the cells entered the stationary phase of growth, the unsaturated fatty acid, C18:1 n11c, produced during the exponential phase of growth was converted to its cyclic form, C19:0 Delta9c . This shift in membrane fatty acid composition was accompanied by an increase in the D values of this bacterium . Data from this study suggest that the membrane fatty acid composition of Pediococcus sp . is dependent on the growth conditions and that membrane fatty acid composition plays a critical role in thermal resistance . Thermal inactivation curves of Pediococcus sp . cells grown in TGY at 28 degrees C indicated the presence of a cell population that is heterogeneous in thermal resistance . The growth of this bacterium in TGY at 37 degrees C and in TSB at 28 and 37 degrees C resulted in cell populations that were uniform in thermal resistance with a lag time for thermal inactivation . Thermal inactivation curves of ME and ST cultures were similar . The data presented here suggest that the cell population's uniformity of thermal inactivation is independent of the growth phase of the culture.

Lett Appl Microbiol, 1999 Mar, 28(3), 226 - 32
Biopreservation in modified atmosphere stored mungbean sprouts: the use of vegetable-associated bacteriocinogenic lactic acid bacteria to control the growth of Listeria monocytogenes; Bennik MH et al.; Two bacteriocinogenic strains of Pediococcus parvulus and one bacteriocinogenic Enterococcus mundtii strain were evaluated for their potential to control the growth of Listeria monocytogenes on refrigerated, modified atmosphere (MA) stored mungbean sprouts . These three strains, which were isolated from minimally-processed vegetables, were shown to grow in culture broth at 4, 8, 15 and 30 degrees C . However, only Ent . mundtii was capable of bacteriocin production at 4-8 degrees C . Examination of the growth of these strains on agar under 1.5% O2 in combination with 0, 5, 20 or 50% CO2 revealed significantly higher maximum specific growth rates for Ent . mundtii than for Pediococcus parvulus at CO2 concentrations below 20%, which are relevant for MA-storage of vegetables . Enterococcus mundtii was subsequently evaluated for its ability to control the growth of L . monocytogenes on vegetable agar and fresh mungbean sprouts under 1.5% O2/20% CO2/78.5% N2 at 8 degrees C . The growth of L . monocytogenes was inhibited by bacteriocinogenic Ent . mundtii on sterile vegetable-medium but not on fresh produce . However, mundticin, the bacteriocin produced by Ent . mundtii, was found to have potential as a biopreservative agent for MA-stored mungbean sprouts when used in a washing step or a coating procedure.

Am Ind Hyg Assoc J, 1999 Jan-Feb, 60(1), 89 - 95
Airborne microflora in Quebec dairy farms: lack of effect of bacterial hay preservatives; Duchaine C et al.; Pediococcus pentosaceus is a lactic-acid producing bacterium inoculated in hay to prevent hay deterioration . This study sought to verify the effect of this treatment on the barn microenvironment . Air samples were obtained from 19 barns using bacterial hay treatment and from 18 control barns with six-stage Andersen samplers and all-glass impingers . Appropriate culture media were used for the recovery and identification of microorganisms . Endotoxins were measured with chromogenic Limulus amoebocyte lysate assay . Median values (respectively for treated and untreated hay barns) were: 5.28 x 10(5) and 3.84 x 10(5) colony-forming units (CFU)/m3 for total bacteria; 3.18 x 10(6) and 4.5 x 10(6) CFU/m3 for molds; 1.36 x 10(3) and 1.74 x 10(3) endotoxin units/m3 for endotoxin levels; and 1.03 x 10(3) and 3.00 x 10(3) CFU/m3 for Saccharopolyspora rectivirgula . No viable P . pentosaceus were recovered . The presence of S . rectivirgula, the causative agent for farmer's lung, was not influenced by the hay treatment . Since no significant difference was observed in any of the airborne contaminants, this type of hay treatment probably does not protect farmers from the respiratory effect of ambient microbial contaminants.

