Exopolysaccharides production by Lactobacillus acidophilus LA5 and Bifidobacterium animalis subsp. lactis BB12: Optimization of fermentation variables and characterization of structure and bioactivities

Fabrication and optimization of bioelectrochemical system using tetracycline-degrading bacterial strains for antibiotic wastewater treatment

In this study, a microbial fuel cell was constructed using Raoultella sp. XY-1 to efficiently degrade tetracycline (TC) and assess the effectiveness of the electrochemical system. The degradation rate reached 83.2 ± 1.8 % during the 7-day period, in which the system contained 30 mg/L TC, and the degradation pathway and intermediates were identified. Low concentrations of TC enhanced anodic biofilm power production, while high concentrations of TC decreased the electrochemical activity of the biofilm, extracellular polymeric substances, and enzymatic activities associated with electron transfer. Introducing electrogenic bacteria improved power generation efficiency. A three-strain hybrid system was fabricated using Castellaniella sp. A3, Castellaniella sp. A5 and Raoultella sp. XY-1, leading to the enhanced TC degradation rate of 90.4 % and the increased maximum output voltage from 200 to 265 mV. This study presents a strategy utilizing tetracycline-degrading bacteria as bioanodes for TC removal, while incorporating electrogenic bacteria to enhance electricity generation.

Characterization and biological activities of a novel exopolysaccharide produced from Geobacillus thermodenitrificans HBB 111 strain

In this study, EPS production conditions of Geobacillus thermodenitrificans HBB 111, a thermophilic microorganism, were optimized and the amount of produced EPS (EPS 111) was found to be 44.0 mg/L. EPS 111 was purified using ion exchange chromatography and gel filtration chromatography, and a single type of exopolysaccharide was obtained. The structure of the purified EPS 111 was evaluated by TLC, FTIR, NMR, and GC-MS, and it was observed that it contained hexose (glucose, fructose, galactose and mannose) and pentose sugars. From the SEM photographs, it was understood that EPS 111 had an amorphous, rough, and layered structure. It was found that purified EPS 111 had low cytotoxicity (2.3%) and exhibited high antioxidant activity and remarkable antidiabetic, prebiotic and fibrinolytic activities. It is very valuable that the purified EPS 111 in this study offers multiple biological activities compared to the thermophilic EPSs reported in the literature and has a high potential for use in biotechnological and biomedical fields.

Metabolomic differences between non-hydrothermal treated water-soluble (WSPs) and hydrothermally treated water-insoluble (WIPs) Maitake polysaccharides fermented by Lactobacillus acidophilus and L. plantarum

Bacterial Metabolite through a fermentation process is a growing trend and a promising alternative for use as functional components. Non-hydrothermal water-soluble (WSPs) and hydrothermally treated water-insoluble (WIPs) Maitake polysaccharides were fermented with Lactobacillus acidophilus (LA) and Lactobacillus plantarum (LP). Chemical composition analysis indicated that Maitake polysaccharides contained 58.22 ± 1.35 % total sugar and 31.46 % β-glucan, essential for metabolites production. 6-glucanase was used to degrade the WIPs, and hydrothermally treated WIP fibers exhibited smooth microstructure. Hence, the LA and LP bacteria investigated the potential fermented metabolic activities and differences between WSPs(Sp1)and WIP(Sp3) Maitake polysaccharides using LC-MS, and 887 metabolites were identified. Using Venn, Partial least squares discriminant analysis (PLS-DA), VIP Metabolites, and other multivariate statistical analysis methods, metabolites were expressed differently in all samples. Due to hydrothermal processing, WIP induced the highest growth of LA and LP, with an abundance of isocitrate metabolites. Furthermore, 50 metabolite correlations were identified, leading to the classification of 6 distinct metabolic groups. Thus, the study offers the initial comprehensive analysis of metabolites in Lactobacillus-fermented Maitake polysaccharides, aiding in understanding its metabolic interactions and facilitating progress in food engineering research.

Biological Activity of Lactic Acid Bacteria Exopolysaccharides and Their Applications in the Food and Pharmaceutical Industries

Exopolysaccharides are natural macromolecular bioactive substances produced by lactic acid bacteria. With their unique physiological activity and structural characteristics, they are gradually showing broad application prospects in the food and pharmaceutical industries. Exopolysaccharides have various biological functions, such as exerting antioxidant and anti-tumor activities and regulating gut microbiota. Meanwhile, as a food additive, exopolysaccharides can significantly enhance the taste and quality of food, bringing consumers a better eating experience. In the field of medicine, exopolysaccharides have been widely used as drug carriers due to their non-toxic properties and good biocompatibility. This article summarizes the biological activities of exopolysaccharides produced by lactic acid bacteria, their synthesis, and their applications in food and pharmaceutical industries, aiming to promote further research and development in this field.

Feasibility of lactiplantibacillus plantarum postbiotics production in challenging media by different techniques

The postbiotic derived from Lactiplantibacillus plantarum bacteria was produced in three culture media: milk, MRS, and whey, and its antibacterial and antifungal properties were evaluated. To investigate the production efficiency of postbiotics, three methods, heating, sonication and centrifugation, were utilized to prepare postbiotics in MRS broth culture medium. The antibacterial potency of the postbiotic was evaluated using the agar well-diffusion method, and MIC and MBC tests were conducted for different treatments. The results of the study showed that the postbiotic prepared in food environments such as milk and cheese whey can have antibacterial and antifungal properties similar to the postbiotic prepared in the MRS culture medium. However, it is possible to enrich food matrices such as milk and cheese whey and make further adjustments in terms of pH settings. Additionally, the thermal process was able to create a nanoscale postbiotic, which is a significant achievement for the application of postbiotics in the food and pharmaceutical industries. The future outlook of postbiotics clearly indicates that the emergence of this generation of probiotics can have an attractive and functional position in the food and pharmaceutical industries. Therefore, future research focusing on this subject will contribute to the development of this generation of postbiotics.

