Alkalilimnicola ehrlichii sp. nov., a novel, arsenite-oxidizing haloalkaliphilic gammaproteobacterium capable of chemoautotrophic or heterotrophic growth with nitrate or oxygen as the electron acceptor.
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.
Hoeft
Shelley E
SE
US Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025, USA.
Blum
Jodi Switzer
JS
US Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025, USA.
Stolz
John F
JF
Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA.
Tabita
F Robert
FR
Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
Witte
Brian
B
Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
King
Gary M
GM
Darling Marine Center, University of Maine, Walpole, ME 04573, USA.
Santini
Joanne M
JM
Department of Biology, UCL, London WC1E 6BT, UK.
Oremland
Ronald S
RS
US Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025, USA.
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
D018053:Arsenites; D009566:Nitrates; D002248:Carbon Monoxide; D012273:Ribulose-Bisphosphate Carboxylase; C015001:arsenite; D008697:Methane; D010100:Oxygen