Survival of kefir bacteria in an acid environment and in the presence of bile
2002
Usajewicz, I. (University of Warmia and Mazury, Olsztyn (Poland). Dept. of Industrial and Food Microbiology)
The survival of kefir streptococci and lactobacilli in the environment with pH 2, 2.5 and 3 in the presence of 3 percent of bile was studied. Both bacterial groups were characterized by similar sensivity to the acid reaction of the environment. In broth with pH 3 and 2.5 they survived 6 hour incubation at a temp. of 37 deg C in the quantities lower than the inoculum by ca. 1 and 2.5 log cycles respectively. At pH 2 a similar survival rate was observed after 2 hours incubation. Among ten strains of streptococci and lactobacilli, isolated from kefir culture and characterized by growth capability in the presence of 1 percent bile, only 6 were still able to growth at its 2 percent concentration. In broth containing 3 percent bile kefir bacteria survived 6-hour incubation at a temperature 37 deg C, but if before the process they were kept at pH 2.5 or 2, they died after 3 and 2 hours of incubation respectively
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