Growth optimization of Bacillus subtilis 11A isolated from Indonesian native chicken (Gallus domesticus) for bacteriocin production

This study aimed to obtain the optimal growth of Bacillus subtilis 11A isolated from Indonesian native chicken (Gallus domesticus). The growth optimization included pH medium conditions (5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5) and different incubation temperatures (31, 33, 35, 37, 39, 41°C). Isolate was incubated for 12 hours using Luria Bertani broth. Optical density was observed using spectrophotometer (λ600) at 0 and 12 hours of incubations. Bacteriocin activity against pathogens Staphylococcus aureus, Salmonella typhimurium and Escherichia coli was determined using a well-diffused method. Data was statistically analyzed using a one-way analysis of variance (ANOVA) followed with Duncan's New Multiple Range Test (DMRT) to distinguish the treatment means. The results showed that the optimum pH for bacterial growth was at pH 6.5. Optimum temperature for bacterial growth was at 39°C. The highest bacteriocin activity of B. subtilis 11A against indicator pathogens was resulted at stationary phase (1906.14, 2179.79, 2343.07 AU/ml). It can be concluded that B. subtilis 11A isolated from Indonesian native chicken grew optimally for bacteriocin production at pH 6.5 and temperature 39°C. The highest bacteriocin production and activity produced by Bacillus subtilis 11A was at stationary phase.