Abstract
Strain DV(T), a halotolerant, Gram-negative, facultatively anaerobic bacterium, was isolated from a hypersaline pond located in Death Valley, California. The cells were non-spore-forming, motile, curved rods (1.0--1.8 x 0.5--0.6 microm) and occurred singly, in pairs or rarely in chains. Strain DV(T) was oxidase-, catalase-, Voges--Proskauer-, amylase-, gelatinase- and lipase-positive and indole-negative. Nitrate, sulfate and fumarate were not used as electron acceptors. Carbohydrates served as energy sources both aerobically and anaerobically. Strain DV(T) grew optimally at 37 degrees C (temperature range 20--50 degrees C) with 2.5% NaCl (NaCl range 0--12.5%) and pH 7.3 (pH range of 5.5--8.5) in a glucose/yeast extract medium with a doubling time of 20 min (aerobically) or 41 min (anaerobically). The end products of glucose fermentation were ethanol, isobutyrate, propionate, lactate, formate and CO(2). Strain DV(T) was resistant to penicillin, D-cycloserine, streptomycin and tetracycline (200 microg ml(-1)). The G+C content was 50 mol%. 16S rRNA gene sequence analysis indicated that it was closely related to Salinivibrio costicola (97.7%) and this was confirmed by DNA--DNA hybridization (93% relatedness). However, phenotypic characteristics such as halotolerance, gas production, growth at 50 degrees C, antibiotic resistance, sugar-utilization spectrum and phylogenetic signatures are sufficiently different from Salinivibrio costicola to warrant designating strain DV(T) as a new subspecies of Salinivibrio costicola, Salinivibrio costicola subsp. vallismortis subsp. nov. (=DSM 8285(T)).