Immunomodulatory effects of exopolysaccharides produced by Bacillus licheniformis and Leuconostoc mesenteroides isolated from Korean kimchi

Probiotic Bacillus as fermentation agents: Status, potential insights, and future perspectives

Probiotic Bacillus strains can solve the problems of single flavor and long fermentation time of fermented products caused by the lack of certain functional genes and insufficient metabolism ability of fermenter strains (Lactobacillus and Bifidobacterium) at the present stage. There is a lack of systematic evaluation and review of probiotic Bacillus as food fermentation agents. In this paper, it is observed that probiotic Bacillus strains are involved to varying degrees in liquid-state, semi-solid state, and solid-state fermentation and are widely present in solid-state fermented foods. Probiotic Bacillus strains not only produce abundant proteases and lipases, but also effective antifungal lipopeptides and extracellular polymers, thus enhancing the flavor, nutritional value and safety of fermented foods. Bacillus with probiotic qualities is an underutilized group of probiotic food fermentation agents, which give a potential for the development of fermentation technology in the food business and the integration of ancient traditional fermentation techniques.

Fermented foods and gastrointestinal health: underlying mechanisms

Although fermentation probably originally developed as a means of preserving food substrates, many fermented foods (FFs), and components therein, are thought to have a beneficial effect on various aspects of human health, and gastrointestinal health in particular. It is important that any such perceived benefits are underpinned by rigorous scientific research to understand the associated mechanisms of action. Here, we review in vitro, ex vivo and in vivo studies that have provided insights into the ways in which the specific food components, including FF microorganisms and a variety of bioactives, can contribute to health-promoting activities. More specifically, we draw on representative examples of FFs to discuss the mechanisms through which functional components are produced or enriched during fermentation (such as bioactive peptides and exopolysaccharides), potentially toxic or harmful compounds (such as phytic acid, mycotoxins and lactose) are removed from the food substrate, and how the introduction of fermentation-associated live or dead microorganisms, or components thereof, to the gut can convey health benefits. These studies, combined with a deeper understanding of the microbial composition of a wider variety of modern and traditional FFs, can facilitate the future optimization of FFs, and associated microorganisms, to retain and maximize beneficial effects in the gut.

The Plethora of Microbes with Anti-Inflammatory Activities

Inflammation, which has important functions in human defense systems and in maintaining the dynamic homeostasis of the body, has become a major risk factor for the progression of many chronic diseases. Although the applied medical products alleviate the general status, they still exert adverse effects in the long term. For this reason, the solution should be sought in more harmless and affordable agents. Microorganisms offer a wide range of active substances with anti-inflammatory properties. They confer important advantages such as their renewable and inexhaustible nature. This review aims to provide the most recent updates on microorganisms of different types and genera, being carriers of anti-inflammatory activity.

Unraveling the carbohydrate metabolic characteristics of Leuconostoc mesenteroides J18 through metabolite and transcriptome analyses

The metabolic characteristics of Leuconostoc mesenteroides subsp. mesenteroides J18, which is mainly responsible for kimchi fermentation, on various carbon sources were investigated through carbon utilization, metabolite, and transcriptome analyses at different culture conditions (10 and 30 °C with/without 2.5% NaCl). The metabolic features of strain J18 were relatively similar across the four culture conditions. However, the metabolic characteristics of strain J18 showed significant variations depending on the carbon source. These distinct metabolic traits of strain J18 on various carbon sources were validated through transcriptomic analyses and the reconstruction of metabolic pathways. The transcriptional expression of the metabolic pathways in response to each carbon source consistently correlated with the production profiles of metabolites, including ethanol, acetoin, diacetyl, and riboflavin, in each carbon source. Our findings suggests that the abundance of Leu. mesenteroides during fermentation and the taste and flavor of fermented food products can be controlled by altering the carbon sources.

Research progress on the functions, preparation and detection methods of l-fucose

l-fucose is a six-carbon sugar that has potential applications in many fields. It exerts antitumor effects and could relieve intestinal disease. It exhibits potential as an emulsifier in the food industry. It is also used as a functional food and in anti-aging skincare products. However, at present, it is not possible to prepare high-purity l-fucose on a large scale, and its preparation needs further development. This review summarizes the preparation methods of l-fucose including chemical synthesis, enzymatic synthesis, microbial fermentation, and separation and purification from algae. The detection methods of l-fucose are also introduced in detail, such as l-fucose-specific lectin, detection l-fucose dehydrogenase, cysteine-sulfuric acid method, high-performance liquid chromatography, gas chromatography, and biosensors. In this review, the properties and pharmacological effects of l-fucose; preparation methods, and the commonly used detection methods of l-fucose are reviewed to serve as a reference material.

