Structural characterization of exopolysaccharides from Weissella cibaria NC516.11 in distiller grains and its improvement in gluten-free dough

Production, purification, and functional characterization of glucan exopolysaccharide produced by Enterococcus hirae strain OL616073 of fermented food origin

Microbial exopolysaccharides (EPS) are high molecular weight polymeric substances with great diversity and variety of applications in the food and pharma industry. In this study, we report the extraction of an EPS from Enterococcus hirae OL616073 strain originally isolated from Indian fermented food and its purification by ion exchange and size exclusion chromatography for physical-functional analyses. The EPS showed two prominent fractions (EPS F1 and EPS F2) with molecular mass 7.7 × 104 and 6.5 × 104 Da respectively by gel permeation chromatography. These fractions were further characterized by FTIR, HPTLC, GC-MS, and NMR as a homopolysaccharide of glucose linked with α-(1 → 6) and α-(1 → 3) glycosidic linkages. The porous, spongy, granular morphology of EPS was observed under scanning electron microscopy. EPS has revealed strong physico-functional properties like water solubility index (76.75 %), water contact angle (65.74°), water activity (0.35), hygroscopicity (3.05 %), water holding capacity (296.19 %), oil holding capacity (379.91 %), foaming capacity (19.58 %), and emulsifying activity (EA1-72.22 %). Rheological analysis showed that aqueous solution of EPS exhibited a non-Newtonian fluid behavior and shear-thinning characteristics. Overall, EPS exhibits techno functional properties with potential applications as a functional biopolymer in food and pharma industry.

A novel exopolysaccharide from Weissella cibaria FAFU821: Structural characterization and cryoprotective activity

Exopolysaccharides produced by Weissella cibaria has attracted increasing attention owing to their biological activity. Here, a strain was isolated from the home-made fermented octopus, which was identified as W. cibaria FAFU821. In addition, the polysaccharide were isolated and purified by cellulose DE-52 column and Sephadex G-100 column, and named EPS821-1. In this work, the structure of EPS821-1 and its cryoprotective activity on Bifidobacterium longum subsp. longum F2 were investigated in vitro. These results suggested that the EPS821-1 is a novel glucan, which mainly consists of α-(1 → 6) linkage with α-(1 → 4), α-(1 → 4,6) and α-(1 → 3,6) residue as branches. In addition, EPS821-1 existed the three-dimensional network structure and exhibited the excellent cryoprotective activities for B. longum subsp. longum F2, which was 2.75 folds higher than that of the controls. This study provided scientific evidence and insights for the application of EPS821-1 as cryoprotection in food field.

The Weissella and Periweissella genera: up-to-date taxonomy, ecology, safety, biotechnological, and probiotic potential

Bacteria belonging to the genera Weissella and Periweissella are lactic acid bacteria, which emerged in the last decades for their probiotic and biotechnological potential. In 2015, an article reviewing the scientific literature till that date on the taxonomy, ecology, and biotechnological potential of the Weissella genus was published. Since then, the number of studies on this genus has increased enormously, several novel species have been discovered, the taxonomy of the genus underwent changes and new insights into the safety, and biotechnological and probiotic potential of weissellas and periweissellas could be gained. Here, we provide an updated overview (from 2015 until today) of the taxonomy, ecology, safety, biotechnological, and probiotic potential of these lactic acid bacteria.

