Exopolysaccharide Yield Research Articles

Evaluation of Safety and Probiotic Properties of Weissella spp. in Fermented Vegetables From Xi'an, Shaanxi, China

ABSTRACTThe genus Weissella, commonly found in fermented foods, is a significant group of lactic acid bacteria (LAB) with potential probiotic properties. Several Weissella strains have been proposed as probiotics due to their biotechnological capabilities. However, a few strains may exhibit opportunistic pathogenic behavior, which restricts the widespread use of all Weissella strains in food applications. This study sought to expand our understanding of the biotechnological capabilities of Weissella spp. by examining the safety and functional characteristics of strains isolated from spontaneous fermentation. In this investigation, nine Weissella strains were evaluated for their safety and probiotic potential. The safety assessment revealed that the antibiotic resistance profiles of strains 16‐2, 38‐3, 69‐3, 91‐3, 91‐5, 104‐4, and 106‐5 were comparable or superior to the reference strain LGG. Hemolytic activity and ammonia production were also evaluated, but no positive results were observed. Further probiotic experiments demonstrated that strain 91‐5 exhibited superior performance in several areas, including survival rates in simulated gastrointestinal fluids, cell surface properties (hydrophobicity and adhesion to Caco‐2 cells), ABTS+ scavenging ability, antimicrobial activity, and cholesterol assimilation in vitro. Additionally, strain 104‐4 produced an exopolysaccharide (EPS) yield of 35.11 g/L after 48 h of culture in MRS‐sucrose (60 g/L) medium, surpassing most previously reported values. These findings suggest that strains 91‐5 and 104‐4 show promise as potential probiotic candidates for the development of new functional food supplements. Furthermore, this research expands the theoretical basis for considering Weissella strains as novel probiotics.

Hidden inside desert rocks: Salinity triggers an increase in exopolysaccharides from endolithic cyanobacteria with anti-inflammatory potential

Endolithic cyanobacteria thriving in rocks of deserts remain an unexplored source for the quest of novel bioproducts in extreme environments. In this work, 7 endolithic cyanobacteria from the polyextreme Atacama Desert, covering four genera and three lithic substrates, were investigated for the production of exopolysaccharides with anti-inflammatory potential. A moderate salinity (20 g NaCl L−1) was tolerated by all strains, triggering a 3–9-fold increase in exopolysaccharides (EPS) yield in 4 of them that counteracted the growth decrease due to NaCl stress. EPS from all strains showed anti-elastase activity with inter-strain and inter-salinity variations. The moderate EPS productivity by Gloeocapsa sp. UAM572 (0.4 mg EPS L−1 day−1), elevated anti-elastase capacity of Chroococcidiopsis sp. UAM579 EPS (IC50 = 78 μg mL−1) and the first biotechnological data of genus Pseudoacaryochloris, provide a promising foundation for potential applications of EPS from endolithic cyanobacteria in cosmetics and biomedicine, whose opportunities and challenges are discussed herein.

Genomic and Transcriptomic Analyses Identify Two Key Glycosyltransferase Genes alhH and alhK of Exopolysaccharide Biosynthesis in Pantoea alhagi NX-11.

The exopolysaccharide (EPS) produced by Pantoea alhagi NX-11, referred to as alhagan, enhances plant stress resistance, improves soil properties, and exhibits notable rheological properties. Despite these benefits, the exact bio-synthetic process of alhagan by P. alhagi NX-11 remains unclear. This study focused on sequencing the complete genome of P. alhagi NX-11 and identifying an alhagan synthesis gene cluster (LQ939_RS12550 to LQ939_RS12700). Gene annotation revealed that alhagan biosynthesis in P. alhagi NX-11 follows the Wzx/Wzy-dependent pathway. Furthermore, transcriptome analysis of P. alhagi NX-11 highlighted significant upregulation of four glycosyltransferase genes (alhH, wcaJ, alhK, and alhM) within the alhagan synthesis gene cluster. These glycosyltransferases are crucial for alhagan synthesis. To delve deeper into this process, two upregulated and uncharacterized glycosyltransferase genes, alhH and alhK, were knocked out. The resulting mutants, ΔalhH and ΔalhK, showed a notable decrease in EPS yield, reduced molecular weight, and altered monosaccharide compositions. These findings contribute to a better understanding of the alhagan biosynthesis mechanism in P. alhagi NX-11.

