The Characterization of an Antagonistic Bacillus thuringiensis Strain Against Crop Pathogens and Pests

Abstract:

Bacillus thuringiensis strain 519-1 was tested for the antagonistic activity against the growth of hyphae of eight fungi including Aspergillium niger, Botrytis cinerea, Fusarium graminearum, Fusarium oxysporum, Penicillium chrysogenum, Physalospora piricola, Rhizoctonia solani, Rhizopus nigricans. It could notably inhibit sporangia germination of all the tested fungi. The culture of 519-1 exhibited high toxicity against Spodoptera exigua and Helicoverpa armigera, with LC50 values of 5.5 μg/mL and 12.5 μg/mL, respectively. PCR analysis with specific primers showed that the strain contained five insecticidal protein encoding genes: cry1Aa, cry1Ab, cry1Ac, cry1I, cry2 and a vegetative insecticidal protein gene, vip3A. Cry proteins with molecular weight about 135 kD~130 kD、95 kD、80 kD、70 kD and 65 kD~60 kD were detected using SDS-PAGE. The chitinase was expressed from the strain independent of any chitin. The results showed that Bt519-1 was a strain which had high activities of broad-spectrum antagonistic and high insecticidal toxicity against lepidopteran pests.