Abstract:
The probiotic potential of Bacillus strains isolated from cassava ferments was evaluated with a view to their use as starters. The objective of this study is to evaluate the resistance of Bacillus strains, notably B. amyloliquefaciens, B. subtilis; B. methylotrophicus; B. toyonensis; B. pumilus and B. vallismortis under conditions of acidic pH of the gastrointestinal tract (pH 2 and pH 3), bile salts (0.3%, 0.6% and 0.9%), temperatures (37 ° C and 45 °C every 4 hours and 24 hours), antibiotics (Amoxicillin, Ciprofaxine, Imipenem, Gentamycin, Penicillin, Oxacillin and Rifampicin) and their antibacterial activity against pathogenic bacteria (E. coli, S. aureus and Salmonella) as well as their biofilm formation capacity. The results of this study showed that all Bacillus strains resisted acidic pH with good growth where B. toyonensis and B. subtilis had the highest growth (9.00±1.06) × 107 CFU/mL at 4 hours and 24 hours (7.29±1.40) × 108 CFU/mL respectively at pH2. Also, at pH3, B. toyonensis showed the highest growth (5.14±0.15) × 108 CFU/mL at 4 hours and (1.14±0.22) × 108 CFU/mL at 24 hours. In addition, the bacteria used have good growth at 37°C and 44°C, knowing that their optimal growth temperature is 30°C. All Bacillus strains tested showed good growth at different concentrations of bile salts and resistance to the antibiotics tested with the exception of the strains B. amyloliquefaciens, B. pumilus and B. vallismortis which were sensitive to rifampicin with diameters inhibition of 21.5±0.76; 16.5±1.41 and 21±1.41 respectively. The vast majority of Bacillus strains inhibited more than half of pathogenic bacteria with the highest inhibition rate (96.7%) obtained with B. amyloliquefaciens and the lowest (50.15%) obtained with B. subtilis. The most inhibited pathogen was Salmonella (80.27%) and the least inhibited was E. coli (65.09%). Bacillus strains also showed a good capacity to form a biofilm with optical density (OD) values between 0.663±00 nm with B. methylotrophicus and 3.15±02 nm with B. vallismortis.
In this work, the public will remember that Bacillus strains derived from traditional cassava ferments can be used as a bank of Bacillus starters with strong probiotic potential. The study will make it possible to fight against poverty through the use of Bacillus starters at lower cost by the population and agri-food professionals. This study will be able to regulate the use of chemicals to control the proliferation of pathogens in food. Bacillus probiotics used are considered an alternative to antimicrobial stewardship programs. At the research level, other professors will be able to use the data from this study to expand their research and promote the development of international research teams through North-South knowledge transfer. This study is a practical solution through the use of Bacillus strains to help the endogenous flora of the intestinal tract and stomach by possessing antimicrobial activities against pathogens. In terms of health, this could warn populations of the beneficial effects of Bacillus probiotics derived from traditional cassava ferments which can improve the health of consumers.
Keywords: Traditional ferment, Cassava, Bacillus, Probiotic.
