Determination of fatty acid composition in Bacillus cereus isolated from dried milk products

A total of 34 presumptive Bacillus cereus cultures were isolated from dried milk products and confirmed on a selective chromogenic BACARA medium as B. cereus. Fatty acids from the colony's material were extracted using n-hexane and methylated with a KOH methanol solution yielding methyl esters. Fatty acids were separated using a gas chromatograph equipped with flame ionization using a 120 m BPX-70 column. A "Supelco 37 Component FAME Mix" reagent kit was used for the identification of fatty acids. Fatty acids produced by more than 50% of all investigated B. cereus were assumed as typical for these isolates. A total of 23 typical fatty acids were identified in B. cereus. There were significant differences in the amounts of fatty acids produced between B. cereus isolates. All B. cereus isolates produced butyric, palmitoleic, oleic and docosahexaenoic fatty acids in the largest amounts of the total fatty acid content. Ten of typical fatty acids in individual B. cereus isolates appeared as minor components and their amounts were less than 2% of the total fatty acid content. Cluster analysis closely related all the isolates. The main difference between the isolates clustered into two groups was the absence of capric and undecanoic fatty acids in group 2.