Spatial disturbances in altered mucosal and luminal gut viromes of diet-induced obese mice

Gut microbial biogeography is a key feature of host-microbe relationships. In gut viral ecology, biogeography and responses to dietary intervention remain poorly understood. Here, we conducted a metagenomic study to determine the composition of the mucosal and luminal viromes of the gut and to evaluate the impact of a Western diet on gut viral ecology. We found that mucosal and luminal viral assemblages comprised predominantly temperate phages. The mucosal virome significantly differed from the luminal virome in low-fat diet-fed lean mice, where spatial variation correlated with bacterial microbiota from the mucosa and lumen. The mucosal and luminal viromes of high-fat, high-sucrose 'Western' diet-fed obese mice were significantly enriched with temperate phages of the Caudovirales order. Interestingly, this community alteration occurred to a greater extent in the mucosa than lumen, leading to loss of spatial differences; however, these changes recovered after switching to a low-fat diet. Temperate phages enriched in the Western diet-induced obese mice were associated with the Bacilli, Negativicutes and Bacteroidia classes and temperate phages from the Bacteroidia class particularly encoded stress and niche-specific functions advantageous to bacterial host adaptation. This study illustrates a biogeographic view of the gut virome and phage-bacterial host connections under the diet-induced microbial dysbiosis.