Probiotic Potential of Bacillus Strains Isolated from Traditional Cassava Ferments (Manihot esculenta Crantz)

ABSTRACT: Probiotic potentials of Bacillus strains isolated from traditional cassava ferments, notably their growth at different pH, bile salts, temperatures, NaCl and antibiotics, their inhibition of pathogenic bacteria, non-production of hemolytic enzymes as well as the formation of biofilm were studied. These different probiotic parameters were determined according to the referenced methods. The results obtained showed that all Bacillus strains resisted acidic pH with the highest growths (7.29± 1.40) × 108 CFU/mL and (5.14±0.15) × 108 CFU /mL obtained with Bacillus toyonensis respectively at pH 2 for 24 hours and at pH 3 for 4 hours. All Bacillus strains grow well at 37°C and 44°C, despite their optimum growth temperature of 30°C. They also showed good growth at different bile salt concentrations and were multi-resistance to antibiotics Ciprofloxacin (100%), as was B. subtilis to Rifampicin (100%) but they were multi-sensitive (100%) to Amoxicillin, Imipenem, Gentamycin, Penicillin, Vancomycin, Chloramphenicol and Rifampicin except B. pumilus and B. methylotrophicus which were sensitive to Rifampicin (77%). Bacillus strains inhibited more than half of the pathogens (80.27% with S. aureus and 65.09% with E. coli). No strain showed hemolytic activity but rather a good capacity to form a biofilm (optical density ranging from 0.663 ± 00 to 3.15 ± 02 nm).