ISOLATION, MOLECULAR CHARACTERIZATION, AND ANTIMICROBIAL ACTIVITY OF THE MEMBERS OF THE FAMILY BACILLACEAE OBTAINED FROM SOIL SAMPLES

Abstract

The soil is a very rich environment in terms of microorganism diversity and the microorganisms in the soil are the source for many secondary metabolites. Bacteria in the family Bacillaceae are commonly found in the soil and can maintain their vitality for many years because of their spore production. At the same time, the species in this family can produce secondary metabolites which have different functions. In this study, Bacillus or Bacillus-like bacteria were isolated from soil samples in wheat fields and they were identified based on their morphological and molecular features using 16S rRNA gene sequencing. In addition, the antimicrobial activities of the isolates were investigated against various important human pathogens. A total of twenty bacteria were isolated and all of them were identified as Bacillus sp., except for ES-18 which is Lysinibacillus xylanilyticus. Six isolates showed antibacterial activity at different levels and the most effective isolate, ES-18, showed antimicrobial activity against Bacillus cereus, B. megaterium, B. subtilis, Stapyhlococcus aureus, Enterococcus faecalis and Listeria monocytogenes. MIC values of the isolate ES-18 were also determined against the related bacteria and the highest dilution factor was determined to be 2-1. It was also determined that all effective dilutions were bacteriostatic. This is the first study showing antimicrobial properties of L. xylanilyticus and the results obtained from this study might be important for the discovery of new antimicrobial compounds.