Effect of the method of agitation on the accumulation of protective antigen in cultures of Bacillus anthracis.
Accumulation of protective antigen was essentially independent of culture volume, provided the organisms were kept in suspension by stirring. Agitation by orbited shaking was unsatisfactory.
Elaboration of Protective Antigen of Bacillus anthracis under Anaerobic Conditions
ELABORATION in vitro of the protective antigen of Bacillus anthracis in serum and plasma was first demonstrated by Gladstone1. Elaboration of the antigen in chemically defined, non-protein media was reported by Wright et al.2,3Z. The non-protein media facilitated practical production of the antigen, and permitted a basic study of its accumulation and properties. Antigen in the culture filtrate was precipitable with alum; the precipitated product was effective in immunization of animals and was well tolerated in man4–6. Elaboration of protective antigen in chemically defined media was confirmed by Belton and Strange7, who also devised a casein hydrolysate medium suitable for production of antigen.
STUDIES ON IMMUNITY IN ANTHRAX IV
Elaboration of the protective antigen of Bacillus anthracis in a chemically defined, nonprotein medium was described in a previous report from these laboratories (Wright et al., 1954). This medium, referred to as 528 medium, was composed of 17 amino acids, glutamine, adenine, guanine, uracil, thiamin, glucose, sodium bicarbonate, and inorganic salts. Sterile filtrates of cultures of B. anthracis in the medium produced effective immunity in rabbits, guinea pigs, and monkeys; the dose required to induce significant immunity in rabbits was of the same order as that of the edema fluid of anthrax lesions (Cromartie et al., 1947). Certain minor modifications in the composition of the medium markedly influenced the antigenic potency, suggesting that elaboration of antigen is associated with a particular type of metabolic activity of the organism. Further knowledge of the conditions for elaboration of antigen was desirable to facilitate production of antigen on a practical scale, to indicate the general relationship of antigen elaboration to growth of the organism, and to provide information desirable for investigating the existence and significance of extracellular antigens of this general type in other organisms. Certain relationships of constituents of the medium and conditions of growth to accumulation of protective antigen were therefore investigated in greater detail; considerable simplification and improvement of the medium and cultural conditions were found to be possible. The results suggest certain preliminary inferences regarding the metabolic processes associated with elaboration of antigen.