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The effect of recovery conditions on the apparent heat resistance of Bacillus cereus spores
Author(s) -
Gonzalez I.,
Lopez M.,
Mazas M.,
Gonzalez J.,
Bernardo A.
Publication year - 1995
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1995.tb03098.x
Subject(s) - spore , agar , bacillus cereus , subculture (biology) , incubation , heat resistance , nutrient agar , strain (injury) , food science , microbiology and biotechnology , cereus , agar plate , biology , bacillales , bacteria , materials science , biochemistry , bacillus subtilis , genetics , anatomy , composite material
The effect of recovery media and incubation temperature on the apparent heat resistance of three ATCC strains (4342, 7004 and 9818) of Bacillus cereus spores were studied. Nutrient Agar (NA), Tryptic Soy Agar (TSA), Plate Count Agar (PCA) and Milk Agar (MA) as the media and temperatures in the range of 15–40°C were used to recover heated spores. Higher counts of heat injured spores were obtained on PCA and NA. The optimum subculture temperature was about 5°C below the optimum temperature for unheated spores. No significant differences in heat resistance were observed with the different recovery conditions except for strains 4342 and 9818 when MA was used as plating medium. Large differences in D ‐values were found among the strains ( D 100 =0·28 min for 7004; D 100 =0·99 min for 4342; D 100 = 4·57 min for 9818). The 7004 strain showed a sub‐population with a greater heat resistance. The z values obtained for the three strains studied under the different recovery conditions were similar (7·64°C 0·25).