Rex (Encoded by DVU_0916) in Desulfovibrio vulgaris Hildenborough Is a Repressor of Sulfate Adenylyl Transferase and Is Regulated by NADH

Although the enzymes for dissimilatory sulfate reduction by microbes have been studied, the mechanisms for transcriptional regulation of the encoding genes remain unknown. In a number of bacteria the transcriptional regulator Rex has been shown to play a key role as a repressor of genes producing proteins involved in energy conversion. In the model sulfate-reducing microbeDesulfovibrio vulgarisHildenborough, the gene DVU_0916 was observed to resemble other known Rex proteins. Therefore, the DVU_0916 protein has been predicted to be a transcriptional repressor of genes encoding proteins that function in the process of sulfate reduction inD. vulgarisHildenborough. Examination of the deduced DVU_0916 protein identified two domains, one a winged helix DNA-binding domain common for transcription factors, and the other a Rossman fold that could potentially interact with pyridine nucleotides. A deletion of the putativerexgene was made inD. vulgarisHildenborough, and transcript expression studies ofsat, encoding sulfate adenylyl transferase, showed increased levels in theD. vulgarisHildenborough Rex (RexDvH) mutant relative to the parental strain. The RexDvH-binding site upstream ofsatwas identified, confirming RexDvHto be a repressor ofsat. We establishedin vitrothat the presence of elevated NADH disrupted the interaction between RexDvHand DNA. Examination of the 5′ transcriptional start site for thesatmRNA revealed two unique start sites, one for respiring cells that correlated with the RexDvH-binding site and a second for fermenting cells. Collectively, these data support the role of RexDvHas a transcription repressor forsatthat senses the redox status of the cell.

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Pseudodesulfovibrio cashew sp. Nov., a Novel Deep-Sea Sulfate-Reducing Bacterium, Linking Heavy Metal Resistance and Sulfur Cycle

Microorganisms ◽

10.3390/microorganisms9020429 ◽

2021 ◽

Vol 9 (2) ◽

pp. 429

Author(s):

Rikuan Zheng ◽

Shimei Wu ◽

Chaomin Sun

Keyword(s):

Heavy Metal ◽

Sulfate Reduction ◽

Marine Sediments ◽

Deep Sea ◽

Sulfur Cycle ◽

Metal Sulfides ◽

Phenotypic Traits ◽

Dissimilatory Sulfate Reduction ◽

Metabolic Potential ◽

Sulfate Reducing

Sulfur cycling is primarily driven by sulfate reduction mediated by sulfate-reducing bacteria (SRB) in marine sediments. The dissimilatory sulfate reduction drives the production of enormous quantities of reduced sulfide and thereby the formation of highly insoluble metal sulfides in marine sediments. Here, a novel sulfate-reducing bacterium designated Pseudodesulfovibrio cashew SRB007 was isolated and purified from the deep-sea cold seep and proposed to represent a novel species in the genus of Pseudodesulfovibrio. A detailed description of the phenotypic traits, phylogenetic status and central metabolisms of strain SRB007 allowed the reconstruction of the metabolic potential and lifestyle of a novel member of deep-sea SRB. Notably, P. cashew SRB007 showed a strong ability to resist and remove different heavy metal ions including Co2+, Ni2+, Cd2+ and Hg2+. The dissimilatory sulfate reduction was demonstrated to contribute to the prominent removal capability of P. cashew SRB007 against different heavy metals via the formation of insoluble metal sulfides.

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Basal Body Structures Differentially Affect Transcription of RpoN- and FliA-Dependent Flagellar Genes in Helicobacter pylori

Journal of Bacteriology ◽

10.1128/jb.02533-14 ◽

2015 ◽

Vol 197 (11) ◽

pp. 1921-1930 ◽

Cited By ~ 5

Author(s):

Jennifer Tsang ◽

Timothy R. Hoover

Keyword(s):