Postbiotics-enriched flaxseed mucilage coating: A solution to improving postharvest quality and shelf life of strawberry

This research aimed to assess the effects of flaxseed mucilage (Mu) coatings supplemented with postbiotics (P) obtained from Lactobacillus acidophilus LA-5 on various physical, biochemical, and microbial characteristics of strawberry fruits. Strawberry fruits were immersed for 2 min in Mu2.5 (2.5 % mucilage in distilled water), Mu5 (5 % mucilage in distilled water), P-Mu2.5 (2.5 % mucilage in undiluted postbiotics) and P-Mu5 (5 % mucilage in undiluted postbiotics) solutions and were stored at 4 °C and 85 RH for 12 days. All coatings were effective in reducing fungal count compared to the uncoated control fruits. Mu5 coating exhibited the highest efficacy, reducing fungal count by 2.85 log10 CFU/g, followed by Mu2.5 (1.47 log10 CFU/g reduction) and P-Mu2.5 groups (0.90 log10 CFU/g reduction). The fruits coated with edible coatings showed significant delays in the change of weight loss, pH, and total soluble solids as compared to the uncoated fruits. The coating containing postbiotics i.e., P-Mu5 also showed a significant increase in the total phenolic contents, total flavonoid content, antioxidant capacity, and total anthocyanin content at the end of storage relative to the uncoated fruits. Thus, Mu and P-Mu coatings may be a useful approach to maintaining the postharvest quality of strawberry fruits during cold storage.

Fermentative optimization and characterization of exopolysaccharides from Enterococcus faecium F58 isolated from traditional fresh goat cheese

This study focused on optimizing the fermentation-based production of Exopolysaccharides (EPS) from Enterococcus faecium F58 initially isolated from traditional Moroccan Jben, a fresh goat cheese. Using the central composite design, yeast extract, MnSO4, and time affect EPS concentration. The highest experimental and predicted EPS production yields were 2.46 g/L ± 0.38 and 2.86 g/L, respectively. Optimal concentrations of yeast extract (4.46 g/L) and MnSO4 (0.011 g/L) were identified after 26 h at 30 °C. Characterization of EPS was conducted using SEM with EDX, XRD, and FTIR analyses. These tests revealed a specific morphology and an amorphous structure. Additionally, thermogravimetric analysis indicated adequate EPS stability up to 200 °C with anti-adhesion properties against different pathogens. This study offers valuable insights into the optimized production of EPS from Enterococcus faecium F58, which exhibits significant structural and functional properties for various applications in the food and biotechnology industries.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01424-9.

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.

Complete genome analysis of Lactiplantibacillus plantarum VHProbi P06, a novel probiotic that resists Streptococcus pneumoniae in the upper respiratory tract

The purpose of this study was to screen lactic acid bacteria active against Streptococcus pneumoniae and to analyze the genetic basis of their probiotic functions from the genome. We isolated a novel Lactiplantibacillus plantarum VHProbi P06 from pickles, which showed strong antibacterial activity against S. pneumoniae, adhesion to 5-8F cells, and inhibition of S. pneumoniae colonization in the respiratory tract. Genome of VHProbi P06 was analyzed, we found one class II bacteriocin synthesis gene cluster. Genome of the strain contained 42 adhesion-related protein-coding genes, and implicated three exopolysaccharide biosynthesis gene clusters with low homologous to L. plantarum WCFS1. Moreover, VHProbi P06 possessed 3 intact phage regions and 117 Carbohydrate Active Enzyme genes. By comparing the genomes of five L. plantarum, 275 unique genes were found in VHProbi P06. Finally, the gene prediction was verified, the bacteriocin PlnJK produced by P06 was identified by LC-MS/MS, and the laminar exopolysaccharide with a weight-averaged molecular of 125.37 KDa was also found. This study provides a theoretical basis for the application of VHProbi P06 to the upper respiratory tract to resist pathogenic bacteria.

Structural Characterization and Immunomodulatory Activity of a Mannose-Rich Polysaccharide Isolated from Bifidobacterium breve H4-2

In this study, a novel homogeneous mannose-rich polysaccharide named EPS-1 from the fermentation broth of Bifidobacterium breve H4-2 was isolated and purified by anion exchange column chromatography and gel column chromatography. The primary structure of EPS-1 was analyzed by high-performance liquid chromatography, Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance. The results indicated that EPS-1 had typical functional groups of polysaccharides. EPS-1 with an average molecular weight of 3.99 × 104 Da was mainly composed of mannose (89.65%) and glucose (5.84%). The backbone of EPS-1 was →2,6)-α-d-Manp-(1→2)-α-d-Manp-(1→2,6)-α-d-Manp-(1→2)-α-d-Manp-(1→2,6)-α-d-Manp-(1→6)-α-d-Glcp-(1→ simultaneously containing two kinds of branched chains (α-d-Manp-(1→3)-α-d-Manp-(1→ and α-d-Manp-(1→). Besides, EPS-1 had a triple-helical conformation and exhibited excellent thermal stability. Moreover, the immunomodulatory activity of EPS-1 was evaluated by RAW 264.7 cells. Results indicated that EPS-1 significantly enhanced the viability of RAW 264.7 cells. EPS-1 could also be recognized by toll-like receptor 4, thereby activating the nuclear factors-κB (NF-κB) signaling pathway, promoting phosphorylation of related nuclear transcription factors, improving cell phagocytic activity, and promoting the secretion of NO, IL-6, IL-1β, and TNF-α. Thus, EPS-1 could activate the TLR4-NF-κB signaling pathway to emerge immunomodulatory activity on macrophages. The above results indicate that EPS-1 can serve as a potential immune-stimulating polysaccharide.

