EFFECT OF NUTRITION ON THE GROWTH AND METABOLISM OF BACILLUS SUBTILIS

Abstract

The type of glucose dissimilatory mechanism formed in B. subtilis Marburg strain during growth is a function of nutrition. Growth in a tryptone-yeast extract-glucose medium yields cells (C-cells) capable of vigorous respiration and fermentation, whereas cells from an inorganic N-salts-glucose medium (S-cells) possess only respiratory activity with practically no fermentative capacity. C-cells oxidize glucose imcompletely to acetic acid, acetylmethylcarbinol, CO2, and H2 2 and H2O; anaerobically, a slow homolactic fermentation also occurs. Addition of amino acids to the inorganic N medium results in a marked increase in the fermentative capacity of S-cells. Increased O2 tension during growth results in the loss of fermentative activity and a simultaneous increase in the respiratory capacity of C-cells. Oxidation of gluconate and ribose by S-cells and insensitivity to fluoride during glucose oxidation indicate that these cells dissimilate glucose via the hexosemonophosphate pathway. Sensitivity to fluoride during glucose oxidation and fermentation by C-cells plus the nature of the end products suggest that these cells dissimilate glucose via the Embden- Meyerhof scheme; however, C-cells also possess the hexosemonophosphate dissimilatory mechanism. The respiration of S-cells is sensitive to cyanide, azide, and carbon monoxide indicating the operation of the cytochrome system whereas C-cells are sensitive only to azide. C-cells contain about 10 times the amt. of ribonucleic acid found in S-cells.