Characterization of Bacillus Cereus Isolates From Raw Soybean Sprouts

Characterization of Bacillus cereus isolates from raw soybean sprouts
May 2004
Journal of Food Protection Vol. 67, No. 5
Kim H-J.[1]; Lee D.S.[1]; Paik H-D.[2]
[1] Division of Life Sciences, Kyungnam University, Masan 631-701, Korea [2] Division of Animal Life Science, Konkuk University, Seoul 143-701, Korea

Raw soybean sprouts, which are used as ingredients in cook-chilled products, were analyzed to evaluate the incidence of mesophilic aerobic microorganisms, psychrotrophic microorganisms, anaerobic microorganisms, coliforms, and spore-forming microorganisms Bacillus cereus, Clostridium botulinum, and Clostridium perfringens. Mesophilic microorganisms on raw soybean sprouts were present in large populations, 5.5 å~ 106 to 1.4 å~ 108 CFU/g, and psychrotrophic microorganisms were found to be more numerous than the other groups. Coliforms accounted for 15% of mesophilic microorganism counts on average, and the average for spore-forming microorganisms was 5.2 å~ 102 CFU/g. B. cereus was isolated from 12 of 17 soybean sprout samples, whereas C. botulinum and C. perfringens were not isolated. B. cereus was isolated in greater numbers at 30°C compared with other temperatures and was not isolated at 4°C. Of the 55 strains isolated from soybean sprouts, 52 were positive for starch hydrolysis, and only 3 strains did not hydrolyze starch. Among the 55 strains of B. cereus isolates, 53 showed the ability to produce diarrheal enterotoxin by CRET-RPLA.