Effect of enzyme inhibitors on the germination and respiration of and growth from Bacillus cereus var. terminalis spores.

The resting bacterial spore is characterized by its unique resistance to destruction by high temperatures and the inability to take up stain. However, when incubated in the proper nutrient medium, it rapidly undergoes several changes without loss of viability. -These changes, collectively known as germination, include, among others, loss of heat resistance, ability to take up stain, decrease in refractive index and a sudden increase in metabolic rate. In our work the first three (also accepted by several other workers in the field, particularly those working on the biochemical nature of germination) were used as the criteria of germination. The specific germination requirements vary with the species, strain, history of the spores, treatment given the spores prior to incubation in the nutrient medium etc. (Hills, 1950; Powell, 1950; Powell and Hunter, 1955; Levinson and Sevag, 1953; and Hachisuka et al., 1955a). Nevertheless, most aerobic bacterial spores rapidly germinate when incubated at 30 to 35 C in a simple, chemically defined. buffered or unbuffered medium consisting of single amino acids and/or adenosine or glucose, after heating for 10 to 15 min at 60 to 65 C (Hills, 1949a, b; Powell, 1951). Stewart and Halvorson (1953) found that a heat shocked suspension of spores (108 spores per ml) of B. cerets var. terminalis (B. terminalis) germinated rapidly and nearly completely when incubated in 67 mm of pyrophosphate at pH 8.3, 6 mm of L-alanine and 12,moles of adenosine. Church (1955) found that these spores germinated equally well in an unbuffered medium. The spores used in this investigation, produced in a metal pilot plant, failed to germinate normally in unbuffered L-alanine and adenosine. This inhibition was believed to be due to metal contamination. As a consequence the effects of various netal ions and sequestering agents on the germi-