Extremely 'vanadiphilic' multiply metal-resistant and halophilic aerobic anoxygenic phototrophs, strains EG13 and EG8, from hypersaline springs in Canada

摘要

Two pinkish peach-colored strains of obligately aerobic phototrophic bacteria, EG13 and EG8, were isolated from a saline spring effluent stream in west central Manitoba, Canada. The strains possessed bacteriochlorophyll a incorporated into a typical purple bacterial light-harvesting complex 1 (870 nm) and reaction center (801 nm). Analysis of 16S rRNA gene sequences indicated 100 % identity among the isolates and 99 % similarity to Roseovarius tolerans EL-172(T). The strains were physiologically well adapted to high salinity (0-22 %), fluctuating pH (7-12) and temperature (7-40 A degrees C) of the exposed hypersaline stream of East German Creek. EG8 and EG13 were also highly resistant to the toxic metal(loid) oxyanions tellurite, selenite and metavanadate (a parts per thousand yen1000 mu g/ml each). Most intriguingly, growth and pigment production of EG13 on glutamate minimal medium was stimulated by 1000-10000 mu g/ml of sodium metavanadate compared to metal-free conditions. Phylogenetic analysis and phenotypic properties such as pigment composition and morphology indicate close relatedness to Roseovarius genus.