ECOLOGICAL AND MOLECULAR ASPECTS OF LIGNOCELLULOSE DIGESTION IN NEOTROPICAL HIGHER TERMITES

Due to their ability in digesting lignocellulose, termites are key organisms in the ecosystems that maintain carbon balance and incorporate organic matter into the soil. They are also considered the world's smallest bioreactors. The evolution of termites was marked by modifications on symbiont composition and acquisition of new feeding strategies that improved the digestion of lignocellulose resulting in the diversification of food sources. Nevertheless, some aspects of lignocellulose digestion in neotropical species are poorly known and studies are necessary to further comprehend their impact on the environment and their potential in the new bioeconomy. The aim of this proposal will be to study the digestion of lignocellulose and the community structure of the symbiotic microbiota in six species of neotropical higher termites by integrating ecological and molecular analyses. We will first compare microbiota functions of Cornitermes cumulans based on metagenomics and metatranscriptomic analyses. Then we will evaluate the activity of lignocellulases and the microbial community composition by six species of higher termites with different feeding strategies using enzymatic assays and 16S and ITS sequencing. We suggest that C. cumulans stores food in order to facilitate the digestion of lignocellulose by soil microorganisms before ingestion. In addition, both lignocellulose digestion and microbiota functional composition will be different according to termite feeding specialization. The results of this study will be significant to further understand the symbiotic relationship between the microbiota and termites.

鉴于白蚁具备降解木质纤维素(lignocellulose)的能力，它们是维持生态系统碳平衡、将有机质融入土壤的关键物种，同时也被视作全球最小的生物反应器(bioreactors)。白蚁的演化以共生体(symbiont)组成的改变与新型取食策略的获得为核心特征——这些变化提升了木质纤维素的降解效率，进而推动了其食物来源的多样化。然而，目前学界对新热带区(neotropical)白蚁物种木质纤维素降解的部分机制仍知之甚少，亟需开展相关研究以进一步厘清其环境效应，以及其在新型生物经济(bioeconomy)中的应用潜能。本研究计划拟整合生态学与分子生物学分析技术，探究6种新热带区高等白蚁(higher termites)的木质纤维素降解过程及其共生微生物群落结构。首先，我们将基于宏基因组学(metagenomics)与宏转录组学(metatranscriptomic)分析，对比堆沙白蚁（Cornitermes cumulans）的微生物群落功能。随后，我们将通过酶活性测定以及16S rRNA与ITS(内转录间隔区)测序技术，分析6种具有不同取食特化策略的高等白蚁的木质纤维素酶(lignocellulases)活性与微生物群落组成。我们提出假说：堆沙白蚁（C. cumulans）会储存食物，以便在取食前借助土壤微生物完成木质纤维素的预降解。此外，根据白蚁的取食特化类型不同，其木质纤维素降解能力与微生物群落功能组成也会存在显著差异。本研究成果将有助于进一步阐明微生物群落与白蚁之间的共生关系。