Metabolism of Tryptophans by Pseudomonas aureofaciens

Twenty-nine strains ofPseudomonas , classified asP. fluorescens biotype D or E or asP. multivorans , were examined for the production of pyrrolnitrin, an antifungal agent synthesized inP. aureofaciens . Eight strains were shown to produce pyrrolnitrin in shake-flask fermentation. Four cultures were from the multivorans taxon, and the remaining four were members of the fluorescens group. The antifungal agent produced in these strains was isolated and shown to be pyrrolnitrin by comparison with an authentic sample. The strains differed markedly with respect to the amount of pyrrolnitrin produced and in their utilization of exogenous tryptophan. Secondary metabolites, not related to pyrrolnitrin, were also examined and compared with those synthesized inP. aureofaciens . Marked differences were noted in both phenazine pigments and phenolic metabolites. The results of the study suggest that the production of pyrrolnitrin may be widespread in selected taxonomic groups ofPseudomonas .