Structural properties and biological activities of the extracellular polysaccharide of Bacillus subtilis LZ13-4

The remarkable functional characteristics of Bacillus subtilis extracellular polysaccharides (BSPS) are of great interest. Therefore, in the present study, BSPS was isolated and characterized to obtain two fractions, BSPS-1 and BSPS-2, respectively, and to investigate their biological activities. BSPS-1 contained fructose, glucose, and galactose (molar ratio: 25.27:43.37:31.36), while BSPS-2 contained fructose with only trace amounts of glucose, galactose, and mannose (molar ratio: 55.08:19.03:19.21:6.68), and their respective average molecular weights were 16.9 kDa and 202.67 kDa. With a 93.55 % clearance of ABTS•+ at a concentration of 2 mg/mL of BSPS-1, the antioxidant activity revealed that BSPS-1 had greater antioxidant activity than BSPS-2 and that both were concentration-dependent. The inhibitory effect on HepG2 cells demonstrated that BSPS-1 and BSPS-2 significantly inhibited the proliferation of HepG2 and increased the expression of apoptotic proteins, causing apoptosis. The inhibition rate on HepG2 cells was dose-dependent and reached 52.7 % and 40.3 % after 48 h of action. BSPS-2 and 800 μg/mL BSPS-1 growth was inhibited in the G1/G0 phase, while 200 and 400 μg/mL BSPS-1 growth was inhibited in the S phase. In conclusion, the study of the BSPS's structure and properties can offer a theoretical foundation for real-world industrial applications.

Exploring the hemicellulolytic properties and safety of Bacillus paralicheniformis as stepping stone in the use of new fibrolytic beneficial microbes

Bacillus strains from the Moroccan Coordinated Collections of Microorganisms (CCMM) were characterised and tested for fibrolytic function and safety properties that would be beneficial for maintaining intestinal homeostasis, and recommend beneficial microbes in the field of health promotion research. Forty strains were investigated for their fibrolytic activities towards complex purified polysaccharides and natural fibres representative of dietary fibres (DFs) entering the colon for digestion. We demonstrated hemicellulolytic activities for nine strains of Bacillus aerius, re-identified as Bacillus paralicheniformis and Bacillus licheniformis, using xylan, xyloglucan or lichenan as purified polysaccharides, and orange, apple and carrot natural fibres, with strain- and substrate-dependent production of glycoside hydrolases (GHs). Our combined methods, based on enzymatic assays, secretome, and genome analyses, highlighted the hemicellulolytic activities of B. paralicheniformis and the secretion of specific glycoside hydrolases, in particular xylanases, compared to B. licheniformis. Genomic features of these strains revealed a complete set of GH genes dedicated to the degradation of various polysaccharides from DFs, including cellulose, hemicellulose and pectin, which may confer on the strains the ability to digest a variety of DFs. Preliminary experiments on the safety and immunomodulatory properties of B. paralicheniformis fibrolytic strains were evaluated in light of applications as beneficial microbes' candidates for health improvement. B. paralicheniformis CCMM B969 was therefore proposed as a new fibrolytic beneficial microbe candidate.

Lactic acid bacteria-derived exopolysaccharide: Formation, immunomodulatory ability, health effects, and structure-function relationship

Exopolysaccharides (EPSs) synthesized by lactic acid bacteria (LAB) have implications for host health and act as food ingredients. Due to the variability of LAB-EPS (lactic acid bacteria-derived exopolysaccharide) gene clusters, especially the glycosyltransferase genes that determine monosaccharide composition, the structure of EPS is very rich. EPSs are synthesized by LAB through the extracellular synthesis pathway and the Wzx/Wzy-dependent pathway. LAB-EPS has a strong immunomodulatory ability. The EPSs produced by different genera of LAB, especially Lactobacillus, Leuconostoc, and Streptococcus, have different immunomodulatory abilities because of their specific structures. LAB-EPS possesses other health effects, including antitumor, antioxidant, intestinal barrier repair, antimicrobial, antiviral, and cholesterol-lowering activities. The bioactivities of LAB-EPS are tightly related to their structures such us monosaccharide composition, glycosidic bonds, and molecular weight (MW). For the excellent physicochemical property, LAB-EPS acts as product improvers in dairy, bakery food, and meat in terms of stability, emulsification, thickening, and gelling. We systematically summarize the detailed process of EPS from synthesis to application, with emphasis on physiological mechanisms of EPS, and specific structure-function relationship, which provides theoretical support for the potential commercial value in the pharmaceutical, chemical, food, and cosmetic industries.

