Pseudomonas stutzeri A1501, an associative nitrogen-fixing bacterium, was isolated from the rice paddy rhizosphere. This bacterium fixes nitrogen under microaerobic conditions. In this study, ge- nome-wide DNA microarrays were used to analyze the global transcription profile of A1501 under aerobic and microaerobic conditions. The expression of 135 genes was significantly altered by more than 2-fold in response to oxygen stress. Among these genes, 68 were down-regulated under aerobic conditions; these genes included those responsible for nitrogen fixation and denitrification. Sixty- seven genes were up-regulated under aerobic conditions; these genes included sodC, encoding a copper-zinc superoxide dismutase, PST2179, encoding an NAD(P)-dependent oxidoreductase, PST3584, encoding a 2OG-Fe(II) oxygenase, and PST3602, encoding an NAD(P)H-flavin oxidoreductase. Addi- tionally, seven genes involved in capsular polysaccharide and antigen oligosaccharide biosynthesis together with 17 genes encoding proteins of unknown function were up-regulated under aerobic con- ditions. The overall analysis suggests that the genes we identified are involved in the protection of the bacterium from oxygen, but the mechanisms of their action remain to be elucidated.
DOU YueTanYAN YongLiangPING ShuZhenLU WeiCHEN MingZHANG WeiWANG YiPingJIN QiLIN Min
