State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, China.
College of Resources and Chemical Engineering, Sanming University, Sanming, Fujian, China.
Pest Manag Sci. 2023 Jun;79(6):2087-2097. doi: 10.1002/ps.7385. Epub 2023 Feb 18.
Bacillus thuringiensis (Bt) is a widely used microbial insecticide. However, its persistence is limited because of ultraviolet (UV) rays or other environmental factors. The yhfS gene, which encodes acetyl-CoA acyltransferase, plays an important role in lipid transport and metabolism in many organisms. To explore whether it is related to the stress resistance of Bt LLP29, the yhfS gene knockout strain LLP29 Δ-yhfS and the complementary strain LLP29 R-yhfS were generated successfully by homologous recombination technology, and the related phenotypic changes were compared in this study.
Gene yhfS was found to be functional in response to UV radiation in Bt by comparing the survival rates of Bt LLP29 harboring yhfS or not under UV light. Enzyme activity assays of key enzymes showed the the Embden-Meyerhof-Parnas pathway was enhanced yet the tricarboxylic acid cycle as well as butanoate synthesis were repressed when the gene was deleted. At the same time, the amino acid content was decreased, but reduced nicotinamide adenine dinucleotide (NADH) and reactive oxygen species (ROS) content were increased. Most noteworthy, antioxidase (such as superoxide dismutase and peroxidase) activities and contents of some potent antioxidants (such as pyruvate, carotenoids and NADPH) were lower in LLP29 Δ-yhfS than in LLP29.
These tests revealed that the loss of the yhfS gene led to metabolic disorders and reduction of the antioxidant ability of Bt. Higher ROS level and lower anti-oxidative capacity might be responsible for the reduced UV resistance when the gene was deleted. These results not only greatly enrich understanding of the mechanism of Bt UV resistance, but also provide an important theoretical basis for Bt application. © 2023 Society of Chemical Industry.
苏云金芽孢杆菌（Bt）是一种广泛使用的微生物杀虫剂。然而，由于紫外线（UV）射线或其他环境因素，其持久性有限。编码乙酰辅酶 A 酰基转移酶的 yhfS 基因在许多生物体的脂质运输和代谢中起着重要作用。为了探讨 yhfS 基因是否与 Bt LLP29 的应激抗性有关，本研究成功地利用同源重组技术生成了 yhfS 基因敲除株 LLP29Δ-yhfS 和互补株 LLP29R-yhfS，并比较了它们相关的表型变化。
通过比较携带 yhfS 基因和不携带 yhfS 基因的 Bt 在 UV 光下的存活率，发现 yhfS 基因在 Bt 中对 UV 辐射有功能。关键酶的酶活性测定表明，当基因缺失时，糖酵解途径增强，三羧酸循环以及丁酸盐合成受到抑制。同时，氨基酸含量减少，但还原型烟酰胺腺嘌呤二核苷酸（NADH）和活性氧（ROS）含量增加。最值得注意的是，抗氧化酶（如超氧化物歧化酶和过氧化物酶）的活性和一些强效抗氧化剂（如丙酮酸、类胡萝卜素和 NADPH）的含量在 LLP29Δ-yhfS 中低于 LLP29。
这些测试表明，yhfS 基因的缺失导致 Bt 的代谢紊乱和抗氧化能力降低。ROS 水平升高和抗氧化能力降低可能是基因缺失导致 UV 抗性降低的原因。这些结果不仅极大地丰富了对 Bt UV 抗性机制的理解，也为 Bt 的应用提供了重要的理论基础。© 2023 化学工业协会。
