Molecular and biochemical characterization of surfactin producing Bacillus species antagonistic to Colletotrichum falcatum Went causing sugarcane red rot

Abstract

Bacillus species suppress phytopathogens by producing lipopeptide antibiotics, hydrolytic enzymes, siderophores and other secondary metabolites. Three bacterial strains Bacillus subtilis NH-100 (EU627167), B. subtilis NH-160 (EU627169) and Bacillus sp. NH-217 (EU627170) with proven ability to suppress red rot disease on sugarcane plants were further characterized to elucidate the multiple modes of action involved in their biocontrol activity. Plate assays pointed out the production of protease and antibiotics. Lipopeptide antibiotic surfactin was detected in the culture extract of B. subtilis NH-160 and Bacillus sp. NH-217 through LC-MS (Liquid chromatography - mass spectrometry). These results were further supported by identifying the presence of sfp and srfAC genes of surfactin biosynthetic operon using specific polymerase chain reaction (PCR) primers. Two strains B. subtilis NH-160 and Bacillus sp. NH-217 were further analyzed for their survival in compost which successfully retained consistency in their population 4.0 - 5.0 log CFUg -1 after 14th day. Bacteria capable of suppressing pathogens and maintaining their population by competing with other microbes can be successfully utilized as biopesticide for sustainable organic farming. © 2010 Academic Journals