Macroparticle-enhanced morphology engineering of Cordyceps sinensis for high glucose fermentation to optimize the production of bioactive exopolysaccharides

Cordyceps sinensis is widely known for its therapeutic properties. Enhancing the yield of exopolysaccharides (EPS), which is crucial for its medicinal efficacy, is a major challenge. In this study, we applied high initial glucose concentrations with talc particles to enhance EPS production and assessed the cell morphology, intracellular biochemical reactants, and bioactivity contribution of glycoproteins. The use of 150 g/L glucose and 10 g/L 2000 mesh talc increased the EPS yield by 1.8-fold to 4.21 g/L. The addition of talc regulated cell morphology, facilitated the entry of oxygen molecules into the cells to produce a large amount of ATP for polysaccharide synthesis, and altered the cell wall structure to facilitate the secretion of EPS. Moreover, environmental stress resulted in a notable increase in intracellular reactive oxygen species levels, which can potentially enhance cell membrane permeability and promote EPS synthesis. Furthermore, the highest protein content in crude EPS corresponded to the maximum activation of alcohol dehydrogenase (ADH) of 44.2 %, suggesting a mechanistic relationship between the proteins and polysaccharides in the glycoproteins that influence the activation of ADH. These findings elucidate the intricate interplay between fermentation conditions and EPS production and provide new avenues for optimizing the fermentation process of CS-HKI to enhance its therapeutic applications.

Genome characterization of Leuconostoc pseudomesenteroides UTNElla29 isolated from Morus nigra (L.) fruits: A promising exopolysaccharides producing strain

Lactic acid bacteria produce various natural polysaccharides that are secreted into the cellular matrix and bonded to the cell surface or released into the surrounding environment. Due to their broad applications in the food industry, the search for novel polysaccharide producer strains remains of interest. In this study, we report the genome sequencing and characterization of Leuconostoc pseudomesenteroides strain UTNElla29 isolated from Morus nigra (L.) fruits. Using in silico different “genome mining” tools we prospect their genetic potential. The genome size was estimated at 2,272,560 bp and a GC content of 39.26%. Of the total proteins, 2170 matched in the EggNOG database. The key genes related to amino acid biosynthesis, carbohydrate metabolism, exopolysaccharide (EPS) production, were annotated. The genome harbors one intact prophage, one CRISPR array, and two putative gene sequences associated with CAS3 Type I, and no plasmids indicating its stability. Moreover, no acquired resistance genes, virulence and pathogenic factors, nor biogenic amines were predicted, suggesting its safety. In vitro preliminary studies showed that EPS yield from 0.4 to 10.2 (g/L) dry biomass and the production varied with the inoculum size and sugar type MRS containing medium. Furthermore, several polyketides and terpenes were predicted, indicating the possibility of generating a wide range of naturally compounds with broad biological functions. However, these promising results suggest that Ella29 is a beneficial strain to be further exploited in vitro for various technological use.

Bioprospecting of exopolysaccharides from the endophytic fungi Epicoccum sorghinum AMFS4, for its structure, composition, bioactivities and application in seed priming

The endophytic fungi, Epicoccum sorghinum AMFS4 was investigated for its metabolic components and composition of bioactive exopolysaccharides (EPS). Metabolic analysis of the ethyl acetate extract majorly detected sugars derivatives such as, 4-Cholesten-3-one semicarbazone (20.9%), d-Fructose (18.96%), and α-d-Galactopyranosiduronicacid (1.71%). The growth curve and EPS yield were determined as 12.22 ± 1.02 g/L and 7.41 ± 0.32 g/L (dry weight) respectively on day 8. The deproteined EPS has been characterised with pyranose ring linked by α-glycosidic bonds, composing fructose, galactose and glucose monosaccharides validated by HPLC. Total sugar content was found to be 93.18 ± 0.81% with detection of proteins and uronate. The viscous EPS appeared filamentous under SEM observation and behaves as emulsifier with notable antioxidant properties. Priming of EPS on tomato seeds showed early induction of secondary rooting than in the control seedlings. Thus, E. sorghinum AMFS4 synthesises bioactive EPS with simple carbohydrate structure, good water absorption and significant metabolic influence on seed germination.

