Okinawa Institute of Science & Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa, 904-0495, Japan.
Faculty of Tropical AgriSciences, Czech University of Life Sciences, Prague, Czech Republic.
Microbiome. 2022 May 27;10(1):78. doi: 10.1186/s40168-022-01258-3.
Termites primarily feed on lignocellulose or soil in association with specific gut microbes. The functioning of the termite gut microbiota is partly understood in a handful of wood-feeding pest species but remains largely unknown in other taxa. We intend to fill this gap and provide a global understanding of the functional evolution of termite gut microbiota.
We sequenced the gut metagenomes of 145 samples representative of the termite diversity. We show that the prokaryotic fraction of the gut microbiota of all termites possesses similar genes for carbohydrate and nitrogen metabolisms, in proportions varying with termite phylogenetic position and diet. The presence of a conserved set of gut prokaryotic genes implies that essential nutritional functions were present in the ancestor of modern termites. Furthermore, the abundance of these genes largely correlated with the host phylogeny. Finally, we found that the adaptation to a diet of soil by some termite lineages was accompanied by a change in the stoichiometry of genes involved in important nutritional functions rather than by the acquisition of new genes and pathways.
Our results reveal that the composition and function of termite gut prokaryotic communities have been remarkably conserved since termites first appeared ~ 150 million years ago. Therefore, the "world's smallest bioreactor" has been operating as a multipartite symbiosis composed of termites, archaea, bacteria, and cellulolytic flagellates since its inception. Video Abstract.
白蚁主要以木质纤维素或土壤为食，并与特定的肠道微生物共生。在少数几种以木材为食的害虫物种中，白蚁肠道微生物群的功能部分被了解，但在其他分类群中仍知之甚少。我们旨在填补这一空白，并提供对白蚁肠道微生物群功能进化的全球理解。
我们对 145 个代表白蚁多样性的样本的肠道宏基因组进行了测序。我们表明，所有白蚁肠道微生物群的原核部分都具有相似的碳水化合物和氮代谢基因，其比例随白蚁系统发育位置和饮食而变化。肠道原核基因的存在表明，现代白蚁的祖先就具有必需的营养功能。此外，这些基因的丰度与宿主的系统发育高度相关。最后，我们发现，一些白蚁谱系适应土壤饮食的同时，参与重要营养功能的基因的化学计量也发生了变化，而不是获得新的基因和途径。
我们的研究结果表明，自 1.5 亿年前白蚁首次出现以来，白蚁肠道原核生物群落的组成和功能一直保持着惊人的保守性。因此，自诞生以来，“世界上最小的生物反应器”一直作为一个由白蚁、古菌、细菌和纤维素鞭毛虫组成的多共生体运作。
