Limosilactobacillus fermentum strains MC1 and D12: Functional properties and exopolysaccharides characterization.

Lactic acid bacteria (LAB) produce a broad spectrum of exopolysaccharides (EPSs), commonly used as texturizers in food products. Due to their potential contribution to LAB probiotic properties, like adhesion to human epithelial cells and competitive exclusion of pathogens from human intestinal epithelial cells, this study was focussed on the structural and functional characterization of the EPSs produced by two Limosilactobacillus fermentum strains - MC1, originating from mother's milk, and D12, autochthonous from Croatian smoked fresh cheese. Whole-genome sequencing and functional annotation of both L. fermentum strains by RAST server revealed the genes involved in EPS production and transport, with some differences in functionally related genes. EPSs were extracted from the cell surface of both bacterial strains and purified by size-exclusion chromatography. Structural characterization of the EPSs, achieved by chemical analyses and 1D and 2D NMR spectroscopy, showed that both strains produce an identical mixture of three different EPSs containing galactofuranose and glucopyranose residues. However, a comparison of the functional properties showed that the MC1 strain adhered better to the Caco-2 cell line and exhibited stronger antimicrobial effect against Salmonella enterica serovar Typhimurium FP1 than the D12 strain, which may be attributed to the potential bacteriocin activity of the MC1 strain.

An Integrated Comprehensive Peptidomics and In Silico Analysis of Bioactive Peptide-Rich Milk Fermented by Three Autochthonous Cocci Strains.

Bioactive peptides (BPs) are molecules of paramount importance with great potential for the development of functional foods, nutraceuticals or therapeutics for the prevention or treatment of various diseases. A functional BP-rich dairy product was produced by lyophilisation of bovine milk fermented by the autochthonous strains Lactococcus lactis subsp. lactis ZGBP5-51, Enterococcus faecium ZGBP5-52 and Enterococcus faecalis ZGBP5-53 isolated from the same artisanal fresh cheese. The efficiency of the proteolytic system of the implemented strains in the production of BPs was confirmed by a combined high-throughput mass spectrometry (MS)-based peptidome profiling and an in silico approach. First, peptides released by microbial fermentation were identified via a non-targeted peptide analysis (NTA) comprising reversed-phase nano-liquid chromatography (RP nano-LC) coupled with matrix-assisted laser desorption/ionisation-time-of-flight/time-of-flight (MALDI-TOF/TOF) MS, and then quantified by targeted peptide analysis (TA) involving RP ultrahigh-performance LC (RP-UHPLC) coupled with triple-quadrupole MS (QQQ-MS). A combined database and literature search revealed that 10 of the 25 peptides identified in this work have bioactive properties described in the literature. Finally, by combining the output of MS-based peptidome profiling with in silico bioactivity prediction tools, three peptides (75QFLPYPYYAKPA86, 40VAPFPEVFGK49, 117ARHPHPHLSF126), whose bioactive properties have not been previously reported in the literature, were identified as potential BP candidates.

Improved sauerkraut production with probiotic strain Lactobacillus plantarum L4 and Leuconostoc mesenteroides LMG 7954.

UNLABELLED: Probiotic strain Lactobacillus plantarum L4 and strain Leuconostoc mesenteroides LMG 7954 were applied for the controlled fermentation of cabbage heads. The parameters of the controlled and spontaneous fermentations, including antimicrobial effect of cabbage brines obtained at the end of both fermentations, were monitored. To check out the influence of starter culture strains, 10 randomly chosen lactic acid bacteria, isolated at the end of controlled cabbage heads fermentation were identified by API 50 CHL test, and the presence of the probiotic culture was confirmed by Pulsed Field Gel Electrophoresis. The starter cultures applied for cabbage heads fermentation allowed lowering of NaCl concentrations from 4.0% to 2.5% (w/v), considerably accelerated fermentation process by 14 d, and improved the product quality. The produced sauerkraut heads are considered probiotic product as viable probiotic cells count in final product was higher than 10(6) colony-forming units (CFU) per gram of product. PRACTICAL APPLICATION: The results of this research could be applied in the production of fermented cabbage heads with added functional (probiotic) value and with lower NaCl concentration with expected shortened fermentation time. This could not only be of economic but also of ecological importance.