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DE NOVO SYNTHESIS OF -AMYLASE BY BACILLUS STEAROTHERMOPHILUS¹

^a Department of Microbiology, School of Medicine, Western Reserve University, Cleveland, Ohio
^b Department of Microbiology, University of Illinois, Urbana, Illinois

ABSTRACT

WELKER, N. E. (Western Reserve University, Cleveland, Ohio and University of Illinois, Urbana), AND L. LEON CAMPBELL. De novo synthesis of -amylase by Bacillus stearothermophilus. J. Bacteriol. 86:1202–1210. 1963.—The pH optimum for the synthesis of -amylase by washed-cell suspensions was 6.7. -Amylase synthesis began soon after the addition of the inducer (maltose, methyl-ß-D-maltoside, or phenyl--D-glucoside, at 10^–3M), proceeded at a linear rate for 60 min, and then leveled off. Cell suspensions without inducer produced small amounts of -amylase. The addition of glucose (2 x 10^–3M), sucrose (10^–3M), or glycerol (4 x 10^–3M) to washed-cell suspensions failed to stimulate the production of -amylase. Nitrogen starvation of washed cells for 60 min with fructose as a carbon source or by induction with pure maltose showed that the ability to produce -amylase was lost. Examination of the amino acid pool at this time showed a general depletion of amino acids and the complete disappearance of tyrosine, phenyl-alanine, proline, and valine. Replenishment of the amino acid pool with casein hydrolysate (0.5%) restored the ability of the cells to produce -amylase. Chloramphenicol and 8-azaguanine were shown to inhibit -amylase synthesis. Inhibition was observed immediately upon the addition of chloramphenicol to cell suspensions preinduced for varying periods of time. Actinomycin D and mitomycin C also inhibited -amylase synthesis when added to induced washed-cell suspensions. The amino acid analogues, norvaline, norleucine, and ethionine, inhibited -amylase formation by 72, 53, and 38%, respectively. p-Fluorophenylalanine inhibited the synthesis of active -amylase by 92% and the incorporation of proline-C¹⁴ into -amylase and cellular proteins by 95 and 74%, respectively.

² Present address: Department of Microbiology, University of Illinois, Urbana.

¹ Part of the dissertation of Neil E. Welker, presented to the Graduate Faculty of Western Reserve University in partial fulfillment of requirements for the Ph.D. degree.