Adhesive Properties, Extracellular Protein Production, and Metabolism in the Lactobacillus rhamnosus GG Strain when Grown in the Presence of Mucin

This paper examines the probiotic bacterium Lactobacillus rhamnosus GC, and how it reacts to the presence of mucin in its extracellular milieu. Parameters studied included cell clustering, adhesion to mucin, extracellular protein production, and formation of final metabolites. L. rhamnosus GG was found to grow efficiently in the presence of glucose, N-acetylglucosamine, or mucin (partially purified or purified) as sole carbon sources. However, it was unable to grow using other mucin constituents, such as fucose or glucuronic acid. Mucin induced noticeable changes in all the parameters studied when compared with growth using glucose, including in the formation of cell clusters, which were easily disorganized with trypsin. Mucin increased adhesion of the bacterium, and modulated the production of extracellular proteins. SDS-PAGE revealed that mucin was not degraded during L. rhamnosus GC growth, suggesting that this bacterium is able to partially use the glucidic moiety of glycoprotein. This study goes some way towards developing an understanding of the metabolic and physiological changes that L. rhamnosus GC undergoes within the human gastrointestinal tract.