Inhibition of Salmonalla enterica by a novel strain of Bacillus subtilis isolated from the faeces of healthy chickens

Abstract

ABSTRACT 1. The objective of the study was to demonstrate that Bacillus subtilis strain VL28 (BS-VL28), a novel strain isolated from faeces of healthy chicken, has potential as a probiotic. 2. The study evaluated the probiotic properties of BS-VL28 and the effects of dietary supplementation of this strain on growth performance and mortality in chickens challenged with Salmonella enterica CT01. 3. BS-VL28 exhibited a specific inhibitory activity against Escherichia coli CT11, Salmonella enterica CT01, Staphylococcus spp. CT21 and Streptococcus spp. CT31. 4. BS-VL28 also showed an auto-aggregation percentage of 82%, co-aggregation activity greater than 60%, high tolerance to low pH (<2.0) under the presence of 0.05% bile salts. However, the results from the antibiotic susceptibility tests demonstrated that this strain was sensitive to erythromycin, gentamycin, doxycycline, norfloxacin, oxytetracycline, trimethoprim-sulfamethoxazole, enrofloxacin but was intermediate to neomycin. 5. Inclusion of probiotic (5 g BS-VL28 (107 CFU/g) per kg of feed to diet of challenged chickens showed better performance and feed conversion rates (FCR). There was a significant decrease (p < 0.05) in mortality in the probiotic-treated group compared to the control and antibiotic-treated groups. 6. From these results, BS-VL28 could potentially function as a probiotic for broilers.