DEGRADATION OF PYRIMIDINE RIBONUCLEOSIDES BY PSEUDOMONAS-AERUGINOSA

Pyrimidine ribonucleoside degradation in the human pathogen Pseudomona s aeruginosa ATCC 15692 was investigated. Either uracil, cytosine, 5-m ethylcytosine, thymine, uridine or cytidine supported P. aeruginosa gr owth as a nitrogen source when glucose served as the carbon source. Us ing thin-layer chromatographic analysis, the enzymes nucleoside hydrol ase and cytosine deaminase were shown to be active in ATCC 15692. Comp ared to (NH4)(2)SO4-grown cells, nucleoside hydrolase activity in ATCC 15692 approximately doubled after growth on 5-methylcytosine as a nit rogen source while its cytosine deaminase activity increased several-f old after growth on the pyrimidine bases and ribonucleosides examined as nitrogen sources. Regulation at the level of protein synthesis by 5 -methylcytosine was indicated for nucleoside hydrolase and cytosine de aminase in P. aeruginosa.