The resident microbial population responsible for lignocellulosic biomass assimilation in the gastrointestinal tract of animals is a rich source for discovering novel biocatalysts finding application in the production of value-added commodities. Herbivorous animals, such as elephants, consume a variety of lignocellulosic materials in bulk amounts to support their high energy requirements. Since the interdependence of host diet and its microbiome is well established, it is necessary to explore the potential resident microbes of obligate herbivores like elephants belonging to different age classes and habitats for mining enzymes involved in complex biomass deconstruction. In the present study, metagenomic analysis of an adult elephant fecal sample using whole-genome shotgun library preparation indicated the dominant representation of microbes belonging to the phylum Proteobacteria. Subsystem- and KEGG-based analyses revealed a high potential for carbohydrate metabolism and membrane transport. CAZy database analysis identified ~55,000 ORFs that had either catalytic domains or carbohydrate-binding modules (CBMs) in the metagenomic data set. Moreover, CBMs and carbohydrate-active enzymes (CAZymes), such as glycoside hydrolases (GHs), glycosyltransferases (GTs), carbohydrate esterases (CEs) were most abundant in microbes of phylum Proteobacteria, and among them, the majority of GHs and GTs were from Bacillus subtilis and Escherichia coli. A comparative GH analysis with other gut metagenomic datasets of herbivorous animals revealed the presence of several unique GHs of the β-glucosidase, endoglucanase, and exoglucanase families thus providing a comprehensive understanding of the diverse CAZymes present in the gut microbiome of an adult elephant.

中文翻译：

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对成年大象粪便微生物组的元基因组学分析揭示了与木质纤维素生物质降解有关的CAZymes的多样性

负责动物胃肠道中木质纤维素生物质吸收的常驻微生物种群为发现新型生物催化剂提供了丰富的资源，这些新型生物催化剂可用于生产增值商品。食草动物（例如大象）会消耗大量木质纤维素材料，以满足其高能量需求。由于宿主饮食与其微生物组之间的相互依存性已得到很好的确立，因此有必要探索专性食草动物（如属于不同年龄类别和栖息地的大象）潜在的微生物，以开采涉及复杂生物质解构的酶。在目前的研究中，使用全基因组shot弹枪文库制备物对成年大象粪便样本进行的宏基因组分析表明，属于门菌属细菌的微生物占主导地位。基于子系统和KEGG的分析显示了碳水化合物代谢和膜运输的巨大潜力。CAZy数据库分析确定了约55,000个在宏基因组数据集中具有催化域或碳水化合物结合模块（CBM）的ORF。此外，门脉微生物中的煤层气和碳水化合物活性酶（CAZymes），如糖苷水解酶（GHs），糖基转移酶（GTs），碳水化合物酯酶（CEs）最丰富。在宏基因组数据集中具有催化域或碳水化合物结合模块（CBM）的000个ORF。此外，门脉微生物中的煤层气和碳水化合物活性酶（CAZymes），如糖苷水解酶（GHs），糖基转移酶（GTs），碳水化合物酯酶（CEs）最丰富。在宏基因组数据集中具有催化域或碳水化合物结合模块（CBM）的000个ORF。此外，门脉微生物中的煤层气和碳水化合物活性酶（CAZymes），如糖苷水解酶（GHs），糖基转移酶（GTs），碳水化合物酯酶（CEs）最丰富。变形杆菌，其中大部分GH和GT来自枯草芽孢杆菌和大肠杆菌。通过与其他食草动物肠道宏基因组学数据集进行的GH比较分析发现，β-葡萄糖苷酶，内切葡聚糖酶和外切葡聚糖酶家族存在多个独特的GH，从而全面了解了成年大象肠道微生物组中存在的各种CAZymes。