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Response of Micromonospora echinospora (NCIMB 12744) spores to heat treatment with evidence of a heat activation phenomenon
Author(s) -
Hoskisson P. A.,
Hobbs G.,
Sharples G. P.
Publication year - 2000
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1046/j.1472-765x.2000.00680.x
Subject(s) - spore , endospore , microbiology and biotechnology , biology , micromonospora , bacteria , d value , food science , botany , streptomyces , genetics
P.A. HOSKISSON, G. HOBBS and G.P. SHARPLES.2000. The effects of heat treatment on spores of the actinomycete Micromonospora echinospora were investigated. The percentage of culturable spores in untreated spore stocks was found to be approximately 20%. A 60 °C treatment of spores in phosphate buffer for 10 min led to an approximately five‐fold increase in the number of culturable units. This indicated that a large proportion of the spores were constitutively dormant. Within 10 min and in the absence of an external energy‐yielding substrate, the heat treatment was found to stimulate spore respiration suggesting that endogenous storage compounds were being utilized. Heating spores at 70 °C shortened the time period required for activation; holding times greater than 10 min, however, resulted in a reduction of culturable cells. Classic thermal death characteristics were seen at temperatures of 80 °C and above with d ‐values of 21·43, 2·67,0·45 and 0·09 min being recorded at 70, 80, 90 and 100 °C, respectively. Spores of this organism, while being weakly heat resistant in comparison with bacterial endospores, are significantly more resistant than vegetative cells.