Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria.
Department of Anthropology, University of Oklahoma, Norman, OK, USA.
BMC Microbiol. 2019 Jul 17;19(1):164. doi: 10.1186/s12866-019-1540-5.
Termites are an important food resource for many human populations around the world, and are a good supply of nutrients. The fungus-farming 'higher' termite members of Macrotermitinae are also consumed by modern great apes and are implicated as critical dietary resources for early hominins. While the chemical nutritional composition of edible termites is well known, their microbiomes are unexplored in the context of human health. Here we sequenced the V4 region of the 16S rRNA gene of gut microbiota extracted from the whole intestinal tract of two Macrotermes sp. soldiers collected from the Limpopo region of South Africa.
Major and minor soldier subcastes of M. falciger exhibit consistent differences in taxonomic representation, and are variable in microbial presence and abundance patterns when compared to another edible but less preferred species, M. natalensis. Subcaste differences include alternate patterns in sulfate-reducing bacteria and methanogenic Euryarchaeota abundance, and differences in abundance between Alistipes and Ruminococcaceae. M. falciger minor soldiers and M. natalensis soldiers have similar microbial profiles, likely from close proximity to the termite worker castes, particularly during foraging and fungus garden cultivation. Compared with previously published termite and cockroach gut microbiome data, the taxonomic representation was generally split between termites that directly digest lignocellulose and humic substrates and those that consume a more distilled form of nutrition as with the omnivorous cockroaches and fungus-farming termites. Lastly, to determine if edible termites may point to a shared reservoir for rare bacterial taxa found in the gut microbiome of humans, we focused on the genus Treponema. The majority of Treponema sequences from edible termite gut microbiota most closely relate to species recovered from other termites or from environmental samples, except for one novel OTU strain, which clustered separately with Treponema found in hunter-gatherer human groups.
Macrotermes consumed by humans display special gut microbial arrangements that are atypical for a lignocellulose digesting invertebrate, but are instead suited to the simplified nutrition in the fungus-farmer diet. Our work brings to light the particular termite microbiome features that should be explored further as avenues in human health, agricultural sustainability, and evolutionary research.
白蚁是世界上许多人类群体的重要食物资源，也是营养物质的良好来源。真菌养殖的“高等”白蚁成员 Macrotermitinae 也被现代大型猿类食用，并被认为是早期人类的关键饮食资源。虽然可食用白蚁的化学营养成分众所周知，但它们的微生物组在人类健康方面尚未得到探索。在这里，我们从南非林波波地区收集的两种 Macrotermes sp. 士兵的整个肠道中提取了肠道微生物群的 16S rRNA 基因 V4 区域进行了测序。
M. falciger 的主要和次要兵蚁亚种在分类学表现上表现出一致的差异，并且与另一种可食用但不太受欢迎的物种 M. natalensis 相比，微生物的存在和丰度模式是可变的。亚种差异包括硫酸盐还原菌和产甲烷古菌丰度的交替模式，以及 Alistipes 和 Ruminococcaceae 之间的丰度差异。M. falciger 次要兵蚁和 M. natalensis 兵蚁具有相似的微生物特征，可能是由于它们与白蚁工蚁亚种的近距离接触，尤其是在觅食和真菌园培养期间。与以前发表的白蚁和蟑螂肠道微生物组数据相比，分类学表现通常分为直接消化木质纤维素和腐殖质底物的白蚁和消耗更纯净营养形式的白蚁，如杂食性蟑螂和真菌养殖白蚁。最后，为了确定可食用白蚁是否可能指向人类肠道微生物组中罕见细菌类群的共同储库，我们专注于 Treponema 属。可食用白蚁肠道微生物群中 Treponema 序列的大多数与从其他白蚁或环境样本中回收的物种最为密切相关，除了一个新的 OTU 菌株，它与在狩猎采集人群中发现的 Treponema 单独聚类。
人类食用的 Macrotermes 表现出特殊的肠道微生物排列，这对于消化木质纤维素的无脊椎动物来说是非典型的，但适合真菌养殖饮食中的简化营养。我们的工作揭示了特别的白蚁微生物组特征，这些特征应该作为人类健康、农业可持续性和进化研究的途径进一步探索。
