Lignocellulosic biomass (LCB) in the form of agricultural, forestry, and agro-industrial wastes is globally generated in large volumes every year. The chemical components of lignocellulosic biomass render them a substrate valuable for biofuel production. However, the rigid association of lignin, cellulose, and hemicellulose component of LCB forms a complex, hierarchical, and recalcitrant structure, which inhibits the solubilization of LCB resources for biofuel production. The learning from termites (wood-feeding and soil-feeding) and further application of their gut bacteria for lignin degradation and bioconversion remain unexplored or at its early stage. With reference to this scientific knowledge gap, this study seeks to highlight the culturable gut bacterial community in soil- and wood-feeding termites, namely Pericapritermes nitobei and Microcerotermes sp., respectively to design a future biorefinery and bioremediation technologies. In this study, a total of 40 and 67 bacterial isolates were indeed identified from Pericapritermes nitobei and Microcerotermes sp., respectively. The identified isolates from both termite species were actually classified into four different phyla: Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes, where the phylum Actinobacteria dominated gut bacteria isolates identified from P. nitobei at 47.5 % while Proteobacteria were dominant in wood-feeding termite, Microcerotermes sp. at 46.27 %. At the genus level, the bacterial isolates enriched from the gut of Microcerotermes sp. belonged to 17 different genera, among which the bacterial genus Streptomyces (28 %) was most prevalent, followed by Enterobacter (11 %). Meanwhile, 9 genera were recorded for gut bacterial isolates from P. nitobei and were dominated by Streptomyces (37.5 %), followed by Acinetobacter (25 %). In general, the gut bacterial symbionts from both termites showed a congruency at the phyla level but were more diverged at a lower classification, inferring that different termite species evolved a unique repertoire of gut bacteria. Moreover, 61 % and 55 % of the gut bacterial isolates from the wood- and soil-feeding termites demonstrated a significant and multifunctional role in the hydrolysis of three lignocellulolytic substrates, including carboxymethyl cellulose, beechwood xylan, and aniline blue dye, indicating their unique functions and assistance to the host for the degradation of lignocellulose or other xenobiotic compounds from soil.

中文翻译：

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探索以木材和土壤为食的白蚁细菌的组成和功能谱，以有效降解木质素基芳烃


全球每年都会产生农业、林业和农工废弃物形式的木质纤维素生物质 （LCB）。木质纤维素生物质的化学成分使其成为生物燃料生产有价值的基质。然而，LCB 的木质素、纤维素和半纤维素成分的刚性结合形成了一个复杂的、分层的和顽固的结构，这抑制了用于生物燃料生产的 LCB 资源的溶解。从白蚁身上学习（以木材为食和以土壤为食）以及进一步应用其肠道细菌进行木质素降解和生物转化仍未得到探索或处于早期阶段。参考这一科学知识差距，本研究旨在突出土壤和木材喂养白蚁中可培养的肠道细菌群落，即 Pericapritermes nitobei 和 Microcerotermes sp.，以设计未来的生物精炼和生物修复技术。在这项研究中，确实分别从 Pericapritermes nitobei 和 Microcerotermes sp. 中鉴定出 40 和 67 个细菌分离株。从两种白蚁物种中鉴定出的分离株实际上分为四个不同的门：放线菌门、变形菌门、厚壁菌门和拟杆菌门，其中放线菌门占 47.5% 的肠道细菌分离株，而变形菌门在以木材为食的白蚁 Microcerotermes sp. 中占主导地位，占 46.27%。在属水平上，从小孢杆菌属肠道中富集的细菌分离株属于 17 个不同的属，其中链霉菌属 （28 %） 最为普遍，其次是肠杆菌属 （11 %）。同时，记录了 9 个属的 P. nitobei 肠道细菌分离株，其中以链霉菌属为主 （37.5 %），其次是不动杆菌 （25 %）。一般来说，两种白蚁的肠道细菌共生体在门水平上表现出一致性，但在较低的分类中差异更大，这表明不同的白蚁物种进化出了独特的肠道细菌库。此外，来自木材和土壤喂养白蚁的 61% 和 55% 的肠道细菌分离物在三种木质纤维素分解底物（包括羧甲基纤维素、山毛榉木酚聚糖和苯胺蓝染料）的水解中表现出显着的多功能作用，表明它们具有独特的功能，并有助于宿主降解土壤中的木质纤维素或其他外源性化合物。