Characterization of Bacillus cereus spores isolated from Algerian processed cheese

The main purpose of this study is to characterize the isolated Bacillus cereus spores from processed cheese manufactured and marketed in Algeria. Sixty samples of four brands of processed cheese were analyzed. The panC gene sequencing identified four B. cereus spores belonging to Group III, according to the classification of Guinebretiere et al. (2010). In nutrient broth, values ​​of D for B. cereus spores (LMBCF001, LMBCF002, LMBCF003, LMBCF004) vary between 4.76 min at 120°C and 93.75 min at 110°C and the values of ZT vary from 7.75 to 21.34°C. In processed cheese, D values ​​obtained for the isolated spores vary between 7.12 min at 120°C and 21.53 min at 110°C. The minimum pH obtained from the four isolated B. cereus spores varies between 4.70 and 5.10. Furthermore the minimum aw varies between 0.940 and 0.951. The studied revealed that processed cheese is contaminated by B. cereus spores in spite of the pasteurization or ultra-high temperature (UHT) treatment. The contamination origin can be raw material such as milk powder or starch or cheddar. The study focused on the importance of bringing out the presence of this Bacillus cereus in such products.