Effects of temperature on the spores of thermophilic actinomycetes

Abstract

The effects of temperature on the germination properties of spores of thermophilic actinomycetes were examined. Temperatures above and below the growth temperature of 55° C were found to produce marked changes in the germination properties of spores. High temperatures caused reductions in the germinative activities of spores. However, heated spore populations regained original germinative activities after maintaining them for suitable periods of time at 25°C. Recovery from the effects of heat on spore germination was also observed at 4°C, but at a much slower rate compared with 25°C. Spores of two strains of thermophilic actinomycetes, grown and prepared at 55°C, failed to germinate. Storage of dormant (nonactivated) spore populations at different temperatures demonstrated a low temperature requirement for the activation of these spores; while little or no activation occurred at 55°C, rapid activation took place at 25°C. Heating the spores at 80°C for 30 min slightly delayed the activation (rates) of spores at 25°C. The requirement of low temperature for spore activation was strain dependent and was influenced by the composition of the germination medium.