Exopolysaccharides (EPSs) are biological polymers secreted by microorganisms including Lactic acid bacteria (LAB) to cope with harsh environmental conditions. EPSs are one of the main components involved in the formation of extracellular biofilm matrix to protect microorganisms from adverse factors such as temperature, pH, antibiotics, host immune defenses, etc.. In this review, we discuss EPS biosynthesis; the role of EPSs in LAB stress tolerance; the impact of environmental stresses on EPS production and on the expression of genes involved in EPS synthesis. The evaluation results indicated that environmental stresses can alter EPS biosynthesis in LAB. For further studies, environmental stresses may be used to generate a new EPS type with high biological activity for industrial applications.

In this study, whey protein, maltodextrin and GOS (Galacto-oligosaccharides) used as microencapsulating agents to protect Lactobacillus casei during spray-drying and mayonnaise storage. The morphology of microcapsules, pH charges, the survival rate during mayonnaise storage as well as survival in simulated gastric fluid (SGF) and intestinal fluid (SIF) was tested in this study. The results indicated that whey protein showed a protective effect better than maltodextrin during spray-drying. The particles showed spherical shape and typical concavity of all samples and encapsulating agents were not affected by the size and surface structure of particles. The pH charges were not significantly different in all mayonnaise samples in this test. The viability of free cell L. casei after 6 weeks storage was significant decrease about 4 log CFU/g compared to 1.55 to 3.27 log CFU/g in the mayonnaise samples containing microcapsules in which maltodextrin showed the lowest of L. casei survival rate. In SGF and SIF conditions, maltodextrin act as prebiotic sufficiently which do not need adding GOS. The combination of whey protein and maltodextrin in which maltodextrin plays a role as supporting agents for the spray-drying process as well as prebiotic potential, while whey protein with high buffer property which enhancing the survival rate of L. casie in low pH.