Isopods have colonized all environments, partly thanks to their ability to decompose the organic matter. Their enzymatic repertoire, as well as the one of their associated microbiota, has contributed to their colonization success. Together, these holobionts have evolved several interesting life history traits to degrade the plant cell walls, mainly composed of lignocellulose. It has been shown that terrestrial isopods achieve lignocellulose degradation thanks to numerous and diverse CAZymes provided by both the host and its microbiota. Nevertheless, the strategies for lignocellulose degradation seem more diversified in isopods, in particular in aquatic species which are the least studied. Isopods could be an interesting source of valuable enzymes for biotechnological industries of biomass conversion. To provide new features on the lignocellulose degradation in isopod holobionts, shotgun sequencing of 36 metagenomes of digestive and non-digestive tissues was performed from several populations of four aquatic and terrestrial isopod species. Combined to the 15 metagenomes of an additional species from our previous study, as well as the host transcriptomes, this large dataset allowed us to identify the CAZymes in both the host and the associated microbial communities. Analyses revealed the dominance of Bacteroidetes and Proteobacteria in the five species, covering 36% and 56% of the total bacterial community, respectively. The identification of CAZymes and new enzymatic systems for lignocellulose degradation, such as PULs, cellulosomes and LPMOs, highlights the richness of the strategies used by the isopods and their associated microbiota. Altogether, our results show that the isopod holobionts are promising models to study lignocellulose degradation. These models can provide new enzymes and relevant lignocellulose-degrading bacteria strains for the biotechnological industries of biomass conversion.

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等足类全生物体作为木质纤维素降解的有希望的模型

等足类动物已经在所有环境中定居，部分原因在于它们分解有机物的能力。他们的酶谱，以及他们相关的微生物群之一，为他们的殖民成功做出了贡献。总之，这些全生物进化出了几个有趣的生活史特征来降解植物细胞壁，主要由木质纤维素组成。已经表明，由于宿主及其微生物群提供的众多多样的 CAZymes，陆地等足类动物实现了木质纤维素降解。然而，木质纤维素降解的策略在等足类动物中似乎更加多样化，特别是在研究最少的水生物种中。等足类动物可能是用于生物质转化的生物技术工业的有价值酶的有趣来源。为了提供等足类全生物中木质纤维素降解的新特征，对四种水生和陆生等足类物种的几个种群的 36 个消化和非消化组织宏基因组进行鸟枪测序。结合我们之前研究的另外一个物种的 15 个宏基因组以及宿主转录组，这个大型数据集使我们能够识别宿主和相关微生物群落中的 CAZymes。分析显示，拟杆菌门和变形杆菌门在五个物种中占优势，分别占总细菌群落的 36% 和 56%。CAZymes 和用于木质纤维素降解的新酶系统（如 PUL、纤维素小体和 LPMO）的鉴定突出了等足类动物及其相关微生物群使用的策略的丰富性。总之，我们的结果表明，等足类全生物是研究木质纤维素降解的有前途的模型。这些模型可以为生物质转化的生物技术产业提供新的酶和相关的木质纤维素降解菌种。