Zhao Dan, Wu Han, Li Yazi, Wang Qian, Ji Yujie, Guo Xiaochang, Guo Wei
College of Plant Protection, Hebei Agricultural University, Baoding, China.
Graduate School of Chinese Academy of Agricultural Sciences, Beijing, China.
Front Microbiol. 2023 Jun 2;14:1182699. doi: 10.3389/fmicb.2023.1182699. eCollection 2023.
The gut microbiota is essential for the growth and development of insects, and the intestinal immune system plays a critical role in regulating the homeostasis of intestinal microorganisms and their interactions with pathogenic bacteria. Infection with (Bt) can disrupt the gut microbiota of insects, but the regulatory factors governing the interaction between Bt and gut bacteria are not well understood. Uracil secreted by exogenous pathogenic bacteria can activate DUOX-mediated reactive oxygen species (ROS) production, which helps maintain intestinal microbial homeostasis and immune balance. To elucidate the regulatory genes involved in the interaction between Bt and gut microbiota, we investigate the effects of uracil derived from Bt on gut microbiota, and host immunity using a uracil deficient Bt strain (Bt GS57△) obtained by homologous recombination. We analyze the biological characteristics of the uracil deficient strain and found that the deletion of uracil in Bt GS57 strain changed the diversity of gut bacteria in , as investigated using Illumina HiSeq sequencing. Furthermore, qRT-PCR analysis showed that compared with Bt GS57 (control), the expression of the SeDuox gene and the level of ROS were significantly decreased after feeding with Bt GS57△. Adding uracil to Bt GS57△ restored the expression level of DUOX and ROS to a higher level. Additionally, we observed that , and genes were significant different in the midgut of infected by Bt GS57 and Bt GS57△, with a trend of increasing first and then decreasing. These results suggest that uracil regulates and activates the DUOX-ROS system, affects the expression of antimicrobial peptide genes, and disturb intestinal microbial homeostasis. We preliminarily speculate that uracil is a key factor in the interaction between Bt and gut microbiota, and these findings provide a theoretical basis for clarifying the interaction between Bt, host, and intestinal microorganisms, as well as for gaining new insights into the insecticidal mechanism of in insects.
肠道微生物群对昆虫的生长和发育至关重要，肠道免疫系统在调节肠道微生物的稳态及其与病原菌的相互作用中起着关键作用。苏云金芽孢杆菌（Bt）感染会破坏昆虫的肠道微生物群，但Bt与肠道细菌之间相互作用的调控因子尚不清楚。外源病原菌分泌的尿嘧啶可激活双氧化酶（DUOX）介导的活性氧（ROS）生成，这有助于维持肠道微生物稳态和免疫平衡。为了阐明参与Bt与肠道微生物群相互作用的调控基因，我们使用通过同源重组获得的尿嘧啶缺陷型Bt菌株（Bt GS57△），研究了Bt来源的尿嘧啶对肠道微生物群和宿主免疫的影响。我们分析了尿嘧啶缺陷型菌株的生物学特性，发现使用Illumina HiSeq测序法研究表明，Bt GS57菌株中尿嘧啶的缺失改变了[昆虫名称]肠道细菌的多样性。此外，qRT-PCR分析表明，与Bt GS57（对照）相比，用Bt GS57△喂食后，SeDuox基因的表达和ROS水平显著降低。向Bt GS57△中添加尿嘧啶可将DUOX和ROS的表达水平恢复到更高水平。此外，我们观察到，[基因名称]基因在受Bt GS57和Bt GS57△感染的[昆虫名称]中肠中存在显著差异，呈现先升高后降低的趋势。这些结果表明，尿嘧啶调节并激活DUOX-ROS系统，影响抗菌肽基因的表达，并扰乱肠道微生物稳态。我们初步推测尿嘧啶是Bt与肠道微生物群相互作用的关键因素，这些发现为阐明Bt、宿主和肠道微生物之间的相互作用以及深入了解[Bt在昆虫中的杀虫机制]提供了理论依据。
