A. Palop et al., OCCURRENCE OF A HIGHLY HEAT-SENSITIVE SPORE SUBPOPULATION OF BACILLUS-COAGULANS STCC-4522 AND ITS CONVERSION TO A MORE HEAT-STABLE FORM, Applied and environmental microbiology, 63(6), 1997, pp. 2246-2251
The profile of the survival curves, at different heating temperatures,
of B. coagulans STCC 4522 sporulated at 52 degrees C has been studied
, focusing on the early moments of treatment. A highly heat-sensitive
spore subpopulation that includes more than 90% of the total spore pop
ulation has been found. This heat-sensitive spore fraction was inactiv
ated after 2 s of treatment at 111 degrees C. Its heat resistance was
as much as 200-fold lower than that of the heat-resistant spore fracti
on (D-111 degrees C of 0.01 min for the heat-sensitive spore fraction
compared with D-111 degrees C of 2 min for the heat-resistant fraction
). The shape of the survival curve at 108.5 degrees C was modified aft
er a sublethal heat shock at 80 degrees C for 3.5 h, resulting in a st
raight-line survival curve. The temperature of treatment also influenc
ed the shape of the survival curves. The conversion of the highly heat
-sensitive spore subpopulation to a more heat-stable form is discussed
.