Ultrasound-assisted production of highly-purified β-glucan schizophyllan and characterization of its immune properties

Schizophyllan from Schizophyllum commune BRM 060008: Potential application as an inhibitor of lipase

β-D-glucan has significant implications in regulating lipid metabolism and preventing diseases associated with lipid accumulation. Schizophyllan (SPG) from Schizophyllum commune fungus is a commercially important β-glucan with applications in the health food industry, pharmacy, and cosmetics. However, SPG was obtained by submerged culture of the wood-rotting and filamentous fungus S. commune BRM 060008, which may have been isolated from the Cerrado Biome of Brazil. In this study, to confirm that the polysaccharide produced by BRM 060008 strain fermentation was indeed (1→3)(1→6)-β-D-glucan, it was purified and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, high-performance size exclusion chromatography, nuclear magnetic resonance, and methylation analysis. The polysaccharide produced was identified as the β-D-glucan expected with a high molecular weight (1.093 × 106 g/mol) and the thermogravimetric analysis indicated a maximum degradation temperature of ~324 °C and a 60 % residual weight, lower than commercial SPG. The molecular structure and thermal properties of the β-D-glucan were similar to the commercial sample. Additionally, the in vitro pancreatic lipase inhibitory activity was evaluated, investigating anti-obesity and anti-lipidemic properties. The results showed unprecedented lipase inhibition activity to SPG prepared using the S. commune strain BRM 060008, making it promising for food and pharmaceutical applications.

Effect of Steaming and Microwave Heating on Taste of Clear Soup with Split-Gill Mushroom Powder

Salt is widely overconsumed. Among the strategies used in low-salt foods, the addition of flavor enhancers to improve saltiness perception through an umami taste is a viable and promising technique. This study investigated using split-gill mushroom (SGM) powder containing umami taste to increase saltiness in a clear soup for two different heating conditions: steaming under high pressure and microwave heating. According to the E-tongue results, the addition of 0.2-0.8% SGM produced a different taste in the soup compared to the addition of salt, and the addition of 0.2-0.8% SGM yielded a similar taste to the addition of 0.4-0.6% MSG in a plain, clear soup. In flavored soup, SGM at a high concentration had a taste-enhancing impact comparable to 0.4% MSG, whereas SGM at a low concentration had no taste-enhancing effect. The flavored soups containing 0.4 or 0.8% SGM consisted of two umami 5'-nucleotides: adenosine 5'-monophosphate (5'-AMP) and guanosine 5'-monophosphate (5'-GMP); however, inosine 5'-monophosphate (5'-IMP) was not detected. The major umami amino acids were glutamic acid, aspartic acid, and arginine. Microwave heating increased the salinity and total nucleotides and could maintain the umami amino acids, whereas aspartic acid (one of the umami amino acids) was reduced by 8.23% after steaming under high pressure. Thus, after microwave heating and steaming under high pressure, the equivalent umami concentration was reduced by 43.11 and 44.53%, respectively. In conclusion, the addition of SGM and volumetric heating using microwaves could be an alternative method for reducing the amount of salt in soup by increasing the umami taste intensity and salinity.

Quantification of schizophyllan directly from the fermented broth by ATR-FTIR and PLS regression

Non-destructive methods that allow the quantification of bioproducts in a simple and quick manner during fermentation are extremely desirable from a practical point of view. Therefore, a 9 day fermentation experiment with Schizophyllum commune was carried out to investigate the possibility of using ATR-FTIR to quantify the schizophyllan biopolymer (SPG) directly from the culture medium. On each day, aliquots of the fermentation were taken, and the cell-free supernatant was analyzed by ATR-FTIR. The main objective of this step was to evaluate whether FTIR would be able to detect the appearance of specific peaks related to the production of SPG. The results of the PCA analysis showed that there was a reasonable separation of the days through the FTIR spectra. Then PCA-LDA was applied to the same dataset, which confirmed the formation of groups for each day of fermentation, after which, a calibration and test set was developed. Through a matrix generated by an experimental design with 2 factors and 5 levels, 25 samples were created with variations in the concentration of the culture medium and SPG. The ATR-FTIR spectra of this data set were modeled using PLS regression with backward selection of predictors. The results revealed that the amount of SPG produced can be quantified directly in the culture medium with excellent precision with R²CV = 0.951, R²P = 0.970, RMECV = 0.205 g, RMSEP = 0.170 g, RPDcv = 4.53 and RPDp = 5.88. The traditional method to quantify SPG is time consuming, requires several steps and uses solvents. In contrast, the method proposed in this work is a viable, faster, and a simpler alternative, which does not use reagents and does not require extensive pre-treatment of the samples.

