Abstract: This study investigated structural and functional differences in the gut microbiota of juvenile and adult captive giant pandas (Ailuropoda melanoleuca) in Qinling using metagenomic sequencing, with the aim of characterizing microbial adaptation to age-related dietary shifts and informing the development of targeted probiotics to support digestion and nutritional health. Fecal samples were collected from three juveniles (2 4 months old) and three adults (62 63 months old) at the Qinling Giant Panda Research Center. After sequencing, we conducted taxonomic profiling, diversity analyses, and functional annotation of the fecal microbiome. In total, 424 716 776 high-quality reads were generated, yielding 318 605 non-redundant genes. Alpha-diversity analyses showed that adults had significantly higher richness (Chao1 and ACE) but significantly lower diversity (Shannon and Simpson) than juveniles (P < 0. 01), suggesting a community with more taxa but greater dominance by a few lineages in adults. Beta-diversity analyses revealed a clear separation in microbial community structure between the two age groups. At the genus level, Lactobacillus predominated in juveniles, whereas Escherichia and Streptococcus were predominant in adults. Notably, several low-abundance bacteria with potential lignocellulose-degrading capacity (e. g., Bacillus licheniformis, Geobacillus galactosidasius, and Thermoclostridium stercorarium) were detected exclusively in adults. Functional annotation indicated that CAZy families (GT4, GH43, and GH73) and functions related to carbohydrate metabolism, amino acid metabolism, translation, lipid metabolism，and ribosome biogenesis were significantly enriched in juveniles compared with adults (P < 0. 05). Overall, this metagenomic analysis delineates distinct gut microbial features of juvenile and adult captive giant pandas and highlights candidate taxa potentially involved in lignocellulose degradation, providing a basis for precision probiotic development and gut-health management in this species.

Key words: Metagenomics, Captive giant pandas in Qinling region, Gut microbiota, Functional analysis

摘要： 本研究旨在通过宏基因组技术探究秦岭圈养大熊猫（Ailuropoda melanoleuca）幼年期与成年期肠道菌群结构和功能差异，为阐明秦岭圈养大熊猫的肠道菌群对不同阶段饮食的适应性响应，开发针对提高秦岭圈养大熊猫的促消化益生菌产品和改善其营养健康提供重要的理论依据。本研究采集秦岭大熊猫研究中心饲养的3只幼年（2~4月龄）和3只成年（62~63月龄）大熊猫粪便样本，通过宏基因组测序技术，对粪便细菌进行物种注释、多样性分析和功能注释与分析。测序共获得424 716 776条有效序列，构建非冗余基因后共获得318 605个基因。α多样性表明，与幼年组相比，成年组Chao1和Ace指数极显著提高（P < 0.01），而Shannon和Simpson指数极显著降低（P < 0.01）；β多样性分析表明，两组样本肠道菌群结构差异明显；物种注释结果表明，幼年组以乳杆菌属（Lactobacillus）为主，成年组则以埃希氏菌属（Escherichia）和链球菌属（Streptococcus）为主，并在成年组中发现地衣芽孢杆菌（Bacillus licheniformis）、半乳糖地质杆菌（Geobacillus galactosidasius）和粪堆梭菌（Thermoclostridi-um stercorarium）等具有木质纤维素降解潜力的低丰度细菌。功能注释结果显示，幼年组GT4、GH43、GH73、碳水化合物代谢、氨基酸代谢、翻译、脂质代谢、核糖体结构和生物合成等通路富集程度显著高于成年组（P <0.05）。本研究基于宏基因组学解析了秦岭圈养大熊猫幼年期与成年期肠道菌群特征与差异，挖掘到与木质纤维素分解相关的菌群，为后续促消化菌剂产品的研发，及助力大熊猫精准营养管理和肠道健康提供重要依据。

关键词: 宏基因组学, 秦岭圈养大熊猫, 肠道菌群, 功能分析