Helicobacter Pylori ◽

Basal Body ◽

Protein Interactions ◽

Transcript Levels ◽

Content Type ◽

Genes Encoding ◽

H Pylori ◽

Flagellar Biogenesis ◽

Flagellar Genes

ABSTRACTFlagellar biogenesis inHelicobacter pyloriis regulated by a transcriptional hierarchy governed by three sigma factors, RpoD (σ80), RpoN (σ54), and FliA (σ28), that temporally coordinates gene expression with the assembly of the flagellum. Previous studies showed that loss of flagellar protein export apparatus components inhibits transcription of flagellar genes. The FlgS/FlgR two-component system activates transcription of RpoN-dependent genes though an unknown mechanism. To understand better the extent to which flagellar gene regulation is coupled to flagellar assembly, we disrupted flagellar biogenesis at various points and determined how these mutations affected transcription of RpoN-dependent (flaBandflgE) and FliA-dependent (flaA) genes. The MS ring (encoded byfliF) is one of the earliest flagellar structures assembled. Deletion offliFresulted in the elimination of RpoN-dependent transcripts and an ∼4-fold decrease inflaAtranscript levels. FliH is a cytoplasmic protein that functions with the C ring protein FliN to shuttle substrates to the export apparatus. Deletions offliHand genes encoding C ring components (fliMandfliY) decreased transcript levels offlaBandflgEbut had little or no effect on transcript levels offlaA. Transcript levels offlaBandflgEwere elevated in mutants where genes encoding rod proteins (fliEandflgBC) were deleted, while transcript levels offlaAwas reduced ∼2-fold in both mutants. We propose that FlgS responds to an assembly checkpoint associated with the export apparatus and that FliH and one or more C ring component assist FlgS in engaging this flagellar structure.IMPORTANCEThe mechanisms used by bacteria to couple transcription of flagellar genes with assembly of the flagellum are poorly understood. The results from this study identified components of theH. pyloriflagellar basal body that either positively or negatively affect expression of RpoN-dependent flagellar genes. Some of these basal body proteins may interact directly with regulatory proteins that control transcription of theH. pyloriRpoN regulon, a hypothesis that can be tested by examining protein-protein interactionsin vitro.

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UHF-1, a factor required for maximal transcription of early and late sea urchin histone H4 genes: analysis of promoter-binding sites

Molecular and Cellular Biology ◽

10.1128/mcb.11.2.1048-1061.1991 ◽

1991 ◽

Vol 11 (2) ◽

pp. 1048-1061

Author(s):

I J Lee ◽

L Tung ◽

D A Bumcrot ◽

E S Weinberg

Keyword(s):

Binding Site ◽

Sea Urchin ◽

Transcriptional Start Site ◽

Sodium Dodecyl ◽

Nuclear Extract ◽

Dnase I ◽

Histone H4 ◽

Band Shift

A protein, denoted UHF-1, was found to bind upstream of the transcriptional start site of both the early and late H4 (EH4 and LH4) histone genes of the sea urchin Strongylocentrotus purpuratus. A nuclear extract from hatching blastulae contained proteins that bind to EH4 and LH4 promoter fragments in a band shift assay and produced sharp DNase I footprints upstream of the EH4 gene (from -133 to -106) and the LH4 gene (from -94 to -66). DNase I footprinting performed in the presence of EH4 and LH4 promoter competitor DNAs indicated that UHF-1 binds more strongly to the EH4 site. A sequence match of 11 of 13 nucleotides was found within the two footprinted regions: [sequence: see text]. Methylation interference and footprinting experiments showed that UHF-1 bound to the two sites somewhat differently. DNA-protein UV cross-linking studies indicated that UHF-1 has an electrophoretic mobility on sodium dodecyl sulfate-acrylamide gels of approximately 85 kDa and suggested that additional proteins, specific to each promoter, bind to each site. In vitro and in vivo assays were used to demonstrate that the UHF-1-binding site is essential for maximal transcription of the H4 genes. Deletion of the EH4 footprinted region resulted in a 3-fold decrease in transcription in a nuclear extract and a 2.6-fold decrease in expression in morulae from templates that had been injected into eggs. In the latter case, deletion of the binding site did not grossly disrupt the temporal program of expression from the injected EH4 genes. LH4 templates containing a 10-bp deletion in the consensus region or base substitutions in the footprinted region were transcribed at 14 to 58% of the level of the wild-type LH4 template. UHF-1 is therefore essential for maximal expression of the early and late H4 genes.

