Heterogeneity in Bacterial Spore Populations
Peter Setlow, Jintao Liu and James R. Faeder
from: Bacterial Spores: Current Research and Applications (Edited by: Ernesto Abel-Santos). Caister Academic Press, U.K. (2012)
Genetically identical populations of spores of Bacillus and Clostridium species invariably exhibit significant heterogeneity, including wide variation in individual spores' resistance to wet heat, speed of germination, and requirements for heat activation before germination. This heterogeneity appears due to both stochasticity in gene expression and variations in culture conditions during sporulation, and presumably facilitates the survival of spore populations. However, small percentages of individuals in spore populations that germinate extremely slowly (superdormant spores) or are much more resistant to environmental insults greatly complicates spore eradication in the food and health care industries. Recently a number of methods have been developed to simultaneously analyze the behavior and biochemical properties of multiple individual spores in populations, in particular their: i) response to wet heat; ii) germination; iii) levels of specific components including dipicolinic acid and individual proteins; and iv) protein status, whether native or denatured. Results using these methods have led to a much greater appreciation of the scope of spore heterogeneity. In addition, analysis of the germination of multiple individual spores has facilitated the development of a quantitative model for spore germination, and such a model suggests experiments to further elucidate the mechanism(s) of spore germination read more ...