Fecal fermentation and high-fat diet-induced obesity mouse model confirmed exopolysaccharide from Weissella cibaria PFY06 can ameliorate obesity by regulating the gut microbiota

Obesity associated with diet and intestinal dysbiosis is a worldwide public health crisis, and exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) have prebiotic potential to ameliorate obesity. Therefore, the present study obtained LAB with the ability to produce high EPS, examined the structure of EPS, and explained its mechanism of alleviating obesity by in vivo and in vitro models. The results showed that Weissella cibaria PFY06 with a high EPS yield was isolated from strawberry juice, and pure polysaccharide (PFY06-EPS) was purified by Sephadex G-100. The structural characteristics of PFY06-EPS showed that the molecular weight was 8.08 × 10⁶ Da and composed of α-(1,6)-D glucosyl residues. An in vitro simulated human colon fermentation test demonstrated that PFY06-EPS increased the abundance of Prevotella and Bacteroides. Cell tests confirmed that PFY06-EPS after fecal fermentation inhibited fat accumulation by promoting the secretion of endogenous gastrointestinal hormones and insulin and inhibiting the secretion of inflammatory factors. Notably, PFY06-EPS reduced weight gain, fat accumulation, inflammatory reactions and insulin resistance in a high-fat diet-induced obesity mouse model and improved glucolipid metabolism. PFY06-EPS intervention reversed obesity-induced microflora disorders, such as reducing the Firmicutes/Bacteroides ratio and increasing butyrate-producing bacteria (Roseburia and Oscillibacter), and reduced endotoxemia to maintain intestinal barrier integrity. Therefore, in vivo and in vitro models showed that PFY06-EPS had potential as a prebiotic that may play an anti-obesity role by improving the function of the gut microbiota.

Impact of exopolysaccharides-producing lactic acid bacteria on the chemical, rheological properties of buckwheat sourdough and the quality of buckwheat bread

Exopolysaccharides (EPS) produced in situ by lactic acid bacteria (LAB) during sourdough fermentation have the potential to replace hydrocolloids in gluten-free sourdoughs. This study investigated effects of an EPS-producing Weissella cibaria NC516.11 fermentation on chemical, rheological properties of sourdough and the quality of buckwheat bread. Results indicate that the buckwheat sourdough fermentation by W. cibaria NC516.11 had lower pH (4.47) and higher total titrable acidity (8.36 mL) compared with other groups, and the polysaccharide content reached 3.10 ± 0.16 g/kg. W. cibaria NC516.11 can significantly improve the rheological properties and viscoelastic properties of sourdough. Compared with control group, the baking loss of NC516.11 group bread decreased by 19.94%, specific volume increased by 26.03%, and showed good appearance and cross-sectional morphology. Scanning electron micrograph revealed an intact and less porous cell structure. Meanwhile, W. cibaria NC516.11 significantly improved the texture of the bread and reduced the hardness and moisture loss during storage.

Biological activities and applications of exopolysaccharides produced by lactic acid bacteria: a mini-review

Exopolysaccharides (EPSs) are naturally occurring high-molecular-weight carbohydrates that have been widely studied for their biological activities, including antioxidant, immunomodulatory, anticancer and gut microbiota regulation activities. Polysaccharides are abundant in nature and can be derived from animals, plants, algae, and microorganisms, but among polysaccharides with potential uses, EPSs from microorganisms have the advantages of a short production cycle, high yield, and independence of production from season and climate and thus have broad prospects. While the safety of the producing microorganism can represent a problem in application of microbial EPSs, lactic acid bacteria (LAB) have been used by humans for thousands of years, and they and their products are generally recognized as safe. This makes LAB excellent sources for exopolysaccharides. EPS-producing LAB are readily found in nature. Through screening of strains, optimization of culture conditions, and improvement of the growth medium, the yield of EPSs from LAB can be increased and the scope of application broadened. This review summarizes EPSs from LAB in terms of structure, function and applications, as well as yield optimization, and introduces recent research on the biological activities and practical applications of LAB EPSs, aiming to provide references for researchers in related areas.

