Adhesion of Lactobacillus rhamnosus GG surface biomolecules to milk proteins

Lactic Acid Bacteria (LAB) are not homogeneously located in the dairy matrix and their spatial distribution seems to be controlled by the establishment of adhesive interactions between matrix components and bacterial surface biomolecules. However the mechanisms of interaction remain unknown although they constitute an interesting way of study to appreciate the interactions. The aim of this work was to understand the role of surface biomolecules in the adhesion of Lactobacillus rhamnosus GG - the most used LAB strain in food products for their health benefits to the consumer - to milk proteins. Adhesions were probed using atomic force microscopy based force spectroscopy. To this end, the wild type strain and three of its surface mutants were employed. The wild type strain interacts with the beta-lactoglobulin through the pili SpaCBA. The use of LGG surface mutants revealed that other surface biomolecules as long/small exopolysaccharides and proteins are involved in adhesion with milk proteins, in a less pronounced way than pili and in absence of pili, as all other surface biomolecules are masked in presence of pili. Altogether, this study demonstrates that adhesive interactions between LGG and milk proteins are governed by the surface composition of the bacteria. (c) 2018 Elsevier Ltd. All rights reserved.