Genomic and toxicity analysis of Lepidopteran toxic novel Bacillus thuringiensis strain T407

Bacillus thuringiensis is a gram-positive and spore-forming bacterium recognized for its pathogenicity against a broad spectrum of insect and nematode pests, and it has been extensively employed as a biopesticide. In this study, we examined the morphological, molecular, and genetic features of a native Bt isolate T407, which demonstrated significant toxicity against lepidopteran pests. Scanning Electron Microscopy confirmed the presence of bipyramidal and cuboidal-shaped crystals in T407. SDS-PAGE examination of spore-crystal mixtures revealed two significant protein bands at ∼135 and ∼ 65 kDa, representing Cry1 and Cry2 proteins. The presence of cry and vip gene combinations in T407 was confirmed by PCR analysis. Probit analysis estimates the LC₅₀ values of 0.771, 1.379, 2.038, and 14.997 μg/mL against Plutella xylostella, Helicoverpa armigera, Spodoptera litura, and Spodoptera frugiperda, respectively. The draft genome assembly of the Bt isolate T407 consists of 228 scaffolds, encompassing a total of 6,148,454 bp, with an N50 value of 93,189 bp. A total of 13 plasmids were identified in this genome through BLAST search similarity analysis. Similarly, 6631 protein-coding genes were identified in this genome with 53 tRNA, 4 rRNA, and 5 ncRNA genes. Similarly, a total of 11 insecticidal toxin proteins such as Cry1Ac5, Cry1Aa18, Cry1Ac5, Cry1Aa6, Cry1Ia42, Cry2Aa9, Cry2Ab41, Vip3Aa86, Mpp46Ab1, Vpb4Ca1, and Spp1Aa1 were identified in this Bt genome. In addition to insecticidal toxin genes few other toxin proteins like Zwa5A, Zwa5B, Zwa6, ChitinaseC, InhA1, InhA2, Enhancin, and Bmp1 also identified in this Bt genome.