Higher Dietary Fibre Increases the Faecal Microbiome Diversity of Golden Lion Tamarins (Leontopithecus rosalia)

Gut microbiota influences host energetics, metabolic rate, and overall health. Optimising the diet, such as by increasing dietary fibre, is a key strategy for promoting a healthy microbiome and improving host energy balance. In this study, we compared the faecal microbiome of five zoo-housed golden lion tamarins (Leontopithecus rosalia) before and after a dietary fibre increase using 16S rRNA gene sequencing. Prevotella, the most abundant genus, declined significantly (FDR-corrected p < 0.05) following the introduction of a higher-fibre diet. The dietary change also significantly altered the overall gut microbial composition, including the emergence of Eisenbergiella (FDR-adjusted p < 0.05), a butyrate-producing genus whose relative abundance increased from 0% to 0.005% (FDR-adjusted p < 0.05). Given the role of Eisenbergiella in butyrate synthesis, this shift may enhance host energy metabolism and microbial interactions. Additionally, both alpha and beta diversity increased significantly (p < 0.05) after the dietary fibre intervention. A significant reduction in Desulfobacterota (FDR-adjusted p < 0.05) following dietary fibre enrichment was observed, suggesting a shift away from microbial groups that may be associated with pathogenicity or pro-inflammatory effects. Collectively, these changes represent a positive shift in the microbiome, supporting improved host energetics and metabolic health.