MECHANICAL GERMINATION OF BACTERIAL SPORES

Abstract

A suspension of spores of Bacillus megaterium and ground glass particles was shaken in a Mickle tissue disintegrator under conditions in which physiological germination was precluded. Approximately 80 to 90% of the viable, colony-forming cells remaining after 12 to 24 min. shaking were heat sensitive, being killed in 20 min. at 65[degree]C. These "abraded" spores were nonrefractile, were stainable with bacteriological stains, were sensitive to a number of lethal agents, oxidized glucose and did not retain their dipicolinic acid and spore peptides. Time lapse photomicrographs showed the outgrowth of individual abraded spores. In all respects, the abraded spores were similar to physiologically germinated spores and they are regarded as mechanically germinated spores. The mechanism of mechanical germination is discussed in terms of a general theory of spores resistance based on the anhydrous state of the spores and its protection by a permeability barrier. Breaching the permeability barrier constitutes the prime event in germination. A striking tolerance to heat by lyophilized (anhydrous) vegetative cells of B. megaterium, as shown by quantitative viability counts, is presented in support of the anhydration theory.