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Lipidic metabolites play essential roles in host physiological health and growth performance, serving as the major structural and signaling components of membranes, energy storage molecules, and steroid hormones. Bamboo, as wild giant pandas' exclusive diet, is the main determinant of giant pandas' lipidome, both as a direct source and through microbiota activity. Interestingly, the consumption of bamboo has attracted little attention from a lipidomic perspective. In the current study, we outline the lipidomic atlas of different parts of bamboo. By gas chromatography—mass spectrometry (GC-MS), we have been able to obtain the absolute quantification of 35 fatty acids pertaining to short chain fatty acids (8), medium chain fatty acids (6), long chain fatty acids (17), and very long chain fatty acids (4), while liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS/MS) allowed us to obtain the relative quantification of another 1638 lipids. Among the fatty acids quantified in absolute terms, eight showed significantly distinct concentrations among different bamboo parts. Subsequently, we investigated how the giant panda's serum and fecal lipidome adapt to the most important annual change in their diet, represented by the consumption of high amounts of bamboo shoots, typical of spring, the weight-gaining season. Five fatty acids were significantly altered in feces and two in serum, respectively, due to the different levels of bamboo shoot consumption. Furthermore, significant differences of the main bacteria strains were observed in feces between the two groups at the genus level, pertaining to Streptococcus, Leuconostoc, and Vagococcus. Correlations between giant panda fecal microbiome and lipidome were evaluated by Pearson correlation analysis. These findings suggest that a balanced diet, important for the overall lipidomic function and giant panda health, could be reached even in this remarkable case of a single food-based diet, by administering to the giant panda's combinations of different parts of bamboo, with specific lipidome profiles. [ABSTRACT FROM AUTHOR]

The giant panda, a strict herbivore that feeds on bamboo, still retains a typical carnivorous digestive system. Reference catalogs of microbial genes and genomes are lacking, largely limiting the antibiotic resistome and functional exploration of the giant panda gut microbiome. Here, we integrated 177 fecal metagenomes of captive and wild giant pandas to construct a giant panda integrated gene catalog (GPIGC) comprised of approximately 4.5 million non-redundant genes and reconstruct 393 metagenome-assembled genomes (MAGs). Taxonomic and functional characterization of genes revealed that the captivity of the giant panda significantly changed the core microbial composition and the distribution of microbial genes. Higher abundance and prevalence of antibiotic resistance genes (ARGs) were detected in the guts of captive giant pandas, and ARG distribution was influenced by geography, for both captive and wild individuals. Escherichia, as the prevalent genus in the guts of captive giant pandas, was the main carrier of ARGs, meaning there is a high risk of ARG transmission by Escherichia. We also found that multiple mcr gene variants, conferring plasmid-mediated mobile colistin resistance, were widespread in the guts of captive and wild giant pandas. There were low proportions of carbohydrate-active enzyme (CAZyme) genes in GPIGC and MAGs compared with several omnivorous and herbivorous mammals. Many members of Clostridium MAGs were significantly enriched in the guts of adult, old and wild giant pandas. The genomes of isolates and MAGs of Clostridiaceae harbored key genes or enzymes in complete pathways for degrading lignocellulose and producing short-chain fatty acids (SCFAs), indicating the potential of these bacteria to utilize the low-nutrient bamboo diet. Overall, our data presented an exhaustive reference gene catalog and MAGs in giant panda gut and provided a comprehensive understanding of the antibiotic resistome and microbial adaptability for a high-lignocellulose diet. [Display omitted] • Captivity of giant panda changed the composition and diversity of gut microbiome. • Lifestyle and geography influenced on ARGs abundance and distribution, respectively. • Escherichia was the main carrier of ARGs in the guts of captive giant pandas. • Clostridium harbored key genes in metabolisms of lignocellulose. [ABSTRACT FROM AUTHOR]