Appl Environ Microbiol, 1998 Nov, 64(11), 4536 - 45
Generation of polyclonal antibodies of predetermined specificity against pediocin PA-1; Martinez JM et al.; Polyclonal antibodies of predetermined specificity for pediocin PA-1 (pedA1) have been generated by immunization of rabbits with a chemically synthesized C-terminal fragment of this bacteriocin (PH2) conjugated to the carrier protein keyhole limpet hemocyanin (KLH) . The sensitivity and specificity of the PH2-KLH-generated antibodies were evaluated by the development of various enzyme-linked immunosorbent assays (ELISAs)-a noncompetitive indirect ELISA (NCI-ELISA), a competitive indirect ELISA (CI-ELISA), and a competitive direct ELISA (CD-ELISA)-and by immunodotting . All immunoassays indicated the existence of pedA1-specific antibodies with high relative affinities and adequate sensitivities in the sera of immunized animals . The limits of detection of pedA1 in MRS medium (Oxoid Ltd., Basingstoke, United Kingdom) were found to be 2.5 microg/ml by immunodotting and 1 microg/ml in the NCI-ELISA . However, the CI-ELISA enhanced the limit of detection of pedA1 to 0.025 microg/ml, while the amount of free pedA1 required for 50% binding inhibition was 10 microg/ml . Moreover, the CD-ELISA increased the affinity of the PH2-KLH-generated antibodies for pedA1; the limit of detection of pedA1 was less than 0.025 microg/ml, and the 50% binding inhibition value was reduced to 0.5 microg of pedA1/ml . All immunoassays and the slot dot assay detected the presence of pedA1 in the supernatant of the producing strain Pediococcus acidilactici 347, with no reactivity or negligible immunoreactivity with the supernatants of other lactic acid bacteria producing or not producing different bacteriocins . The approaches taken for the generation of antibodies and the development of immunoassays could prove useful for the generation and evaluation of antibodies of predetermined specificity for other bacteriocins of interest in the food industry.

Int J Food Sci Nutr, 1998 Mar, 49(2), 101 - 8
Nutritional quality of lactic fermented bitter gourd and fenugreek leaves; Gupta U et al.; Pediococcus pentosaceus was selected from isolates obtained from the naturally fermenting bitter gourd and fenugreek leaves based on its high titre and broad spectrum of inhibitory activity against spoilage organisms . This strain was then employed for fermentation of bitter gourd and fenugreek which resulted in a more acceptable product having enhanced fat, pyridoxine and ascorbic acid levels . It was of interest to note that vitamin B12 was formed in the fenugreek as a result of the fermentation.

J Food Prot, 1998 May, 61(5), 578 - 81
Influence of growth medium on thermal resistance of Pediococcus sp . NRRL B-2354 (formerly Micrococcus freudenreichii) in liquid foods; Annous BA et al.; Pediococcus sp . is a nonpathogenic heat-resistant spoilage organism that has been used as a test organism in milk pasteurization studies . These characteristics make this bacterium an attractive test organism to study the mode of bacterial thermal inactivation in a food pilot plant . We report here the effect of growth medium on the thermal D value of this organism in skim milk, whole liquid egg, 10% glucose solution, pineapple juice, apple juice, tomato juice, and water at 60 degrees C . Thermal inactivation was done in a submerged coil; D values were calculated from the linear portion of the survival curves by linear regression analysis . The range of D values of stationary-phase cells grown at 28 degrees C in tryptone glucose yeast extract (TGY) or tryptic soy broth (TSB) was 0.14 to 12.05 min in all heating menstrua tested . The TSB-grown cells exhibited the highest thermal resistance with skim milk and 10% glucose solution as the heating menstrua . Survival curves of the TGY-grown cells indicated the presence of a cell population heterogeneous in thermal resistance . The TSB-grown cells exhibited a cell population uniform in thermal resistance and with a lag time for thermal inactivation . When compared to TGY-grown cells, Pediococcus sp . grown in TSB showed a significant (P < 0.05) increase in D values by up to eightfold in all heating menstrua . Results from this study suggested that thermal inactivation of Pediococcus sp . was dependent on the growth medium and on the heating menstruum with respect to both pH and composition.

