Lactobacilli survival and adhesion to colonic epithelial cell lines is dependent on long chain fatty acid exposure

Abstract

Lactobacilli and long chain polyunsaturated fatty acids are commonly consumed as functional foods. However, there is very little research into their interactions. The aim of the present study was to investigate the interaction between fatty acids (FA) and lactobacilli by exploring lactobacilli survival following exposure to different FA and their adhesion to epithelial cells pre‐treated with different FA. Three strains of lactobacilli were cultured with 20 µM eicosapentaenoic acid (EPA, n‐3), docosahexaenoic acid (DHA, n‐3), arachidonic acid (AA, n‐6) or oleic acid (OA, n‐9) to assess survival. Additionally, adhesion of radioactively labelled bacteria to confluent layers of three colorectal cell lines was measured following pre‐treatment of the epithelial cells with 50 µM EPA, DHA, AA. or OA. Results show that exposure to FA slowed log‐phase growth of two human derived strains of lactobacilli, but reduced survival of a chicken derived strain to 20%. Survival was associated with the formation of the FA cyc19:0 in the human derived strains. The chicken derived strain showed greatest adherence to epithelial cells and adhesion was increased following epithelial cell exposure to DHA. In conclusion, the survival and adhesion of lactobacilli in the intestinal tract is likely to be affected by FA content of the diet.Practical applications: The fatty acid composition of the diet has the potential to modulate the behaviour of probiotic bacteria in the gut and in probiotic foods. We showed that combining high polyunsaturated fatty acids (PUFA) with certain probiotics may lead to reduced numbers of probiotic bacteria. Despite this, we showed that PUFA could enhance adhesion of some lactobacilli strains and that increasing the PUFA content of epithelial cells via the diet may aid the adherence of some potentially beneficial lactobacilli. We also highlight a potential concern for the chicken industry whereby PUFA inhibited the growth of the lactobacilli isolated from chicken. With the increasing use of PUFA in chicken feed this could lead to a dysbiosis in normal chicken microflora and requires further investigation.Overview of polyunsaturated fatty acids (PUFA) potential effects on bacteria adhesion. (1) Unabsorbed PUFA directly effects bacteria in the colon. (2) Systemic delivery of PUFA following absorption can (a) Bind peroxisome proliferator‐activated receptors (PPAR), that can lead to production of transforming growth factor‐β resulting in tolerance towards bacteria. (b) Be precursors for series 3 prostaglandins (PG) that lead to lower inflammatory responses. (c) Be precursors to series 2 PG and enhance inflammatory products, however, precursors can bind PPAR and result in inhibition of inflammatory responses. (d) Unsaturated PUFAs lead to a more fluidic membrane composition, potentially altering bacterial adhesion sites.