Abstract

In this study, the bacterial population dynamics during solid substrate fermentation of cassava at different time regimes was determined, and the Bacillus species isolated were identified phenotypically of probable identity as Bacillus subtilis (47%), Bacilluspumilus (26%) and Bacillus mycoides (27%). The bacterial population increased as fermentation progressed. 8.32 log₁₀ cfu/g at 0 h increased subsequently to 8.90 log₁₀cfu/g at 72 h for Atiba sample, and 8.28 - 8.80 log₁₀ cfu/g for Ijebu-Ode sample. The reduction in pH correlates with the increase in total titratable acidity (TTA) as being mediated by lactic acid bacteria (LAB). Diversity occurred in the antibiotic sensitivity pattern of the isolates. Nevertheless, all the isolates were resistant to gentamicin, ampiclox and zinnacef, and susceptible to ciprofloxacin. Caution should then be made not to include antibiotic resistance strains of Bacillus in the development of starter cultures or probiotic microorganisms for cassava fermentation as they may have the potential to transfer antibiotic resistance genes to intestinal pathogens. 

Key words: Gari, solid substrate fermentation, Bacillus species, antibiotics, α-amylase.