A Role of Intracellular Polysaccharide in the Sporulation of "Bacillus Cereus"
Schmid, Steven MacKay
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The problem. "Bacillus cereus" accumulates an intracellular polysaccharide under conditions of nutritional stress. The polysaccharide is then degraded as the organism begins sporulation. This study concerns intracellular polysaccharide and its possible involvement in sporulation as a source of carbon and energy. Procedures. Ethyl methanesulphonate mutagenized cells of "Bacillus cereus" 10702 were screened for the ability to accumulate glucose during growth with glucostat reagent. Glucose deficient mutants were assayed for the ability to accumulate poly-B-hydroxybutyric acid and intracellular polysaccharide followed by comparison to wild type levels. Endotrophic sporulation capabilities with exogenous glucose were determined by the heat resistance of spores in both mutant and wild type. Dipicolinic acid levels in spores were assayed with modified Janssen reagent. Findings. A mutant of "Bacillus cereus" strain T isolated was deficient in the ability to accumulate intracellular polysaccharide. The mutant produced low levels of heat sensitive spores. Heat sensitivity was dependent upon poly-B-hydroxybutyric acid accumulation and levels of exogenous glucose during sporulation. Inhibition of poly-B-hydroxybutyric acid accumulation increased heat resistance of spores subjected to sporulation in low levels of glucose and CaCl2. Conclusions. The data indicated that intracellular polysaccharide supplied the sporulation process with a carbon and/or energy source involved in spore formation and heat resistance.
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