BIOCHEMICAL CHANGES OCCURRING DURING SPORULATION OF BACILLUS CEREUS T II

Sporulation of Bacillus thuringiensis without concurrent derepression of the tricarboxylic acid cycle

Bacillus thuringiensis sporulates in a glucose-glutamate medium without concurrent derepression of the tricarboxylic acid cycle. Glutamate appears to regulate tricarboxylic acid cycle activity as well as to influence spore heat resistance and production of dipicolinic acid.

Inactivation of aspartic transcarbamylase in sporulating Bacillus subtilis: demonstration of a requirement for metabolic energy

The aspartic transcarbamylase (ATCase) activity of Bacillus subtilis cells disappears rapidly from stationary-phase cells prior to sporulation. ATCase activity does not appear in the culture fluid during the stationary phase; hence the enzyme appears to be inactivated in the cells. The enzyme is inactivated normally in two different mutants lacking proteases; the activity is very stable in crude extracts of cells or in the culture fluid. These results suggest that ATCase is not inactivated by the general proteolysis that occurs in sporulating bacteria. The inactivation of ATCase can be completely inhibited after it has begun by oxygen starvation or addition of fluoroacetate. Inhibitors of oxidative phosphorylation and electron transport also interrupt the inactivation of ATCase. The inactivation of ATCase is very slow in two mutant strains that are deficient in enzymes of tricarboxylic acid cycle. Addition of gluconate to stationary cultures of the mutant strains, which is known to restore depleted adenosine 5'-triphosphate pools in these bacteria, also restores inactivation of ATCase. These experiments support the conclusion that the generation of metabolic energy is necessary for the inactivation of ATCase in stationary cells. ATCase activity is stable in growing cells in which ATCase synthesis is repressed by addition of uracil; the enzyme is inactivated normally, however, when such cells cease growing.

Glyoxylate metabolism in growth and sporulation of Bacillus cereus

Megraw, Robert E. (Iowa State University, Ames), and Russell J. Beers. Glyoxylate metabolism in growth and sporulation of Bacillus cereus. J. Bacteriol. 87:1087-1093. 1964.-Isocitrate lyase and malate synthetase were found in cell-free extracts of Bacillus cereus T. The patterns of synthesis of enzymes of the glyoxylic acid cycle were dependent upon the medium in which the organism was grown. Cells grown in acetate or in an acetate precursor, such as glucose, produced enzymes of the glyoxylic acid cycle in greatly diminished quantities, as compared with cells grown in media containing glutamate or yeast extract as principal carbon sources. Glutamate-grown cells had high isocitrate lyase activity but very low malate synthetase activity. Glyoxylate produced in this situation is metabolized by alternate pathways: conversion to tartronic semialdehyde and the latter to glyceric acid, thus providing evidence for a glycerate pathway; and reduction to glycolate (the reverse of this reaction was present at a low rate). Enzymatic activity of the glyoxylic acid cycle declines at the point where sporogenesis begins, indicating a metabolic shift for the synthesis of spore material.