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Chthoniobacter flavus gen . nov., sp . nov., the First Pure-Culture Representative of Subdivision Two, Spartobacteria classis nov., of the Phylum Verrucomicrobia. Parveen Sangwan, 2004.The phylum Verrucomicrobia is increasingly recognized as an environmentally significant group of bacteria, particularly in soil habitats . At least six subdivisions of the Verrucomicrobia are resolved by comparative analysis of 16S rRNA genes, mostly obtained directly from environmental samples . To date, only two of these subdivisions (1 and 4) have characterized pure-culture representatives . We have isolated and characterized the first known pure-culture representative of subdivision 2 . Strain Ellin428 is an aerobic heterotrophic bacterium that is able to grow with many of the saccharide components of plant biomass but does not grow with amino acids or organic acids other than pyruvate . Cells are yellow, rod-shaped, nonmotile, and gram-stain negative, and they contain peptidoglycan with direct cross-linkages of the A1  meso-Dpm type . The isolate grows well at 25°C on a variety of standard biological media, including some used in the routine cultivation of bacteria from soil . The pH range for growth is 4.0 to 7.0 . Low levels of menaquinones MK-10 and MK-11 were detected . The major cellular fatty acids are C14:0, a-C15:0, C16:1 7c, and/or 2OH i-C15:0, and C16:0 . The G+C content of the genomic DNA is 61 mol% . We propose a new genus and species, Chthoniobacter flavus gen . nov., sp . nov., with isolate Ellin428 as the type strain, and a new class for the subdivision to which it belongs, Spartobacteria classis nov . Environmental sequences indicate that the class Spartobacteria is largely represented by globally distributed, abundant, and active soil bacteria .
Roles for the Two 1-Butanol Dehydrogenases of Pseudomonas butanovora in Butane and 1-Butanol Metabolism. Alisa S. Vangnai, 2002.Pseudomonas butanovora grown on butane or 1-butanol expresses two 1-butanol dehydrogenases, a quinoprotein (BOH) and a quinohemoprotein (BDH) . BOH exhibited high affinity towards 1-butanol (Km = 1.7 ± 0.2 µM) . BOH also oxidized butyraldehyde and 2-butanol (Km = 369 ± 85 µM and Km = 662 ± 98 µM, respectively) . The mRNA induction profiles of BOH and BDH at three different levels of 1-butanol, a nontoxic level (0.1 mM), a growth-supporting level (2 mM), and a toxic level (40 mM), were similar . When cells were grown in citrate-containing medium in the presence of different levels of 1-butanol, wild-type P . butanovora could tolerate higher levels of 1-butanol than the P . butanovora boh::tet strain and the P . butanovora bdh::kan strain . A model is proposed in which the electrons from 1-butanol oxidation follow a branched electron transport chain . BOH may be coupled to ubiquinone, with the electrons being transported to a cyanide-sensitive terminal oxidase . In contrast, electrons from BDH may be transferred to a terminal oxidase that is less sensitive to cyanide . The former pathway may function primarily in energy generation, while the latter may be more important in the detoxification of 1-butanol . Glutathione S-Transferase Isoenzymes from Streptomyces griseus. Kajari Dhar, 2003.An inducible, cytosolic glutathione S-transferase (GST) was purified from Streptomyces griseus . GST isoenzymes with pI values of 6.8 and 7.9 used standard GST substrates including 1-chloro-2,4-dinitrobenzene . GST had subunit and native Mrs of 24 and 48, respectively, and the N-terminal sequence SMILXYWDIIRGLPAH . Nitrogen-Regulated Hypermutator Strain of Synechococcus sp . for Use in In Vivo Artificial Evolution. Daniel Emlyn-Jones, 2003.Artificially evolved variants of proteins with roles in photosynthesis may be selected most conveniently by using a photosynthetic organism, such as a cyanobacterium, whose growth depends on the function of the target protein . However, the limited transformation efficiency of even the most transformable cyanobacteria wastes much of the diversity of mutant libraries of genes produced in vitro, impairing the coverage of sequence space . This highlights the advantages of an in vivo approach for generating diversity in the selection organism itself . We constructed two different hypermutator strains of Synechococcus sp . strain PCC 7942 by insertionally inactivating or nutritionally repressing the DNA mismatch repair gene, mutS . Inactivation of mutS greatly increases the mutation rate of the cyanobacterium's genes, leading to an up-to-300-fold increase in the frequency of resistance to the antibiotics rifampin and spectinomycin . In order to control the rate of mutation and to limit cellular damage resulting from prolonged hypermutation, we placed the uninterrupted mutS gene in the cyanobacterial chromosome under the transcriptional control of the cyanobacterial nirA promoter, which is repressed in the presence of NH4+ as an N source and derepressed in its absence . By removing or adding this substrate, hypermutation was activated or repressed as required . As expected, hypermutation caused by repression in PnirA-mutS transformants led to an accumulation of spectinomycin resistance mutations during growth .
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