Effect of surfactants on the production of polysaccharides from Schizophyllum commune through submerged fermentation

Roles of α-1,3-glucosyltransferase in growth and polysaccharides biosynthesis of Ganoderma lucidum

Ganoderma lucidum polysaccharides are valuable natural compounds possessing significant biological activity, with glycosyltransferases playing a crucial role in their biosynthesis. Although the function of β-1,3-glucosyltransferase in polysaccharides production is well understood, the role of α-1,3-glucosyltransferase in edible fungi remains unclear. In this study, over-expression of the α-1,3-glucosyltransferase gene in G. lucidum (glagt) was found to suppress the growth, with the maximum biomass and mycelial growth rate decreasing by 21.78 % and 79.61 %, respectively, a behavior distinct from β-1,3-glucosyltransferase. The fungal pellet diameter decreased by 38 % and the cell-wall thickness by 32.44 %, whereas intracellular and extracellular polysaccharides production increased by 27.58 % and 66.08 %, respectively. In the transcription level, overexpressing the glagt gene i) downregulated the citrate synthase and isocitrate dehydrogenase gene in the TCA cycle, disrupting energy metabolism and fungal growth; ii) upregulated key enzymes involved in UDP-glucose synthesis and glycosyltransferases (gl24465, gl24971, and gl22535); and iii) universally increased the transcriptional level of glucosidases gl21451, gl30087, and gl24581 by 22 %-397 %, contributing to cell-wall thinning to facilitate polysaccharides export. Conversely, the glagt gene downregulation promoted G. lucidum growth and decreased polysaccharides production. The results elucidate the roles of GLAGT and are expected to inspire in-depth exploration of polysaccharides biosynthesis pathways.

Bioguided isolation, identification and bioactivity evaluation of anti-fatigue constituents from Schizophyllum commune

This study aims to clarify the specific anti-fatigue components of Schizophyllum commune (S.commune) and analyze its potential anti-fatigue mechanism. The main anti-fatigue active ingredient of S.commune was locked in n-butanol extract (SPE-n) by activity evaluation. Twelve compounds were identified by high performance liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS). The anti-fatigue effect of morusin is the most predominant among these 12 ingredients. The determination of biochemical indices showed that morusin could increase liver glycogen reserves, improve the activity of antioxidant enzymes in liver, and reduce reactive oxygen species (ROS) content in muscle tissue, thereby reducing myocyte damage. Further studies revealed that morusin could reduce the level of oxidative stress by activating Nrf2/HO-1 pathway, thus alleviating the fatigue of mice caused by exhaustive exercise. The current findings provide a theoretical basis for the development of natural anti-fatigue functional food.

Adaptive laboratory evolution of Naematelia aurantialba under high temperature for efficient production of exopolysaccharide

Liquid fermentation could revolutionize mushroom polysaccharide production, but the low temperature constraint hampers the process. This study implemented adaptive laboratory evolution (ALE) to enhance the thermotolerance of Naematelia aurantialba strains and increase expolysaccharide production. After 75 ALE cycles at 30 °C, the adaptive strain surpassed the wild-type strain by 5 °C. In a 7.5 L fermentor at 30 °C, the ALE strain yielded 17 % more exopolysaccharide than the wild type strain at 25 °C. Although the exopolysaccharide synthesized by both strains shares a consistent monosaccharide composition, infrared spectrum, and glycosidic bond composition, the ALE strain's exopolysaccharide has a larger molecular weight. Furthermore, the ALE strain's exopolysaccharide exhibits superior cryoprotection performance compared to that produced by the original strain. The adapted strain demonstrated lower ROS levels and increased activity of antioxidant enzymes, indicating improved performance. Fatty acid profiling and transcriptomics revealed reconfiguration of carbohydrate metabolism, amino acid metabolism, and membrane lipid synthesis in thermophilic strains, maintaining cellular homeostasis and productivity. This study provides efficient strains and fermentation methods for high-temperature mushroom polysaccharide production, reducing energy consumption and costs.

Emulsion for stabilizing β-carotene and curcumin prepared directly using a continuous phase of polysaccharide-rich Schizophyllum commune fermentation broth

In this study, we examined the effect of Schizophyllum commune fermentation broth (SCFB) rich in polysaccharides (SCFP) on the stability and bioaccessibility of β-carotene and curcumin. An SCFB-stabilized oil-in-water (o/w) emulsion (SCFBe) was prepared using SCFB as the continuous phase, and then evaluated for storage stability using an SCFP-based emulsion (SCFPe) as the control. The findings revealed that SCFBe is more stable at 60 °C than SCFPe, and stratification or droplet size varied at differing pH levels (3-9) and concentrations of Na+ (0.1-0.5 M) and Ca2+ (0.01-0.05 M). Since the absolute value of the zeta potential of SCFBe is much lower at 60 °C than that at 4 °C and 25 °C, a higher temperature (60 °C) may enhance the reactivity of polysaccharides and proteins in SCFB to improve the stability of SCFBe. Both the protective impact of SCFB on functional food molecules and their capacity to block lipid oxidation increased as polysaccharide content improved. The bioaccessibility of β-carotene after in vitro simulated gastrointestinal digestion is 11.18 %-12.28 %, whereas that of curcumin is 31.64 %-33.00 %. By fermenting edible and medicinal fungi in liquid, we created a unique and environmentally friendly approach for getting food-grade emulsifiers without extraction.

