AGING OF PENICILLIUM-CHRYSOGENUM CULTURES UNDER CARBON STARVATION .2.PROTEASE AND N-ACETYL-BETA-D-HEXOSAMINIDASE PRODUCTION

In aging carbon-depleted cultures of Penicillium chrysogenum the fragm entation and autolysis of old mycelia were coupled with the production of high levels of extracellular protease and N-acetyl-beta-D-hexosami nidase; this could be stopped by the addition of an extra dose of gluc ose at any incubation time tested, but was not affected by endogenous NH3, After the addition of glucose, intracellular enzyme accumulation was observed only for the N-acetyl-beta-D-hexosaminidase, and the conc omitant decrease in both the extracellular protease and N-acetyl-beta- D-hexosaminidase activities was not caused by the action of extracellu lar proteases, The physiological function of the N-acetyl-beta-D-hexos aminidase remains to be elucidated because the P. chrysogenum culture studied did not utilize N-acetyl-D-glucosamine as a carbon source, How ever, the proteases (mainly serine and, to a much smaller extent, meta lloproteases) might provide surviving hyphal fragments with sufficient amino acids to maintain the cryptic growth observed in aging carbon-d epleted cultures.