Production, structural characterization, and antiproliferative activity of exopolysaccharide produced by Scleroderma areolatum Ehrenb with different carbon source

Chemical Characterization and Anti-Obesity Activity of Exopolysaccharide Isolated from Scleroderma areolatum (Agaricomycetes)

Two polysaccharide fractions were successfully isolated from the crude exopolysaccharide (EPS) of Scleroderma areolatum via gel filtration chromatography. Size exclusion chromatography/multi-angle laser light scattering (SEC/MALLS) analysis showed that the weight of average molecular weights (Mw) of these fractions was 3.162 ȕ 106 (Fr-I) and 2.613 ȕ 106 (Fr-II). Both EPS fractions exhibited a compact globular structure in aqueous solution. Monosaccharide composition analysis revealed that they were primarily composed of mannose and glucuronic acid. FT-IR spectral analysis identified prominent functional groups, such as hydroxyl and carboxylic, typical of heteropolysaccharides. When administered as supplements in high-fat diets to obese rats for 8 weeks, the EPS fractions reduced body weight, serum inflammatory factor levels, and significantly regulated serum lipid levels. Additionally, they increased the total concentration of short-chain fatty acids (SCFA) in colonic digesta. These results suggest a potential role for EPS in mitigating obesity and related metabolic disorders in high-fat diet-induced obese rats.

Response surface methodology and artificial neural network based media optimization for pullulan production in Aureobasidium pullulans

The selection and optimization of carbon and nitrogen sources are essential for enhancing pullulan production in Aureobasidium pullulans. In this study, combinations of carbon (sucrose, fructose, glucose) and nitrogen sources ((NH4)2SO4, urea, NaNO3) were screened, where sucrose and NaNO3 offered the highest pullulan yield (9.33 g L-1). Plackett-Burman design of experiment identified KH2PO4, NaCl, and sucrose as significant factors, which were further optimized using a central composite design. A hyperparameter-optimized artificial neural network (ANN) model with a 3-6-2-1 architecture demonstrated superior predictive accuracy (R2: 0.96) and generalizability (R2CV: 0.74) over a reduced quadratic model (R2: 0.82). The predicted pullulan yield (31.9 g L-1) under ANN model optimized conditions (sucrose: 79.9 g L-1, KH2PO4: 0.25 g L-1, NaCl: 4.3 g L-1) closely matched with the observed yield (30.17 g L-1), while quadratic model showed a significant deviation (39.7 g L-1 vs. 21.0 g L-1), highlighting the reliability of the ANN model.

Effect of Different Carbon Sources on Antioxidant Properties of Exopolysaccharides Produced by Scleroderma areolatum (Agaricomycetes)

Five kinds of exopolysaccharides (EPS) were obtained by fermentation of Scleroderma areolatum Ehrenb. with sucrose, glucose, maltose, lactose, and fructose as carbon sources. Antioxidant abilities of the obtained EPSs were evaluated by inhibiting AAPH, HO·, and glutathione (GS·) induced oxidation of DNA and quenching 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS· and galvinoxyl radicals. The effects of carbon sources on the antioxidant properties of EPSs could be examined. The results showed that five EPSs can effectively inhibit radicals induced oxidation of DNA, and the thiobarbituric acid reactive substances (TBARS) percentages were 44.7%-80.8%, 52.3%-77.5%, and 44.7%-73.3% in inhibiting AAPH, HO·, and GS· induced oxidation of DNA, respectively. All five EPSs could scavenge ABTS· and galvinoxyh, and exhibit superior activity in scavenging free radicals. Antioxidant abilities of EPS with fructose as carbon source were highest among five EPS.

Effect of fermentation pH on the structure, rheological properties, and antioxidant activities of exopolysaccharides produced by Alteromonas australica QD

The pH value was essential for the growth and metabolism of microorganisms. Acidic pH exopolysaccharide (AC-EPS) and alkaline pH exopolysaccharide (AL-EPS) secreted by A. australica QD mediated by pH were studied in this paper. The total carbohydrate content and molecular weight of AC-EPS (79.59% ± 2.24% (w/w), 8.374 × 10⁵ Da) and AL-EPS (82.48% ± 1.46% (w/w), 6.182 × 10⁵ Da) were estimated and compared. In AC-EPS, mannose (3.78%) and galactose (3.24%) content was more, while the proportion of glucuronic acid was less in comparison to AL-EPS. The scanning electron microscopy revealed the structural differences among the AC-EPS and AL-EPS. Thermogravimetric analysis showed degradation temperatures of 272.8 °C and 244.9 °C for AC-EPS and AL-EPS, respectively. AC-EPS was found to exhibit better rheological properties and emulsifying capabilities, while AL-EPS had superior antioxidant activities. Overall, both AC-EPS and AL-EPS have the potential to be used as emulsifiers and biological antioxidants.

Sustainable use of agro-industrial wastes as potential feedstocks for exopolysaccharide production by selected Halomonas strains

Large quantities of waste biomass are generated annually worldwide by many industries and are vastly underutilized. However, these wastes contain sugars and other dissolved organic matter and therefore can be exploited to produce microbial biopolymers. In this study, four selected Halomonas strains, namely, Halomonas caseinilytica K1, Halomonas elongata K4, Halomonas smyrnensis S3, and Halomonas halophila S4, were investigated for the production of exopolysaccharides (EPS) using low-cost agro-industrial wastes as the sole carbon source: cheese whey, grape pomace, and glycerol. Interestingly, both yield and monosaccharide composition of EPS were affected by the carbon source. Glucose, mannose, galactose, and rhamnose were the predominant monomers, but their relative molar ratio was different. Similarly, the average molecular weight of the synthesized EPS was affected, ranging from 54.5 to 4480 kDa. The highest EPS concentration (446 mg/L) was obtained for H. caseinilytica K1 grown on cheese whey that produced an EPS composed mostly of galactose, rhamnose, glucose, and mannose, with lower contents of galacturonic acid, ribose, and arabinose and with a molecular weight of 54.5 kDa. Henceforth, the ability of Halomonas strains to use cost-effective substrates, especially cheese whey, is a promising approach for the production of EPS with distinct physicochemical properties suitable for various applications.