Transcriptome Analysis Reveals the Role of Sucrose in the Production of Latilactobacillus sakei L3 Exopolysaccharide.

Latilactobacillus (L.) sakei is a species of lactic acid bacteria (LAB) mostly studied according to its application in food fermentation. Previously, L. sakei L3 was isolated by our laboratory and possessed the capability of high exopolysaccharide (EPS) yield during sucrose-added fermentation. However, the understanding of sucrose promoting EPS production is still limited. Here, we analyzed the growth characteristics of L. sakei L3 and alterations of its transcriptional profiles during sucrose-added fermentation. The results showed that L. sakei L3 could survive between pH 4.0 and pH 9.0, tolerant to NaCl (<10%, w/v) and urea (<6%, w/v). Meanwhile, transcriptomic analysis showed that a total of 426 differentially expressed genes and eight non-coding RNAs were identified. Genes associated with sucrose metabolism were significantly induced, so L. sakei L3 increased the utilization of sucrose to produce EPS, while genes related to uridine monophosphate (UMP), fatty acids and folate synthetic pathways were significantly inhibited, indicating that L. sakei L3 decreased self-growth, substance and energy metabolism to satisfy EPS production. Overall, transcriptome analysis provided valuable insights into the mechanisms by which L. sakei L3 utilizes sucrose for EPS biosynthesis. The study provided a theoretical foundation for the further application of functional EPS in the food industry.

Investigation on the exopolysaccharide production from blueberry juice fermented with lactic acid bacteria: Optimization, fermentation characteristics and Vis-NIR spectral model

The exopolysaccharide production from blueberry juice fermented were investigated. The highest exopolysaccharide yield of 2.2 ± 0.1 g/L (increase by 32.5 %) was reached under the conditions of temperature 26.5 °C, pH 5.5, inoculated quantity 5.4 %, and glucose addition 9.1 % using the artificial neural network and genetic algorithm. Under the optimal conditions, the viable cell counts and total acids were increased by 2.0 log CFU/mL and 1.6 times, respectively, while the content of phenolics and anthocyanin was decreased by 9.26 % and 7.86 %, respectively. The changes of these components affected the exopolysaccharide biosynthesis. The absorption bands of –OH and –CH associated with the main functional groups of exopolysaccharide were detected by Visible near-infrared spectroscopy. The prediction model based on spectrum results was constructed. Competitive adaptive reweighted sampling and the random forest were used to enhance the model's prediction performance with the value of RC = 0.936 and RP = 0.835, indicating a good predictability of exopolysaccharides content during fermentation.

The optimization of in situ exopolysaccharides production in Lactobacillus helveticus MB2-1 fermented milk and its functional characteristics in vitro

In order to improve the in situ exopolysaccharides (EPS) production of Lactobacillus helveticus MB2-1 fermented milk and explore its functional characteristics, the production optimization conditions, structural characteristics of fermented milk, emulsifying properties, antioxidant, and antibiofilm activities of in situ produced EPS were investigated. The fermentation conditions were optimized using response surface methodology. When the optimal temperature was 37 °C for 8.0 h with 7.0% w/w of inoculum size, the EPS yield could be up to 340 mg L−1. The L. helveticus MB2-1 fermented milk presented better gel structure than the control under the optimized conditions. The in situ produced EPS presented fine emulsifying properties, exhibited potent antioxidant activities as well as obvious antibiofilm activities against foodborne biofilm-forming pathogens. These findings demonstrated that in situ produced EPS in L. helveticus MB2-1 fermented milk has multiple functional qualities and can be a potent ingredient for supplementation and fortification of functional food products.

