Incidence and characterization of Bacillus cereus isolated from traditional fermented meals in Nigeria

Abstract

The aim of this study was to examine the presence of Bacillus cereus in fermented meals used in food seasoning in Nigeria. The microbial profiles of iru and ogiri, two Nigerian fermented vegetable proteins, were examined for presence of B. cereus. In the 50 samples tested, B. cereus was detected in all the samples, with the level of detection ranging from log 6.3 to log 8.3 g -1 sample. Phenotypic characteristics of the B. cereus isolates showed that all of them could not ferment many sugars, most especially mannitol, but they utilized propionate citrate as a source of carbon and grew anaerobically. The isolates do not produce gas from glucose but hydrolyzed starch, casein, and gelatin. API-50CHB combined with API-20E identified the isolates as B. cereus. The diarrheal enterotoxin was detected by a reversed passive latex agglutination test kit. Results showed no significant difference in toxin production between ogiri and iru B. cereus isolated from different sources; all the isolates also demonstrated positive hemolytic activity. The API-ZYM enzyme profile showed that the strains have poor hydrolytic enzyme potential; hence, their possible contributions to the fermentation of vegetable protein is doubtful. This study established the proliferation of B. cereus in fermented protein meal and determined the diarrheal toxin production potential of the organism.