A SINGLE ADAPTIVE ENZYME IN SACCHAROMYCES ELICITED BY SEVERAL RELATED SUBSTRATES

Abstract

A culture of Saccharomyces able to ferment maltose, turanose, sucrose, melezitose and alpha-methyl glycoside, carrying the MZ gene, produced the same enzyme (alpha-gluco-melezitase) on adaptation to either maltose, sucrose, or alpha-methyl glycoside. It was capable of heterologous adaptation; growth on maltose resulted in ability to ferment either maltose, sucrose, or alpha-methyl glycoside. A culture carrying an allele of MZ which had lost the ability to grow on alpha-methyl glycoside, melezitose, or sucrose gave negative fermentation tests in Durham tubes containing these sugars. It was also found to be capable of heterologous adaptation: growth on maltose resulted in ability to ferment sucrose, melezitose, or alpha-methyl glycoside; sucrose added to the adaptive medium inhibited adaptation to maltose. The MZ gene in its various manifestations appears to control the production of a single enzyme which is capable of breaking down maltose, turanose, sucrose, melezitose, and alpha-methyl glycoside (but not raffinose).