Display of B. pumilus chitinase on the surface of B. subtilis spore as a potential biopesticide

Chitinases can inhibit the growth of many fungal diseases which are a great threat for global agricultural production. Biological control of pathogens like fungi, is believed to be one of the best ways to eliminate the adverse effects of plant pathogens. To this end, we expressed and displayed a chitinase from Bacillus pumilus (ChiS) on the surface of Bacillus subtilis spores, as a biocontrol agent.ChiS enzyme from B. pumilus was expressed on the spores of B. subtilis using CotG as a carrier protein. Immunofluorescence microscopy confirmed the expression of ChiS on the surface of the spores. Enzyme activity assay showed that the surface displayed ChiS was active and was also able to inhibit the growth of Rhizoctonia solani and Trichoderma harzianum fungi. Western blot analysis also indicated that CotG-ChiS is partially processed after display. Molecular dynamics simulation showed that the stability of the heterologous protein was decreased after fusion.ChiS was successfully displayed on the surface of Bacillus spores by fusion to the CotG, one of the main spore coat proteins. In-vitro experiments showed that the displayed enzyme was effective in growth inhibition of R. solani and T. harzianum fungi.