Role of Competition for Inorganic Nutrients in the Biodegradation of Mixtures of Substrates

A study was conducted to determine whether competition for inorganic nutrients affects the biodegradation of mixtures of substrates. Little benzylamine was mineralized by Pseudomonas putida in solutions with no added P, but the substrate was degraded if the medium contained 100 nM P. The enhancement by P addition did not occur if the medium also contained caprolactam and a caprolactam-utilizing strain of Pseudomonas aeruginosa. The suppression by the second bacterium was overcome by a higher P concentration. The rate of caprolactam utilization by P. aeruginosa was reduced if benzylamine and P. putida were also present in media with 100 nM P, but the suppression was absent if the solution contained a higher P concentration. Glutamate increased and inorganic N plus P decreased the length of the acclimation phase prior to benzylamine mineralization in lake water. We suggest that the effect of one biodegradable substrate on the metabolism of a second often results from a competition for inorganic nutrients.