The effects of different plant extracts on bile salt hydrolase activity of Lactobacillus strains isolated from the gastrointestinal tract of poultry

The bile salt hydrolysis (BSH) enzyme weakens fat metabolism through bile salt deconjugation and reduces poultry performance, in order to cope with the antibacterial properties of the bile. Therefore, reducing the activity of this enzyme through the use of feed additives is probably a promising alternative to antibiotics for improving poultry performance. Plant extracts have long been used as feed additives for promoting poultry growth. In the current experiment, five Lactobacillus strains including Lactobacillus animalis, Lactobacillus acidophillus, Lactobacillus gallinarum, Lactobacillus lactis, and Lactobacillus returi were obtained from the poultry hindgut and were used as the probiotic application. A plate test and two-step enzymatic reaction method were used for deconjugation activity determination of the Lactobacillus strains. Further, four plant extracts (i.e., the aerial parts of Rosemary (Rosmarinus officinalis), Roselle calyx (Hibiscus sabdariffa), Berberis vulgaris root, and Green tea) were examined in terms of BSH enzyme inhibitors using the cell-free extracts as the potential antibiotic alternative. Furthermore, the gallbladders of the broilers were freshly collected from the poultry slaughterhouses, and their contents were extracted. The results showed that all Lactobacillus strains could hydrolyze the taurocholate acid (TCA) and chicken bile salt mixture (CBSM) to unconjugated bile acid. Moreover, ethanolic extracts of B. vulgaris root and Green tea relatively reduced the activity of the BSH enzyme that could potentially be investigated as an appropriate alternative in poultry feed in vivo. In conclusion, all five Lactobacillus strains were resistant to bile salts (i.e. TCA and CBSM) by BSH activity, and the addition of Green tea and B. vulgaris root extracts to the bacterial medium demonstrated inhibitory effects against the BSH enzyme.