Screening a surfactin and iturin A producing strain and characterization of its lipopeptide products

Abstract:

After preliminarily isolated from soil of vegetable gardens by using blood-agar method, eight strains were further examined by oil-spreading test and inhibitory test. Primers were designed according to genes (sfp, ituD, lpa-14) related to surfactin and iturinA synthesis, and one bacterial strain XZ-173 with a broad spectrum of phytopathogens was screened out by PCR of the sfp, ituD, lpa-14 gene. Based on the physiological and biochemical properties and 16S rDNA sequence analysis, it was identified as Bacillus amyloliquefaciens. The FT-IR and HPLC results indicated that the biosurfactnat produced by strain XZ-173 was lipopeptides that contained surfactin and iturin A. The prepared crude lipopeptides reduced the surface tension of water to 26.6 mN/m with a critical micelle concentration (CMC) of 500 mg/L and showed stable emulsification capability and strong inhibition against Rhizoctonia solani and Ralstonia solanacearum. Lipopeptide-producing stain XZ-173 had potential to be used in biological control of soil-borne plant diseases.