Growth and sporulation characteristics of Bacillus megaterium under different conditions of nutrient limitation

Abstract

Abstract The quantitative nutritional requirements to achieve specific cell densities have been studied for B. megaterium. Growth of batch cultures was separately limited by depletion of glucose, ammonium, sulphate, potassium, phosphate, manganese and magnesium. Maximum population density (E420) for graded concentrations of each limiting nutrient was plotted against nutrient concentration and a linear plot was obtained below a critical concentration. Under conditions of magnesium depletion, two phases of growth occurred separated by a plateau. Proposals are made for the use of these cultures in drug resistance studies. Sporulation occurred in all cultures except those limited by potassium, manganese or magnesium. Spores were produced in magnesium-limited cultures provided that glucose was simultaneously depleted. Spores produced under different conditions of nutrient depletion varied in germination characteristics, heat resistance and spore volume.