Studies on the Bacterial Formation of a Peptide Antibiotic, Colistin

Part I. On the Enyzmatic Inactivation of Colistin by Bacillus colistinus

Abstract

Colistinase, an enzyme inactivating colistin, which appeared in a fermented broth of Bacillus colistinus attending with decay of colistin production was studied. The enzyme was partially purified and also chromatographed by DEAE-cellulose column. It was a heat labile, mostly basic protein, had optimum pH at 9.0 and was active against peptide anti-biotics such as colistin and polymyxin and also against casein. Bacterial proteinase, Nagarse, exhibited colistinase activity exclusively among tested proteinases and immunochemical studies revealed that colistinase was identical with bacterial proteinase Nagarse.