Structural characterization and partial properties of dextran produced by Leuconostoc mesenteroides RSG7 from pepino

Exopolysaccharides (EPSs) produced by lactic acid bacteria possess various bioactivities and potential attractions for scientific exploration and commercial development. An EPS-producing bacterial strain, RSG7, was previously isolated from the pepino and identified as Leuconostoc mesenteroides. Based on the analyses of high-performance size exclusion chromatography, high-performance ion chromatography, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and methylation, the RSG7 EPS was identified as a dextran with a molecular weight of 5.47 × 10⁶ Da and consisted of α-(1→6) glycosidic linkages as backbone and α-(1→2), α-(1→3), α-(1→4), and α-(1→6) glycosidic linkages as side chains. Scanning electron microscopy observed a honeycomb-like porous structure of RSG7 dextran, and this dextran formed aggregations with irregular hill-shaped lumps according to atomic force microscopy analysis. Physical-chemical investigations suggested that RSG7 dextran possessed excellent viscosity at high concentration, low temperature, and high pH; showed a superior emulsifying capacity of tested vegetable oils than that of hydrocarbons; and owned the maximal flocculating activity (10.74 ± 0.23) and flocculating rate (93.46 ± 0.07%) in the suspended solid of activated carbon. In addition, the dextran could coagulate sucrose-supplemented milk and implied potential probiotics in vitro. Together, these results collectively describe a valuable dextran with unique characteristics for exploitation in food applications.

Structural characterization and hepatoprotective activity of exopolysaccharide from Bacillus velezensis SN-1

BACKGROUND

Exopolysaccharide biopolymers produced by microorganisms are crucial to the environment. They contribute to areas such as the health and bionanotechnology sectors, food and cosmetic industries as gelling agents, and environmental sector as flocculants owing to their biodegradability and non-toxic nature. The current study aimed to isolate the fraction of released exopolysaccharide (rEPS) by Bacillus velezensis SN-1 from Chinese Da-Jiang.

RESULTS

The weighted average molecular weight of the major isolated component, rEPS-2, was 202 kDa, and its monosaccharide composition included mannose, glucose, and galactose at a molar ratio of 0.38:0.30:0.32. Further, the rEPS-2 was characterized using methylation analysis and one-dimensional/two-dimensional nuclear magnetic resonance (1D/2D NMR) spectroscopy. In vivo hepatoprotective effects indicated that rEPS-2 could alleviate carbon tetrachloride (CCl₄ )-induced liver injury in mice by lowering the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and the malondialdehyde (MDA) levels. Furthermore, rEPS-2 can increase the expression of antioxidant genes HO-1, GCLC and NQO1 in the Nrf2/ARE signaling pathway, thereby increasing the activity of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and reduced catalase (CAT) in liver cells. Furthermore, the rEPS-2 can be used and modulate the gut microbiota of mice with liver injury caused by CCl₄ .

CONCLUSIONS

These results suggest that rEPS-2 has promising potential to serve as hepatoprotective agents. © 2022 Society of Chemical Industry.

Probiotics in the Sourdough Bread Fermentation: Current Status

Sourdough fermentation is an ancient technique to ferment cereal flour that improves bread quality, bringing nutritional and health benefits. The fermented dough has a complex microbiome composed mainly of lactic acid bacteria and yeasts. During fermentation, the production of metabolites and chemical reactions occur, giving the product unique characteristics and a high sensory quality. Mastery of fermentation allows adjustment of gluten levels, delaying starch digestibility, and increasing the bio-accessibility of vitamins and minerals. This review focuses on the main steps of sourdough fermentation, the microorganisms involved, and advances in bread production with functional properties. The impact of probiotics on human health, the metabolites produced, and the main microbial enzymes used in the bakery industry are also discussed.

Microbial exopolysaccharides-β-glucans-as promising postbiotic candidates in vaccine adjuvants

The urgent task of creating new, enhanced adjuvants is closely related to our comprehension of their mechanisms of action. A few adjuvants have shown sufficient efficacy and low toxicity to be allowed for use in human vaccines, despite the fact that they have a long history and an important function. Adjuvants have long been used without a clear understanding of how precisely they augment the immune response. The rational production of stronger and safer adjuvants has been impeded by this lack of information, which necessitates more mechanistic research to support the development of vaccines. Carbohydrate structures-polygalactans, fructans, β-D-glucans, α-D-glucans, D-galactose, and D-glucose-are desirable candidates for the creation of vaccine adjuvants and immunomodulators because they serve important functions in nature and are often biocompatible, safe, and well tolerated. In this review, we have discussed recent advances in microbial-derived carbohydrate-based adjuvants, their immunostimulatory activity, and the implications of this for vaccine development, along with the critical view on the microbial sources, chemical composition, and biosynthetic pathways.

