title: Bacillus arsenicoselenatis, sp. nov., and Bacillus selenitireducens, sp. nov.: two haloalkaliphiles from Mono Lake, California that respire oxyanions of selenium and arsenic.
abstract: Two gram-positive anaerobic bacteria (strains E1H and MLS10) were isolated from the anoxic muds of Mono Lake, California, an alkaline, hypersaline, arsenic-rich water body. Both grew by dissimilatory reduction of As(V) to As(III) with the concomitant oxidation of lactate to acetate plus CO2. Bacillus arsenicoselenatis (strain E1H) is a spore-forming rod that also grew by dissimilatory reduction of Se(VI) to Se(IV). Bacillus selenitireducens (strain MLS10) is a short, non-spore-forming rod that grew by dissimilatory reduction of Se(IV) to Se(0). When the two isolates were cocultured, a complete reduction of Se(VI) to Se(0) was achieved. Both isolates are alkaliphiles and had optimal specific growth rates in the pH range of 8.5-10. Strain E1H had a salinity optimum at 60 g l-1 NaCl, while strain MLS10 had optimal growth at lower salinities (24-60 g l-1 NaCl). Both strains have limited abilities to grow with electron donors and acceptors other than those given above. Strain MLS10 demonstrated weak growth as a microaerophile and was also capable of fermentative growth on glucose, while strain E1H is a strict anaerobe. Comparative 16S rRNA gene sequence analysis placed the two isolates with other Bacillus spp. in the low G+C gram-positive group of bacteria.
authors.affiliation: US Geological Survey, ms 480, 345 Middlefield Road, Menlo Park, CA 94025, USA.
authors.forename: J
authors.initials: J
authors.lastname: Switzer Blum
authors.forename: A
authors.initials: A
authors.lastname: Burns Bindi
authors.forename: J
authors.initials: J
authors.lastname: Buzzelli
authors.forename: J F
authors.initials: JF
authors.lastname: Stolz
authors.forename: R S
authors.initials: RS
authors.lastname: Oremland
mesh_terms: D000693:Anaerobiosis; D001151:Arsenic / Q000378:metabolism*; D001407:Bacillus / Q000145:classification / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D002140:California; D018920:Coculture Techniques; D005947:Glucose / Q000378:metabolism; D006094:Gram-Positive Bacteria / Q000145:classification / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D019344:Lactic Acid / Q000378:metabolism; D008854:Microscopy, Electron; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012643:Selenium / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D019344:Lactic Acid; D012643:Selenium; D005947:Glucose; D001151:Arsenic