Diversity and Composition of Gut Bacterial Community in Giant Panda with Anorexia.

The giant panda (GP) is the most precious animal in China. Gastrointestinal tract disease, especially associated with dysbiosis of gut microbiota, is the leading cause of death in GPs. Here, we performed 16S rRNA high-throughput sequencing to investigate the gut microbiota of GPs having symptoms of anorexia. Results showed that gut microbiota of GP with anorexia had lower richness (Chao1 index) than the healthy GP. However, no significant differences in alpha diversity were observed. There is a significance in the microbial structure between anorexia and healthy GPs. The abundance of phylum Firmicutes (99.23% ± 7.1%), unidentified genus Clostridiales (24.75% ± 2.5%), was significantly higher in the subadult anorexia group (P < 0.01), and that of the unidentified genus Clostridiales (4.53% ± 1.2%) was also significantly higher in the adult anorexia group (P < 0.01). Weissella and Streptococcus were found to be decreased in both anorexia groups. The decreased abundance of Weissella (0.02% ± 0.0%, 0.08% ± 0.0%) and Streptococcus (73.89% ± 4.3%, 91.15% ± 7.6%) and increase in Clostridium may cause symptoms of anorexia in giant pandas. The correlation analysis indicated that there is a symbiotic relationship among Streptococcus, Leuconostoc, Weissella, and Bacillus which are classified as probiotics (r > 0.6, P < 0.05). Importantly, a negative correlation has been found between Streptococcus and unidentified_Clostridium in two groups (r > 0.6, P < 0.05). Our results suggested that Streptococcus might be used as probiotics to control the growth of Clostridium causing the anorexia.

Diet, habitat environment and lifestyle conversion affect the gut microbiomes of giant pandas.

Gut microbiota (GM) are important for the health of giant pandas (GPs), in addition to the utilization of bamboo in their diets. However, it is not fully understood how diet, habitat environment and lifestyle contribute to the composition of GM in GP. Consequently, we evaluated how dietary changes, habitat environment conversions and lifestyle shifts influence the GM of GPs using high-throughput sequencing and genome-resolved metagenomics. The GM of GPs were more similar when their hosts exhibited the same diet. High fiber diets significantly increased the diversity and decreased the richness of gut bacterial communities alone or interacted with the age factor (p < 0.05). The abundances of Streptococcus, Pseudomonas, Enterococcus, Lactococcus, Acinetobacter, and Clostridium significantly increased during diet conversion process (Non-parametric factorial Kruskal-Wallis sum-rank test, LDA > 4). Reconstruction of 60 metagenome-assembled-genomes (MAGs) indicated that these bacteria were likely responsible for bamboo digestion via gene complements involved in cellulose, hemicellulose, and lignin degradation. While habitat environment may play a more important role in shaping the GM of GP, lifestyle can also greatly affect bacterial communities. The GM structure in reintroduced GPs notably converged to that of wild pandas. Importantly, the main bacterial genera of wild GPs could aid in lignin degradation, while those of reintroduced GPs were related to cellulose and hemicellulose digestion. Streptococcus, Pseudomonas, Enterococcus, Lactococcus, Acinetobacter, and Clostridium may contribute to lignocellulose digestion in GP. The results revealed that diet conversion, habitat environment and lifestyle could remarkably influence the GM of GP. In addition, results suggested that increasing the ability of lignin degradation with GM may aid to change the GM of reintroduced pandas to resemble those of wild pandas.

Metagenomic analysis revealed a wide distribution of antibiotic resistance genes and biosynthesis of antibiotics in the gut of giant pandas.

BACKGROUND: The gut microbiome is essential for the host's health and serves as an essential reservoir of antibiotic resistance genes (ARGs). We investigated the effects of different factors, including the dietary shifts and age, on the functional characteristics of the giant panda's gut microbiome (GPs) through shotgun metagenome sequencing. We explored the association between gut bacterial genera and ARGs within the gut based on network analysis. RESULTS: Fecal samples (n=60) from captive juvenile, adult, and geriatric GPs were processed, and variations were identified in the gut microbiome according to different ages, the abundance of novel ARGs and the biosynthesis of antibiotics. Among 667 ARGs identified, nine from the top ten ARGs had a higher abundance in juveniles. For 102 ARGs against bacteria, a co-occurrence pattern revealed a positive association for predominant ARGs with Streptococcus. A comparative KEGG pathways analysis revealed an abundant biosynthesis of antibiotics among three different groups of GPs, where it was more significantly observed in the juvenile group. A co-occurrence pattern further revealed a positive association for the top ten ARGs, biosynthesis of antibiotics, and metabolic pathways. CONCLUSION: Gut of GPs serve as a reservoir for novel ARGs and biosynthesis of antibiotics. Dietary changes and age may influence the gut microbiome's functional characteristics; however, it needs further studies to ascertain the study outcomes.