Recent advances and potentiality of postbiotics in the food industry: Composition, inactivation methods, current applications in metabolic syndrome, and future trends

Postbiotics are defined as "preparation of inanimate microorganisms and/or their components that confers a health benefit on the host". Postbiotics have unique advantages over probiotics, such as stability, safety, and wide application. Although postbiotics are research hotspots, the research on them is still very limited. This review provides comprehensive information on the scope of postbiotics, the preparation methods of inanimate microorganisms, and the application and mechanisms of postbiotics in metabolic syndrome (MetS). Furthermore, the application trends of postbiotics in the food industry are reviewed. It was found that postbiotics mainly include inactivated microorganisms, microbial lysates, cell components, and metabolites. Thermal treatments are the main methods to prepare inanimate microorganisms as postbiotics, while non-thermal treatments, such as ionizing radiation, ultraviolet light, ultrasound, and supercritical CO2, show great potential in postbiotic preparation. Postbiotics could ameliorate MetS through multiple pathways including the modulation of gut microbiota, the enhancement of intestinal barrier, the regulation of inflammation and immunity, and the modulation of hormone homeostasis. Additionally, postbiotics have great potential in the food industry as functional food supplements, food quality improvers, and food preservatives. In addition, the SWOT analyses showed that the development of postbiotics in the food industry exists both opportunities and challenges.

Bacillus-derived probiotics: metabolites and mechanisms involved in bacteria-host interactions

Bacillus probiotics have a sporulation capacity that makes them more suitable for processing and storage and for surviving passage through the gastrointestinal tract. The probiotic functions and regulatory mechanisms of different Bacillus have been exploited in many reports, but little is known about how various Bacillus probiotics perform different functions. This knowledge gap results in a lack of specificity in the selection and application of Bacillus. The probiotic properties are strain-specific and cell-type-specific, and are related to the germination potential and to the diversity of metabolites produced following intestinal germination, as this causes the variation in probiotic function and mechanisms. In this review, we discuss the Bacillus metabolites produced during germination and sporulation in the GI tract, as well as possible processes affecting intestinal homeostasis. We conclude that the oxygen-capturing capability and the production of antimicrobials, exoenzymes, competence and sporulation factors (CSF), exopolysaccharides, lactic acid, and cell components are specifically associated with the functional mechanisms of probiotic Bacillus. The aim of this review is to guide the screening of potential Bacillus strains for probiotics and their application in nutrition research. The information provided will also promote further research on Bacillus-derived functional metabolites in human nutrition.

Dietary Bacillus licheniformis improves the effect of Astragalus membranaceus extract on blood glucose by regulating antioxidation activity and intestinal microbiota in InR[E19]/TM2 Drosophila melanogaster

Background

The diabetes mellitus prevalence is rapidly increasing in most parts of the world and has become a vital health problem. Probiotic and herbal foods are valuable in the treatment of diabetes.

Methods and performance

In this study, Bacillus licheniformis (BL) and Astragalus membranaceus extract (AE) were given with food to InR^[E19]/TM2 Drosophila melanogaster, and the blood glucose, antioxidation activity and intestinal microbiota were investigated. The obtained results showed that BA (BL and AE combination) supplementation markedly decreased the blood glucose concentration compared with the standard diet control group, accompanied by significantly increased enzymatic activities of catalase (CAT), decreased MDA levels and prolonged lifespan of InR^[E19]/TM2 D. melanogaster. The treatments with BL, AE and BA also ameliorated intestinal microbiota equilibrium by increasing the population of Lactobacillus and significantly decreasing the abundance of Wolbachia. In addition, clearly different evolutionary clusters were found among the control, BL, AE and BA-supplemented diets, and the beneficial microbiota, Lactobacillaceae and Acetobacter, were found to be significantly increased in male flies that were fed BA. These results indicated that dietary supplementation with AE combined with BL not only decreased blood glucose but also extended the lifespan, with CAT increasing, MDA decreasing, and intestinal microbiota improving in InR^[E19]/TM2 D. melanogaster.

Conclusion

The obtained results showed that dietary supplementation with BL and AE, under the synergistic effect of BL and AE, not only prolonged the lifespan of InR^[E19]/TM2 D. melanogaster, increased body weight, and improved the body’s antiaging enzyme activity but also effectively improved the types and quantities of beneficial bacteria in the intestinal flora of InR^[E19]/TM2 D. melanogaster to improve the characteristics of diabetes symptoms. This study provides scientific evidence for a safe and effective dietary therapeutic method for diabetes mellitus.

