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SHV-49, a Novel Inhibitor-Resistant ß-Lactamase in a Clinical Isolate of Klebsiella pneumoniae. Véronique Dubois, 2004.A clinical strain of Klebsiella pneumoniae carried the blaSHV-49 gene, encoding a novel inhibitor-resistant ß-lactamase of pI 7.6, derived from SHV-1 by the single substitution M69I . It also harbored a gene differing from blaSHV-11 by four silent mutations and coding for a penicillinase . Both genes were chromosome located and might represent either a species-specific gene or an acquired resistance gene . High-Level Genotypic Variation and Antibiotic Sensitivity among Escherichia coli O157 Strains Isolated from Two Scottish Beef Cattle Farms. Leila Vali, 2004.Escherichia coli O157:H7 is a human pathogen that is carried and transmitted by cattle . Scotland is known to have one of the highest rates of E . coli O157 human infections in the world . Two hundred ninety-three isolates were obtained from naturally infected cattle and the environment on two farms in the Scottish Highlands . The isolates were typed by pulsed-field gel electrophoresis (PFGE) with XbaI restriction endonuclease enzyme, and 19 different variations in patterns were found . There was considerable genomic diversity within the E . coli O157 population on the two farms . The PFGE pattern of one of the observed subtypes matched exactly with that of a strain obtained from a Scottish patient with hemolytic-uremic syndrome . To examine the stability of an individual E . coli O157 strain, continuous subculturing of a strain was performed 110 times . No variation from the original PFGE pattern was observed . We found three indistinguishable subtypes of E . coli O157 on both study farms, suggesting common sources of infection . We also examined the antibiotic resistance of the isolated strains . Phenotypic studies demonstrated resistance of the strains to sulfamethoxazole (100%), chloramphenicol (3.07%), and at a lower rate, other antibiotics, indicating the preservation of antibiotic sensitivity in a rapidly changing population of E . coli O157 . "Candidatus Endobugula glebosa," a Specific Bacterial Symbiont of the Marine Bryozoan Bugula simplex. Grace E. Lim, 2004.The bryozoans Bugula neritina and Bugula simplex harbor bacteria in the pallial sinuses of their larvae as seen by electron microscopy . In B . neritina, the bacterial symbiont has been characterized as a gamma-proteobacterium, "Candidatus Endobugula sertula." "Candidatus E . sertula" has been implicated as the source of the bryostatins, polyketides that provide chemical defense to the host and are also being tested for use in human cancer treatments . In this study, the bacterial symbiont in B . simplex larvae was identified by 16S rRNA-targeted PCR and sequencing as a gamma-proteobacterium closely related to and forming a monophyletic group with "Candidatus E . sertula." In a fluorescence in situ hybridization, a 16S ribosomal DNA probe specific to the B . simplex symbiont hybridized to long rod-shaped bacteria in the pallial sinus of a B . simplex larva . The taxonomic status "Candidatus Endobugula glebosa" is proposed for the B . simplex larval symbiont . Degenerate polyketide synthase (PKS) primers amplified a gene fragment from B . simplex that closely matched a PKS gene fragment from the bryostatin PKS cluster . PCR surveys show that the symbiont and this PKS gene fragment are consistently and uniquely associated with B . simplex . Bryostatin activity assays and chemical analyses of B . simplex extracts reveal the presence of compounds similar to bryostatins . Taken together, these findings demonstrate a symbiosis in B . simplex that is similar and evolutionarily related to that in B . neritina . Purification, Overproduction, and Partial Characterization of ß-RFAP Synthase, a Key Enzyme in the Methanopterin Biosynthesis Pathway  .Joseph W. Scott, 2002.Methanopterin is a folate analog involved in the C1 metabolism of methanogenic archaea, sulfate-reducing archaea, and methylotrophic bacteria . Although a pathway for methanopterin biosynthesis has been described in methanogens, little is known about the enzymes and genes involved in the biosynthetic pathway . The enzyme ß-ribofuranosylaminobenzene 5'-phosphate synthase (ß-RFAP synthase) catalyzes the first unique step to be identified in the pathway of methanopterin biosynthesis, namely, the condensation of p-aminobenzoic acid with phosphoribosylpyrophosphate to form ß-RFAP, CO2, and inorganic pyrophosphate . The enzyme catalyzing this reaction has not been purified to homogeneity, and the gene encoding ß-RFAP synthase has not yet been identified . In the present work, we report on the purification to homogeneity of ß-RFAP synthase . The enzyme was purified from the methane-producing archaeon Methanosarcina thermophila, and the N-terminal sequence of the protein was used to identify corresponding genes from several archaea, including the methanogen Methanococcus jannaschii and the sulfate-reducing archaeon Archaeoglobus fulgidus . The putative ß-RFAP synthase gene from A . fulgidus was expressed in Escherichia coli, and the enzymatic activity of the recombinant gene product was verified . A BLAST search using the deduced amino acid sequence of the ß-RFAP synthase gene identified homologs in additional archaea and in a gene cluster required for C1 metabolism by the bacterium Methylobacterium extorquens . The identification of a gene encoding a potential ß-RFAP synthase in M . extorquens is the first report of a putative methanopterin biosynthetic gene found in the Bacteria and provides evidence that the pathways of methanopterin biosynthesis in Bacteria and Archaea are similar .
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