Isolation and identification of Bacillus cereus from fermented red pepper-soybean paste (Kochujang), and its heat resistance characteristics

To isolate Bacillus cereus presenting at a level of 5 log CFU/g in kochujang, a primary dilution (10^-1) of kochujang was heated at 85°C for 5 min. Two isolated strains Voges-Proskauer positive colony (KBC) and a negative colony (KBM) were identified as B. cereus and Bacillus mycoides, respectively, by biochemical test and 16S rDNA sequencing. D _100°C-Values of KBC and KBM strains was 8.37 and 7.08 min, respectively. When spores of KBC strain were inoculated to kochujang at the level of 4-5 log spores/g, the number of spores was no significant difference (p<0.05) for each sample from 1 up to 60 day of aging. When kochujang was inoculated with 4 log spores/g and heated at 85°C for 15 min, the number of spores was similar to that of unheated kochujang. Therefore, we estimated that B. cereus isolated from kochujang resistant on the heat treatment (85°C, 15 min) and its heat resistance characteristics could be used to count the number in kochujang.