The effect of different carbohydrates on the biofilm formation and surface antigenicity of Lactobacillus rhamnosus GG

Health benefits associated with the ingestion of certain lactobacilli known as probiotics have increased the research and incorporation of these bacteria into food products. Lactobacillus rhamnosus GG is a well-known and studied probiotic organism. Upon ingestion, probiotics survive acid and bile stress and then adhere to the epithelial cell walls to elicit health benefits. Adhesion promotes interaction between probiotic cells and epithelial cells which is necessary for probiotics to confer health benefits. Adhesion is also the first step in biofilm formation which aids adaptability and cell-cell interaction. The aim of this work was to investigate the effect of different carbohydrates on the biofilm formation and antigenicity of Lb. rhamnosus GG. Biofilm formation was performed using 96-well microtiter plating method under elevated carbon dioxide (5% CO2) conditions for 24, 48 and 72 hours in the presence of fourteen different carbohydrates. Certain carbohydrates were found to promote the biofilm formation. The expressed antigenic proteins at the cell surface of biofilms from these carbohydrates were also isolated and investigated using 1DE immunoblot analysis. Four carbohydrates were shown to markedly increase the biofilm of Lb. rhamnosus GG under the indicated conditions. For three of the tested carbohydrates the most efficient biofilm formation was obtained after 48 hours of cultivation, whereas for one of the carbohydrates longer time was required to achieve the same biofilm formation efficiency. One dimensional gel electrophoresis coupled with immunoblotting using antibodies raised against whole Lb. rhamnosus GG cells indicated that the increased biofilm formation is closely associated with the increased surface antigenicity. The obtained findings suggest that certain carbohydrates have a central role in stimulating biofilm mode of growth as well as improving the probiotic features of Lb. rhamnosus GG strain