Effects of Carbon Sources and Base Analogues of Nucleic Acid on the Formation of Bacterial Amylase

Abstract

A WASHED suspension of Bacillus amyloliquefaciens Fukumoto cells¹, which is a strain of Bacillus subtilis that has been used for the industrial production of bacterial α-amylase, secretes a small but distinct amount of amylase when shaken aerobically in the presence of phosphate. Under the same conditions, the addition of a sugar or a salt of an organic acid as the carbon source causes a great increase in the formation of amylase without any addition of nitrogen source². Since the enzyme detected in the autolysate or lysozyme-lysed solution of the bacterial cells is very small, it seems to be certain that the amylase appearing in the cell suspension did not pre-exist in the bacterial cells, but is newly formed and secreted by the cells. In this experiment, however, the amount of enzyme formed differs markedly according to the type of carbon source³. As seen in Table 1, there is no clear adaptive relationship between the formation of enzyme and the carbon sources, and also the amount of amylase formed is not in any way parallel to the respiration activity of the cell, which is related to the carbon sources. This characteristic effect of carbon source on enzyme formation is almost always observed, regardless of the type of carbon source on which the cells are grown. Sugars such as glucose and fructose are not only ineffective but may be even somewhat inhibitory, and adding them to other carbon sources which are available for enzyme formation completely nullifies their effect. This diauxic effect⁵ appears almost immediately after the addition of these sugars, and remains constant during the course of the experiment, although no metabolic product inhibitory to enzyme formation has yet been detected in the cell suspension system. However, even on a glucose carbon source, good formation of the enzyme occurs to the same extent as from a galactose carbon source, if the glucose concentration is maintained at a very low level (about 0.01–0.02 per cent).