Submerged production of mycelium biomass and bioactive compounds from P. ostreatus in a controlled fermentation medium

Pleurotus ostreatus is commonly consumed mushroom species around the world due to its unique taste, flavor, and presence of biologically active compounds. The current study investigated the biological activities of P. ostreatus in submerged cultivation. Cultivation factors such as pH, temperature, inoculum density, and cultivation time with different carbon and nitrogen sources were optimized to obtain a high yield of biomass and exopolysaccharides (EPSs). The maximum biomass and EPS obtained were 24.66 ± 0.2 g/L and 4.8 ± 0.1 g/L respectively. The protein content and total phenolic content (TPC) were achieved as 0.936 ± 0.005 g/L and 16.484 ± 0.06 mg GAE/g respectively at 12th day of cultivation. Antioxidant activity of P. ostreatus was obtained as 49.59 ± 1.09%. Under optimized conditions, the P. ostreatus was also cultivated in a rotary bed reactor (RBR). Furthermore, different kinetic models were studied to observe the growth behaviour of mycelium biomass. The best fit was obtained for the contois model, which gave the maximum specific growth rate (µmax, hr−1) of 0.0235 hr−1 and R2 value of 0.976.

Application of exopolysaccharides synthesized by Xanthomonas campestris in an efficient separation system of refractory chalcopyrite and molybdenite

Bacterial polysaccharides get an abundance of attention owing to their distinctive biological activity and promising applications. Recent research found that the specificity of the molecular structure of exopolysaccharides (EPS) can be used to accomplish selective regulation of the physicochemical properties of mineral surfaces. The development and application of novel microbial EPS as a flotation reagent for chalcopyrite and molybdenite separation possesses a promising development prospect. Consequently, we attempted to create effective and sustainable molybdenite depressants in this work by optimizing the strain's fermentation settings and identifying the molecular structure of the generated EPS. Fermentation condition tests revealed patterns of influence of fermentation parameters on EPS yield, the viscosity average molecular weight, and biomass during the fermentation process, and optimized the optimal fermentation conditions. Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and ion chromatography (IC) analyses clarified the structure of the EPS in terms of monosaccharide composition, glycosidic bonding, and functional groups. Mixed mineral flotation tests proved that a low dosage of polysaccharide reagent (100 mg/L) at pH 10 effectively inhibited molybdenite and achieved separation targets of 21.96% Cu and 2.63% Mo in the concentrate, with separation efficiencies (SE) of 72.67% and 55.78% for Cu and Mo, respectively.

Exploration of Exopolysaccharide from Leuconostoc mesenteroides HDE-8: Unveiling Structure, Bioactivity, and Food Industry Applications.

A strain of Leuconostoc mesenteroides HDE-8 was isolated from homemade longan fermentation broth. The exopolysaccharide (EPS) yield of the strain was 25.1 g/L. The EPS was isolated and purified, and the structure was characterized using various techniques, including X-ray diffraction (XRD), nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, high-performance size exclusion chromatography (HPSEC), and scanning electron microscopy (SEM). The monosaccharide composition of the EPS was glucose, with a molecular weight (Mw) of 1.7 × 106 Da. NMR spectroscopy revealed that the composition of the HDE-8 EPS consisted of D-glucose pyranose linked by α-(1→4) and α-(1→6) bonds. The SEM analysis of the EPS showed an irregular sheet-like structure. Physicochemical analysis demonstrated that EPSs exhibit excellent thermal stability and high viscosity, making them suitable for fermentation in heat-processed and acidic foods. Additionally, milk coagulation tests showed that the presence of EPSs promotes milk coagulation when supplemented with sucrose. It suggests that EPSs have wide-ranging potential applications as food additives, improving the texture and taste of dairy products. This study provides practical guidance for the commercial use of HDE-8 EPSs in the food and related industries.

