苏云金芽孢杆菌是应用最广泛的生物农药,目标是属于几个订单的多种害虫。然而,有关苏云金芽孢杆菌菌株和毒素的信息非常有限。因此,在本研究中,我们分离并鉴定了五种对瓜科幼虫有毒的本地苏云金芽孢杆菌菌株。然而,与参考菌株苏云金芽孢杆菌var相比,五个菌株NBAIRBtPl的死亡率最高(LC50=37.3μg/mL)。以色列(4Q1)(LC50=45.41μg/mL)。因此,NBAIRBtPl被考虑用于全基因组测序以鉴定其中存在的cry基因。我们的菌株的全基因组测序显示基因组大小为6.87Mb,GC含量为34.95%。通过BLAST算法进行的同源性搜索显示,NBAIRBtPl与苏云金芽孢杆菌血清型tolworthi相似度为99.8%,通过Prokka的基因预测揭示了7406个基因,7168种蛋白质,5个rRNAs,和66个tRNA。BtToxin_Digger对NBAIRBtPl基因组的分析揭示了四个cry基因家族:cry1,cry2,cry8Aa1和cry70Aa1。当在其他本地菌株中测试这四个cry基因的存在时,结果显示cry70Aa1缺失。因此,该研究为预测cry70Aa1可能是毒性的原因提供了依据。在这项研究中,除了新的基因,我们还鉴定了其他编码两性霉素的毒力基因,几丁质酶,芬霉素,和杆菌素。因此,目前的研究有助于预测潜在的毒素编码基因对Z.cucurbatae的毒性,从而为开发基于苏云金芽孢杆菌的配方和转基因作物以管理双翅目害虫铺平了道路。
Bacillus thuringiensis is the most widely used biopesticide, targets a diversity of insect pests belonging to several orders. However, information regarding the B. thuringiensis strains and toxins targeting Zeugodacus cucurbitae is very limited. Therefore, in the present study, we isolated and identified five indigenous B. thuringiensisstrains toxic to larvae of Z. cucurbitae. However, of five strains NBAIR BtPl displayed the highest mortality (LC50 = 37.3 μg/mL) than reference strain B. thuringiensis var. israelensis (4Q1) (LC50 = 45.41 μg/mL). Therefore, the NBAIR BtPl was considered for whole genome sequencing to identify the cry genes present in it. Whole genome sequencing of our strain revealed genome size of 6.87 Mb with 34.95% GC content. Homology search through the BLAST algorithm revealed that NBAIR BtPl is 99.8% similar to B. thuringiensis serovar tolworthi, and gene prediction through Prokka revealed 7406 genes, 7168 proteins, 5 rRNAs, and 66 tRNAs. BtToxin_Digger analysis of NBAIR BtPl genome revealed four cry gene families: cry1, cry2, cry8Aa1, and cry70Aa1. When tested for the presence of these four cry genes in other indigenous strains, results showed that cry70Aa1 was absent. Thus, the study provided a basis for predicting cry70Aa1 be the possible reason for toxicity. In this study apart from novel genes, we also identified other virulent genes encoding zwittermicin, chitinase, fengycin, and bacillibactin. Thus, the current study aids in predicting potential toxin-encoding genes responsible for toxicity to Z. cucurbitae and thus paves the way for the development of B. thuringiensis-based formulations and transgenic crops for management of dipteran pests.