Molecular identification of lantibiotic- producing Bacillus toyonensis isolated from soil and evaluation of its antibacterial activity

Lantibiotics are small peptide antibiotics that produced by a large number of gram positive bacteria to limit growth of other bacteria. This study was performed with the aim of isolation and molecular identification of lantibiotic producer Bacilli from soil, also to optimize the production conditions and antibacterial activity of the product.

In this basic research, soil samples were collected from green bean fields located at Kazerun. The vegetative cells were killed by pasteurization method and the Gram positive spore former colonies were selected for further studies. These bacteria were grown in the broth media and their culture extracts were examined for lantibiotic production by well diffusion method. Appropriate colonies with high ability for lantibiotic production were selected and identified by biochemical and molecular methods. Also lantibiotic production at different temperatures and pH values was investigated.

The isolated strain was identified as Bacillus toyonensis based on DNA sequencing. Maximum lantibiotic production was determined after 24h incubation at 30°C and pH 7. These results showed that the addition of 1% glucose and pepton can improve lantibiotic production. The purified lantibiotic showed inhibitory effects on some gram positive bacteria.

According to ability of this isolated strain in lantibiotic production, further studies is required for more accurate identification of produced lantibiotic in order to be employed in pharmaceutical applications.