Biosurfactant lipopeptides and polyketide biosynthetic gene in rhizobacterium Achromobacter kerstersii to induce systemic resistance in tomatoes

Discovery of novel fungicides for disease management improve on our panoply of known pharmaceuticals. The prime mechanisms of action of agricultural fungicides are by pathogen antagonism or destruction and induced plant systemic resistance. In this study, we describe lipopeptides from tomato rhizobacterium, Achromobacter kerstersii JKP9 exhibiting effective antagonism to Fusarium wilt. Induced systemic resistance potentials were screened after inoculation of bioactive rhizosphere bacterial consortium (Mycoclear) into tomato rhizosphere. Mild biosurfactant properties were observed in drop collapse, and oil displacement assays. The isolated lipopeptides were chemically characterized using FT-IR, HR-NMR. Fatty acid tails were profiled by GC-MS/MS and lipopeptide types were predicted in LC-MS/MS. Polyketide synthase II gene (PKS2) for antibiotic biosynthesis was detected in Achromobacter kerstersii JKP9. Fungal membrane damages and cell wall disruptions due to the interactions of lipopeptides were studied using live/dead fluorescent probes in a dosage-dependent manner. The characterized lipopeptides exhibited broad spectrum of antifungal action against virulent Fusarium spp. and Sarocladium sp. Hence, our findings support cultivable rhizobacteria and their lipopeptides, as promising rhizotechnological tools, rather than synthetics to warrant wilt-free landscape for agriculture.