Structural Analysis and Antioxidant and Immunoregulatory Activities of an Exopolysaccharide Isolated from Bifidobacterium longum subsp. longum XZ01

Bifidobacterium longum subsp. longum XZ01 (BLSL1) is a new strain (isolated from the intestines of healthy people and deposited with the preservation number GDMCC 61618). An exopolysaccharide, S-EPS-1, was successfully isolated from the strain and then systematically investigated for the first time. Some structural features of S-EPS-1 were analyzed by chemical component, HPLC, ultraviolet, infrared, and nuclear magnetic resonance spectrum analyses. These analyses revealed that S-EPS-1 is a neutral heteropolysaccharide with an α-configuration. It contains mainly mannose and glucose, as well as small amounts of rhamnose and galactose. The molecular weight of S-EPS-1 was calculated to be 638 kDa. Several immunoregulatory activity assays indicated that S-EPS-1 could increase proliferation, phagocytosis, and NO production in vitro. In addition, S-EPS-1 could upregulate the expression of cytokines at the mRNA level through TLR4-mediated activation of the NF-κB signaling pathway in RAW 264.7 cells. Finally, S-EPS-1 was demonstrated to exhibit antioxidant activity by ABTS+• scavenging, DPPH• scavenging, and ferric-ion reducing power assays. Furthermore, S-EPS-1 can protect cells from oxidative stress and shows no cytotoxicity. These beneficial effects can be partly attributed to its antioxidant ability. Thus, the antioxidant S-EPS-1 may be applied as a functional food in the future.

Development and properties of functional yoghurt enriched with postbiotic produced by yoghurt cultures using cheese whey and skim milk

This study aimed to examine the effects of supplementation of postbiotics derived from Streptococcus thermophilus (ST) and Lactobacillus delbrueckii subsp. bulgaricus (LB) in cheese whey (CW) and skim milk (SM) on antioxidant activity, viability of yoghurt starters, and quality parameters of low-fat yoghurt during 22 days of storage. The LB-CW (L delbrueckii ssp. bulgaricus postbiotic-containing cheese whey) sample exhibited the highest antioxidant activity, with 18.71% inhibition (p > 0.05). This sample also showed the highest water holding capacity (77.93%; p < 0.05) and a trend toward receiving the most favorable sensory attributes (p > 0.05) compared to the other samples. The LB-CW and LB-SM yoghurt samples exhibited significantly higher body and texture scores compared to the ST-SM-fortified yoghurt (p < 0.05). However, there was no significant difference in the overall acceptability of the LB-SM and ST-SM yoghurt samples across both starters (p > 0.05). Such findings highlight the potential of postbiotics as functional ingredients to enhance the nutritional and sensory aspects of yoghurt, further contributing to its appeal as a health-promoting product.

The potential of postbiotics as a novel approach in food packaging and biopreservation: a systematic review of the latest developments

Metabolic by-products are part of the so-called postbiotics of probiotics and other beneficial microorganisms, particularly lactic acid bacteria, which have gained popularity as a feasible alternative to improving food quality and safety. Postbiotics in dry and liquid forms can be easily integrated into food formulations and packaging materials, exhibiting antimicrobial and antioxidant effects owing to the presence of multiple antimicrobials, such as organic acids, bacteriocins, exopolysaccharides and bioactive peptides. Postbiotics can thus control the growth of pathogens and spoilage microorganisms, thereby extending the shelf life of food products. Because of their ability to be easily manufactured without requiring extensive processing, postbiotics are regarded as a safer and more sustainable alternative to synthetic preservatives, which can have negative environmental consequences. Additionally, food manufacturers can readily adopt postbiotics in food formulations without significant modifications. This systematic review provides an in-depth analysis of studies on the use of postbiotics in the biopreservation and packaging of a wide range of food products. The review evaluates and discusses the types of microorganisms, postbiotics preparation and modification techniques, methods of usage in dairy products, meat, poultry, seafood, fruits, vegetables, bread, and egg, and their effects on food quality and safety.

Improvement and enhancement of oligosaccharide production from Lactobacillus acidophilus using statistical experimental designs and its inhibitory effect on colon cancer

Colorectal cancer (CRC) is the third cause of death by cancers worldwide and is one of the most common cancer types reported in both Egypt and the United States. The use of probiotics as a dietary therapy is increasing either as a prevention or as a treatment for many diseases, particularly, in the case of CRC. The increasing acceptance of lactic acid bacterial (LAB) oligosaccharides as bioactive agents has led to an increase in the demand for the large-scale production of LAB-oligosaccharides using fermentation technology. Therefore, in the current study, we are using the Plackett- Burman design (PBD) approach, where sixteen experimental trials were applied to optimize the production of the target oligosaccharide LA-EPS-20079 from Lactobacillus acidophilus. Glucose, yeast extract and sodium acetate trihydrate were the top three significant variables influencing LA-EPS production. The maximum concentration of LA-EPS-20079 achieved by L. acidophilus was 526.79 μg/ml. Furthermore, Box-Behnken design (BBD) as response surface methodology (RSM) was used to complete the optimization procedure. The optimal levels of the chosen variables which were 30.0 g/l, glucose; 5 g/l, yeast extract and 10.0 g/l sodium acetate trihydrate with the predicted LA-EPS-20079 concentration of 794.82 μg/ml. Model validity reached 99.93% when the results were verified. Both optimized trials showed great cytotoxic effects against colon cancer line (CaCo-2) with inhibition percentages ranging from 64.6 to 81.9%. Moreover, downregulation in the expression level of BCL2 and Survivin genes was found with a fold change of 3.377 and 21.38, respectively. Finally, we concluded that the optimized LA-EPS-20079 has maintained its anticancer effect against the CaCo-2 cell line that was previously reported by our research group.

