Deconstruction of a multi-strain Bacillus-based probiotic used for poultry: an in vitro assessment of its individual components against C. perfringens

Objective: Probiotics have been used in poultry production to improve the performance and health of chickens raised without antibiotics. The combination of different probiotic strains has been used with the hope of conferring multiple benefits to the host. However, the inclusion of several strains does not necessarily boost benefits. There is a lack of studies that compare the efficacy of multi-strain probiotics to their individual components. In this study, the effects of a Bacillus-based probiotic product mix containing B. coagulans, B. licheniformis, B. pumilus, and B. subtilis against Clostridium perfringens were tested in vitro using a co-culture method. The individual strains and different combinations of the strains used in the product were also tested against C. perfringens. Results: The probiotic product mix tested in this study did not show effects against C. perfringens (P = 0.499). When tested individually, the strain of B. subtilis was the most efficient strain to decrease C. perfringens concentrations (P ≤ 0.01), and the addition of other Bacillus species strains significantly decreased its efficacy against C. perfringens. We concluded that the probiotic mix of Bacillus strains used in this study (B. coagulans, B. licheniformis, B. pumilus and B subtilis) was not effective in decreasing C. perfringens concentrations in vitro. However, when deconstructing the probiotic, the strain of B. subtilis alone or combined with the strain of B. licheniformis were effective against C. perfringens. This suggests that the anticlostridial properties of the particular strains of Bacillus used in this study were negatively affected when combined with other Bacillus spp. strains.