Analysis of Lactobacilli evolved in a mouse and in vivo in the presence of 18:2

Diet acts as a strong selective pressure on the gut microbiome to which the microbial population adapts. Adaptation can occur through taxonomic shifts in the composition of the microbiome and through adaptation of individual microbial strains producing strain variation. The greatest change in the American diet over the 20th century is in the increased consumption of soybean oil raising the question of how gut microbes were subsequently impacted. The long chain fatty acid linoleic acid found in soybean is inhibitory towards microbes that live in the dietary tract. Lactobacilli, in particular, are growth inhibited by linoleic acid but also show variation in the degree to which they are inhibited suggesting that exposure to linoleic acid may produce functional variation. By utilizing a high fat soybean oil diet in a mouse and an in vitro evolution system, we investigated if Lactobacillus reuteri and L. johnsonii can functionally evolve resistance to linoleic acid. Mice were placed on either a high or low soybean oil diet and the 16S rRNA gene was sequenced from the small intestine contents of the mice.