Identification of Antagonistic Bacterium SB1 and Analysis on Its Antibacterial Substance

Abstract:

A bacterial strain SB1, isolated from tomato roots, was tested for its antimicrobial activities. Results indicated that strain SB1 showed strong inhibitory activities against various plant pathogenic fungi and pathogenic bacteria, exhibiting wide antimicrobial spectrum. Strain SB1 was identified as Bacillus subtilis subsp. endophyticus based on its morphological, physiological characteristics and 16S rDNA sequence. In addition, properties of antibacterial substances of strain SB1 were examined using Ralstonia solanacearum as an indicator. The results showed that antibacterial substances were heat-stable, water-soluble, alcohol-soluble, and resistant to ultraviolet radiation and protease K. High performance liquid chromatography (HPLC) results further suggested that one of the antibacterial substances was surfactin.