title: Alkalilimnicola ehrlichii sp. nov., a novel, arsenite-oxidizing haloalkaliphilic gammaproteobacterium capable of chemoautotrophic or heterotrophic growth with nitrate or oxygen as the electron acceptor.
abstract: A facultative chemoautotrophic bacterium, strain MLHE-1(T), was isolated from Mono Lake, an alkaline hypersaline soda lake in California, USA. Cells of strain MLHE-1(T) were Gram-negative, short motile rods that grew with inorganic electron donors (arsenite, hydrogen, sulfide or thiosulfate) coupled with the reduction of nitrate to nitrite. No aerobic growth was attained with arsenite or sulfide, but hydrogen sustained both aerobic and anaerobic growth. No growth occurred when nitrite or nitrous oxide was substituted for nitrate. Heterotrophic growth was observed under aerobic and anaerobic (nitrate) conditions. Cells of strain MLHE-1(T) could oxidize but not grow on CO, while CH(4) neither supported growth nor was it oxidized. When grown chemoautotrophically, strain MLHE-1(T) assimilated inorganic carbon via the Calvin-Benson-Bassham reductive pentose phosphate pathway, with the activity of ribulose 1,5-bisphosphate carboxylase (RuBisCO) functioning optimally at 0.1 M NaCl and at pH 7.3. Strain MLHE-1(T) grew over broad ranges of pH (7.3-10.0; optimum, 9.3), salinity (15-190 g l(-1); optimum 30 g l(-1)) and temperature (13-40 degrees C; optimum, 30 degrees C). Phylogenetic analysis of 16S rRNA gene sequences placed strain MLHE-1(T) in the class Gammaproteobacteria (family Ectothiorhodospiraceae) and most closely related to Alkalispirillum mobile (98.5 %) and Alkalilimnicola halodurans (98.6 %), although none of these three haloalkaliphilic micro-organisms were capable of photoautotrophic growth and only strain MLHE-1(T) was able to oxidize As(III). On the basis of physiological characteristics and DNA-DNA hybridization data, it is suggested that strain MLHE-1(T) represents a novel species within the genus Alkalilimnicola for which the name Alkalilimnicola ehrlichii is proposed. The type strain is MLHE-1(T) (=DSM 17681(T)=ATCC BAA-1101(T)). Aspects of the annotated full genome of Alkalilimnicola ehrlichii are discussed in the light of its physiology.
authors.affiliation: US Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025, USA.
authors.forename: Shelley E
authors.initials: SE
authors.lastname: Hoeft
authors.affiliation: US Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025, USA.
authors.forename: Jodi Switzer
authors.initials: JS
authors.lastname: Blum
authors.affiliation: Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Stolz
authors.affiliation: Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: F Robert
authors.initials: FR
authors.lastname: Tabita
authors.affiliation: Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Witte
authors.affiliation: Darling Marine Center, University of Maine, Walpole, ME 04573, USA.
authors.forename: Gary M
authors.initials: GM
authors.lastname: King
authors.affiliation: Department of Biology, UCL, London WC1E 6BT, UK.
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Santini
authors.affiliation: US Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025, USA.
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Oremland
mesh_terms: D018053:Arsenites / Q000378:metabolism; D002248:Carbon Monoxide / Q000378:metabolism; D052837:Chemoautotrophic Growth; D004583:Electrons; D020563:Gammaproteobacteria / Q000145:classification* / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D005798:Genes, Bacterial; D052836:Heterotrophic Processes; D008697:Methane / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010802:Phylogeny; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism
chemical_list: D018053:Arsenites; D009566:Nitrates; D002248:Carbon Monoxide; D012273:Ribulose-Bisphosphate Carboxylase; C015001:arsenite; D008697:Methane; D010100:Oxygen