title: Diversity of culturable halophilic sulfur-oxidizing bacteria in hypersaline habitats.
abstract: Unexpectedly high culturable diversity of moderately and extremely halophilic obligately chemolithoautotrophic sulfur-oxidizing bacteria (SOB) was discovered in the sediments of various hypersaline habitats, including chloride-sulfate lakes in Mongolia, Russia and Ukraine, a sea saltern in Slovenia and a deep-sea salt brine from the Mediterranean. Six different groups of halophilic SOB, including four new genera, all belonging to the Gammaproteobacteria, were found. Two groups of moderately halophilic strictly aerobic SOB dominated at 2 M NaCl, including representatives of the genus Halothiobacillus (in fully aerobic conditions) and Thiomicrospira (in micro-oxic conditions). Under denitrifying conditions at 2 M NaCl, a group of moderately halophilic and facultatively anaerobic SOB was selected, capable of complete denitrification of nitrate. The group represents a new genus with closest relatives among as yet undescribed marine thiodenitrifying isolates. With thiocyanate as a substrate, an enrichment culture at 2 M NaCl yielded a pure culture of moderately halophilic SOB capable of aerobic growth with thiocyanate and thiosulfate at up to 4 M NaCl. Furthermore, this bacterium also grew anaerobically using nitrite as electron acceptor. It formed a new lineage distantly related to the genus Thiomicrospira. Enrichments at 4 M NaCl resulted in the domination of two different, previously unknown, groups of extremely halophilic SOB. Under oxic conditions, they were represented by strictly aerobic spiral-shaped bacteria, related to the Ectothiorhodospiraceae, while under denitrifying conditions a group of facultatively anaerobic nitrate-reducing bacteria with long rod-shaped cells was selected, distantly related to the genus Acidithiobacillus.
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.|Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-let Octyabrya 7/2, 117811 Moscow, Russia.
authors.forename: Dimitry Yu
authors.initials: DY
authors.lastname: Sorokin
authors.affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-let Octyabrya 7/2, 117811 Moscow, Russia.
authors.forename: Tatjana P
authors.initials: TP
authors.lastname: Tourova
authors.affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-let Octyabrya 7/2, 117811 Moscow, Russia.
authors.forename: Anatoly M
authors.initials: AM
authors.lastname: Lysenko
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors.forename: Gerard
authors.initials: G
authors.lastname: Muyzer
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D044822:Biodiversity; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020563:Gammaproteobacteria / Q000145:classification* / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism; D019015:Geologic Sediments / Q000382:microbiology*; D008522:Mediterranean Sea; D008853:Microscopy; D008969:Molecular Sequence Data; D008986:Mongolia; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012426:Russia; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D017524:Slovenia; D012965:Sodium Chloride; D013455:Sulfur / Q000378:metabolism*; D013861:Thiocyanates / Q000378:metabolism; D014455:Ukraine; D014871:Water Microbiology
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D009566:Nitrates; D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D013861:Thiocyanates; D012965:Sodium Chloride; D013455:Sulfur; C031760:thiocyanate