BACKGROUND The insect gut microbiota has been shown to contribute to the host's digestion, detoxification, development, pathogen resistance, and physiology. However, there is poor information about the ranking of these roles. Most of these results were obtained with cultivable bacteria, whereas the bacterial physiology may be different between free-living and midgut-colonizing bacteria. In this study, we provided both proteomic and genomic evidence on the ranking of the roles of gut bacteria by investigating the anal droplets from a weevil, Cryptorhynchus lapathi. RESULTS The gut lumen and the anal droplets showed qualitatively and quantitatively different subsets of bacterial communities. The results of 16S rRNA sequencing showed that the gut lumen is dominated by Proteobacteria and Bacteroidetes, whereas the anal droplets are dominated by Proteobacteria. From the anal droplets, enzymes involved in 31 basic roles that belong to 7 super roles were identified by Q-TOF MS. The cooperation between the weevil and its gut bacteria was determined by reconstructing community pathway maps, which are defined in this study. A score was used to rank the gut bacterial roles. The results from the proteomic data indicate that the most dominant role of gut bacteria is amino acid biosynthesis, followed by protein digestion, energy metabolism, vitamin biosynthesis, lipid digestion, plant secondary metabolite (PSM) degradation, and carbohydrate digestion, while the order from the genomic data is amino acid biosynthesis, vitamin biosynthesis, lipid digestion, energy metabolism, protein digestion, PSM degradation, and carbohydrate digestion. The PCA results showed that the gut bacteria form functional groups from the point of view of either the basic role or super role, and the MFA results showed that there are functional variations among gut bacteria. In addition, the variations between the proteomic and genomic data, analyzed with the HMFA method from the point of view of either the bacterial community or individual bacterial species, are presented. CONCLUSION The most dominant role of gut bacteria is essential nutrient provisioning, followed by digestion and detoxification. The weevil plays a pioneering role in diet digestion and mainly digests macromolecules into smaller molecules which are then mainly digested by gut bacteria.

中文翻译：

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昆虫肠道细菌最主要的作用是：消化、解毒还是提供必需的营养？

背景技术昆虫肠道微生物群已被证明有助于宿主的消化、解毒、发育、病原体抗性和生理学。然而，有关这些角色排名的信息很少。这些结果大部分是通过可培养的细菌获得的，而自由生活的细菌和中肠定殖细菌之间的细菌生理学可能不同。在这项研究中，我们通过研究象鼻虫（Cryptorhynchus lapathi）的肛门飞沫，提供了关于肠道细菌作用排名的蛋白质组学和基因组学证据。结果肠腔和肛门液滴显示出定性和定量不同的细菌群落子集。16S rRNA测序结果显示，肠腔以Proteobacteria和Bacteroidetes为主，而肛门液滴以Proteobacteria为主。通过 Q-TOF MS 从肛门液滴中鉴定出参与 31 种基本作用（属于 7 个超级作用）的酶。象鼻虫与其肠道细菌之间的合作是通过重建本研究中定义的群落通路图来确定的。使用评分对肠道细菌的作用进行排名。蛋白质组数据结果表明，肠道细菌最主要的作用是氨基酸生物合成，其次是蛋白质消化、能量代谢、维生素生物合成、脂质消化、植物次级代谢产物（PSM）降解和碳水化合物消化，而顺序为基因组数据包括氨基酸生物合成、维生素生物合成、脂质消化、能量代谢、蛋白质消化、PSM降解和碳水化合物消化。PCA结果显示肠道细菌从基本作用或超级作用的角度形成功能群，MFA结果显示肠道细菌之间存在功能变异。此外，还介绍了从细菌群落或单个细菌物种的角度使用 HMFA 方法分析的蛋白质组和基因组数据之间的差异。结论 肠道细菌最主要的作用是提供必需的营养，其次是消化和解毒。象鼻虫在饮食消化中发挥着先锋作用，主要将大分子消化成小分子，然后主要被肠道细菌消化。