Characterization of the digestive microbiome of invasive Limnoperna fortunei (Dunker, 1857) collected in different seasons in the upper Uruguay River, Santa Catarina, Brazil

We aimed to identify the digestive microbiota of the golden mussel Limnoperna fortunei, and characterize its structure in different seasons. Limnoperna fortunei specimens were sampled in winter (September 2019) and summer (March 2020) in five reservoirs of hydroelectric power plants in southern Brazil. In each reservoir, we sampled 15 individuals at three different points. We collected the digestive diverticulum and portions of the intestine for bacterial DNA extraction, and subsequently conducted metagenomic analysis. The intestinal microbial communities of L. fortunei occurring in the upper Uruguay River region showed significant differences during winter and summer. Although the phyla Proteobacteria, Bacteroidetes, and Cyanobacteria were dominant regardless of the season, the microbial communities showed greater richness and bacterial diversity in the summer. Additionally, we found 143 species of bacteria in the digestive samples collected during both winter and summer, which may indicate a central microbial community for the species. The microbial communities in the digestive tract of L. fortunei showed greater bacterial richness and diversity in summer samples, which existed at a significantly higher temperature than those in winter samples. We observed seasonal variations in the microbiota of L. fortunei in the upper Uruguay River region, with increased bacterial richness and diversity in the digestive tract during summer, attributed to higher temperatures. However, Proteobacteria, Bacteroidetes, and Cyanobacteria consistently dominated the digestive tract of the golden mussel, regardless of seasonal fluctuations.