Factors affecting the accumulation of exocellular exo-β- d-galactofuranosidase and other enzymes from Penicillium charlesii

Abstract

exo-β- d-galactofuranosidase and β- d-glucosidase first appeared in culture filtrates of Day 14 cultures of Penicillium charlesii and after the medium was depleted of glucose. Acid phosphatase, ribonuclease, and protease activities appeared about 7 days earlier. The appearance of the glycohydrolases also occurred in Day 7 culture filtrates if the growth medium of Day 3 cultures was titrated to 4 with alkali. This treatment of the growth medium did not change the initial appearance of acid phosphatase, ribonuclease, or protease activities. Addition of protease inhibitors to the modified growth medium further enhanced galactofuranosidase activity and the maximum activity attained was severalfold greater than that obtained in untreated cultures. These data suggest that galactofuranosidase activity is destroyed by acid protease(s) and that galactofuranosidase activity appears in the medium only after it is depleted of glucose and sufficient organic acid has been taken up to increase the pH of the medium above 4. A possible role of organic acids in regulating the onset of release of glycohydrolases into the medium is discussed.