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Antimicrobial Activity of Ceftazidime-Avibactam Tested against Multidrug-Resistant Enterobacteriaceae and Pseudomonas aeruginosa Isolates from U.S. Medical Centers, 2013 to 2016

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01045-17 ◽

2017 ◽

Vol 61 (11) ◽

Cited By ~ 52

Author(s):

Helio S. Sader ◽

Mariana Castanheira ◽

Dee Shortridge ◽

Rodrigo E. Mendes ◽

Robert K. Flamm

Keyword(s):

Pseudomonas Aeruginosa ◽

Multidrug Resistant ◽

Drug Resistant ◽

Large Collection ◽

Content Type ◽

Negative Results ◽

Medical Centers ◽

Extensively Drug Resistant ◽

Genes Encoding

ABSTRACT The in vitro activity of ceftazidime-avibactam and many comparator agents was determined against various resistant subsets of organisms selected among 36,380 Enterobacteriaceae and 7,868 Pseudomonas aeruginosa isolates. The isolates were consecutively collected from 94 U.S. hospitals, and all isolates were tested for susceptibility by reference broth microdilution methods in a central monitoring laboratory (JMI Laboratories). Enterobacteriaceae isolates resistant to carbapenems (CRE) and/or ceftazidime-avibactam (MIC ≥ 16 μg/ml) were evaluated for the presence of genes encoding extended-spectrum β-lactamases and carbapenemases. Ceftazidime-avibactam inhibited >99.9% of all Enterobacteriaceae at the susceptible breakpoint of ≤8 μg/ml and was active against multidrug-resistant (MDR; n = 2,953; MIC50/90, 0.25/1 μg/ml; 99.2% susceptible), extensively drug-resistant (XDR; n = 448; MIC50/90, 0.5/2 μg/ml; 97.8% susceptible), and CRE (n = 513; MIC50/90, 0.5/2 μg/ml; 97.5% susceptible) isolates. Only 82.2% of MDR Enterobacteriaceae (n = 2,953) and 64.2% of ceftriaxone-nonsusceptible Klebsiella pneumoniae (n = 1,063) isolates were meropenem susceptible. Among Enterobacter cloacae (22.2% ceftazidime nonsusceptible), 99.8% of the isolates, including 99.3% of the ceftazidime-nonsusceptible isolates, were ceftazidime-avibactam susceptible. Only 23 of 36,380 Enterobacteriaceae (0.06%) isolates were ceftazidime-avibactam nonsusceptible, including 9 metallo-β-lactamase producers and 2 KPC-producing strains with porin alteration; the remaining 12 strains showed negative results for all β-lactamases tested. Ceftazidime-avibactam showed potent activity against P. aeruginosa (MIC50/90, 2/4 μg/ml; 97.1% susceptible), including MDR (MIC50/90, 4/16 μg/ml; 86.5% susceptible) isolates, and inhibited 71.8% of isolates nonsusceptible to meropenem, piperacillin-tazobactam, and ceftazidime (n = 628). In summary, ceftazidime-avibactam demonstrated potent activity against a large collection (n = 44,248) of contemporary Gram-negative bacilli isolated from U.S. patients, including organisms resistant to most currently available agents, such as CRE and meropenem-nonsusceptible P. aeruginosa.

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Binding Site Determinants for the LysR-Type Transcriptional Regulator PcaQ in the Legume Endosymbiont Sinorhizobium meliloti

Journal of Bacteriology ◽

10.1128/jb.01456-07 ◽

2007 ◽

Vol 190 (4) ◽

pp. 1237-1246 ◽

Cited By ~ 15

Author(s):

Allyson M. MacLean ◽

Michelle I. Anstey ◽

Turlough M. Finan

Keyword(s):

Binding Site ◽

Sinorhizobium Meliloti ◽

Rhizobium Leguminosarum ◽

Transcriptional Start Site ◽

Mesorhizobium Loti ◽

Equilibrium Dissociation ◽

Dyad Symmetry

ABSTRACT LysR-type transcriptional regulators represent one of the largest groups of prokaryotic regulators described to date. In the gram-negative legume endosymbiont Sinorhizobium meliloti, enzymes involved in the protocatechuate branch of the β-ketoadipate pathway are encoded within the pcaDCHGB operon, which is subject to regulation by the LysR-type protein PcaQ. In this work, purified PcaQ was shown to bind strongly (equilibrium dissociation constant, 0.54 nM) to a region at positions −78 to −45 upstream of the pcaD transcriptional start site. Within this region, we defined a PcaQ binding site with dyad symmetry that is required for regulation of pcaD expression in vivo and for binding of PcaQ in vitro. We also demonstrated that PcaQ participates in negative autoregulation by monitoring expression of pcaQ via a transcriptional fusion to lacZ. Although pcaQ homologues are present in many α-proteobacteria, this work describes the first reported purification of this regulator, as well as characterization of its binding site, which is conserved in Agrobacterium tumefaciens, Rhizobium leguminosarum, Rhizobium etli, and Mesorhizobium loti.

