How do living conditions affect the gut microbiota of endangered Père David's deer (Elaphurus davidianus)? Initial findings from the warm temperate zone

Characterization and Optimization of Cellulose-Degrading Bacteria Isolated from Fecal Samples of Elaphurus davidianus Through Response Surface Methodology

The screening of cellulose-degrading microorganisms from herbivores and the optimization of fermentation conditions are of great significance for the utilization of cellulose resources. In this study, we initially employed a metagenomic analysis to investigate the fecal microbiota of both captive and semi-free-ranging Père David's deer (Elaphurus davidianus) under varying environmental conditions. Subsequently, we isolated and cultured cellulase-degrading microorganisms from the fecal samples using Congo red medium. There was consistency in the dominant phyla and genera of gut microorganisms between the two groups, with only differences in abundance. Then, a cellulose-degrading strain identified as Bacillus pumilus XM was isolated after a morphological analysis and molecular identification by 16S rRNA amplicon. In addition, a series of single factor experiments and response surface analysis were conducted to determine the optimal conditions for best cellulase activity. The optimum temperature, culture time, and shaking speed for the reaction of cellulase produced by the strain Bacillus pumilus XM were 34 °C, 28 h, and 154 r/min, respectively. Under these conditions, the cellulase activity reached a maximum of 10.96 U/mL, which was relatively close to the predicted value of 10.975 U/mL. The results have enriched the existing bacterial resources and laid a foundation for the development of new enzymes, providing a theoretical basis for the rational utilization of cellulase from wild animal resources.

Impact of Environmental Food Intake on the Gut Microbiota of Endangered Père David's Deer: Primary Evidence for Population Reintroduction

Reintroduction has been successful in re-establishing several endangered wild animals in their historical habitats, including Père David's deer (Elaphurus davidianus). Continuous monitoring of reintroduced individuals is essential for improving the sustainability of ex situ conservation efforts. Despite an increased recognition of the significance of the gut microbiome for animal health, the correlation between diet and the gut microbiome in E. davidianus is unclear. In this study, 15 fresh fecal samples of E. davidianus were collected from Tianjin Qilihai Wetland and the association between dietary and gut microbiota composition was evaluated. Microscopic observations showed that Nymphoides peltata [relative density (RD = 0.3514), Phragmites australis (RD = 0.2662), Setaria viridis (RD = 0.1211), and Typha orientalis (RD = 0.1085) were the main dietary plants in the fecal samples. High-throughput 16S rRNA sequencing showed a predominance of the phyla Firmicutes and Proteobacteria and the genus Psychrobacillus (26.53%) in the gut microbiota. The RD of N. peltata was significantly positively correlated with the abundance of Firmicutes (p = 0.005) and the genus UCG-005 (p = 0.024). This study indicates a close association between food digestion and nutrient intake, providing basic monitoring data for the full reintroduction and recovery of wild E. davidianus.