Anaerobic production and biosynthesis mechanism of exopolysaccharides in Schizophyllum commune 20R-7-F01

Exopolysaccharides (EPS) produced by microorganisms play a vital role in physiological and ecological processes. However, the mechanisms of EPS synthesis and release in anaerobic environments remain poorly understood. Here, we provide the first evidence of anaerobic EPS synthesis by the fungus Schizophyllum commune 20R-7-F01, isolated from coal-bearing sediments ~2.0 km below the seafloor. Under anaerobic conditions, the fungus exhibited significantly higher specific EPS production (1.57 times) than under aerobic conditions. Transcriptomic analysis revealed 2057 differentially expressed genes (DEGs) in the strain cultured anaerobically for 7 days compared to aerobically. Among these genes, 642 were significantly upregulated, while 1415 were significantly downregulated, mainly associated with carbon metabolism pathways. Genes involved in glycolysis and EPS synthesis, including hexokinase (HK), phosphoglucomutase (PGM), and (1 → 3)-β-glucan synthase (GLS), were significantly upregulated, while those related to the TCA cycle, respiratory chain, and pentose phosphate pathway were downregulated under anaerobic conditions. These findings highlight the oxygen-dependent regulation of EPS synthesis and suggest that EPS may serve as a key mechanism for fungal adaptation to anaerobic environments.

Production, Extraction, and Solubilization of Exopolysaccharides Using Submerged Cultures of Agaricomycetes

Macrofungi, also known as mushrooms, can produce various bioactive compounds, including exopolysaccharides (EPS) with distinct biological properties and subsequent industrial applications in the preparation of cosmetics, pharmaceuticals, and food products. EPS are extracellular polymers with diverse chemical compositions and physical properties secreted by macrofungi in the form of capsules or biofilms into the cellular medium. Submerged cultivation is an industrially implemented biotechnological technique used to produce a wide variety of fungal metabolites, which are of economic and social importance due to their food, pharmaceutical, and agronomic applications. It is a favorable technique for cultivating fungi because it requires little space, minimal labor, and low production costs. Moreover, it allows for control over environmental variables and nutrient supply, essential for the growth of the fungus. Although this technique has been widely applied to yeasts, there is limited knowledge regarding optimal growth conditions for filamentous fungi. Filamentous fungi exhibit different behavior compared to yeast, primarily due to differences in cell morphology, reproductive forms, and the type of aggregates generated during submerged fermentation. Furthermore, various growing conditions can affect the production yield of metabolites, necessitating the development of new knowledge to scale up metabolite production from filamentous fungi. This protocol implements the following culture conditions: an inoculum of three agar discs with mycelium, agitation at 150 rpm, a temperature of 28 °C, an incubation time of 72 h, and a carbon source concentration of 40 g/L. These EPS are precipitated using polar solvents such as water, ethanol, and isopropanol and solubilized using water or alkaline solutions. This protocol details the production procedure of EPS using submerged culture; the conditions and culture medium used are described. A detailed description of the extraction is performed, from neutralization to lyophilization. The concentrations and conditions necessary for solubilization are also described. Key features • Production and extraction of EPS from submerged cultures of mycelial forms of macrofungi. • Modification of the method described by Fariña et al. (2001), extending its application to submerged cultures of mycelial forms of the macrofungi. • Determination of EPS production parameters in submerged cultures of mycelial forms of macrofungi. • EPS solubilization using NaOH (0.1 N). Graphical overview.

Efficient production and skincare activity evaluation of schizophyllan, a β-glucan derived from Schizophyllum commune NTU-1

Schizophyllan (SPG), a β-glucan produced by the fungus Schizophyllum commune, possesses a β-(1 → 3)-linked backbone with single β-(1 → 6)-linked glucose side chains at approximately every third residue. In this study, we screened SPG-producing strains of S. commune from different provinces in China. A candidate strain (NTU-1) with a high SPG yield was chosen, and the fermentation conditions were optimized. The optimal carbon and nitrogen sources were sucrose (40 g/L) and yeast extract (20 g/L), respectively. The optimal conditions for pH and temperature were 5.0 and 28 °C, respectively. Inclusion of 0.2 mg/L of 2,4-Dichlorophenoxyacetic acid in the medium further increased the SPG concentration. In a 5-L bioreactor, the fermentation cycle was reduced from the initial seven days to five days, and the concentration of SPG obtained was 21.3 g/L, which is the highest reported to date. In addition, we evaluated the bioactivity of the SPG prepared using strain NTU-1. The results showed that SPG had certain characteristics of anti-oxidation, anti-photoaging, and inhibition of melanin production, making it a promising reagent for skin care.

