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Abstract:
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When Bacillus thuringiensis HD-1 is grown in a glucose-ryptonemineral salts broth either left unsupplemented or supplemented with 0.1 M potassium phosphate buffer (pH 7.2), the pattern of production and utilization of lactate, pyruvate, acetate, intermediates of the 2,3 butanediol cycle, and poly-betahydroxybutyrate are identical. Lactate is formed from the tryptone supplement in the early stages of growth while glucose is oxidized to pyruvate, which provides acetate for polybetahydroxybutyrate synthesis via the 2,3 butanediol cycle. A pH-control over pyruvate utilization is absent. A pH effect is observed as less lactate and pyruvate are produced in unbuffered broth and utilization of glucose and acetate is slower in unbuffered medium. The results indicate that Bacillus thuringiensis HD-1 lacks the activity of pyruvate dehyrogenase or phosphate acetyltransferase. L-malate may serve as a hydrogen sink for the regeneration of NAD from NADH. |