Biological functions of exopolysaccharides from probiotic bacteria

Probiotic bacteria have the ability to produce exocellular polymers called exopolysaccharides (EPS). It has been suggested that the health benefit of probiotic bacteria can be attributed to the production of EPS. However, the composition, structure and biological functions of EPS may vary depending on the type of microorganism and environmental conditions. Some data suggest that EPS production is under control of quorum sensing (QS) through regulation of gene expression for proteins involved in EPS biosynthesis [1]. EPS is the main substance involved in biofilm formation and may achieve 50-90% of the total organic substances such as proteins, lipids and nucleic acids [1]. Bacteria develop biofilms to protect the microbial community against environmental stress. It has been established that both pathogenic, as well as commensal bacteria, generate biofilms in human mucosas. Biofilm formation is associated with bacterial infection but it may also play a protective role. For example, biofilm-like communities of the gastrointestinal and female urogenital tracts contain beneficial lactic acid bacteria. It has been shown that the cell wall components of probiotic bacteria, such as peptidoglycans or teichoic acids play an important role in activation of immune cells. By contrast, the role of EPS in modulation of the immune system is still unclear.