Zhang Xiancui, Feng Huihui, He Jintao, Muhammad Abrar, Zhang Fan, Lu Xingmeng
College of Animal Sciences, Institute of Sericulture and Apiculture, Zhejiang University, Hangzhou, China.
Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Science, Shandong Normal University, Jinan, China.
Front Microbiol. 2022 Jun 24;13:921330. doi: 10.3389/fmicb.2022.921330. eCollection 2022.
The complex gut microbiome is a malleable microbial community that can undergo remodeling in response to many factors, including the gut environment and microbial properties. has emerged as one of the predominant gut commensal bacterial and plays a fundamental role in the host physiology and health of the major economic agricultural insect, Although extensive research on gut structure and microbiome diversity has been carried out, how these microbial consortia are established in multifarious niches within the gut has not been well characterized to date. Here, an species that was stably associated with its host, the model organism , was identified in the larval gut. GFP-tagged LX10 was constructed as a model bacterium to track the colonization mechanism in the intestine of . The results revealed that the minimum and optimum colonization results were obtained by feeding at doses of 10 CFU/silkworm and 10 CFU/silkworm, respectively, as confirmed by bioassays and fluorescence-activated cell sorting analyses (FACS). Furthermore, a comprehensive genome-wide exploration of signal sequences provided insight into the relevant colonization properties of LX10. LX10 grew well under alkaline conditions and stably reduced the intestinal pH through lactic acid production. Additionally, the genomic features responsible for lactic acid fermentation were characterized. We further expressed and purified bacteriocin and found that it was particularly effective against other gut bacteria, including , , , In addition, the successful colonization of LX10 led to drastically increased expression of all adhesion genes (, , , , , and ), defense genes (, and ), regulation gene (), secretion gene () and immune evasion genes ( and ), while the expression of iron acquisition genes ( and ) was largely unchanged or decreased. This work establishes an unprecedented conceptual model for understanding -gut microbiota interactions in an ecological context. Moreover, these results shed light on the molecular mechanisms of gut microbiota proliferation and colonization in the intestinal tract of this insect.
复杂的肠道微生物群是一个具有可塑性的微生物群落，可因应包括肠道环境和微生物特性在内的多种因素而发生重塑。已成为主要的肠道共生细菌之一，并在主要经济农业昆虫的宿主生理和健康中发挥着重要作用。尽管已经对肠道结构和微生物群多样性进行了广泛研究，但这些微生物群落如何在肠道内的多种生态位中建立，迄今为止尚未得到充分表征。在此，在幼虫肠道中鉴定出一种与其宿主——模式生物稳定相关的物种。构建了绿色荧光蛋白标记的LX10作为模型细菌，以追踪其在肠道中的定殖机制。生物测定和荧光激活细胞分选分析（FACS）证实，结果显示，分别以10 CFU/蚕和10 CFU/蚕的剂量喂食时，获得了最低和最佳定殖结果。此外，对信号序列进行全面的全基因组探索，深入了解了LX10的相关定殖特性。LX10在碱性条件下生长良好，并通过产生乳酸稳定降低肠道pH值。此外，还对负责乳酸发酵的基因组特征进行了表征。我们进一步表达并纯化了细菌素，发现它对其他肠道细菌特别有效，包括、、、。此外，LX10的成功定殖导致所有粘附基因（、、、、、和）、防御基因（和）、调节基因（）、分泌基因（）和免疫逃避基因（和）的表达大幅增加，而铁获取基因（和）的表达基本不变或下降。这项工作建立了一个前所未有的概念模型，用于在生态背景下理解肠道微生物群相互作用。此外，这些结果揭示了这种昆虫肠道中肠道微生物群增殖和定殖的分子机制。
