Abstract
This study was carried out to screen for antimicrobial activities against common pathogenic and food spoilage bacteria, yeasts and molds, toxinogenic potential and sensitivity to antibiotics of 26 Bacillus strains (11 Bacillus subtilis, 5 Bacillus megaterium, 4 Bacillus amyloliquefaciens, 4 Bacillus pumilus and 2 Bacillus thuringiensis) isolated from different samples of Hibiscus sabdariffa fermented seeds (Mbuja). Antimicrobial assays were realised according to the cross-streak and the overlay methods. The main toxin and bacteriocin encoding genes were screened by PCR using specific primers and antibiotic resistance was assessed by the disc diffusion method. Bacillus species showed variable ability to inhibit bacterial and/or fungal species. The most antibacterial strains were B. amyloliquefaciens (S1 and S5) and B. subtilis (S12) whereas the most antifungal ones were B. megaterium S8 and S9. Subtilin and subtilosin A genes were detected in seven strains of B. subtilis but they were not associated with antimicrobial activities. All strains, except B. thuringiensis, did not contain toxin encoding genes and were sensitive to most tested antibiotics. This suggests that antimicrobial strains could be used in starter cultures for a controlled fermentation to produce Mbuja in order to better control the fermentation process of Mbuja and to increase consumer’s safety. Key words: Bacillus, antimicrobial activities, toxins, antibiotic resistance.
Highlights
H. sabdariffa seeds) (Mohamadou et al, 2009) and identified with molecular and phenotypic methods (Mohamadou et al, 2013). Their antimicrobial activity was investigated against 6 indicators or pathogenic bacteria
The antibacterial behaviour of Bacillus strains strongly varied between Bacillus strains and targets
Bacillus cereus ATCC6464 was inhibited by 14 strains, Listeria innocua HPB13 by 10 and
Summary
Mbuja is commonly used in the diet of people from the Sahelian region, especially for those living in rural areas with low incomes. The condiment is mostly appreciated for its nutritional value and organoleptic properties and it is used to flavour soups and sauces (Mohamadou et al., 2009). Earlier studies revealed that Mbuja could contribute to consumers’ health through its anti-oxidants and phenolic compounds (Mohamadou et al, 2007)
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