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Evaluation of Physiological Parameters of Intestinal Sulfate-Reducing Bacteria Isolated from Patients Suffering from IBD and Healthy People

Journal of Clinical Medicine ◽

10.3390/jcm9061920 ◽

2020 ◽

Vol 9 (6) ◽

pp. 1920 ◽

Cited By ~ 2

Author(s):

Ivan Kushkevych ◽

Jorge Castro Sangrador ◽

Dani Dordević ◽

Monika Rozehnalová ◽

Martin Černý ◽

...

Keyword(s):

Sulfate Reduction ◽

Biomass Accumulation ◽

Sulfate Reducing Bacteria ◽

Dissimilatory Sulfate Reduction ◽

Healthy Individuals ◽

Fecal Samples ◽

Sulfate Reducing ◽

Cell Extracts ◽

Production Of Hydrogen ◽

Reducing Bacteria

Background: Inflammatory bowel diseases (IBDs) are multifactorial illnesses of the intestine, to which microorganisms are contributing. Among the contributing microorganisms, sulfate-reducing bacteria (SRB) are suggested to be involved in the process of bowel inflammation due to the production of hydrogen sulfide (H2S) by dissimilatory sulfate reduction. The aims of our research were to physiologically examine SRB in fecal samples of patients with IBD and a control group, their identification, the study of the process of dissimilatory sulfate reduction (sulfate consumption and H2S production) and biomass accumulation. Determination of biogenic elements of the SRB and evaluation of obtained parameters by using statistical methods were also included in the research. The material for the research consisted of 14 fecal samples, which was obtained from patients and control subjects. Methods: Microscopic techniques, microbiological, biochemical, biophysical methods and statistical analysis were included. Results: Colonies of SRB were isolated from all the fecal samples, and subsequently, 35 strains were obtained. Vibrio-shaped cells stained Gram-negative were dominant in all purified studied strains. All strains had a high percentage of similarity by the 16S rRNA gene with deposited sequences in GenBank of Desulfovibrio vulgaris. Cluster analysis of sulfate reduction parameters allowed the grouping of SRB strains. Significant (p < 0.05) differences were not observed between healthy individuals and patients with IBD with regard to sulfate reduction parameters (sulfate consumption, H2S and biomass accumulation). Moreover, we found that manganese and iron contents in the cell extracts are higher among healthy individuals in comparison to unhealthy individuals that have an intestinal bowel disease, especially ulcerative colitis. Conclusions: The observations obtained from studying SRB emphasize differences in the intestinal microbial processes of healthy and unhealthy people.

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Multiyear, Multinational Survey of the Incidence and Global Distribution of Metallo-β-Lactamase-Producing Enterobacteriaceae and Pseudomonas aeruginosa

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02379-15 ◽

2015 ◽

Vol 60 (2) ◽

pp. 1067-1078 ◽

Cited By ~ 85

Author(s):

Krystyna M. Kazmierczak ◽

Sharon Rabine ◽

Meredith Hackel ◽

Robert E. McLaughlin ◽

Douglas J. Biedenbach ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Surveillance Study ◽

