Probiotic Assessment of Bacillus Species Isolated from Soil Samples

Antibiotic use in poultry production to treat infections caused by bacteria has led to antibiotic resistance. Many countries have resorted to banning antibiotics in livestock rearing. Probiotics can be used as an alternative to antibiotics as they have the potential to boost bird health and aid in the production of safe consumable produce. The study aimed to isolate Bacillus spp. from samples collected from the vegetable garden, sewage works site, maize milling site, and chicken coop soil. Four isolates were subjected to probiotic screening test. One isolate was further characterized according to 16S gene sequencing. The tested Bacillus spp. indicated resistance to low pH, gastric juice, bile salts and negative test to haemolysis. The isolates exhibited broad spectrum antimicrobial potency against E. coli, Salmonella Typhi, and Staphylococcus aureus. Three Bacillus spp. were resistant to at least one tested antibiotic, while Bacillus PW3 was susceptible to all antibiotics. Further characterization of one Bacillus isolate was done by PCR amplification and sequencing of the 16S rDNA gene. The results confirmed this isolate as Bacillus-related spp. and closely related to Bacillus velezensis. Bacillus PW1 and Bacillus GM3 exhibited potential probiotic characteristics and potential for use in poultry production.