J Food Prot, 1998 Apr, 61(4), 383 - 9
Survival of Escherichia coli O157:H7 in full- and reduced-fat pepperoni after manufacture of sticks, storage of slices at 4 degrees C or 21 degrees C under air and vacuum, and baking of slices on frozen pizza at 135, 191 and 246 degrees C; Faith NG et al.; Pepperoni batter was prepared with fat contents of about 15, 20, and 32% (wt/wt) and inoculated with a pediococcal starter culture and > or = 2.0 x 10(7) CFU/g of a five-strain inoculum of Escherichia coli O157:H7 . The batter was fermented at 96 degrees F (ca . 36 degrees C and 85% relative humidity (RH) to pH < or = 4.8 and then dried at 55 degrees F (ca . 13 degrees C) and 65% RH to a moisture/protein ratio of < or = 1.6:1 . For storage, slices were packaged under air or vacuum and stored at 39 degrees F (ca . 4 degrees C) and 70 degrees F (ca . 21 degrees C) . For baking, frozen slices were placed on retail frozen cheese pizzas that were subsequently baked at 275 degrees F (ca . 135 degrees C), 375 degrees F (ca . 191 degrees C), or 475 degrees F (ca . 246 degrees C) for 0 to 20 min . Appreciable differences related to fat levels were observed after drying; pathogen numbers decreased by 1.04, 1.31 and 1.62 log10 units in sticks prepared from batter at initial fat levels of 15, 20, and 32%, respectively . During storage, the temperature rather than the atmosphere had the greater effect on pathogen numbers, with similar viability observed among the three fat levels tested . At 70 degrees F (ca . 21 degrees C), compared to original levels, pathogen numbers decreased by > or = 5.56 and > or = 4.53 log10 units within 14 days in slices stored under air and vacuum, respectively, whereas at 39 degrees F (ca . 4 degrees C) numbers decreased by < or = 2.43 log10 CFU/g after 60 days of storage under either atmosphere . Baking, as expected, resulted in greater reductions in pathogen numbers as the temperature and/or time of baking increased . However, it was still possible to recover the pathogen by enrichment after baking frozen slices on frozen pizza at 475 degrees F (ca . 246 degrees C) for 10 min or at 375 degrees F (ca . 191 degrees C) for 15 min . The calculated D values for all three temperatures tested increased as the fat content of the batter increased from 15 to 20 to 32% . The present study confirmed that fermentation and drying were sufficient to reduce levels of E . coli O157:H7 in pepperoni sticks by < 2.0 log10 CFU/g . Storage of slices for at least 14 days at ambient temperature under air resulted in a > 5.5-log10-unit total reduction of the pathogen . Baking slices on frozen pizza for at least 15 min at 475 degrees F (ca . 246 degrees C) or 20 min at 375 degrees F (ca . 191 degrees C) was necessary to reduce pathogen numbers to below detection by both direct plating and enrichment.

J Food Prot, 1998 Apr, 61(4), 377 - 82
Viability of Escherichia coli O157:H7 in salami following conditioning of batter, fermentation and drying of sticks, and storage of slices; Faith NG et al.; The fate of Escherichia coli O157:H7 was monitored in salami during conditioning of batter, fermentation and drying of sticks, and storage of slices . The raw batter (75% pork: 25% beef, wt/wt, fat content about 20%) was inoculated with a pediococcal starter culture (about 10(8) CFU/g) and a five-strain cocktail of E . coli O157:H7 ( > or = 2 x 10(7) CFU/g) and stuffed into 104-mm diameter fibrous casings . After being refrigerated at 4 degrees C or being tempered at 13 degrees C, frozen at -20 degrees C, and thawed at 4 degrees C, or being frozen at -20 degrees C, and thawed at 4 degrees C, the inoculated batter was fermented at 24 degrees C and 90% relative humidity (RH) to pH < or = 4.8, dried at 13 degrees C and 65% RH to a moisture/protein ratio of < or = 1.9:1, and then stored at 4 or 21 degrees C under air or vacuum . For salami sticks sampled immediately after drying, appreciable differences were evident among the various batter-conditioning treatments; pathogen numbers were reduced from original levels by 2.1, 1.6, or 1.1 log10 units when batter was tempered, frozen, and thawed, frozen and thawed, or refrigerated, respectively . Similarly, regardless of storage temperature or atmosphere, within 7 days salami slices cut from sticks prepared from batter that was tempered, frozen, and thawed (2.7- to 4.9-log10-unit reduction) or frozen and thawed (2.3- to 4.8-log10-unit reduction) displayed a greater impact on pathogen numbers than slices cut from sticks prepared from batter that was refrigerated (1.6- to 3.1-log10-unit reduction) . The effects of batter conditioning notwithstanding, a greater reduction in levels of E . coli O157:H7 was observed when slices were stored at 21 degrees C compared to otherwise similar slices stored at 4 degrees C . After storage for 60 days the pathogen was only detected by enrichment in slices stored at 21 degrees C, whereas pathogen levels ranged from 1.4 to 4.5 log10 CFU/g in slices stored at 4 degrees C . Differences related to storage atmosphere were first observed after slices were stored for 21 days . Such differences were more readily demonstrable after 60 and 90 days, with pathogen numbers for treatments that were statistically different ranging from 0.6- to 1.5-log10 units higher on slices stored under vacuum than in air . These data emphasize the need to implement multiple barriers to appreciably reduce numbers of E . coli O157:H7 in salami.