Evaluation of kefir grain microbiota, grain viability, and bioactivity from fermenting dairy processing by-products

Four dairy foods processing by-products (acid whey permeate (AWP), buttermilk (BM), sweet whey permeate (SWP), and sweet whey permeate with added milk fat globule ingredient (SWP+MFGM)) were fermented for 4 weeks and compared with traditional kefir milks for production of novel kefir-like dairy products. AU: Sweet whey permeates and SWP supplemented with 1.5% milk fat globule membrane (MFGM) showed to be the most viable by-products for kefir grain fermentation, exhibiting diverse abundance of traditional kefir microorganisms and positive indicators of bioactive properties. Grain viability was assessed with shotgun metagenomics, texture profile analysis, live cell counts, and scanning electron microscopy. Assessed bioactivities of the kefir-like products included antibacterial, antioxidant, potential anticancerogenic properties, and membrane barrier effect on human colorectal adenocarcinoma Caco-2 cells. All kefir grains were most abundant in Lactobacillus kefiranofaciens when analyzed with shotgun metagenomics. When analyzed with live cell counts on selective media, AWP kefir-like product had no countable Lactococcus spp. indicating suboptimal conditions for kefir grain microbiota survival and application for fermented dairy starter culture bacterium. Live cell counts were affirmed with kefir grain surface scanning electron microscopy images. SWP had the most adhesive kefir grain surface while SWP+MFGM had the largest exopolysaccharide (EPS) yield from grain extraction. All kefir and kefir-like products were able to achieve a 6-log reduction against Listeria innocua and Escherichia coli. Traditional milk kefirs had the highest antioxidant capacity for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. AWP had a significantly higher DPPH antioxidant activity and SWP had the lowest Trolox equivalence concentration in the ABTS assay. Sweet whey and supplemented milk fat sweet whey had upregulation of Cldn-1 and Ocln-1 gene expression, which correspond with a significant increase in transepithelial electrical resistance.

Obtaining Edible Pullulan-based Films with Antimicrobial Properties

A nutrient medium was selected for the efficient production of exopolysaccharide (EPS) by A. pullulans C7 strain. The production of pullulan polysaccharide was evaluated on nutrient media with traditional carbon sources and cheap substrates that were plant wastes. For maximum EPS accumulation, we proposed an optimized Czapek-Dox medium with glucose as a carbon source, sodium nitrate as a nitrogen source, and C/N=232:1 ratio (EPS yield 12.79±0.64 g/l). Medium with grape pomace 5% (EPS yield was 15.08±0.34 g/l) and medium with topinambour tuber hydrolysate 5% (EPS yield was 14.44±0.21 g/l) was proposed as a cheap substrate. Edible films with antimicrobial activity were obtained on the basis of the isolated polysaccharide. The antibacterial activity of films against Escherichia coli 603 and Staphylococcus aureus ST228 was shown when essential oils of rosemary (zones of growth inhibition from 8.41±0.71 to 9.98±0.32 mm) and oregano (zones of growth inhibition from 8.09±0.51 to 9.54±0.24 mm) were added to pullulan. The addition of xanthan gum and glycerol to the films increased their strength and elasticity. The infrared spectrum of the pullulan film showed absorption bands characteristic of polysaccharide structures.

The role of iron-uptake factor PiuB in pathogenicity of soybean pathogen Xanthomonas axonopodis pv. glycines

Iron is an essential element for living organisms that plays critical roles in the process of bacterial growth and metabolism. However, it remains to be elucidated whether piuB encoding iron-uptake factor is involved in iron uptake and pathogenicity of Xanthomonas axonopodis pv. glycines (Xag). To investigate the function of piuB, we firstly generated a piuB deletion mutant (ΔpiuB) by homologous recombination. Compared with the wild-type, the piuB mutant exhibited significantly reduced growth and virulence in host soybean. The mutant displayed markedly increased siderophore secretory volume, and its sensitivity to Fe3+, Cu2+, Zn2+ and Mn2+ was significantly enhanced. Additionally, the H2O2 resistance, exopolysaccharide yield, biofilm formation, and cell mobility of ΔpiuB were significantly diminished compared to that of the wild-type. The addition of exogenous Fe3+ cannot effectively restore the above characteristics of ΔpiuB. However, expressing piuB in trans rescued the properties lost by ΔpiuB to the levels in the wild-type. Taken together, our results demonstrated that PiuB is a potential factor for Xag to assimilate Fe3+, and is necessary for Xag to be pathogenic in host soybean.

