INITIATION OF GROWTH OF BACILLUS SPECIES IN A CHEMICALLY DEFINED MEDIUM

Abstract

Autoclaved solutions of glucose and phosphate (GP) stimulate growth of small inocula of certain Bacillus spp. in a filtered medium containing glucose, DL-glutamate, biotin, NH4 + and salts. The stimulation is referable to a decrease in the initial stationary and lag phases, growth occurring eventually in the absence of GP. Rate of growth and maximum cell density are independent of GP, and delayed growth in its absence appears due to a temporary ?"adjustment" rather than to selection of non-dependent mutant cells. The ratio of the growth time of cultures without GP to those with the factor increases from 1 to 3 as the size of the inoculum is decreased, or as the concentration of GP is increased from 0 to a maximum. Concentrations higher than 300 [mu]g GP per ml (as glucose) increase lag. An activity assay for GP factor is based upon the growth response (turbidity) of Bacillus globigii to graded doses within a limited incubation time. Thus it was determined that GP factor is non-volatile, thermostabile and acidic. It is adsorbed on charcoal, from which it is eluted partially by pyridine, and is partially extracted by ether, properties which distinguish it from the functionally similar GP factor for lactic acid bacteria. Assays of residual activity in chemically-treated concentrates (50-fold potency) indicate that GP factor possesses unsaturated bonds, at least one carboxyl and one hydroxyl, and that it is not phosphorylated.