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

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.

KEYWORDS:

• Antibiotics
• broilers
• FCR
• probiotics
• Salmonella

Acknowledgments

The authors would like to thank the Can Tho Department of Science and Technology for financial support of this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).