Efficient Screening and Enhanced Exopolysaccharide Production by Functional Lactic Acid Bacteria (LAB) in Lactose Supplemented Media

Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) can be considered as natural biological thickeners that have attracted considerable attention in the food industry. This study aimed to evaluate and select potentially EPS-producing strains LAB and to assess the influence of carbon source and aeration on EPS production. Nine LAB strains were assessed as potential EPS producers, and Rahnella aquatilis ATCC 55046 was employed as the positive control strain for EPS. The compaction test and the observation of viscous colonies in a solid medium did not yield sufficient evidence for the presence of EPS. The assessment of capsules through staining provided evidence of EPS presence only for Rahnella aquatilis ATCC 55046. The EPS yield was subsequently assessed in De-Man Rogosa and Sharpe (MRS) broth medium supplemented with 2% (w/w) fructose (MRS-f) or lactose (MRS-l), as well as in whey (Whey) and whey supplemented with 2% (w/w) lactose (Whey-l). The EPS production in the various culture media under study ranged from 194 to 1,187 mg of EPS/g of polymer dry mass (PDM). These results suggest that the culture medium and carbon sources had an impact on the EPS production of the different strains. Bifidobacterium animalisBb12 achieved the highest EPS production in MRS-f. In the case of MRS-l, the control strain recorded the highest EPS value, along with Lactobacillus acidophilus LAC-1. Regarding Whey, Lentilactobacillus Kefir NCFB 2753 exhibited the highest EPS production, while in Whey-l, Lacticaseibacillus paracasei LCS-1 emerged as the top performer in terms of EPS production. This suggests that certain strains exhibit potential for use in the production of novel fermented EPS products, whether dairy or non-dairy.

Temperature stress improved exopolysaccharide yield from Tetragenococcus halophilus: Structural differences and underlying mechanisms revealed by transcriptomic analysis

This study aimed to enhance exopolysaccharide production by Tetragenococcus halophilus, and results showed that low temperature (20 °C) significantly improved exopolysaccharide production. Based on the analysis of batch fermentation kinetic parameters, a temperature-shift strategy was proposed, and the exopolysaccharide yield was increased by 28 %. Analysis of the structure of exopolysaccharide suggested that low temperature changed the molecular weight and monosaccharide composition. Transcriptomic analysis was performed to reveal mechanisms of low temperature improving exopolysaccharide production. Results suggested that T. halophilus regulated utilization of carbon sources through phosphotransferase system and increased the expression of key genes in exopolysaccharide biosynthesis to improve exopolysaccharide production. Meanwhile, metabolic pathways involved in glycolysis, amino acids synthesis, two-component system and ATP-binding cassette transporters were affected at low temperature. Results presented in this paper provided a theoretical basis for biosynthetic pathway of exopolysaccharide in T. halophilus and aided to strengthen its production and application in many areas.

The mechanistic study of using microparticle Al2O3 to promote the production of exopolysaccharides in submerged fermentation of Antrodia cinnamomea