Leuconostoc mesenteroides LVBH107 Antibacterial Activity against Porphyromonas gingivalis and Anti-Inflammatory Activity against P. gingivalis Lipopolysaccharide-Stimulated RAW 264.7 Cells

Probiotics, active microorganisms benefiting human health, currently serve as nutritional supplements and clinical treatments. Periodontitis, a chronic infectious oral disease caused by Porphyromonas gingivalis (P. gingivalis), activates the host immune response to release numerous proinflammatory cytokines. Here, we aimed to clarify Leuconostoc mesenterica (L. mesenteroides) LVBH107 probiotic effects based on the inhibition of P.gingivalis activities while also evaluating the effectiveness of an in vitro P.gingivalis lipopolysaccharide-stimulated RAW 264.7 cell-based inflammation mode. L. mesenteroides LVBH107 survived at acid, bile salts, lysozyme, and hydrogen peroxide conditions, auto-aggregated and co-aggregated with P. gingivalis, exhibited strong hydrophobicity and electrostatic action, and strongly adhered to gingival epithelial and HT-29 cells (thus exhibiting oral tissue adherence and colonization abilities). Moreover, L.mesenteroides LVBH107 exhibited sensitivity to antibiotics erythromycin, doxycycline, minocycline, ampicillin, and others (thus indicating it lacked antibiotic resistance plasmids), effectively inhibited P.gingivalis biofilm formation and inflammation (in vitro inflammation model), reduced the secretion of pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) and inflammatory mediators (NO and PGE₂), and decreased the expression levels of inflammation related genes. Thus, L.mesenterica LVBH107 holds promise as a probiotic that can inhibit P.gingivalis biofilm formation and exert anti-inflammatory activity to maintain oral health.

Structure characterization, antioxidant and emulsifying capacities of exopolysaccharide derived from Tetragenococcus halophilus SNTH-8

Tetragenococcus halophilus exopolysaccharides (THPS) are metabolites released by T. halophilus SNTH-8 to resist a high-salt environment. Although many studies have investigated the mechanisms underlying salt tolerance shown by T. halophilus, structural characteristics as well as antioxidant and emulsifying capacities of THPS remain unclear. In this study, we isolated and purified two components, THPS-1 and THPS-2, from T. halophilus SNTH-8. Purified THPS-1 and THPS-2 were composed of arabinose, xylose, fucose, galactose, glucose, and glucuronic acid at a molar ratio of 1.66:38.95:2.11:26.12:29.73:1.43 and 0.46:40.3:0.54:30.8:1.36:25.54, respectively. The average molecular weights of THPS-1 and THPS-2 were 14.98 kDa and 21.03 kDa, respectively. Moreover, the structures of THPS-1 and THPS-2 were investigated via fourier-transform infrared spectroscopy(FT-IR), nuclear magnetic resonance spectroscopy(NMR), scanning electron microscopy(SEM), and methylation analysis. THPS-1 was a highly branched polysaccharide with a backbone of α-D-(1,4)-Xyl, α-D-(1,6)-Glc and α-D-Xyl as the terminal, while THPS-2 was a highly branched polysaccharide with a backbone of α-D-(1,4)-Xyl and β-D-GlcA as the terminal. The branches were identified as β-D-(1,4,6)-Gal and β-D-(1,6)-Gal. Both THPS-1 and THPS-2 exhibited high antioxidant and emulsifying capacities. Overall, our structural analysis of THPS may further enhance research on natural emulsifiers and antioxidants.

Fucose-containing bacterial exopolysaccharides: Sources, biological activities, and food applications

Bacterial exopolysaccharides are high molecular weight polysaccharides that are secreted by a wide range of bacteria, with diverse structures and easy preparation. Fucose, fucose-containing oligosaccharides (FCOs), and fucose-containing polysaccharides (FCPs) have important applications in the food and medicine fields, including applications in products for removing Helicobacter pylori and infant formula powder. Fucose-containing bacterial exopolysaccharide (FcEPS) is a prospective source of fucose, FCOs, and FCPs. This review systematically summarizes the common sources and applications of FCPs and FCOs and the bacterial strains capable of producing FcEPS reported in recent years. The repeated-unit structures, synthesis pathways, and factors affecting the production of FcEPS are reviewed, as well as the degradation methods of FcEPS for preparing FCOs. Finally, the bioactivities of FcEPS, including anti-oxidant, prebiotic, anti-cancer, anti-inflammatory, anti-viral, and anti-microbial activities, are discussed and may serve as a reference strategy for further applications of FcEPS in the functional food and medicine industries.

