Studying the stability to antibiotics of bacteria of the genus Bacillus by serial breeding method

The purpose of the researches was studying the resistance to antibiotics of bacteria of genus Bacillus by method of serial dilutions. The results of the research on studying the sensitivity of probiotic microorganisms of Bacillus subtilis, Bacillus cereus and Bacillus licheniformis to antibiotics were presented. The sensitivity of microorganisms to the following antibiotics - chloramphenicol, tetracycline and gentamicin was determined. The antibiotic activity was determined by the value of its minimum inhibitory concentration, which caused a complete inhibition of spore germination. As a nutrient medium sterile decoction of wheat bran served. A basic antibiotic solution was prepared at the concentration of 160.0 μg/ml; working solutions were prepared from it with a 2-fold decrease in the concentration of the antibiotic at each subsequent dilution. Bacillus subtilis was found to be the most resistant to antibiotics, while Bacillus licheniformis had the lowest resistance...