Citrobacter Freundii ◽

Effective Agent ◽

Gram Negative ◽

Content Type ◽

Species Numbers ◽

Medical Centers ◽

Genes Encoding

ABSTRACTMetallo-β-lactamases (MBLs) hydrolyze all classes of β-lactams except monobactams and are not inhibited by classic serine β-lactamase inhibitors. Gram-negative pathogens isolated from patient infections were collected from 202 medical centers in 40 countries as part of a global surveillance study from 2012 to 2014. Carbapenem-nonsusceptibleEnterobacteriaceaeandPseudomonas aeruginosawere characterized forblagenes encoding VIM, IMP, NDM, SPM, and GIM variants using PCR and sequencing. A total of 471 MBL-positive isolates included the following species (numbers of isolates are in parentheses):P. aeruginosa(308),Klebsiellaspp. (85),Enterobacterspp. (39),Proteeae(16),Citrobacter freundii(12),Escherichia coli(6), andSerratia marcescens(5) and were submitted by sites from 34 countries. Of these, 69.6% were collected in 9 countries (numbers of isolates are in parentheses): Russia (72), Greece (61), Philippines (54), Venezuela (29), and Kuwait, Nigeria, Romania, South Africa, and Thailand (20 to 25 isolates each). Thirty-two different MBL variants were detected (14 VIM, 14 IMP, and 4 NDM enzymes). Seven novel MBL variants were encountered in the study, each differing from a previously reported variant by one amino acid substitution: VIM-42 (VIM-1 [V223I]), VIM-43 (VIM-4 [A24V]), VIM-44 (VIM-2 [K257N]), VIM-45 (VIM-2 [T35I]), IMP-48 (IMP-14 [I69T]), IMP-49 (IMP-18 [V49F]), and NDM-16 (NDM-1 [R264H]). Thein vitroactivities of all tested antibiotics against MBL-positiveEnterobacteriaceaewere significantly reduced with the exception of that of aztreonam-avibactam (MIC90, 0.5 to 1 μg/ml), whereas colistin was the most effective agent against MBL-positiveP. aeruginosaisolates (>97% susceptible). Although the global percentage of isolates encoding MBLs remains relatively low, their detection in 12 species, 34 countries, and all regions participating in this surveillance study is concerning.

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In VitroStudies Indicate a High Resistance Potential for the Lantibiotic Nisin in Staphylococcus aureus and Define a Genetic Basis for Nisin Resistance

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01077-10 ◽

2011 ◽

Vol 55 (5) ◽

pp. 2362-2368 ◽

Cited By ~ 49

Author(s):

Katy L. Blake ◽

Chris P. Randall ◽

Alex J. O'Neill

Keyword(s):

Staphylococcus Aureus ◽

Bacterial Infections ◽

Fold Increase ◽

Peptide Antibiotics ◽

Uncharacterized Protein ◽

Content Type ◽

Development Of Resistance ◽

Genes Encoding ◽

Bacterial Fitness

ABSTRACTLantibiotics such as nisin (NIS) are peptide antibiotics that may have a role in the chemotherapy of bacterial infections. A perceived benefit of lantibiotics for clinical use is their low propensity to select resistance, although detailed resistance studies with relevant bacterial pathogens are lacking. Here we examined the development of resistance to NIS inStaphylococcus aureus, establishing that mutants, including small-colony variants, exhibiting substantial (4- to 32-fold) reductions in NIS susceptibility could be selected readily. Comparative genome sequencing of a single NISrmutant exhibiting a 32-fold increase in NIS MIC revealed the presence of only two mutations, leading to the substitutions V229G in the purine operon repressor, PurR, and A208E in an uncharacterized protein encoded by SAOUHSC_02955. Independently selected NISrmutants also harbored mutations in the genes encoding these products. Reintroduction of these mutations into theS. aureuschromosome alone and in combination revealed that SAOUHSC_02955(A208E) made the primary contribution to the resistance phenotype, conferring up to a 16-fold decrease in NIS susceptibility. Bioinformatic analyses suggested that this gene encodes a sensor histidine kinase, leading us to designate it “nisin susceptibility-associated sensor (nsaS).” Doubling-time determinations and mixed-culture competition assays between NISrand NISsstrains indicated that NIS resistance had little impact on bacterial fitness, and resistance was stable in the absence of selection. The apparent ease with whichS. aureuscan develop and maintain NIS resistancein vitrosuggests that resistance to NIS and other lantibiotics with similar modes of action would arise in the clinic if these agents are employed as chemotherapeutic drugs.

