In addition to forming spores, Bacillus thuringiensis (Bt) 4.0718 can produce toxins, insecticidal crystal protein (ICP) and vegetative insecticidal protein (Vip). The Bt spoIVA was successfully knocked out by gene recombination and was shown to inhibit sporulation. The mutant strain also exhibited significantly decreased growth and crystal formation, which inhibited spore formation and partially reduced the rate of crystal synthesis.

The 50 % lethal concentrations (LC₅₀) values of Bt 4.0718, replacement, complementation and multi-copy mutant strains against the fourth larval stage of H. armigera was determined as 5.422, 6.776, 6.223 and 5.018 μg/mL, respectively. A total of 1814 proteins were identified through isobaric tags for relative and absolute protein (iTRAQ), with 41 and 54 up and downregulated proteins observed. Gene ontology enrichment analysis showed that differentially expressed proteins were primarily involved in the biological process and molecular function. Quantitative real-time PCR analysis confirmed that 9 differential expressed genes exhibited a positive correlation between changes at transcriptional and translational levels. The results of this study provide a basis for further studies of the metabolic regulatory network of spores and crystal protein formation. Moreover, they can be used to ecologically safe insecticide of farmland production because the constructed Bt spoIVA mutants did not produce spores.Provides new ideas for the targeted improvement and application of environmentally friendly spore-free strains.

除形成孢子外，苏云金芽孢杆菌（Bt）4.0718还可产生毒素，杀虫晶体蛋白（ICP）和植物性杀虫蛋白（Vip）。Bt spoIVA通过基因重组成功敲除并显示出抑制孢子形成的作用。该突变菌株还表现出生长和晶体形成的显着降低，这抑制了孢子的形成并部分降低了晶体的合成速率。

针对棉铃虫第四幼虫期的Bt 4.0718，替代，互补和多拷贝突变菌株的50％致死浓度（LC ₅₀）值分别确定为5.422、6.776、6.223和5.018μg/ mL。通过同量异位标记为相对和绝对蛋白（iTRAQ）鉴定出总共1814个蛋白，观察到41和54个上调和下调蛋白。基因本体富集分析表明差异表达的蛋白质主要参与生物过程和分子功能。实时定量PCR分析证实9个差异表达基因在转录和翻译水平的变化之间表现出正相关。这项研究的结果为进一步研究孢子和晶体蛋白形成的代谢调控网络提供了基础。此外，由于构建的Bt spoIVA，它们可用于生态安全的农田生产杀虫剂 突变体不产生孢子。为有针对性地改良和应用环境友好型无孢子菌株提供了新思路。