Biochim Biophys Acta, 1998 Apr 29, 1397(2), 137 - 40
Characterization of the region downstream of the pilus biogenesis gene pilC1 in Neisseria gonorrhoeae; Kallstrom H et al.; The nucleotide sequence of a 3 kb region downstream of pilC1 in Neisseria gonorrhoeae MS11 was analyzed . This region contains two open reading frames, ORF1 and ORF2, and several repetitive DNA elements . ORF1 encodes an outer membrane protein that shows homology to orf98 of Pediococcus acidilactici . PCR with primers specific for ORF1 revealed that the gene is present in all gonococcal strains tested . The other open reading frame, ORF2, is highly homologous to the putative integral membrane protein HI1680 of Haemophilus influenzae .

Int J Food Microbiol, 1998 Jan 6, 39(1-2), 79 - 85
Pediocin N5p from Pediococcus pentosaceus: adsorption on bacterial strains; Manca de Nadra MC et al.; Pediocin N5p is a bacteriocin produced by Pediococcus pentosaceus isolated from wine . It is absorbed on both sensitive and resistant Gram-positive and Gram-negative bacteria in non specific (non lethal) sites and higher values, up to 30% are observed in sensitive strains suggesting the presence of particular (lethal) receptors . Cell death without lysis is produced by the action of pediocin on sensitive strains . The cations Mg2+ and Mn2+ increase the pediocin binding by 80 and 100%, respectively . Treatment of sensitive cells with proteolytic enzymes and 1% SDS increases the subsequent binding of bacteriocin by 100 and 25%, respectively . As a lipid moiety of pediocin N5p is critical to its activity, probably a hydrophobic interaction with the peptidic receptor, stabilized by Mn2+ or Mg2+ might be established . Pediocin N5p adsorption is not affected by ethanol and SO2, two factors involved in vinification.

Can J Microbiol, 1998 Feb, 44(2), 109 - 15
Binding of heterocyclic amines by lactic acid bacteria from miso, a fermented Japanese food; Rajendran R et al.; Miso, a widely used Japanese fermented food was analysed for its lactic acid bacterial count on bromocresol purple agar . The binding of eight different foodborne carcinogenic heterocyclic amines to 25 bacterial isolates from miso were investigated . The heterocyclic amines used were 3-amino-1,4-dimethyl{5H}pyrido(4,3-b)indole (Trp-P-1), 3-amino-1-methyl{5H}pyrido(4,3-b)indole (Trp-P-2), 2-amino-6-methyldipyrido(1,2-a:3'2'-d)imidazole (Glu-P-1), 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP), 2-amino-dimethylimidazo(4,5f)quinoline (IQ), 2-amino-3,4-dimethylimidazo(4,5-f) quinoline (MeIQ), 2-amino-3,8-dimethylimidazo(4,5-f)quinoxaline (MeIQx), and 2-amino-3-methyl-9H-pyrido(2,3)indole (MeA alpha C) . The lyophilized cells of all of the isolates exhibited high binding activity towards Trp-P-1, Trp-P-2, MeA alpha C, and PhIP, while Glu-P-1 and IQ were not effectively bound . Of the isolates tested, the strongest and weakest binders were identified as Pediococcus acidilactici 1 and 2, respectively . Lyophilized cell wall fractions, heat-treated cells, and the cytoplasmic contents of P . acidilactici 1 and 2 were analysed for their ability to bind to different mutagens . Pure cell wall and peptidoglycan showed greater binding activity than the bacterial cells . Cytoplasmic content also showed some binding, but it was much less effective . The impact of enzymes (amylase, protease, cellulase, chitinase, muraminase, and peptidase) and acetylation of Trp-P-1 and IQ on the binding action of bacteria and cell wall material were also analysed to understand the possible processes involved in the binding of lactic acid bacteria to carcinogenic heterocyclic amines.