Exploitation of Ultrasound Technique for Enhancement of Microbial Metabolites Production

Microbial metabolites have significant impacts on our lives from providing valuable compounds for nutrition to agriculture and healthcare. Ever-growing demand for these natural compounds has led to the need for smart and efficient production techniques. Ultrasound is a multi-applicable technology widely exploited in a range of industries such as chemical, medical, biotechnological, pharmaceutical, and food processes. Depending on the type of ultrasound employed, it can be used to either monitor or drive fermentation processes. Ultrasonication can improve bioproduct productivity via intensifying the performance of living organisms. Controlled ultrasonication can influence the metabolites' biosynthesis efficiency and growth rates by improvement of cell permeability as well as mass transfer and nutrient uptake rates through cell membranes. This review contains a summarized description about suitable microbial metabolites and the applications of ultrasound technique for enhancement of the production of these metabolites as well as the associated downstream processing.

Electrospun Membranes Based on Schizophyllan-PVOH and Hamamelis Virginiana Extract: Antimicrobial Activity Against Microorganisms of Medical Importance

Electrospinning is a micrometric or nanometric scale fiber manufacturing technique with structural factors such as greater contact surface and pore size that allows the incorporation of biological agents in its structure, increasing their potential for medical applications. Due to the conditions required for the electrospinning process, such as high voltage, in the present work, the evaluation of the antimicrobial activity of schizophyllan-based membranes elaborated by electrospinning at 20 kV incorporated with Hamamelis virginiana was carried out against Staphylococcus aureus, Candida albicans and Pseudomonas aeruginosa. The schizophyllan production was 1.97 gL^-1 from strain Schizophyllum commune ScIBL1. The conditions for the process were standardized for voltage, feed flow, and the distance from the injector to the collector. Membranes with smooth-edged fibers, diameter of 819 nm without the presence of beads were obtained. However, it was found that the membranes lost antimicrobial activity against all the microorganisms evaluated, whereas, bioassays showed that null toxicity was presented.

Bioactive exopolysaccharide from Neopestalotiopsis sp. strain SKE15: Production, characterization and optimization

Fungal exopolysaccharides are powerful resources of medicinal applications. Neopestalotiopsis sp. SKE15 was isolated and identified according to phenotypical and genotypical analyses (GenBank Accession No. MG649986). The exopolysaccharide (EPS) was produced by cultivation of mycelia in broth culture and extracted. The production was optimized to 2.02 g/l after selection of agitation, temperature, FeSO₄ and K₂HPO₄ concentrations as the most influencing factors using Placket-Burman design and then by applying response surface methodology. Analytical Tools showed that the EPS is composed of a polysaccharide (1.5-2.1 × 10⁶ Da) and its probable low molecular weight derivatives, in a wide range of chain lengths, among them an oligosaccharide of about 1970 Da was dominant. GC-MS (Gas chromatography-mass spectrometry) analysis revealed the EPS was mainly constructed from d-glucose, sorbitol and D-galactose. The EPS showed antibacterial activity against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633 and Pseudomonas aeruginosa ATCC 27853. DPPH (1,1-diphenyl-2-picryl-hydrazyl) and hydroxyl radical scavenging activity assays showed strong antioxidant activity of the EPS. A challenge with three different cancerous cell lines showed cytotoxic activity of the EPS at final concentration of 100 and 200 μg/ml. Further investigation on medicinal applications of the biopolymer is promising.

Current status of biotechnological production and applications of microbial exopolysaccharides

Microbial exopolysaccharides (EPS) are an abundant and important group of compounds that can be secreted by bacteria, fungi and algae. The biotechnological production of these substances represents a faster alternative when compared to chemical and plant-derived production with the possibility of using industrial wastes as substrates, a feasible strategy after a comprehensive study of factors that may affect the synthesis by the chosen microorganism and desirable final product. Another possible difficulty could be the extraction and purification methods, a crucial part of the production of microbial polysaccharides, since different methods should be adopted. In this sense, this review aims to present the biotechnological production of microbial exopolysaccharides, exploring the production steps, optimization processes and current applications of these relevant bioproducts.