Genome Analysis of Bifidobacterium Bifidum E3, Structural Characteristics, and Antioxidant Properties of Exopolysaccharides

In this study, the antioxidant properties of intact cells (IC), cell-free supernatant (CFS), and cell-free extracts (CFE) and whole genome sequencing of Bifidobacterium bifidum E3 (B. bifidum E3), as well as the structural characteristics and antioxidant properties of EPS-1, EPS-2, and EPS-3, were evaluated. The results revealed that intact cells (IC), cell-free supernatant (CFS), and cell-free extracts (CFE) had potent DPPH (1,1-Diphenyl-2-picrylhydrazyl radical), hydroxyl, and superoxide anion radical scavenging capacities, among which CFS was the best. At the genetic level, we identified a strong carbohydrate metabolism capacity, an EPS synthesis gene cluster, and five sugar nucleotides in B. bifidum E3. Therefore, we extracted cEPS from B. bifidum E3 and purified it to obtain EPS-1, EPS-2, and EPS-3. EPS-1, EPS-2, and EPS-3 were heteropolysaccharides with an average molecular weight of 4.15 × 104 Da, 3.67 × 104 Da, and 5.89 × 104 Da, respectively. The EPS-1 and EPS-2 are mainly comprised of mannose and glucose, and the EPS-3 is mainly comprised of rhamnose, mannose, and glucose. The typical characteristic absorption peaks of polysaccharides were shown in Fourier transform infrared spectroscopy (FT-IR spectroscopy). The microstructural study showed a rough surface structure for EPS-1, EPS-2, and EPS-3. Furthermore, EPS-1, EPS-2, and EPS-3 exhibited potent DPPH, hydroxyl, and superoxide anion radical scavenging capacities. Correlation analysis identified that antioxidant capacities may be influenced by various factors, especially molecular weight, chemical compositions, and monosaccharide compositions. In summary, the EPS that was produced by B. bifidum E3 may provide insights into health-promoting benefits in humans.

The structure, characterization and immunomodulatory potential of exopolysaccharide produced by Planococcus rifietoensis AP-5 from deep-sea sediments of the Northwest Pacific

Polysaccharides derived from microorganisms exhibit diverse structures and bioactivities, making them promising candidates for the treatment of various diseases. However, marine-derived polysaccharides and their activities are relatively little known. In this work, fifteen marine strains were isolated from surface sediments in the Northwest Pacific Ocean for screening of EPS production. Planococcus rifietoensis AP-5 produced a maximum yield of EPS at 4.80 g/L. The purified EPS (referred to as PPS) had a molecular weight of 51,062 Da and contained amino, hydroxyl, and carbonyl groups as its major functional groups. PPS primarily consisted of →3)-α-D-Galp-(1 → 4)-α-D-Manp-(1 → 2)-α-D-Manp-(1 → 4)-α-D-Manp-(1 → 4,6)-α-D-Glcp-(1 → 6)-β-D-Galp-(1→, with a branch consisting of T-β-D-Glcp-(1→. Additionally, surface morphology of PPS was hollow, porous, and sphere-like stack. PPS primarily contained C, N, and O elements, with a surface area of 33.76 m2/g, a pore volume of 0.13 cc/g, and a pore diameter of 1.69 nm, respectively. Based on the TG curve, the degradation temperature of PPS was measured to be 247 °C. Furthermore, PPS demonstrated immunomodulatory activity through dose-dependently upregulating the expression level of cytokines. It significantly enhanced the cytokine secretion at a concentration of 5 μg/mL. To sum up, this study offers valuable insights for screening marine polysaccharide-based immunomodulators.

Advances in Polysaccharide Production Based on the Co-Culture of Microbes

Microbial polysaccharides are natural carbohydrates that can confer adhesion capacity to cells and protect them from harsh environments. Due to their various physiological activities, these macromolecules are widely used in food, medicine, environmental, cosmetic, and textile applications. Microbial co-culture is an important strategy that is used to increase the production of microbial polysaccharides or produce new polysaccharides (structural alterations). This is achieved by exploiting the symbiotic/antagonistic/chemo-sensitive interactions between microbes and stimulating the expression of relevant silent genes. In this article, we review the performance of polysaccharides produced using microbial co-culture in terms of yield, antioxidant activity, and antibacterial, antitumor, and anti-inflammatory properties, in addition to the advantages and application prospects of co-culture. Moreover, the potential for microbial polysaccharides to be used in various applications is discussed.

Physicochemical, rheological, and bioactive properties of exopolysaccharide produced by a potential probiotic Enterococcus faecalis 84B

Exopolysaccharides (EPS) have attracted a great interest due to their potential health-promoting properties and industrial applications. This study aimed to investigate the physicochemical, rheological, and biological properties of an EPS produced by a potential probiotic strain Enterococcus faecalis 84B. The results show that the extracted EPS, designated EPS-84B, had an average molecular weight of 604.8 kDa, particles size diameter of 322.0 nm, and mainly composed of arabinose and glucose with a molar ratio of 1:2. Furthermore, EPS-84B exhibited a shear-thinning behavior and had a high melting point. The rheological properties of EPS-84B were strongly influenced by the type of salt than by the pH value. EPS-84B displayed ideal viscoelastic properties, with both viscous and storage moduli increasing with frequency. The antioxidant activity of EPS-84B at a concentration of 5 mg/mL was 81.1 % against DPPH and 35.2 % against ABTS. At 5 mg/mL, the antitumor activity of EPS-84B against Caco-2 and MCF-7 cell lines was 74.6 and 38.6 %, respectively. In addition, the antidiabetic activity of EPS-84B towards α-amylase and α-glucosidase was 89.6 and 90.0 %, respectively at 100 μg/mL. The inhibition of foodborne pathogens by EPS-84B was up to 32.6 %. Overall, EPS-84B has promising properties that could be utilized in food and pharmaceutical industries.

