Studies on α-amylase formation by Bacillus subtilis

Abstract

A-Amylase formation was studied in growing cultures of Bacillus subtilis and a requirement for Fe+++ demonstrated. The distribution of a-amylase between the extra- and intra-cellular phases in washed-cell suspensions that were actively producing the enzyme was examined. The cell-bound a-amylase remained constant at a low value; whereas, the extracellular enzyme rapidly increased in amount. The failure of the cells to accumulate a-amylase supports the concept that this enzyme is "secreted" as a truly extracellular product. Formation of the enzyme by washed-cell suspensions of B. subtilis is stimulated by a carbohydrate source and to a much lesser extent by NH4+. Amino acids are inhibitory. Formation of [alpha]-amylase by washed-cell suspensions is strongly inhibited by anaerobiosis, 2,4- dinitrophenol, chloramphenicol and slightly by p-fluorophenylalanine. The relationship of these results to the mechanism of a-amylase formation and to the findings of previous workers is discussed.