Production of 1,3-propanediol using enzymatic hydrolysate derived from pretreated distillers' grains

To minimize environmental pollution and waste of resources, distillers' grains (DG) was used to produce 1,3-propanediol. Biological, physical, and chemical methods were used for pretreatment. The correlation between features of pretreated samples and enzymatic digestibility was analyzed. The results showed that the glucan and xylan conversion of dilute sulfuric acid pretreated DG increased by 69.59% and 413.68%, respectively. The glucan conversion of microwave pretreated and xylan conversion of laccase pretreated DG increased by 14.22% and 34.19%, respectively. Pretreatment enhanced enzymatic digestibility through changing the dense structure and features of DG making them conductive to enzymatic hydrolysis. The production of 1,3-propanediol using enzymatic hydrolysate of pretreated DG and glycerol in shake-flask was 17 g/L. The utilization of DG not only provides plentiful raw materials replacing fossil fuels to produce biofuels and other chemicals but efficiently reduces environmental waste.

Dextran Formulations as Effective Delivery Systems of Therapeutic Agents

Dextran is by far one of the most interesting non-toxic, bio-compatible macromolecules, an exopolysaccharide biosynthesized by lactic acid bacteria. It has been extensively used as a major component in many types of drug-delivery systems (DDS), which can be submitted to the next in-vivo testing stages, and may be proposed for clinical trials or pharmaceutical use approval. An important aspect to consider in order to maintain high DDS' biocompatibility is the use of dextran obtained by fermentation processes and with a minimum chemical modification degree. By performing chemical modifications, artefacts can appear in the dextran spatial structure that can lead to decreased biocompatibility or even cytotoxicity. The present review aims to systematize DDS depending on the dextran type used and the biologically active compounds transported, in order to obtain desired therapeutic effects. So far, pure dextran and modified dextran such as acetalated, oxidised, carboxymethyl, diethylaminoethyl-dextran and dextran sulphate sodium, were used to develop several DDSs: microspheres, microparticles, nanoparticles, nanodroplets, liposomes, micelles and nanomicelles, hydrogels, films, nanowires, bio-conjugates, medical adhesives and others. The DDS are critically presented by structures, biocompatibility, drugs loaded and therapeutic points of view in order to highlight future therapeutic perspectives.

Novel Insights Into the Phylogeny and Biotechnological Potential of Weissella Species

In this study, the genomes of the Weissella (W.) beninensis, W. diestrammenae, W. fabalis, W. fabaria, W. ghanensis, and W. uvarum type strains were sequenced and analyzed. Moreover, the ability of these strains to metabolize 95 carbohydrates was investigated, and the genetic determinants of such capability were searched within the sequenced genomes. 16S rRNA gene and genome-based-phylogeny of all the Weissella species described to date allowed a reassessment of the Weissella genus species groups. As a result, six distinct species groups within the genus, namely, W. beninensis, W. kandleri, W. confusa, W. halotolerans, W. oryzae, and W. paramesenteroides species groups, could be described. Phenotypic analyses provided further knowledge about the ability of the W. beninensis, W. ghanensis, W. fabaria, W. fabalis, W. uvarum, and W. diestrammenae type strains to metabolize certain carbohydrates and confirmed the interspecific diversity of the analyzed strains. Moreover, in many cases, the carbohydrate metabolism pathway and phylogenomic species group clustering overlapped. The novel insights provided in our study significantly improved the knowledge about the Weissella genus and allowed us to identify features that define the role of the analyzed type strains in fermentative processes and their biotechnological potential.

Antifungal Mechanisms and Application of Lactic Acid Bacteria in Bakery Products: A Review

Bakery products are nutritious, but they are susceptible to fungal contamination, which leads to a decline in quality and safety. Chemical preservatives are often used to extend the shelf-life of bakery products, but long-term consumption of these preservatives may increase the risk of chronic diseases. Consumers increasingly demand food with fewer chemical preservatives. The application of lactic acid bacteria (LAB) as a novel biological preservative not only prolongs the shelf-life of bakery products but also improves the baking properties of bakery products. This review summarizes different types and action mechanisms of antifungal compounds produced by LAB, factors affecting the production of antifungal compounds, and the effects of antifungal LAB on bakery products, providing a reference for future applications of antifungal LAB in bakery products.