Structural analysis and prebiotic activity of exopolysaccharide produced by probiotic strain Bifidobacterium bifidum EPS DA-LAIM

Exopolysaccharide (EPS)-producing Bifidobacterium bifidum EPS DA-LAIM was isolated from healthy human feces, the structure of purified EPS from the strain was analyzed, and its prebiotic activity was evaluated. The EPS from B. bifidum EPS DA-LAIM is a glucomannan-type heteropolysaccharide with a molecular weight of 407-1007 kDa, and its structure comprises 2-mannosyl, 6-mannosyl, and 2,6-mannosyl residues. The purified EPS promoted the growth of representative lactic acid bacteria and bifidobacterial strains. Bifidobacterium bifidum EPS DA-LAIM increased nitric oxide production in RAW 264.7 macrophage cells, indicating its immunostimulatory activity. Bifidobacterium bifidum EPS DA-LAIM also exhibited high gastrointestinal tract tolerance, gut adhesion ability, and antioxidant activity. These results suggest that EPS from B. bifidum EPS DA-LAIM is a potentially useful prebiotic material, and B. bifidum EPS DA-LAIM could be applied as a probiotic candidate.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01213-w.

Exopolysaccharide-producing Lacticaseibacillus paracasei strains isolated from kefir as starter for functional dairy products

Exopolysaccharides (EPS) produced by lactic acid bacteria are molecules of great interest for the dairy food industry. Lacticaseibacillus paracasei CIDCA 8339, CIDCA 83123, and CIDCA 83124 are potentially probiotic strains isolated from kefir grains whose EPS-production on MRS broth is dependent on incubation temperature. The aim of the present work is to evaluate the effect of fermentation temperature on the characteristics of EPS produced in milk by L. paracasei strains and the consequent impact on the rheological properties of the fermented products. Additionally, the protective effect of these EPS against Salmonella infection was evaluated in vitro. Acid gels with each strain were obtained by milk fermentation at 20°C, 30°C, and 37°C evidencing for all the strains a reduction in growth and acidification rate at lower temperature. Lacticaseibacillus paracasei CIDCA 83123 showed low fermentation rate at all temperatures requiring between 3 and 8 days to obtain acids gels, whereas CIDCA 8339 and 83124 needed between 24 and 48 h even when the temperature was 20°C. Fermentation temperature led to changes in crude EPS characteristics of the three strains, observing an increase in the relative amount of the high molecular weight fraction when the fermentation temperature diminished. Additionally, EPS₈₃₁₂₄ and EPS₈₃₁₂₃ presented modifications in monosaccharide composition, with a reduction of rhamnose and an increase of amino-sugars as temperature rise. These changes in the structure of EPS₈₃₁₂₄ resulted in an increase of the apparent viscosity of milks fermented at 20°C (223 mPa.s) and 30°C (217 mPa.s) with respect to acid gels obtained at 37°C (167 mPa.s). In order to deepen the knowledge on EPS characteristics, monosaccharide composition of low and high molecular weight EPS fractions were evaluated. Finally, it was evidenced that the preincubation of intestinal epithelial cells Caco-2/TC-7 with EPS₈₃₃₉ and EPS₈₃₁₂₄ partially inhibit the association and invasion of Salmonella. In light of these results, it can be concluded that the selection of the EPS-producing strain along with the appropriate fermentation conditions could be an interesting strategy to improve the technological properties of these L. paracasei fermented milks with potential protective effects against intestinal pathogens.

A novel source of food hydrocolloids from Trigonella elliptica seeds: extraction of mucilage and comprehensive characterization

BACKGROUND

In this study, the effects of seed weight (4, 8, and 12 g), extraction temperature (30, 60, and 90 °C), and pH (4, 7, and 10) on the yield of mucilage extraction from fenugreek seeds and its chemical properties were investigated using response-surface methodology.

RESULTS

The optimum condition for mucilage extraction was a seed weight of 8.30 g, a temperature of 86.10 °C, and pH 6.90. The results showed that the dry weight of extracted mucilage increased with increase and decrease of extraction temperature and pH respectively at high seed weight. Increasing temperature and pH increased the extraction yield, and the effect was more considerable at low seed weight. The maximum carbohydrate content of mucilage was achieved at average levels of variables. The protein, flavonoid, and total phenolic contents of extracted mucilage increased with increasing temperature. Both flavonoid and total phenolic contents were maximum at neutral pH, but they were maximum at moderate and low levels of seed weight respectively. Maximum antioxidant activity was obtained at the highest extraction temperature, seed weight of 8 g, and neutral pH. The study of rheological properties indicated that extracted mucilage solution showed mainly elastic and shear-thinning behavior.

CONCLUSION

The Fourier transform infrared spectra of extracted mucilage exhibited the existence of polysaccharides and protein chains in fenugreek seeds mucilage. The X-ray diffraction corroborated the presence of crystals in the mucilage structure. The proton nuclear magnetic resonance spectra confirmed the polysaccharides and protein composition of extracted mucilage. The maximum mucilage mass loss was observed at 190-350 °C using thermogravimetric analysis. © 2022 Society of Chemical Industry.

Probiotics media: significance, challenges, and future perspective - a mini review

The health benefits associated with probiotics have increased their application in pharmaceutical formulations and functional food development. High production of probiotic biomass requires a cost-effective production method and nutrient media optimization. The biomass production of probiotics can be enhanced by optimizing growth parameters such as substrate, pH, incubation time, etc. For economical industrial production of probiotic biomass, it is required to design a new medium with low cost. Wastes from the food industries are promising components for the development of the low-cost medium. Industrial wastes such as cheese whey and corn steep liquor are excellent examples of reliable sources of nitrogen for the biomass production of probiotic bacteria. The increased yield of biomass reduced the cost of production. This review focuses on the importance of probiotic media for biomass production and its challenges.

