RESUMO
IN S. viridosporus, L- phenylanine ammonia lyase [PAL] was detected during the exponential growth as well as the stationary phase in the absence of exogenous L-phenylalanine in complex medium. Cultures grown in the defined medium produced little PAL unless supplemented with L-phenylalanine. A higher specific activity of PAL [10-fold higher than in the defined medium without L-phenylalanine] can be obtained during 48 hr of growth in the defined medium containing L-phenylalanine. This amino acid also induces lyase synthesis in a defined medium when used as the sole source of nitrogen, whereas other amino acids completely failed to induce PAL activity. Maximal induction of PAL occurred when L-phenylalanine was used as the nitrogen or carbon source at 0.6% final concentration. On the other hand, ammonia repressed the PAL synthesis in presence of glucose. Moreover, increasing the concentration of glucose up to 2.0% repressed the lyase activity