Nitrogen Fixation Activity and Genome Analysis of a Moderately Haloalkaliphilic Anoxygenic Phototrophic Bacterium .

The genome of the moderately haloalkaliphilic diazotrophic anoxygenic phototrophic bacterium A-36s isolated from an alkaline lake was analyzed and compared to the genomes of the closest species A-20s and DSM 11289. The genomic features of three organisms are quite similar, reflecting their ecological and physiological role of facultative photoheterotrophs. Nevertheless, the nitrogenase activity of the pure cultures of the studied bacteria differed significantly: the highest rate (4066 nmoles CH/mg of dry weight per hour) was demonstrated by while the rates in and were an order of magnitude lower (278 and 523 nmoles CH/mg of dry weight per hour, respectively). This difference can be attributed to the presence of an additional nitrogenase operon found exclusively in and to the structural variation in nitrogenase operon in .