Immunomodulatory Activity of Extracellular Vesicles of Kimchi-Derived Lactic Acid Bacteria (Leuconostoc mesenteroides, Latilactobacillus curvatus, and Lactiplantibacillus plantarum)

Lactic acid bacteria present in Kimchi, such as Leuconostoc mesenteroides (Lm), Latilactobacillus curvatus (Lc), and Lactiplantibacillus plantarum (Lp) produce extracellular vesicles (ECVs) that modulate immune responses. The ECVs of probiotic Kimchi bacteria are abbreviated as LmV, LcV, and LpV. Treatment of macrophages (RAW264.7) with ECVs (LmV, LcV, and LpV) increased the production of nitric oxide (NO), tumor necrosis factor (TNF)-α, and interleukin-6 (IL-6). Immunostimulatory effects exerted on the RAW264.7 cells were stronger after treatments with LmV and LcV than with LpV. Treatment of mice with LcV (1 mg/kg, orally) induced splenocyte proliferation and subsequent production of both NO and cytokines (INF-γ, TNF-α, IL-4, and IL-10). Furthermore, pre-treatment of macrophages and microglial cells with ECVs prior to LPS stimulation significantly attenuated the production of NO and pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). Therefore, ECVs (LmV, LcV, and LpV) prevent inflammatory responses in the LPS-stimulated microglial cells by blocking the extracellular signal-regulated kinase (Erk) and p38 signaling pathways. These results showed that LmV, LcV, and LpV from Kimchi probiotic bacteria safely exert immunomodulatory effects.

Application of Liposome Encapsulating Lactobacillus curvatus Extract in Cosmetic Emulsion Lotion

Probiotic extracts have various positive attributes, such as antioxidant, tyrosinase inhibitory, and antimicrobial activity. Lactobacillus curvatus produces bacteriocin, which activates the lipid membrane structure and has potential as a natural preservative for cosmetic emulsions. In this study, L. curvatus extract was encapsulated in liposomes and formulated as an oil-in-water (O/W) emulsion. Radical scavenging activity, tyrosinase inhibition, and challenge tests were conducted to confirm the liposome activity and the activity of the applied lotion emulsion. The liposome-encapsulated extract had a relatively high absolute ζ-potential (52.53 > 35.43), indicating its stability, and 96% permeability, which indicates its potential as an active agent in lotion emulsions. Characterization of emulsions containing the liposomes also indicated a stable state. The liposome-encapsulated extract exhibited a higher radical scavenging activity than samples without the extract and non-encapsulated samples, and the functionality was preserved in the lotion emulsion. The tyrosinase inhibition activity of the lotion emulsion with the liposome-encapsulated extract was similar to that of the non-treated extract. Candida albicans and Aspergillus niger were also inhibited in the challenge test with the lotion emulsions during storage. Collectively, these findings indicate that the liposome-encapsulated extract and the lotion containing the encapsulated extract have potential applicability as natural preservatives.

Some Important Metabolites Produced by Lactic Acid Bacteria Originated from Kimchi

Lactic acid bacteria (LAB) have been used for various food fermentations for thousands of years. Recently, LAB are receiving increased attention due to their great potential as probiotics for man and animals, and also as cell factories for producing enzymes, antibodies, vitamins, exopolysaccharides, and various feedstocks. LAB are safe organisms with GRAS (generally recognized as safe) status and possess relatively simple metabolic pathways easily subjected to modifications. However, relatively few studies have been carried out on LAB inhabiting plants compared to dairy LAB. Kimchi is a Korean traditional fermented vegetable, and its fermentation is carried out by LAB inhabiting plant raw materials of kimchi. Kimchi represents a model food with low pH and is fermented at low temperatures and in anaerobic environments. LAB have been adjusting to kimchi environments, and produce various metabolites such as bacteriocins, γ-aminobutyric acid, ornithine, exopolysaccharides, mannitol, etc. as products of metabolic efforts to adjust to the environments. The metabolites also contribute to the known health-promoting effects of kimchi. Due to the recent progress in multi-omics technologies, identification of genes and gene products responsible for the synthesis of functional metabolites becomes easier than before. With the aid of tools of metabolic engineering and synthetic biology, it can be envisioned that LAB strains producing valuable metabolites in large quantities will be constructed and used as starters for foods and probiotics for improving human health. Such LAB strains can also be useful as production hosts for value-added products for food, feed, and pharmaceutical industries. In this review, recent findings on the selected metabolites produced by kimchi LAB are discussed, and the potentials of metabolites will be mentioned.

Temperature mediates metabolism switching of Bacillus sp. ZT-1: Analysis of the properties and structure of exopolysaccharides

Microorganism was very sensitive to external temperature change, which also affected its normal metabolism and secretion. Low temperature exopolysaccharides (LT-EPS) and normal temperature exopolysaccharides (NT-EPS) secreted by Bacillus sp. ZT-1 mediated by temperature were studied in this paper. The total carbohydrate in the LT-EPS and NT-EPS were found to be 82.54 ± 2.56 % and 94.23 ± 1.59 % (w/w). The High Performance Liquid Chromatography (HPLC) revealed the mannose and galacturonic acid accounted for 45.52 and 23.49 % in LT-EPS, respectively. In like manner, mannose and galacturonic acid contained 43.99 and 25.24 % in NT-EPS. One-dimensional nuclear magnetic resonance (NMR) revealed the connection mode of sugar chains. NT-EPS exhibited higher viscosity, better emulsification properties and the larger molecular weight than LT-EPS. Scanning electron microscopy (SEM) showed that LT-EPS was sheet-like with sugar chain branches while NT-EPS was showed as network structure. Furthermore, the 2812 differentially expressed genes (DEGs) were analyzed by Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and located 739 biological pathways. Finally, transcriptome analysis revealed differences in gene expression of the pentose phosphate pathway of carbohydrate metabolism might be the main reason for this difference.