Graphical Abstract

Effects of amino acid composition of yeast extract on the microbiota and aroma quality of fermented soy sauce

Yeast extracts, of which amino acids are the main component, can be directly applied to improve the flavor of final soy sauce. In this study, the potential of commercial yeast extracts was explored from amino acid approach to enhance the flavor quality of soy sauce by shaping the core fermentation microbiota. Alkaline and neutral amino acids favored the competitive benefits of flavor-producing bacteria, while acidic amino acids promoted the stress resistance of the fermentation microbiota, especially the abundance of Lactobacillus, which increased to 18.03-23.78% and became the predominant microbiota. The mass ratio of neutral-nonpolar: neutral-polar: acidic: alkaline amino acids was 40: 18: 27: 15, which provided the optimal improvement of soy sauce aroma. The formulation and activated the metabolic pathways of 3-methyl-1-butyraldehyde, 3-methyl-1-butanol and 2-methyl-1-propanol through Leu and Ile, resulting in a 52.6% increase in malt-like aroma. This study provides a new idea for the regulation of soy sauce fermentation.

Application of Cheese Whey Containing Postbiotics of Lactobacillus acidophilus LA5 and Bifidobacterium animalis BB12 as a Preserving Liquid in High-Moisture Mozzarella

High-moisture mozzarella cheese (HMMC) is a highly perishable cheese with a short shelf life. In this study, the effects of UF cheese whey containing postbiotics from Lactobacillus acidophilus LA-5 (P-LA-5), Bifidobacterium animalis BB-12 (P-BB-12), and their combination on the microbial (i.e., psychrophiles, mesophiles, lactic acid bacteria, and mold-yeast population) and sensory properties of HMMC were investigated. Postbiotics were prepared in a cheese whey model medium as a novel growth media and used as a preserving liquid in HMMC. The results demonstrate that postbiotics reduced the growth of all microorganisms (1.5-2 log CFU/g reduction) and P-LA5 and P-BB12 had the highest antibacterial performance on mesophiles and psychrophiles, respectively. Mold and yeast had the highest susceptibility to the postbiotics. Postbiotics showed a significant effect on maintaining the microbial quality of HMMC during storage, proposing postbiotics as a new preserving liquid for HMMC.

Effect of nickel (II) on the performance of anodic electroactive biofilms in bioelectrochemical systems

The impact of nickel (Ni²⁺) on the performance of anodic electroactive biofilms (EABs) in the bioelectrochemical system (BES) was investigated in this study. Although it has been reported that Ni²⁺ influences microorganisms in a number of ways, it is unknown how its presence in the anode of a BES affects extracellular electron transfer (EET) of EABs, microbial viability, and the bacterial community. Results revealed that the addition of Ni²⁺ decreased power output from 673.24 ± 12.40 mW/m² at 0 mg/L to 179.26 ± 9.05 mW/m² at 80 mg/L. The metal and chemical oxygen demand removal efficiencies of the microbial fuel cells (MFCs) declined as Ni²⁺ concentration increased, which could be attributed to decreased microbial viability as revealed by SEM and CLSM. FTIR analysis revealed the involvement of various microbial biofilm functional groups, including hydroxyl, amides, methyl, amine, and carboxyl, in the uptake of Ni²⁺. The presence of Ni²⁺ on the anodic biofilms was confirmed by SEM-EDS and XPS analyses. CV demonstrated that the electron transfer performance of the anodic biofilms was negatively correlated with the various Ni²⁺ concentrations. EIS showed that the internal resistance of the MFCs increased with increasing Ni²⁺ concentration, resulting in a decrease in power output. High-throughput sequencing results revealed a decrease in Geobacter and an increase in Desulfovibrio in response to Ni²⁺ concentrations of 10, 20, 40, and 80 mg/L. Furthermore, the various Ni²⁺ concentrations decreased the expression of EET-related genes. The Ni²⁺-fed MFCs had a higher abundance of the nikR gene than the control group, which was important for Ni²⁺ resistance. This work advances our understanding of Ni²⁺ inhibition on EABs, as well as the concurrent removal of organic matter and Ni²⁺ from wastewater.

Multispecies biofilms in fermentation: Biofilm formation, microbial interactions, and communication

Food fermentation is driven by microorganisms, which usually coexist as multispecies biofilms. The activities and interactions of functional microorganisms and pathogenic bacteria in biofilms have important implications for the quality and safety of fermented foods. It was verified that the biofilm lifestyle benefited the fitness of microorganisms in harsh environments and intensified the cooperation and competition between biofilm members. This review focuses on multispecies biofilm formation, microbial interactions and communication in biofilms, and the application of multispecies biofilms in food fermentation. Microbial aggregation and adhesion are important steps in the early stage of multispecies biofilm formation. Different biofilm-forming abilities and strategies among microorganisms lead to several types of multispecies biofilm formation. The spatial distribution of multispecies biofilms reflects microbial interactions and biofilm function. Then, we discuss the intrinsic factors and external manifestations of multispecies biofilm system succession. Several typical interspecies cooperation and competition modes and mechanisms of microbial communication were reviewed in this review. The main limitations of the studies included in this review are the relatively small number of studies of biofilms formed by functional microorganisms during fermentation and the lack of direct evidence for the formation process of multispecies biofilms and microbial interactions and communication within biofilms. This review aims to provide the food industry with a sufficient understanding of multispecies biofilms in food fermentation. Practical Application: Meanwhile, it offers a reference value for better controlling and utilizing biofilms during food fermentation process, and the improvement of the yield, quality, and safety of fermented products including Chinese Baijiu, cheeese,kefir, soy sauce, kombucha, and fermented olive.

Screening, optimization and characterization of exopolysaccharides produced by novel strains isolated from Moroccan raw donkey milk

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EPS producing bacteria was isolated and identified as Leuconostoc mesenteroides SL and Enterococcus viikkiensis N5.

