The Profile of Exopolysaccharides Produced by Various Lactobacillus Species from Silage during Not-Fat Milk Fermentation

Abstract

The exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) and released into fermented milk play a protective role from stress factors as well as improve emulsifying and thickening properties of the product, reduce syneresis, and increase elasticity. Here we report the relationship between the properties, composition, and microstructure of EPS produced by six different strains of lactobacilli (L. bulgaricus and five strains isolated from silage). The presence of fructose together with negative-charged uronic acid was found to play a significant role in changing the EPS properties. Thus, the increased fraction of rhamnose and arabinose and a decrease in xylose leads to compaction of the EPS, decreased porosity and increased both OH- and superoxide scavenging and Fe-chelating activities. By contrast, increased xylose and low rhamnose and arabinose apparently leads to loss of large aggregates and high DPPH activity and FRAP. The high content of glucose, however, provides the formation of large pores. The increased fructan fraction (69.9 mol%) with a high fraction of galacturonic (18.2 mol%) and glucuronic acids (6.7 mol%) apparently determines the highly porous spongy-folded EPS microstructure. Taken together, our results indicate that both the quantitative characteristics of the individual components of the fraction and the structural features of EPS are important for the antioxidant potential of fermented milk and depend on the strain used for milk fermentation, suggesting the advantage of a multicomponent starter to achieve the optimal beneficial properties of fermented milk.

Repression of Staphylococcus aureus and Escherichia coli by Lactiplantibacillus plantarum Strain AG10 in Drosophila melanogaster In Vivo Model

“…While broth acidification seems to be the main factor of antagonism in both agar drop diffusion and milk fermentation tests, antimicrobial peptides could play the leading role in vivo [ 33 , 34 ]. Moreover, it has been reported previously that L. plantarum AG10 acidifies the milk in a less pronounced manner than the industrial strains [ 52 , 53 ], assuming that the production of antimicrobial peptides could be apparently responsible for the observed effects both in vitro and in vivo. Indeed, the screening of putative antimicrobial peptides in the genome of L. plantarum AG10 in comparison with the dbAMP database allowed identification of three peptides with over 90% homology with peptides characterized by presumable antimicrobial activity ( Table 3 ).…”

“…Recent data indicate that the L. plantarum AG10 strain, isolated previously from clover silage, demonstrates promising antagonistic activity and probiotic properties in vitro [ 50 , 52 ]. In this work, we also show that it competes with pathogens in vivo, as well as diminishes their negative effects on the host.…”

“…In previous studies, several strains of lactic acid bacteria with probiotic properties were isolated from clover silage [ 50 , 51 , 52 ]. Among them, L. plantarum AG10 demonstrated the most promising probiotic features, as well as antimicrobial activity against pathogens in both liquid medium and biofilm.…”

“…At the same time, it produces less lactic acid during milk fermentation and, as a result, has a lower acidification rate. On the other hand, the amount of EPS in fermented milk L. plantarum AG10 is higher when compared to a control industrial strain [ 52 ]. As a consequence of the larger production of expanded polystyrene, fat-free samples obtained from L. plantarum AG10 fermented milk demonstrated significantly higher viscosity, product adhesion and higher resistance to destruction [ 53 ].…”

A review on proteolytic fermentation of dietary protein using lactic acid bacteria for the development of novel proteolytically fermented foods

“…In Rui et al (2019) study, the soymilk yogurt fermented with L. plantarum B1-6 (3% v/v) at 37 °C had high hardness and gumminess values at low pH (5.1-5.4), indicating high gel strength and dense structure of the gel due to the hydrophobic interactions. The exopolysaccharides produced during fermentation play a significant role in the microstructure and elasticity of gels, and enhance the emulsifying and thickening characteristics of the products (Nikitina et al, 2023). All in all, proteolytic fermentation breaks down the protein into smaller peptides, thus increasing its solubility.…”