engleski

S-layer proteins and bacteriocins in probiotics as living drugs – impact on microbiota

A rich collection of autochthonous lactic acid bacteria (LAB) was screened for the presence of S- layer proteins and production of bacteriocins. Analyses of bacterial surface proteins using SDS- PAGE, 2D-PAGE and PCR with specific primers for slp genes, discovered that only four Lactobacillus brevis strains express S-layer proteins, while using antibacterial activity assays and PCR with specific primers for genes encoding various bacteriocins, only three Lactobacillus plantarum strains were confirmed as bacteriocin producers. Biological functions of Lactobacillus S-layer proteins are still poorly understood, however, our investigations confirmed that they mediate bacterial adherence to intestinal epithelial cells and extracellular matrix proteins and also influence the immune response, which are important probiotic properties. When applied as mixed culture, S-layer protein carrying strain and bacteriocin producing strain made strong influence on microbiota composition of rats used as animal models in investigation of Alzheimer’s disease. Purified S-layer proteins of L. brevis SF9B strain, with MW of 50.9 kDa and pI of 9.54, were identified using LC/MS method, while the prediction of their secondary structure was generated using I-TASSER modelling. The fact that purified S-layers are stable toward non- physiological pH and that they protect the cell against various stress conditions, opens an interesting perspective in the development of vehicles for oral administration of drugs or vaccines, specially taking into account GRAS (Generally Regarded as Safe) status of LAB.

Living drugs ; S-layer proteins ; bacteriocins ; probiotic ; microbiota

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