Isolation and optimization of bacillus amyloliquefaciens, bascillus cereus, and lactobacillus plantarum

Abstract

Attempts were made to optimize bacterial growth in pure cultures of Lactobacillus plantarum, Bacillus cereus, Bacillus amyloliquefaciens. These bacteria were isolated from shrimps’s intestine, water samples from shrimp ponds and a commercial probiotic product. Two media were used De Man Rogosa Sharpe (MRS) for Lactobacillus sp. and Trypton soy agar (TSA) or Trypton Soy broth (TSB) for Bacillus sp. Then, they were optimized growth conditions (pH, time incubation, salinity), and checked antimicrobial activity. Results showed that the most suitable pH of Lactobacillus plantarum, Bacillus amyloliquefaciens and Bacillus cereus were between 6 and 8. Log phase of three strains began during first 20 hours, and only Lactobacillus plantarum tolerated with high salinity. Furhtermore, Lactobacillus plantarum has ability to inhibit Escherichia coli and Staphylococcus aureus. Key words: Lactobacillus plantarum, Bacillus cereus, Bacillus amyloliquefaciens, isolation, culture condition, antimicrobial activity.