Mirza, B. S. | Search bioRxiv

bioRxiv2026

Effects of Liraglutide on Gut Bacterial Community Dynamics

Liraglutide, a GLP-1 receptor agonist, is used to induce weight loss. However, limited information exists on liraglutides effects on the gut bacterial community and their restoration after washout. We investigated liraglutides effect on the gut bacterial community in diet-induced obese (DIO) mice and whether these changes persist after washout. Twenty-four male C57BL/6J mice on high-fat (HFC) or low-fat (LFC) diets were monitored for 21 days. A subgroup of high-fat mice received daily liraglutide for 14 days (HFL), followed by a 7-day washout. Liraglutide induced significant weight loss by Day 4, which persisted during treatment and partially reversed post-treatment. For bacterial community analysis, 7.1 million 16S rRNA gene sequences were retrieved using Illumina paired-end sequencing. We observed distinct shifts in gut bacterial community structure during liraglutide treatment, which mostly returned to baseline after the 7-day washout. Using SIMPER analysis, 21 amplicon sequence variants (ASVs) were identified as major contributors. Nine ASVs, related to Lactobacillus gasseri, L. paragasseri, L. johnsonii, and Leptogranulimonas caecicola, significantly increased during treatment and declined post-washout. The remaining 12 ASVs, associated with protein- and carbohydrate-fermenting bacteria (Romboutsia, Faecalicatena, Oscillibacter), decreased during treatment. Comparison across all groups identified 29 ASVs, clustering into seven phylogenetic groups, highlighting liraglutides enrichment of bile-acid- and mucin-associated taxa and suppression of carbohydrate-fermentative genera. These findings demonstrate that liraglutide induces rapid, diet-dependent, yet reversible shifts in the gut microbiome, favoring lactic acid-producing bacteria while reducing fermentative taxa. Such microbial changes may contribute to liraglutides metabolic effects and provide insight into host- microbiome interactions in obesity treatment. IMPORTANCEObesity and overweight states are intricately linked to the gut bacterial community, yet the effects of common obesity treatments such as GLP-1 receptor agonists on gut bacteria remain unclear. Here, we show that liraglutide, a GLP-1 analog, reshapes the gut bacterial community in diet-induced obese mice relative to untreated obese and lean controls. By including baseline samples when mice were at a normal weight, we distinguished bacterial changes due to the drug from those due to obesity progression, as well as how the community structure is affected during a washout period. Liraglutide treatment selectively increased beneficial gut bacteria (e.g., Lactobacillaceae) under high-fat conditions. These bacterial shifts during GLP-1 therapy may contribute to its metabolic benefits and broaden our understanding of host bacterial interactions in the context of diet and weight management.

microbiology↗

bioRxiv2025

Soybean Root Nodule Occupancy: Competition Between Bradyrhizobium and Sinorhizobium Strains Inoculated at Different Plant Growth Stages

Soybean is frequently nodulated by species from the Bradyrhizobium (BR) and/or Sinorhizobium (SR) genera. Several factors, such as soil pH, host genotype, geographic location, and other environmental variables, are reported to influence the preferential selection between BR or SR species within soybean root nodules. However, it remains unclear whether the age of the host plant at the time of inoculation affects preferential rhizobial selection. To investigate this, we inoculated soybean plants with different cell densities of BR and SR strains at three time points: at sowing (T0), two weeks after germination (T2), and four weeks after germination (T4). We used 16S rRNA gene amplicon sequencing of root nodule and rhizosphere samples to assess the relative abundance of BR and SR in nodule and rhizosphere. We observed a clear shift in nodule occupancy that favored BR at the time of seed sowing (T0) but increasingly favored SR when plants were inoculated at T2 and T4 stages. Specifically, at T4, SR dominated in nodules across all treatments, representing 88-99% of total sequences, regardless of applied inoculum ratio. In contrast, a similar number of sequences for both strains were detected in the rhizosphere at the time of the final harvest. These results highlight host age as an important ecological driver in legume-rhizobium interactions and suggest that inoculation time strongly influences microsymbiont selection. This information is important in understanding rhizobial competition and optimizing the timing of inoculation for soybean. IMPORTANCESoybean is one of the worlds most valuable crops and fulfills most of its nitrogen requirements by developing symbiotic associated with nitrogen-fixing rhizobia. This reduces the need for chemical fertilizers by converting atmospheric nitrogen into a plant useable form of nitrogen. Multiple species from four rhizobial genera can nodulate soybean, and the plants choice of rhizobial partner is reported to change depending on environmental conditions such as pH, host genotype, geographic location, and other environmental factors. This study explores how the age of the soybean plant affects its preference for two frequently reported beneficial rhizobial species (B. diazoefficiens and S. fredii). By testing inoculation at different growth stages, we discovered that at early growth stages plants favored BR, while older plants increasingly selected SR for nodule formation. These findings highlight the level of complexity in plant-microbe interactions and could help optimize bioinoculant strategies for improving sustainability and crop yields.

microbiology↗