Enhancement of functional activity and biosynthesis of exopolysaccharides in Monascus purpureus by genistein treatments

The exopolysaccharides (EPS) produced by the edible medicinal fungus Monascus purpureus (EMP) become the center of growing interest due to their techno-functional properties and their numerous applications in the food industries; however, the low EPS yields limit its application. In this study, the effect of genistein supplementation on the production, rheological and antioxidant properties of EPS by M. purpureus and its biosynthesis mechanism were explored. The results indicated that the addition of genistein (3 g/L) generated a 110% and 59% increase in the maximum mycelial biomass and EPS yield, respectively. The genistein supplementation group (G-EMP) had higher molar percentages of Xyl and Man, and significantly decreased molecule weight and particle size of EPS, which resulted in stronger antioxidant effect and cell growth promotion. Rheological analysis showed that both EMP and G-EMP demonstrated pseudoplastic fluid behavior and G-EMP exhibited strong gel-like elastic behavior (G' > G"). Furthermore, genistein not only facilitated the production of EPS by regulating cell membrane permeability, enhancing cellular respiratory metabolism and monosaccharide precursor synthesis pathways, and enhancing antioxidant enzyme activity to reduce oxidative stress damage, but also affected the composition of the monosaccharides by increasing enzyme activity in the underlying synthesis pathways. These findings expand the application of M. purpureus resources and provide a paradigm for future study of the structural and functional characteristics of EPS.

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Genistein (3 g/L) significantly stimulate yield of biomass and exopolysaccharides (EPS) from M. purpureus.

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The physicochemical and rheological properties of EPS were significantly changed.

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Their antioxidant and cytoprotective effect were compared.

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A possible mechanism for the response of genistein to increase EPS yield is proposed.

Whole-Genome Sequencing and Transcriptome Analysis of Ganoderma lucidum Strain Yw-1-5 Provides New Insights into the Enhanced Effect of Tween80 on Exopolysaccharide Production

Ganoderma lucidum is an important medicinal mushroom widely cultured in Asian countries. Exopolysaccharides are bioactive compounds of G. lucidum with health benefits. Limited exopolysaccharide content hinders its extraction from G. lucidum. The addition of Tween80 had an enhanced effect on G. lucidum exopolysaccharide production in submerged fermentation. However, the mechanism of this effect remains unclear. In this study, we report on a high-quality assembly of G. lucidum strain yw-1-5 to lay the foundation for further transcriptome analysis. The genome sequence was 58.16 Mb and consisted of 58 scaffolds with an N50 of 4.78 Mb. A total of 13,957 protein-coding genes were annotated and Hi-C data mapped to 12 pseudo-chromosomes. Genes encoding glycosyltransferases and glycoside hydrolases were also obtained. Furthermore, RNA-seq was performed in a Tween80-treated group and control group for revealing the enhanced effect of Tween80 on exopolysaccharide production. In total, 655 genes were identified as differentially expressed, including 341 up-regulated and 314 down-regulated. Further analysis of differentially expressed genes showed that groups of MAPK, amino sugar and nucleotide sugar metabolism, autophagy, ubiquitin-mediated proteolysis, peroxisome, starch and sucrose metabolism, TCA cycle, glycolysis/gluconeogenesis KEGG pathway, glycosyltransferases and glycoside hydrolases played important roles in the enhanced effect of Tween80 on exopolysaccharide production. This work provides a valuable resource for facilitating our understanding of the synthesis of polysaccharides and accelerating the breeding of new strains with a high content of exopolysaccharides.

Potential use of industrial by-products as promising feedstock for microbial lipid and lipase production and direct transesterification of wet yeast into biodiesel by lipase and acid catalysts

This work attempted the conversion of crude glycerol to lipid and lipase by Yarrowia lipolytica and the direct transesterification of wet yeast by its lipase into biodiesel via response surface methodology to enhance the cost-effectiveness of biodiesel production from the lipids. The yeast grew better and accumulated a high amount of lipids on the waste combined with fish waste hydrolysate, but only exhibited high lipase activity on the waste supplemented with surfactants (i.e., gum Arabic, Tween 20, Tween 80). However, the combination of both wastes and Tween 80 further improved growth, lipid productivity, and lipase activity. More importantly, lipase-direct transesterification under optimal conditions (wet cell concentration of 17.97 mg-DCW, methanol loading of 8.21 µL, and hexane loading of 10.26 µL) followed by acid-catalyst transesterification (0.4 M H₂SO₄), offered high FAME yields (>90%), showing the efficiency of the process when applied for the industrialization of biodiesel production from microbial lipids.