To obtain a more detailed understanding of organismal acid tolerance, the larval microbiomes of 11 Chironomus species collected from acidic or neutral pH areas in Japan and reared at pH 7-8 under laboratory conditions were systematically compared using an amplicon sequencing ana-lysis. Evenness values were lower for the larval microbiomes of acid-tolerant Chironomus cf. riparius, Chironomus fusciceps, and Chironomus sulfurosus than for eight acid-sensitive species based on an alpha diversity ana-lysis. The lower evenness observed suggested a biased abundance of microorganisms, which was consistent with the identification of Chironomus species-specific microorganisms (such as Agromyces mediolanus and Comamonas odontotermitis related bacteria) with high abundance in acid-tolerant larvae. The abundance of specific microorganisms was also high in the microbiome of acid-tolerant larvae of Chironomus acerbiphilus reared at pH 4, but not in that of acid-sensitive larvae. Based on a PICRUSt2 ana-lysis, genes involved in saccharide transport were less abundant in the microbiome of acid-tolerant larvae than in that of acid-sensitive larvae, indicating nutrient-poor acidic environments. Although these results were obtained from single datasets, acid-tolerant larvae appeared to establish Chironomus species-specific interactions with microorganisms independent of saccharides, in contrast to acid-sensitive larvae. The present study is the first step towards understanding organismal acid tolerance.

中文翻译：

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实验室条件下中性 pH 范围内饲养的耐酸摇蚊幼虫中的物种特异性微生物：单一数据集分析。

为了更详细地了解有机体的耐酸性，我们使用扩增子测序分析系统地比较了从日本酸性或中性 pH 地区收集并在 pH 7-8 的实验室条件下饲养的 11 种摇蚊幼虫微生物组。耐酸摇蚊幼虫微生物组的均匀度值较低。基于α多样性分析，河岸摇蚊、摇蚊和硫磺摇蚊与八种酸敏感物种相比。观察到的较低均匀度表明微生物丰度存在偏差，这与耐酸幼虫中具有高丰度的摇蚊属物种特异性微生物（例如中部农杆菌和齿白蚁丛毛菌相关细菌）的鉴定一致。在 pH 4 下饲养的摇蚊耐酸幼虫的微生物组中，特定微生物的丰度也很高，但在酸敏感幼虫的微生物组中则不然。根据 PICRUSt2 分析，耐酸幼虫微生物组中参与糖转运的基因比酸敏感幼虫微生物组中的含量少，这表明酸性环境营养贫乏。尽管这些结果是从单个数据集中获得的，但与酸敏感幼虫相比，耐酸幼虫似乎与独立于糖类的微生物建立了摇蚊物种特异性相互作用。本研究是了解有机体酸耐受性的第一步。