In this study, a notable increase of 136.9% in the production of exopolysaccharides (EPS) was observed during the submerged fermentation of Antrodia cinnamomea when microparticle (4 g/L of Al2O3) was applied. By evaluating the activities of key enzymes involved in EPS synthesis in A. cinnamomea, it was found that the addition of Al2O3 enhanced the activities of phosphoglycerate mutase (PGM), UDP-glucose pyrophosphorylase (UGP), and GDP-mannose pyrophosphorylase (GMPPB). To further elucidate the mechanism through which Al2O3 enhances the production of EPS in A. cinnamomea, a transcriptomic analysis was conducted to compare the gene expression levels. The results showed that there was a significant up-regulation of genes associated with the synthesis and assembly of polysaccharide repeating units, as well as genes responsible for the regulation of ABC transporter complex enzymes. To verify the above hypothesis, the ABC transporter inhibitor MK-571 sodium salt was added to the fermentation broth of A. cinnamomea. The study demonstrated that when the ABC transporter was inhibited, the yield of EPS was significantly reduced, which further confirmed that the addition of Al2O3 could improve the activity of ABC transporter and promote the production of EPS in submerged fermentation of A. cinnamomea.

On the Molecular Selection of Exopolysaccharide-Producing Lactic Acid Bacteria from Indigenous Fermented Plant-Based Foods and Further Fine Chemical Characterization.

Exopolysaccharides (EPSs) produced by lactic acid bacteria present a particular interest for the food industry since they can be incorporated in foods via in situ production by selected starter cultures or applied as natural additives to improve the quality of various food products. In the present study, 43 strains were isolated from different plant-based fermented foods and identified by molecular methods. The species found were distinctively specific according to the food source. Only six Lactiplantibacillus plantarum strains, all isolated from sauerkraut, showed the ability to produce exopolysaccharide (EPS). The utilization of glucose, fructose and sucrose was explored with regard to EPS and biomass accumulation by the tested strains. Sucrose was clearly the best carbon source for EPS production by most of the strains, yielding up to 211.53 mg/L by strain Lactiplantibacillus plantarum ZE2, while biomass accumulation reached the highest levels in the glucose-based culture medium. Most strains produced similar levels of EPS with glucose and fructose, while fructose was utilized more poorly for biomass production, yielding about 50% of biomass compared to glucose for most strains. Composition analysis of the EPSs produced by strain Lactiplantibacillus plantarum ZE2 from glucose (EPS-1) and fructose (EPS-2) revealed that glucose (80-83 mol%) and protein (41% w/w) predominated in both analyzed EPSs. However, the yield of EPS-1 was twice higher than that of EPS-2, and differences in the levels of all detected sugars were found, which shows that even for the same strain, EPS yield and composition vary depending on the carbon source. These results may be the basis for the development of tailored EPS-producing starter cultures for food fermentations, as well as technologies for the production of EPS for various applications.

Necessity of Different Lignocellulose on Exopolysaccharide Synthesis and Its Hypoglycemic Activity In Vitro of Inonotus obliquus.

Current work proposes elm sawdust, poplar sawdust, pine sawdust, and cotton straw with different lignocellulose compositions and structures as the research objects to investigate the relationship between the hypoglycemic activity of mycelium polysaccharides from Inonotus obliquus and lignocellulose biodegradation. Four kinds of lignocellulosic materials could significantly increase the exopolysaccharide content and α-glucosidase inhibition rate and advance the occurrence time of α-glucosidase inhibition activity. Among all groups, the polysaccharide synthesis promotion effect of the cotton straw group was the best, which exopolysaccharide yield was 92.05% higher than that of the control group after 11-day fermentation. Meanwhile, the highest α-glucosidase inhibitory activity was found in the elm sawdust group on the 11th day (30.99%, which was 137.47% higher than control), and the exopolysaccharide in the elm sawdust group showed its effectiveness on glucose consumption of insulin resistant HepG2 cells at the concentration of 20 µg/mL, significantly higher than that of the metformin group (P < 0.05). The cellulose in the non-crystalline region of elm and pine and the hemicellulose of poplar were mainly used in the fermentation of I. obliquus, while the cellulose in the crystalline zone and amorphous zone of cotton straw was degraded to improve the exopolysaccharide content of I. obliquus. This paper revealed the necessity of different kinds of lignocellulose for the synthesis of active polysaccharide from I. obliquus and provided a new idea for the regulation of polysaccharide synthesis pathway.