SNR, NEW GENETIC-LOCI COMMON TO THE NITRATE REDUCTION SYSTEMS OF PSEUDOMONAS-AERUGINOSA PAO1

Pseudomonas aeruginosa is able to both assimilate and dissimilate nitr ate. On the basis of the characteristics of mutants unable to dissimil ate or assimilate nitrate to nitrite, it was revealed that two differe nt sets of genes (represented by Class I and Class II mutants) were sh ared between the nitrate-to-nitrite reduction steps of both pathways. The genes represented by Class I and II mutants have been separated in to distinct genetic loci using two cosmids, pAD1695/96. The two differ ent genetic loci have been designated snr (shared citrate reduction) a nd mol (MoCo processing genes) based on the phenotypic characteristics of the mutants complemented. Restriction analyses of pAD1695/96 follo wed by subcloning confirmed the complementation results. The snr loci, which represent a unique and hitherto uninvestigated set of genes for nitrate reduction, were mapped on the P. aeruginosa chromosome by lin kage analysis with sex factor FP2.