Major changes in microbial diversity and community composition across gut sections of a juvenile Panchlora cockroach

Investigations of gut microbiomes have shed light on the diversity and genetic content of these communities, and helped shape our understanding of how host-associated microorganisms influence host physiology, behavior, and health. Despite the importance of gut microbes to metazoans, our understanding of the changes in diversity and composition across the alimentary tract, and the source of the resident community are limited. Here, using community metagenomics and 16S rRNA gene sequencing, we assess microbial community diversity and coding potential in the foregut, midgut, and hindgut of a juvenile Panchlora cockroach, which resides in the refuse piles of the leaf-cutter ant species Atta colombica. We found a significant shift in the microbial community structure and coding potential throughout the three gut sections of Panchlora sp., and through comparison with previously generated metagenomes of the cockroach’s food source and niche, we reveal that this shift in microbial community composition is influenced by the ecosystems in which Panchlora sp. occurs. While the foregut is composed of microbes that likely originate from the symbiotic fungus gardens of the ants, the midgut and hindgut are composed of a microbial community that is likely cockroach-specific. Analogous to mammalian systems, the midgut and hindgut appear to be dominated by Firmicutes and Bacteroidetes with the capacity for polysaccharide degradation, suggesting they may assist in the degradation of dietary plant material. Our work underscores the prominence of community changes throughout gut microbiomes and highlights ecological factors that underpin the structure and function of the symbiotic microbial communities of metazoans.对肠道微生物组（gut microbiome）的研究已揭示了这类群落的多样性与遗传组成，并助力我们深化对宿主相关微生物调控宿主生理、行为与健康机制的认知。尽管肠道微生物对后生动物（metazoans）至关重要，但我们对整个消化道内微生物多样性与组成的变化规律，以及定植菌群的来源仍知之甚少。本研究借助群落宏基因组学（community metagenomics）与16S rRNA基因（16S rRNA gene）测序技术，对栖息于哥伦比亚切叶蚁（Atta colombica）垃圾堆中的幼年蔗蠊属（Panchlora）蟑螂的前肠、中肠与后肠内的微生物群落多样性及编码潜力进行了评估。研究发现，蔗蠊属（Panchlora sp.）三个肠道区段的微生物群落结构与编码潜力均存在显著差异；通过与该蟑螂食物来源及其栖息微环境的已报道宏基因组数据进行比对，我们揭示了该群落组成的变化受到其宿主生存生态系统的调控。前肠内的微生物大概率源自蚂蚁的共生真菌园，而中肠与后肠的微生物群落则很可能为蟑螂特异性菌群。与哺乳动物系统类似，该蟑螂的中肠与后肠似乎以具备多糖降解能力的厚壁菌门（Firmicutes）和拟杆菌门（Bacteroidetes）微生物为主，这提示这些菌群可能参与宿主膳食中植物材料的降解过程。本研究强调了肠道微生物组群落动态变化的普遍性，并揭示了支撑多细胞生物共生微生物群落结构与功能的关键生态因素。