The effect of thiols and the Ca2+ ionophore A23817 on growth and antibiotic production in Cephalosporium acremonium

Yeast-like blastosporic growth, lowered levels of isopenicillin N synthetase and deacetoxycephalosporin C synthetase/hydroxylase, and lowered antibiotic production were induced in Cephalosporium acremonium strain C.O. 728 by inclusion of cysteine or glutathione in the growth medium. These effects were similar to those observed under normal conditions with strain M 8650/4, which had higher levels of glutathione reductase and protein disulphide reductase than strain C.O. 728. The addition of cytochalasins A and B slightly increased yeast-like growth in C.O. 728, although levels of biosynthetic enzyme activity and antibiotic secretion were not significantly affected. The Ca2+ ionophore A23187 inhibited C.O. 728 growth, slowed penicillin secretion into the medium, and totally inhibited cephalosporin secretion. These results show that maintenance of Ca2+ levels and the absence of thiols are important for antibiotic production in Cephalosporium acremonium.