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Small-Molecule Inhibition of Choline Catabolism in Pseudomonas aeruginosa and Other Aerobic Choline-Catabolizing Bacteria

Applied and Environmental Microbiology ◽

10.1128/aem.00504-11 ◽

2011 ◽

Vol 77 (13) ◽

pp. 4383-4389 ◽

Cited By ~ 12

Author(s):

Liam F. Fitzsimmons ◽

Stevenson Flemer ◽

A. Sandy Wurthmann ◽

P. Bruce Deker ◽

Indra Neil Sarkar ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Burkholderia Cepacia ◽

Sinorhizobium Meliloti ◽

Growth Inhibitor ◽

Bioinformatic Analysis ◽

Content Type ◽

Genes Encoding ◽

Dependent Growth

ABSTRACTCholine is abundant in association with eukaryotes and plays roles in osmoprotection, thermoprotection, and membrane biosynthesis in many bacteria. Aerobic catabolism of choline is widespread among soil proteobacteria, particularly those associated with eukaryotes. Catabolism of choline as a carbon, nitrogen, and/or energy source may play important roles in association with eukaryotes, including pathogenesis, symbioses, and nutrient cycling. We sought to generate choline analogues to study bacterial choline catabolismin vitroandin situ. Here we report the characterization of a choline analogue, propargylcholine, which inhibits choline catabolism at the level of Dgc enzyme-catalyzed dimethylglycine demethylation inPseudomonas aeruginosa. We used genetic analyses and13C nuclear magnetic resonance to demonstrate that propargylcholine is catabolized to its inhibitory form, propargylmethylglycine. Chemically synthesized propargylmethylglycine was also an inhibitor of growth on choline. Bioinformatic analysis suggests that there are genes encoding DgcA homologues in a variety of proteobacteria. We examined the broader utility of propargylcholine and propargylmethylglycine by assessing growth of other members of the proteobacteria that are known to grow on choline and possess putative DgcA homologues. Propargylcholine showed utility as a growth inhibitor inP. aeruginosabut did not inhibit growth in other proteobacteria tested. In contrast, propargylmethylglycine was able to inhibit choline-dependent growth in all tested proteobacteria, includingPseudomonas mendocina,Pseudomonas fluorescens,Pseudomonas putida,Burkholderia cepacia,Burkholderia ambifaria, andSinorhizobium meliloti. We predict that chemical inhibitors of choline catabolism will be useful for studying this pathway in clinical and environmental isolates and could be a useful tool to study proteobacterial choline catabolismin situ.

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Identification of the genes for hydrogenase and cytochrome c3 in Desulfovibrio

Canadian Journal of Microbiology ◽

10.1139/m87-177 ◽

1987 ◽

Vol 33 (11) ◽

pp. 1006-1010 ◽

Cited By ~ 10

Author(s):

Gerrit Voordouw ◽

Helen M. Kent ◽

John R. Postgate

Keyword(s):

Cytochrome C ◽

Sequence Divergence ◽

Desulfovibrio Vulgaris ◽

Gene Probe ◽

Cytochrome C3 ◽

Sulfate Reducing ◽

Genes Encoding ◽

Reducing Bacteria ◽

Cryptic Plasmids ◽

Amino Acid Sequence Divergence

Cloned genes encoding cytochrome c3 and hydrogenase from Desulfovibrio vulgaris Hildenborough have been used to probe the genomes of 15 other desulfovibrios. The D. vulgaris strains Wandle and Brockhurst Hill cannot be distinguished from the Hildenborough strain by Southern hybridization using either probe, indicating similar genomes. Desulfovibrio vulgaris Groningen is completely different and lacks homologous cytochrome c3 and hydrogenase genes. The genomes of D. vulgaris ssp. oxamicus Monticello and D. desulfuricans strains El Agheila Z, Berre sol, and Canet 41 contain genes encoding a homologous but not identical periplasmic hydrogenase and cytochrome c3. Weak hybridization was observed with the cytochrome c3 gene probe for genomes of seven other sulfate-reducing bacteria, which reflects the known amino acid sequence divergence of cytochrome c3 in Desulfovibrio. The hydrogenase gene probe shows weak hybridization to the DNA from two strains of D. salexigens only, while the gene may be absent from D. vulgaris Groningen, two strains of D. africanus, D. thermophilus, D. gigas, and D. desulfuricans strains Norway and Teddington R. In desulfovibrios carrying cryptic plasmids the cytochrome c3 and hydrogenase genes are apparently chromosomal.

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