Bacillus amyloliquefaciens SCGB1 Alleviates Dextran Sulfate Sodium-Induced Colitis in Mice Through Immune Regulation

Probiotics, as living microorganisms, exert health benefits to the host by alleviating excess inflammation through modulating the immune system and establishing intestinal homeostasis. In this study, we evaluated the probiotic characteristics and inflammation alleviatory effects of Bacillus amyloliquefaciens isolated from traditional Korean fermented foods. The strains withstood the acidic environment of the digestive process, extended the lifespan of Caenorhabditis elegans, and enhanced pmk-1 expression. However, only B. amyloliquefaciens SCGB1 could attach to C. elegans in the intestines, which enhanced their survival upon exposure to Escherichia coli O157:H7. We also investigated the anti-inflammatory effect of SCGB1 using the RAW264.7 macrophage stimulated with lipopolysaccharide. The strain treatment enhanced anti-inflammatory cytokine interleukin (IL)-10 secretion and downregulated proinflammatory cytokine IL-6 expression in vitro. Next, we used a dextran sulfate sodium (DSS)-induced colitis mouse model to investigate whether SCGB1 can ameliorate gut inflammation in vivo. Compared to those in the DSS-induced mice, histological damage and IL-6 cytokine levels were significantly reduced in SCGB1-fed mice. These results suggest that B. amyloliquefaciens SCGB1 as potential probiotics may have health-promoting effects by reduction of inflammatory responses.

Purification, Structural Characteristics, and Biological Activities of Exopolysaccharide Isolated From Leuconostoc mesenteroides SN-8

In this study, a novel exopolysaccharide (EPS) was extracted from Leuconostoc mesenteroides Shen Nong's (SN)-8 which can be obtained from Dajiang. After the purification step, EPS-8-2 was obtained with molecular weights of 1.46 × 105 Da. The structural characterization of EPS indicated that the EPS belonged to the class polysaccharide, mainly composed of glucan and also contained certain mannose residues that were found to be connected by α-1,6 glycosidic bonds. Moreover, the results demonstrated that EPS displayed a significant capacity to scavenge free radical to some extent, and this anti-oxidant potential was found to be concentration dependent. The results further revealed that EPS displayed a significant inhibitory potential on the growth of HepG2 cells by promoting apoptosis and induced cell cycle arrest in G1 and G2 phases. Overall, these results suggested that EPS can be explored as a possible anti-cancer agent.

Exopolysaccharides from probiotic bacteria and their health potential

Exopolysaccharides (EPS) are extracellular macromolecules excreted as tightly bound capsule or loosely attached slime layer in microorganisms. They play most prominent role against desiccation, phagocytosis, cell recognition, phage attack, antibiotics or toxic compounds and osmotic stress. In the last few decades, natural polymers have gained much attention among scientific communities owing to their therapeutic potential. In particular the EPS retrieved from probiotic bacteria with varied carbohydrate compositions possess a plenty of beneficial properties. Different probiotic microbes have unique behavior in expressing their capability to display significant health promoting characteristics in the form of polysaccharides. In this new era of alternative medicines, these polysaccharides are considered as substitutes for synthetic drugs. The EPS finds applications in various fields like textiles, cosmetics, bioremediation, food and therapeutics. The present review is focused on sources, chemical composition, biosynthetic pathways of EPS and their biological potential. More attention has been given to the scientific investigations on antimicrobial, antitumor, anti-biofilm, antiviral, anti-inflammatory and immunomodulatory activities.

Bacterial Natural Compounds with Anti-Inflammatory and Immunomodulatory Properties (Mini Review)

Inflammation is part of the body's complex biological response to harmful stimuli such as damaged cells, pathogens, or irritants. It is a protective response involving blood cells, immune cells, and molecular mediators. The inflammation not only can eliminate the primary cause of cell injury but also clears out necrotic cells, tissue damaged from the original insults and inflammatory process. Furthermore, it can initiate tissue repair. Pro-inflammatory cytokines are produced predominantly by activated macrophages and are involved in the up-regulation of inflammatory reactions. They are involved in further regulating inflammatory reactions. There is ample evidence that some pro-inflammatory cytokines, such as interleukin 1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), are involved in the pathological pain process. Some of the natural compounds promote cytokines production and inhibit inflammatory responses. The natural compounds which are produced from microorganisms such as omega-3 fatty acid, cyclic peptide, antimicrobial peptide, oligosaccharides, and polysaccharides can reduce inflammation and could be easily incorporated into the diet without any adverse effects. For example, SCFA (short-chain fatty acids), peptide bacteriocin, and polycyclic peptide bacteriocin (nisin) could be used in the treatment of atherosclerosis, orthopedic postoperative infections, and mycobacterium tuberculosis infection, respectively. Also, fatty acids (saturated and unsaturated fatty acids) can be introduced as anti-inflammatory drugs. This review article summarizes bacterial natural compounds with modulating effects on cytokines that are surveyed which may have potential anti-inflammatory drug-like activity.

