GROWTH OF BACILLUS-STEAROTHERMOPHILUS ON GLYCEROL IN CHEMOSTAT CULTURE - EXPRESSION OF AN UNUSUAL PHENOTYPE

Bacillus stearothermophilus grew readily on glycerol in carbon-limited chemistat culture and expressed a high carbon conversion efficiency. However, the strain of organism used (probably B. stearothermophilus var. non-diastaticus) proved particularly sensitive to glycerol, both respiration and growth being severely impeded by any surfeit of this compound. Sensitivity was found to correlate with an exceptionally high level of expression of glycerol kinase [activities of more than 80 μmol min-1 (mg protein)-1 were manifest in crude cell-free extracts], coupled with low activities of methylglyoxal synthase and of glyoxylase (enzymes of the methylglyoxal bypass). It is proposed that metabolic dysfunction results from an uncontrolled gross accumulation of glycerol phosphate (and early products of its metabolism) within the cells, coupled with depletion of the intracellular phosphate pool.