title: Functional diversity of bacteria in a ferruginous hydrothermal sediment.
abstract: A microbial community showing diverse respiratory processes was identified within an arsenic-rich, ferruginous shallow marine hydrothermal sediment (20-40 degrees C, pH 6.0-6.3) in Santorini, Greece. Analyses showed that ferric iron reduction with depth was broadly accompanied by manganese and arsenic reduction and FeS accumulation. Clone library analyses indicated the suboxic-anoxic transition zone sediment contained abundant Fe(III)- and sulfate-reducing Deltaproteobacteria, whereas the overlying surface sediment was dominated by clones related to the Fe(II)-oxidizing zetaproteobacterium, Mariprofundus ferroxydans. Cultures obtained from the transition zone were enriched in bacteria that reduced Fe(III), nitrate, sulfate and As(V) using acetate or lactate as electron donors. In the absence of added organic carbon, bacteria were enriched that oxidized Fe(II) anaerobically or microaerobically, sulfide microaerobically and aerobically and As(III) aerobically. According to 16S rRNA gene analyses, enriched bacteria represented a phylogenetically wide distribution. Most probable number counts indicated an abundance of nitrate-, As(V)- and Fe(III)((s,aq))-reducers, and dissolved sulfide-oxidizers over sulfate-reducers, and FeS-, As(III)- and nitrate-dependent Fe(II)-oxidisers in the transition zone. It is noteworthy that the combined community and geochemical data imply near-surface microbial iron and arsenic redox cycling were dominant biogeochemical processes.
authors.affiliation: School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester, UK. kim.handley@berkeley.edu
authors.forename: Kim M
authors.initials: KM
authors.lastname: Handley
authors.forename: Christopher
authors.initials: C
authors.lastname: Boothman
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Mills
authors.forename: Richard D
authors.initials: RD
authors.lastname: Pancost
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Lloyd
mesh_terms: D000085:Acetates / Q000378:metabolism; D000693:Anaerobiosis; D001151:Arsenic / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism*; D044822:Biodiversity; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D006115:Greece; D045482:Hot Springs / Q000382:microbiology*; D007501:Iron / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D054892:Metagenome; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013431:Sulfates / Q000378:metabolism
chemical_list: D000085:Acetates; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D009566:Nitrates; D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D019344:Lactic Acid; D008345:Manganese; D007501:Iron; D001151:Arsenic