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Relationship between Triclosan and Susceptibilities of Bacteria Isolated from Hands in the Community. Allison E. Aiello, 2004.The possible association between triclosan and bacterial susceptibility to antibiotic was examined among staphylococci and several species of gram-negative bacteria (GNB) isolated from the hands of individuals in a community setting . Hand cultures from individuals randomized to using either antibacterial cleaning and hygiene products (including a hand soap containing 0.2% triclosan) or nonantibacterial cleaning and hygiene products for a 1-year period were taken at baseline and at the end of the year . Although there was no statistically significant association between triclosan MICs and susceptibility to antibiotic, there was an increasing trend in the association the odds ratios (ORs) for all species were compared at baseline (OR = 0.65, 95% confidence interval [95%CI] = 0.33 to 1.27) versus at the end of the year (OR = 1.08, 95%CI = 0.62 to 1.97) and for GNB alone at baseline(OR = 0.66, 95%CI = 0.29 to 1.51) versus the end of year (OR = 2.69, 95%CI = 0.78 to 9.23) regardless of the hand-washing product used . Moreover, triclosan MICs were higher in some of the species compared to earlier reports on household, clinical, and industrial isolates, and some of these isolates had triclosan MICs in the range of concentrations used in consumer products . The absence of a statistically significant association between elevated triclosan MICs and reduced antibiotic susceptibility may indicate that such a correlation does not exist or that it is relatively small among the isolates that were studied . Still, a relationship may emerge after longer-term or higher-dose exposure of bacteria to triclosan in the community setting . Impact of Heterologous Expression of Escherichia coli UDP-Glucose Pyrophosphorylase on Trehalose and Glycogen Synthesis in Corynebacterium glutamicum. Leandro Padilla, 2004.Trehalose is a disaccharide with a wide range of applications in the food industry . We recently proposed a strategy for trehalose production based on improved strains of the gram-positive bacterium Corynebacterium glutamicum . This microorganism synthesizes trehalose through two major pathways, OtsBA and TreYZ, by using UDP-glucose and ADP-glucose, respectively, as the glucosyl donors . In this paper we describe improvement of the UDP-glucose supply through heterologous expression in C . glutamicum of the UDP-glucose pyrophosphorylase gene from Escherichia coli, either expressed alone or coexpressed with the E . coli ots genes (galU otsBA synthetic operon) . The impact of such expression on trehalose accumulation and excretion, glycogen accumulation, and the growth pattern of new recombinant strains is described . Expression of the galU otsBA synthetic operon resulted in a sixfold increase in the accumulated and excreted trehalose relative to that in a wild-type strain . Surprisingly, single expression of galU also resulted in an increase in the accumulated trehalose . This increase in trehalose synthesis was abolished upon deletion of the TreYZ pathway . These results proved that UDP-glucose has an important role not only in the OtsBA pathway but also in the TreYZ pathway . The stm4066 Gene Product of Salmonella enterica Serovar Typhimurium Has Aminoimidazole Riboside (AIRs) Kinase Activity and Allows AIRs To Satisfy the Thiamine Requirement of pur Mutant Strains. Michael Dougherty, 2003.In bacteria the biosynthetic pathways for purine mononucleotides and the hydroxymethyl pyrimidine moiety of thiamine share five reactions that result in the formation of aminoimidazole ribotide, the last metabolite common to both pathways . Here we describe the characterization of a Salmonella enterica mutant strain that has gained the ability to efficiently use exogenous aminoimidazole riboside (AIRs) as a source of thiamine . The lesion responsible for this phenotype is a null mutation in a transcriptional regulator of the GntR family (encoded by stm4068) . Lack of this protein derepressed transcription of an associated operon (stm4065-4067) that encoded a predicted kinase . The stm4066 gene product was purified and shown to have AIRs kinase activity in vitro . This activity was consistent with the model presented to explain the phenotype caused by the original mutation . This mutation provides a genetic means to isolate the synthesis of the hydroxymethyl pyrimidine moiety of thiamine from the pathway for purine mononucleotide biosynthesis and thus facilitate in vivo analyses . The Metabolic Pathway of 4-Aminophenol in Burkholderia sp . Strain AK-5 Differs from That of Aniline and Aniline with C-4 Substituents. Shinji Takenaka, 2003.Burkholderia sp . strain AK-5 utilized 4-aminophenol as the sole carbon, nitrogen, and energy source . A pathway for the metabolism of 4-aminophenol in strain AK-5 was proposed based on the identification of three key metabolites by gas chromatography-mass spectrometry analysis . Strain AK-5 converted 4-aminophenol to 1,2,4-trihydroxybenzene via 1,4-benzenediol . 1,2,4-Trihydroxybenzene 1,2-dioxygenase cleaved the benzene ring of 1,2,4-trihydroxybenzene to form maleylacetic acid . The enzyme showed a high dioxygenase activity only for 1,2,4-trihydroxybenzene, with Km and Vmax values of 9.6 µM and 6.8 µmol min-1 mg of protein-1, respectively .
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