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Optimization was carried out by Response Surface Methodology using Box Behnken Design.

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The GC–MS, FTIR, and NMR analysis showed that the EPS-SL and EPS-N5 are heteropolysaccharides connected by α-(1 → 6) and -(1 → 3) linkages.

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Both EPSs has high thermal stability.

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EPS exhibited appreciable antibacterial and antioxidant activity.

Two exopolysaccharides (EPS) producing strains, isolated from raw donkey milk were identified as Leuconostoc mesenteroides SL and Enterococcus viikkiensis N5 using 16S rDNA sequencing. The Box Benheken design exhibited the highest yield of EPS-SL (672.342 mg/L) produced by SL and of EPS-N5 (901 mg/L) produced by N5. The molecular weight was 1.68×10⁴ for EPS-SL and 1.55×10⁴ Da for EPS-N5. FTIR, NMR and GC–MS analysis showed that the EPS are heteropolysaccharides. The SEM image showed that the EPS-SL was smooth and represented a lotus leaf shape and EPS-N5 revealed a stiff-like, porous appearance and was more compact than EPS-SL. The TGA analyses showed high thermal stability and degradation temperature. Additionally, the two EPSs possessed antibacterial and antioxidant activity, and the EPS-SL had the stronger antioxidant activity. Consequently, these results suggest that the functional and biological properties of EPS-SL and EPS-N5 imply the potential application in the food and pharmaceutical industries.

In situ exopolysaccharides produced by Lactobacillus helveticus MB2-1 and its effect on gel properties of Sayram ketteki yoghurt

In order to study the mechanism of high viscosity of Sayram ketteki yoghurt, the growth, acidification properties, in situ exopolysaccharides (EPS) production of Lactobacillus helveticus MB2-1 in milk medium were investigated. The microstructure of the yoghurt was analyzed. The characteristics of in situ EPS produced by this strain in yoghurt were studied by high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-vis) analysis. The amount of in situ EPS produced could be up to 689.47 mg/L. The micrographs of Sayram ketteki yoghurt demonstrated that the in situ EPS secreted by ropy L. helveticus MB2-1 were closely connected with proteins, effectively filling the three-dimensional network structure of casein clusters, thereby resulting in high viscosity of yoghurt. Besides, the molecular weight of in situ EPS was 9.34 × 10⁴ Da, and the in situ EPS was determined to be a new heteropolysaccharide, containing fucose, which made it unique. Moreover, the set yoghurts added with in situ EPS were demonstrated fine effects on the texture improvement. These results illustrated that L. helveticus MB2-1 could be set as a good starter and the in situ EPS could be considered as a probiotic stabilizer substitute for fermented dairy products.

Exopolysaccharides synthesized by lactic acid bacteria: biosynthesis pathway, structure-function relationship, structural modification and applicability

Probiotics and their fermentation products are increasingly been focused on due to their health-boosting effects. Exopolysaccharides (EPS) synthetized by lactic acid bacteria (LAB) are widely applied as texture modifiers in dairy, meat and bakery products owning to their improved properties. Moreover, LAB-derived EPS have been confirmed to possess diverse physiological bioactivities including antioxidant, anti-biofilm, antiviral, immune-regulatory or antitumor. However, the low production and high acquisition cost hinder their development. Even though LAB-derived EPS have been extensively studied for their production-improving, there are only few reports on the systematic elucidation and summary of the relationship among biosynthesis pathway, strain selection, production parameter, structure-function relationship. Therefore, a detailed summary on biosynthesis pathway, production parameter and structure-function relationship of LAB-derived EPS is provided in this review, the structural modifications together with the current and potential applications are also discussed in this paper.

Biosynthesis of c9,t11-conjugated linoleic acid and the effect on characteristics in fermented soy milk

The objective of this work was to investigate the effect of fermentation conditions on c9,t11-conjugated linoleic acid (CLA) synthesized by Lactobacillus casei and the variation of physicochemical characteristics, including pH, viable cell number, syneresis and texture profile, of fermented soy milk (FSM) during storage at 4 °C for 28 days. Fermentation in 7°Brix of soy milk (SM) supplemented with 0.1% linoleic acid and incubated at 37 °C for 72 h was found to be the optimal conditions for c9,t11-CLA biosynthesis. Within the storage of 14 days, viable cell number, total flavonoid content, water-holding capacity, spontaneous syneresis and texture profile in FSM remained stable. During the storage of 28 days, the viable cell number and c9,t11-CLA level were higher than 6.58 log CFU/mL and 816.33 μg/g, respectively.

The Possible Link Between Manufacturing and Probiotic Efficacy; a Molecular Point of View on Bifidobacterium

Probiotics for food or supplement use have been studied in numerous clinical trials, addressing a broad variety of diseases, and conditions. However, discrepancies were observed in the clinical outcomes stemming from the use of lactobacillaceae and bifidobacteria strains. These differences are often attributed to variations in the clinical trial protocol like trial design, included target population, probiotic dosage, or outcome parameters measured. However, a contribution of the methods used to produce the live bioactive ingredients should not be neglected as a possible additional factor in the observed clinical outcome variations. It is well established that manufacturing conditions play a role in determining the survival and viability of probiotics, but much less is known about their influence on the probiotic molecular composition and functionality. In this review, we briefly summarize the evidence obtained for Lacticaseibacillus rhamnosus GG and Lactiplantibacillus plantarum WCFS1, highlighting that expression and presence of probiotic niche factor (NF) and/or effector molecules (EM) may be altered during production of those two well-characterized lactobacillaceae probiotic strains. Subsequently, we summarize in more depth what is the present state of knowledge about bifidobacterial probiotic NF and EM; how their expression may be modified by manufacturing related environmental factors and how that may affect their biological activity in the host. This review highlights the importance of gathering knowledge on probiotic NF and EM, to validate them as surrogate markers of probiotic functionality. We further propose that monitoring of validated NF and/or EM during production and/or in the final preparation could complement viable count assessments that are currently applied in industry. Overall, we suggest that implementation of molecular level quality controls (i.e., based on validated NF and EM), could provide mode of action based in vitro tests contributing to better control the health-promoting reliability of probiotic products.

