Cyclic AMP and low molecular weight effector(s) present in yeast extract are involved in pectin lyase production by Penicillium griseoroseum culturedon sucrose

Pectin lyase (PL) induction by organic and inorganic components of yeast ex tract (YE) was evaluated in Penicillium griseoroseum, cultured in a mineral medium containing sucrose, by determining Pt activity (A,,,) and mycelial growth (mycelial dry weight). The lowest YE concentration that promoted sig nificant Pt induction without acting as a carbon source for the fungus corr esponded to 0.0075%. Neither calcined YE nor a nutrient solution containing micronutrients induced Pt production, indicating that the inducer was an o rganic compound. Vitamins, phospholipid components, amino acids, and nitrog enous bases were tested in place of YE and promoted no significant Pt induc tion. A Pt, inducer compound was found to be soluble in the nucleotide frac tion obtained during extraction of YE. The inducer was shown to be a thermo stable polar substance dialyzable at 2000 Daltons, hydrolyzable by HCl, and activated by boiling for up to 60 min. Cyclic AMP (cAMP) exogenously added to the culture medium at 5 and 10 mM was capable of inducing Pt in P. gris eoroseum grown on sucrose, suggesting that at least one compound may be pre sent in YE acting in a cooperative fashion for the maintenance of high leve ls of cAMP into the cell. Pt activity and the level of cAMP inside the fung al cells increased after the addition of YE to the culture medium, suggesti ng the participation of this messenger in this enzyme's synthesis.