SUMMARY: grows poorly on -lysine as sole source of carbon but mutant derivatives which grow rapidly were readily isolated. Studies with one such mutant, 586, supported the existence of a route for -lysine catabolism which differs from those reported previously in other species of Pseudomonas. The postulated route, the cadaverine or decarboxylase pathway, is initiated by the decarboxylation of -lysine and involves the following steps: -lysine → cadaverine → -piperideine → 5-aminovalerate → glutarate semialdehyde → glutarate. Evidence for this pathway is based on the characterization of the pathway reactions and the induction of the corresponding enzymes by growth on -lysine. The first three enzymes were also induced by growth on cadaverine and to a lesser extent by 5-aminovalerate. No evidence was obtained for the presence of pathways involving -lysine 2-monooxygenase or -pipecolate dehydrogenase, but another potential route for -lysine catabolism initiated by -lysine 6-aminotrans-ferase was detected. Studies with mutants unable to grow on -lysine supported the existence of more than one catabolic pathway for -lysine in this organism and indicated that all routes converge on a pathway for glutarate catabolism which generates acetyl-CoA. Pipecolate catabolism also appeared to converge on the glutarate pathway in . The results suggested that the growth rate of the parental strain is limited by the rate of transport and/or decarboxylation of -lysine. The cadaverine pathway was present, but not so highly induced, in the parental strain . contained enzymes of both the cadaverine (decarboxylase) and oxygenase pathways, strains of (biotypes and ) contained enzymes of the oxygenase pathway but not the decarboxylase pathway and appeared deficient in both. All these species possessed -lysine aminotransferase activity.


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