Exopolysaccharides Produced by Lactic Acid Bacteria: From Biosynthesis to Health-Promoting Properties

The production of exopolysaccharides (EPS) by lactic acid bacteria (LAB) has attracted particular interest in the food industry. EPS can be considered as natural biothickeners as they are produced in situ by LAB and improve the rheological properties of fermented foods. Moreover, much research has been conducted on the beneficial effects of EPS produced by LAB on modulating the gut microbiome and promoting health. The EPS, which varies widely in composition and structure, may have diverse health effects, such as glycemic control, calcium and magnesium absorption, cholesterol-lowering, anticarcinogenic, immunomodulatory, and antioxidant effects. In this article, the latest advances on structure, biosynthesis, and physicochemical properties of LAB-derived EPS are described in detail. This is followed by a summary of up-to-date methods used to detect, characterize and elucidate the structure of EPS produced by LAB. In addition, current strategies on the use of LAB-produced EPS in food products have been discussed, focusing on beneficial applications in dairy products, gluten-free bakery products, and low-fat meat products, as they positively influence the consistency, stability, and quality of the final product. Highlighting is also placed on reports of health-promoting effects, with particular emphasis on prebiotic, immunomodulatory, antioxidant, cholesterol-lowering, anti-biofilm, antimicrobial, anticancer, and drug-delivery activities.

Exopolysaccharide produced by Lactiplantibacillus plantarum RO30 isolated from Romi cheese: characterization, antioxidant and burn healing activity

Microbial exopolysaccharides (EPSs) extracted from lactic acid bacteria (LAB) are generally recognized as safe. They have earned popularity in recent years because of their exceptional biological features. Therefore, the present study main focus was to study EPS-production from probiotic LAB and to investigate their antioxidant and burn wound healing efficacy. Seventeen LAB were isolated from different food samples. All of them showed EPS-producing abilities ranging from 1.75 ± 0.05 to 4.32 ± 0.12 g/l. RO30 isolate (from Romi cheese) was chosen, due to its ability to produce the highest EPS yield (4.23 ± 0.12 g/l). The 16S rDNA sequencing showed it belonged to the Lactiplantibacillus plantarum group and was further identified as L. plantarum RO30 with accession number OL757866. It displayed well in vitro probiotic properties. REPS was extracted and characterized. The existence of COO⁻, OH and amide groups corresponding to typical EPSs was confirmed via FTIR. It was constituted of glucuronic acid, mannose, glucose, and arabinose in a molar ratio of 2.2:0.1:0.5:0.1, respectively. The average molecular weight was 4.96 × 10⁴ g/mol. In vitro antioxidant assays showed that the REPS possesses a DPPH radical scavenging ability of 43.60% at 5 mg/ml, reducing power of 1.108 at 10 mg/ml, and iron chelation activity of 72.49% and 89.78% at 5 mg/ml and 10 mg/ml, respectively. The healing efficacy of REPS on burn wound models in albino Wistar rats showed that REPS at 0.5% (w/w) concentration stimulated the process of healing in burn areas. The results suggested that REPS might be useful as a burn wound healing agent.

Optimization of food-grade medium for co-production of bioactive substances by Lactobacillus acidophilus LA-5 for explaining pharmabiotic mechanisms of probiotic

This study aimed to optimize the co-production of conjugated linoleic acid (CLA), exopolysaccharides (EPSs) and bacteriocins (BACs) by Lactobacillus acidophilus LA-5 in dairy food-grade by-product. The factorial design revealed that the significant factors were temperature, time, and yeast extract. Then the response surface methodology was used for optimization. At the optimal conditions the viable cell number, CLA, EPSs, and inhibition activity were 2.62 ± 0.49 × 108 CFU/mL, 51.46 ± 1.50 μg/mL, 348.24 ± 5.61 mg/mL and 12.46 ± 0.80 mm, respectively. FTIR, GC, TLC, and SDS page analysis revealed the functional groups of pharmabiotics. The FTIR, GC, TLC, and SDS page analysis showed that both CLA isomers (c-9, t-11, and t-10, c-12) produced. The FTIR, GC, TLC, and SDS page analysis indicated that produced EPSs were composed of glucose, mannose, galactose, xylose, and fructose. FTIR, GC, TLC, and SDS page used to report BACs molecular weight, which showed two fractions by molecular mass 35 and 63 kDa. Previously the ability of different probiotic bacteria investigated and optimized the production of CLA, EPSs, and BACs, but, there was no report on the co-producing capacity of these bioactive metabolites by probiotics. The present work was investigated to optimize the co-production of pharmabiotic metabolites by L. acidophilus LA-5, in supplemented cheese whey as a cultivation medium.

Challenges in the production and use of probiotics as therapeuticals in cancer treatment or prevention

Probiotics were defined as microbial strains that confer health benefits to their consumers. The concept has evolved during the last twenty years, and today metabolites produced by the strains, known as postbiotics, and even dead cells, known as paraprobiotics are closely associated to them. The isolation of commensal strains from human microbiome has led to the development of next generation probiotics. This review aims to present an overview of the developments in the area of cancer prevention and treatment, intimately related to advances in the knowledge of the microbiome role in its genesis and therapy. Strain identification and characterization, production processes, delivery strategies and clinical evaluation are crucial to translate results into the market with solid scientific support. Examples of recent tools in isolation, strain typification, quality control and development of new probiotic strains are described. Probiotics market and regulation were originally developed in the food sector, but these new strategies will impact the pharmaceutical and health sectors, requiring new considerations in regulatory frameworks.

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.