Appl Environ Microbiol, 1998 Jan, 64(1), 14 - 20
Production of active chimeric pediocin AcH in Escherichia coli in the absence of processing and secretion genes from the Pediococcus pap operon; Miller KW et al.; Minimum requirements have been determined for synthesis and secretion of the Pediococcus antimicrobial peptide, pediocin AcH, in Escherichia coli . The functional mature domain of pediocin AcH (Lys+1 to Cys+44) is targeted into the E . coli sec machinery and secreted to the periplasm in active form when fused in frame to the COOH terminus of the secretory protein maltose-binding protein (MBP) . The PapC-PapD specialized secretion machinery is not required for secretion of the MBP-pediocin AcH chimeric protein, indicating that in Pediococcus, PapC and PapD probably are required for recognition and processing of the leader peptide rather than for translocation of the mature pediocin AcH domain across the cytoplasmic membrane . The chimeric protein displays bactericidal activity, suggesting that the NH2 terminus of pediocin AcH does not span the phospholipid bilayer in the membrane-interactive form of the molecule . However, the conserved Lys(+1)-Tyr-Tyr-Gly-Asn-Gly-Val(+7)-sequence at the NH2 terminus is important because deletion of this sequence abolishes activity . The secreted chimeric protein is released into the culture medium when expressed in a periplasmic leaky E . coli host . The MBP fusion-periplasmic leaky expression system should be generally advantageous for production and screening of the activity of bioactive peptides.

Carbohydr Res, 1997 Oct 7, 303(4), 453 - 8
Structural analysis of the exopolysaccharide produced by Pediococcus damnosus 2.6; Duenas-Chasco MT et al.; The exopolysaccharide produced by a ropy strain of Pediococcus damnosus (2.6) in a semi-defined medium was found to be an homopolymer composed of D-glucose . On the basis of monosaccharide and methylation analysis, 1H, 13C, 1D and 2D NMR experiments the polysaccharide was shown to consist of repeating units with the following structure . {sequence: see text}

What Is Molecular Biology?, What Is Nitrification?, What Is Antibiotic?, What Is Staphylococcus Aureus?, What Is Genetics?, e, Microbe, o, Microbes, r, Microorganisms, o, Microbiology, o, Bacteriology, e, Escherichia coli, c, S. cerevisiae, a, Escherichia coli, s, Edwardsiella, n, Escherichia coli, s, Gram negative, e, Cholera, s, Streptococci, i, Antibiotic treatment, o, Pseudomonas aeruginosa, a, Pasteurella, s, Streptococci, s, Bacillus subtilis, r, Escherichia coli, r, Fermentations, i, Escherichia coli, a, Pseudomonas aeruginosa, c, Microorganisms, o, Salmonella, a, Denitrifying, i, Salmonella

Scientific Publications - Work Done by Microbiology Reader Bioscreen C
Agricultural Microbiology Anaerobic Microbiology Antimicrobial Susceptibility Artificial Atmosphere Bioassay of Antibiotics Biofilm Microbiology Bioreactor Technology Biotechnology Cell Biology Clinical Microbiology Environmental Microbiology Experiments with Yeast	Fermentation Food Microbiology Functional Genomics Gene Technology Growth Media Development Growth Rate and Lag Time Industrial Microbiology Medical/Pharmaceutical Field Microbiological Assay Microbiological Research Microbiology of Cosmetics go to a specific theme...	Military Microbiology Molecular Microbiology Mutagenicity and Genotoxicity Oral Microbiology Patents Postantibiotic Studies Soil Microbiology Spore Microbiology Veterinary Microbiology Waste/Wastewater Treatment Water Microbiology Wine Microbiology

� 2005 Transgalactic Ltd (manufacturer of Bioscreen C software) | Privacy Statement | P.O. Box 1393, 00101 Helsinki, Finland, phone: +358 9 85172920, fax: +358 9 8749481, e-mail: microbiology@bionewsonline.com

Last modified: May 25, 2005