Biochemical Factors Influencing Sporulation in a Strain of Bacillus Cereus

Abstract

The influence of the environment on the formation of bacterial endospores has only lately been reviewed comprehensively and expertly by Knaysi (1948), and it would be superfluous to repeat the literature coverage, except where special points have direct bearing on the work presented here. The foregoing authority summarizes (p. 63) his views of the subject as follows: "The conclusion that an endospore is formed by a healthy cell facing starvation is undoubtedly true for all strongly aerobic members of BaciUus....." This representation, suggested also by earlier workers (see Knaysi's review, 1948), is frequently encountered. Viewed in a different sense, a spore may be thought of as the end product of a series of enzymatic reactions in the proper balance and integrated toward the generation of the spore. If this hypothesis is correct, any circumstance disrupting this balance would interrupt sporogenesis at any one of a number of stages in the biochemical sequence. Furthermore, such a disruption could be a function of the nutritional environment, a situation analogous to numerous other physiological processes in cells. The experiments reported below are not inconsistent with these ideas. Also established is the point that sporogenesis is independent of growth and that the latter may be abundant, healthy, and starved, and yet fail to generate spores. METHODS The strain of BaciUus cereus used came from the departmental collection. Its identity was confirmed by a positive phospholipinase test (McGaughey and Chu, 1948). To secure unambiguous results, uniform and homogeneous physiological conditions for all cells in the cultures were adjudged as being a prime requisite in work of this nature. Incubation of broth cultures on a continuous shaking machine accomplishes this objective. It also accelerates markedly the rate and increases the final total percentage of spores in the culture as compared to identical flasks incubated in the conventional stationary manner. This was true of all 8 species of Bacillus tested in many different media, and the data of table 1 are representative of the effect. Incubation always was at 30 C. Loop samples were removed daily for 4 days; films were prepared and heat-fixed in the usual way. The spores were stained green and vegetative cells pink by the malachite 1 This paper reports research undertaken in cooperation with the Quartermaster Food and Container Institute for the Armed Forces. The views or conclusions contained in this report are those of the authors. They are not to be construed as necessarily reflecting the views or having the endorsement of the Department of the Army.

SOME EFFECTS OF ULTRAVIOLET RADIATION ON SPORULATING CULTURES OF BACILLUS CEREUS

“…The cultures were prepared by inoculating a glucose-glutamic acid salts medium (GGS) used by Foster and Heiligman (1949) with a standard spore suspension previously pasteurized at 65 C for 20 min. The cultures were incubated at suboptimal temperatures of about 20 C with vigorous aeration until the population reached a density of about 108 cells/ml.…”

Metabolite Reversal of Antibiotic Inhibition, Especially Reversal of Aureomycin Inhibition by Riboflavin

“…Reversal of aureomycin inhibition of other bacteria. Twelve different organisms which grew well in M-9 medium and which were sensitive to (Foster and Heiligman, 1949).…”

Survival and growth of Bacillus cereus in bread

“…7H20, 0.005; CuSO, . 5H20, 0.005; FeS0,.7H,O, 0.0005; (NH,),SO,, 2; pH 7.0 (Foster & Heligman 1949;Kim & Goepfert 1974).…”