Structural characterization and antioxidant potential of a novel exopolysaccharide produced by Bacillus velezensis SN-1 from spontaneously fermented Da-Jiang

The aim of this study was to characterize the exopolysaccharide (EPS) produced by Bacillus velezensis SN-1 (B. velezensis SN-1) (EPS-SN-1), which was isolated from the fermented Da jiang. The microbe made crude exopolysaccharides EPS-SN-1 was produced throughout the bacterial growth period, and the highest yield (2.7 g/L) was obtained with sucrose as the carbon source. As per high performance liquid chromatography (HPLC), EPS-SN-1 is a heteropolysaccharide consisting of glucose, mannose and fructose, with a high molecular weight of 2.21 × 10⁵ Da. FTIR spectra further indicated the presence of hydroxyl and carbonyl groups, and NMR analysis confirmed both α- and β-glycosidic bonds. Furthermore, differential scanning calorimetry (DSC) showed that EPS-SN-1 has high thermal stability with fusion point of 270.7 °C. Finally, EPS-SN-1 demonstrated strong antioxidant capacity via its ability to scavenge hydroxyl radical (^•OH), 1,1-diphenyl-2-picrylhydrazyl (DPPH^•) radical, ABTS radical (ABTS^•+) and oxygen radical (O₂^-•). Taken together, EPS-SN-1 is a promising natural antioxidant and probiotic with potential applications in the food industry.

Collagen Peptides Isolated from Salmo salar and Tilapia nilotica Skin Accelerate Wound Healing by Altering Cutaneous Microbiome Colonization via Upregulated NOD2 and BD14

Collagen peptides can promote wound healing and are closely related to microbiome colonization. We investigated the relationship among collagen peptides, wound healing, and wound microflora colonization by administering the murine wound model with Salmo salar skin collagen peptides (Ss-SCPs) and Tilapia nilotica skin collagen peptides (Tn-SCPs). We analyzed the vascular endothelial growth factor (VEGF), fibroblast growth factors (β-FGF), pattern recognition receptor (NOD2), antimicrobial peptides (β-defence14, BD14), proinflammatory (TNF-α, IL-6, and IL-8) and anti-inflammatory (IL-10) cytokines, macrophages, neutrophil infiltration levels, and microbial communities in the rat wound. The healing rates of the Ss-SCP- and Tn-SCP-treated groups were significantly accelerated, associated with decreased TNF-α, IL-6, and IL-8 and upregulated BD14, NOD2, IL-10, VEGF, and β-FGF. Accelerated healing in the collagen peptide group shows that the wound microflora such as Leuconostoc, Enterococcus, and Bacillus have a positive effect on wound healing (P < 0.01). Other microbiome species such as Stenotrophomonas, Bradyrhizobium, Sphingomonas, and Phyllobacterium had a negative influence and decreased colonization (P < 0.01). Altogether, these studies show that collagen peptide could upregulate wound NOD2 and BD14, which were implicated in microflora colonization regulation in the wound tissue and promoted wound healing by controlling the inflammatory reaction and increasing wound angiogenesis and collagen deposition.

Mucosal

Probiotic lactobacilli and their exopolysaccharides (EPS) are thought to modulate mucosal homeostasis; however, their mechanisms remain elusive. Thus, we tried to clarify the role of exopolysaccharides from Lactobacillus plantarum NCU116 (EPS116) in the intestinal mucosal homeostasis. Our results indicated that EPS116 regulated the colon mucosal healing and homeostasis, enhanced the goblet cell differentiation, and promoted the expression of Muc2 gene in vivo and in vitro. Further experiments showed that EPS116 promoted the expression and phosphorylation of transcription factor c-Jun and facilitated its binding to the promoter of Muc2. Moreover, knocking down c-Jun or inhibiting its function in LS 174T cells treated with EPS116 led to decreased expression of Muc2, implying that EPS116 promoted the colonic mucosal homeostasis and Muc2 expression via c-Jun. Therefore, our study uncovered a novel model where EPS116 enhanced colon mucosal homeostasis by controlling the epithelial cell differentiation and c-Jun/Muc2 signaling.