The role of bacterial exopolysaccharides on the antidiarrheal bioactivity of fermented soybeans.

Carbohydrate from soybean tempeh has been reported to be capable of inhibiting the adhesion of enterotoxigenic Escherischia coli (ETEC) to epithelial cells. The presence of these bioactive carbohydrate might be due to the breakdown of soy matrix polysaccharides by fungi. Other than fungi, bacteria are also present in tempeh but so far there has been no report regarding the effect of bacteria on anti-adhesion bioactivity in tempeh. Lactic acid bacteria (LAB) have been reported to be able of producing exo-polysaccharide (EPS) which can bind to ETEC. Therefore, we hypothesized that the addition of LAB culture in tempeh fermentation might contribute to an increase in anti-adhesion bioactivity of the product. This research is aimed to characterize the chemical structure of bacterial EPS that can bind to ETEC and determine whether the addition of EPS-producing LAB to tempeh can improve anti-adhesion bioactivity of the product. EPS will be extracted from various LAB isolated from tempeh and characterized for its chemical structure. Carbohydrates that play roles in anti-adhesion bioactivity will be identified by subjecting them to specific carbohydrate-degrading enzymes and testing the anti-adhesion bioactivity. LAB will also be incubated with soybeans to assess its anti-adhesion mechanism and EPS-producing capability in solid fermentation. Selected LAB strain will later be added to tempeh fermentation to assess its influence on anti-adhesion bioactivity. Altogether, this research is expected to develop tempeh into a functional food product that can reduce the severity of diarrhea and thus adding a value to the product.