Genomic and physiological characterization of the chromate-reducing, aquifer-derived Firmicute Pelosinus sp. strain HCF1.
Pelosinus spp. are fermentative firmicutes that were recently reported to be prominent members of microbial communities at contaminated subsurface sites in multiple locations. Here we report metabolic characteristics and their putative genetic basis in Pelosinus sp. strain HCF1, an isolate that predominated anaerobic, Cr(VI)-reducing columns constructed with aquifer sediment. Strain HCF1 ferments lactate to propionate and acetate (the methylmalonyl-coenzyme A [CoA] pathway was identified in the genome), and its genome encodes two [NiFe]- and four [FeFe]-hydrogenases for H(2) cycling. The reduction of Cr(VI) and Fe(III) may be catalyzed by a flavoprotein with 42 to 51% sequence identity to both ChrR and FerB. This bacterium has unexpected capabilities and gene content associated with reduction of nitrogen oxides, including dissimilatory reduction of nitrate to ammonium (two copies of NrfH and NrfA were identified along with NarGHI) and a nitric oxide reductase (NorCB). In this strain, either H(2) or lactate can act as a sole electron donor for nitrate, Cr(VI), and Fe(III) reduction. Transcriptional studies demonstrated differential expression of hydrogenases and nitrate and nitrite reductases. Overall, the unexpected metabolic capabilities and gene content reported here broaden our perspective on what biogeochemical and ecological roles this species might play as a prominent member of microbial communities in subsurface environments.
Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA. HRBeller@lbl.gov
Harry R
HR
Beller
Ruyang
R
Han
Ulas
U
Karaoz
Hsiaochien
H
Lim
Eoin L
EL
Brodie
D019342:Acetic Acid / Q000378:metabolism; D002840:Chromates / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D005285:Fermentation; D005420:Flavoproteins / Q000235:genetics; D016680:Genome, Bacterial; D060587:Groundwater / Q000382:microbiology; D007501:Iron / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D010084:Oxidation-Reduction; D011422:Propionates / Q000378:metabolism; D017422:Sequence Analysis, DNA; D045854:Veillonellaceae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*
D002840:Chromates; D004269:DNA, Bacterial; D005420:Flavoproteins; D009566:Nitrates; D011422:Propionates; D019344:Lactic Acid; D007501:Iron; D019342:Acetic Acid