Effect of wheat agglutinin (WGA) on the adhesion of lactic acid bacteria to intestinal epithelial cells of BB chicks

BABOT, JAIME DANIEL; ARGAÑARAZ MARTÍNEZ, ELOY; APELLA, MARÍA CRISTINA; PEREZ CHAIA, ADRIANA

Rosario - Santa Fe

Congreso; IX Congreso Argentino de Microbiología General; 2013

SAMIGE

Lectins are glycoproteins highly resistant to heat, proteolysis and pH that are present in broiler feed. They have the ability to bind reversibly to specific carbohydrates. Once ingested, they interact with surface carbohydrates of intestinal epithelial cells (IEC) impairing epithelia development and enzyme digestive activity in BB chicks with the consequent growth depression. The lectin WGA is a secondary metabolite of wheat and binds specifically to N-acetyl-D-glucosamine and/or NeuNAc. Previous studies of our group showed that lactic acid bacteria (LAB) bind WGA through interaction with N-acetyl-D-glucosamine in the bacterial surface. IEC could be protected by LAB adhered to them by capturing WGA that reach the cells and further detachment of these bacteria from the cells surface. Thus, the aim of this study was to assess the effect of WGA in bacteria adhered to IEC of BB chicks. A total of 6 LAB strains, selected because of their endurance to gastrointestinal tract transit, hydrophobicity, adhesion properties and lectin binding pattern, were evaluated. In order to obtain IEC, 2-weeks old chicks were slaughtered by cervical dislocation, the jejunum was extracted, washed and its surface scraped with a sterile spatula. IEC collected were washed, treated with trypsin-EDTA and adjusted to 5×105 IEC/mL. IEC were incubated 30 min with each strain of LAB (1×108 CFU/mL) and washed to eliminate non-adhered bacteria. Cells were resuspended in WGA 50 µg/mL and incubated for 2 h. Finally, IEC were fixed in microscopic slides and Gram stained. The adhesion percentage and index were calculated for each strain before and after the incubation with WGA. Adhesion percentage decreased significantly (p ≤ 0.05) for 5 out of 6 strains after the incubation with WGA, being L. reuteri LET211 the only strain without changes. This bacterium expresses several carbohydrates in its surface, which may be responsible for its strong adhesion. On the other hand, the adhesion index remained unaltered (p ≤ 0.05) for all the evaluated strains. These results indicate that the incubation with WGA removes bacteria from the majority of IEC, but not from certain group of cells, which would keep them attached. In conclusion, almost all the strains studied would exert a protective effect on epithelial cells as they are detached with the lectin bound to their surface and are eliminated along with digesta.