State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Biopesticide Research Center, College of Life Sciences & College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
World J Microbiol Biotechnol. 2024 Nov 18;40(12):383. doi: 10.1007/s11274-024-04195-5.
Ultraviolet radiation (UV) is a major abiotic stress resulting in relative short duration of Bacillus thuringiensis (Bt) biopesticides in the field, which is expected to be solved by formation of Bt biofilm with higher UV resistance. Therefore, one of the important prerequisite works is to clarify the functions of biofilm-associated genes on biofilm formation and UV resistance of Bt. In this study, comparative genomics and bioinformatic analysis indicated that BTXL6_19475 gene involved in biofilm formation of Bt XL6 was likely to encode a galactose-1-phosphate uridylyltransferase (GalT, E.C. 2.7.7.12). Heterologous expression of the BTXL6_19475 gene in Escherichia coli and detection of its GalT enzyme activity in vitro proved that the gene did encode GalT. Comparing the wild type Bt strain XL6 with galT gene knockout mutant Bt XL6ΔgalT and its complementary strain Bt XL6ΔgalT::19,475, GalT promoted the biofilm formation and enhanced the UV-B resistance of Bt XL6 likely by increasing its D-ribose production and reducing its alanine aryldamidase activity. GalT did not affect the growth and the cell motility of Bt XL6. A regulation map had been proposed to elucidate how GalT promoted biofilm formation and enhanced UV-B resistance of Bt XL6 by the cross-talk between Leloir pathway, Embden-Meyerhof glycolysis pathway and pentose phosphate pathway. Our finding provides a theoretical basis for the efficient use of biofilm genes to improve the UV resistance of Bt biofilms and thus extend field duration of Bt formulations based on biofilm engineering.
紫外线（UV）是一种主要的非生物胁迫因素，导致苏云金芽孢杆菌（Bt）生物农药在田间的相对短暂存在，预计通过形成具有更高抗 UV 能力的 Bt 生物膜来解决这个问题。因此，重要的前提工作之一是阐明生物膜相关基因在 Bt 生物膜形成和抗 UV 中的功能。在本研究中，比较基因组学和生物信息学分析表明，BTXL6_19475 基因可能编码一种半乳糖-1-磷酸尿苷酰转移酶（GalT，E.C.2.7.7.12），参与 Bt XL6 的生物膜形成。在大肠杆菌中异源表达 BTXL6_19475 基因，并在体外检测其 GalT 酶活性，证明该基因确实编码 GalT。将野生型 Bt 菌株 XL6 与 galT 基因敲除突变体 Bt XL6ΔgalT 及其互补菌株 Bt XL6ΔgalT::19,475 进行比较，GalT 促进了 Bt XL6 的生物膜形成，并增强了其对 UV-B 的抗性，可能是通过增加其 D-核糖的产生和降低其丙氨酸芳基酰胺酶活性来实现的。GalT 不影响 Bt XL6 的生长和细胞迁移能力。提出了一个调控图来阐明 GalT 如何通过 Leloir 途径、Embden-Meyerhof 糖酵解途径和戊糖磷酸途径之间的相互作用来促进 Bt XL6 的生物膜形成和增强其对 UV-B 的抗性。我们的发现为有效利用生物膜基因来提高 Bt 生物膜的抗 UV 能力提供了理论依据，从而基于生物膜工程延长 Bt 制剂在田间的有效期。
