Gut bacterial and fungal communities of François' langur (Trachypithecus francoisi) changed coordinate to different seasons

Abstract

Introduction: François' langur (Trachypithecus francoisi), an endangered primate endemic to limestone forests in Vietnam and China, relies on gut microbiota to maintain gastrointestinal stability and adapt to dietary shifts. While gut microbial communities are dynamic and sensitive to seasonal and resource variations, their specific responses in François' langurs remain poorly characterized. This study investigates seasonal variations in the composition and diversity of gut bacterial and fungal communities in this species to enhance understanding of its ecological adaptations.

Methods: Fresh fecal samples from 22 François' langurs in Mayanghe National Nature Reserve, China, were collected across four seasons. Bacterial and fungal communities were analyzed using high-throughput sequencing to assess taxonomic composition and α-diversity. Statistical comparisons were conducted to evaluate seasonal differences at phylum and genus levels.

Results: Significant seasonal shifts occurred in both bacterial and fungal communities. Bacterial α-diversity peaked in warmer seasons, whereas fungal diversity was higher in colder months. At the genus level, Akkermansia (1.3% relative abundance in summer), a mucin-degrading bacterium linked to gut health, dominated warmer seasons. In contrast, the fungal genus Cercophora, associated with plant biomass degradation, was enriched during colder seasons. Seasonal factors strongly influenced microbial structure, with distinct community assemblages observed across all seasons.

Discussion: The inverse diversity patterns of bacterial and fungal communities suggest complementary roles in nutrient extraction under seasonal dietary constraints. Akkermansia's summer prevalence may reflect enhanced mucin utilization during fruit-rich periods, while Cercophora's cold-season dominance likely aids cellulose breakdown in leaf-heavy diets. These dynamics highlight the microbiota's role in optimizing energy harvest from seasonally variable diets. By elucidating microbial seasonal plasticity, this study provides critical insights for developing conservation strategies tailored to the nutritional ecology of François' langurs.

Keywords: Akkermansia; Cercophora; François’ langur; bacterial diversity; fungal diversity; gut microbiota; seasonal variation.

FIGURE 1

Characterization of gut microbial communities in François’ langur: (A) rarefaction curves reflecting the diversity of bacterial and fungal OTUs from François’ langur gut. (B) Venn diagram illustrating the overlap of OTUs across different seasons, with numbers indicating the counts of OTUs unique to each section. Bar charts depicting the relative abundance of dominant gut bacterial (C) and fungal (D) species at the phylum and genus levels.

FIGURE 2

Seasonal variations in gut microbiota of François’ langur. Variation coefficients of relative abundance of bacteria (A) and fungal (B) at the genus level. Green represents the ten genera with the greatest significant variation coefficients at the genus level, and purple represents the ten genera with the least. Sankey map showing the relative abundances of bacteria (C) and fungal (D) at the genus level over the four seasons.

FIGURE 3

Box plots illustrating species richness within samples, which represent seasonal fluctuations in the α diversity of the gut bacteria (A,B) and fungal (C,D) of François’ langurs. Richness is measured by the Shannon and Simpson indexes. *P < 0.05 (Wilcoxon rank-sum test), **P < 0.01.

FIGURE 4

PCoA analysis of the composition of the gut microbial of François’ langurs in different seasons. PCoA score plot based on Bray–Curtis distance analysis among the four seasons for bacterial (A) and fungal (B).

FIGURE 5

Heatmap illustrating LEfSe test results (with LDA scores > 3 and P < 0.05) for the phylum and genus levels of gut microbiota in François’ langur across the four seasons. Heatmap displays bacteria at the phylum (A) and genus (B) levels, as well as fungal at the phylum (C) and genus (D) levels.

FIGURE 6

Functional predictions of bacteria (A) and fungal (B) using 16S rRNA and ITS results combined with genomic databases.