Anaerobic Degradation of Cystine and Cysteine

Abstract

THE bacterial degradation of cystine and cysteine under anaerobic conditions with liberation of hydrogen sulphide and ammonia has recently formed the subject of interesting papers by Desnuelle, and by Desnuelle, Wookey and Fromageot. The former author worked with suspensions of non-proliferating B. coli¹, whereas the latter authors used suspensions of propionic acid bacteria². A systematic study by Tarr³ of the production of hydrogen sulphide by washed bacterial suspensions showed that cysteine and cystine are decomposed anaerobically by numerous bacteria with formation of hydrogen sulphide. Desnuelle and Fromageot⁴ pointed out that a specific enzyme which they termed cysteinase was responsible for the breakdown of the amino acid.