Preparation and Bioactivity of Exopolysaccharide from an Endophytic Fungus Chaetomium sp. of the Medicinal Plant Gynostemma Pentaphylla

Separation, Purification, Structural Characterization, and Anticancer Activity of a Novel Exopolysaccharide from Mucor sp

Mucor sp. has a wide range of applications in the food fermentation industry. In this study, a novel exopolysaccharide, labeled MSEPS, was separated from Mucor sp. fermentation broth through ethanol precipitation and was purified by ion-exchange chromatography, as well as gel filtration column chromatography. MSEPS was composed mostly of mannose, galactose, fucose, arabinose, and glucose with a molar ratio of 0.466:0.169:0.139:0.126:0.015 and had a molecular weight of 7.78 × 10⁴ Da. The analysis of methylation and nuclear magnetic resonance results indicated that MSEPS mainly consisted of a backbone of →3,6)-α-d-Manp-(1→3,6)-β-d-Galp-(1→, with substitution at O-3 of →6)-α-d-Manp-(1→ and →6)-β-d-Galp-(1→ by terminal α-l-Araf residues. MTT assays showed that MSEPS was nontoxic in normal cells (HK-2 cells) and inhibited the proliferation of carcinoma cells (SGC-7901 cells). Additionally, morphological analysis and flow cytometry experiments indicated that MSEPS promoted SGC-7901 cell death via apoptosis. Therefore, MSEPS from Mucor sp. can be developed as a potential antitumor agent.

Biotransformation ability of endophytic fungi: from species evolution to industrial applications

Increased understanding of the interactions between endophytic fungi and plants has led to the discovery of a new generation of chemical compounds and processes between endophytic fungi and plants. Due to the long-term co-evolution between fungal endophytes and host plants, endophytes have evolved special biotransformation abilities, which can have critical consequences on plant metabolic processes and their composition. Biotransformation or bioconversion can impact the synthesis and decomposition of hormones, sugars, amino acids, vitamins, lipids, proteins, and various secondary metabolites, including flavonoids, polysaccharides, and terpenes. Endophytic fungi produce enzymes and various bioactive secondary metabolites with industrial value and can degrade or sequester inorganic and organic small molecules and macromolecules (e.g., toxins, pollutants, heavy metals). These fungi also have the ability to cause highly selective catalytic conversion of high-value compounds in an environmentally friendly manner, which can be important for the production/innovation of bioactive molecules, food and nutrition, agriculture, and environment. This work mainly summarized recent research progress in this field, providing a reference for further research and application of fungal endophytes. KEY POINTS: •The industrial value of degradation of endophytes was summarized. • The commercial value for the pharmaceutical industry is reviewed.

An excellent antibacterial and high self-adhesive hydrogel can promote wound fully healing driven by its shrinkage under NIR

The lacks of antibacterial properties, low adhesion and delayed wound healing of the hydrogel wound dressings limit their applications in wound treatment. To resolve these, a novel hydrogel composed of polydopamine (PDA), Ag and graphene oxide (GO) is fabricated for wound dressing via the chemical crosslinking of N-isopropylacrylamide (NIPAM) and N,N'-methylene bisacrylamide (BIS). The prepared hydrogel containing PDA@Ag5GO1 (Ag5GO1 denotes the mass ratio between Ag and GO is 5:1) exhibits effective antibacterial properties and high inhibition rate against E. coli and S. aureus. It shows high adhesion ability to various substrate materials, implying a simpler method to the wound obtained by self-fixing rather than suturing. More important, it can produce strong contractility under the irradiation of near-infrared light (NIR), exerting a centripetal force that helps accelerate wound healing. Thus, the hydrogel containing a high concentration PDA@Ag5GO1 irradiated by NIR can completely repair the wound defect (1.0 × 1.0 cm²) within 15 days, the wound healing rate can reach 100%, which was far higher than other groups. Taken together, the new hydrogel with excellent antibacterial, high adhesion and strong contractility will subvert the traditional treatment methods on wound defect, extending its new application range in wound dressing.

Bioactivity assessment of exopolysaccharides produced by Pleurotus pulmonarius in submerged culture with different agro-waste residues

Pleurotus spp. are white-rot fungi that utilize different agro-wastes to produce useful biologically active compounds. In this study, exopolysaccharides (EPS) were produced by Pleurotus pulmonarius in submerged culture supplemented with different agro-wastes. Functional groups in EPS were revealed using Fourier Transform-Infrared (FT-IR) spectroscopy. Antimicrobial activity of EPS was tested against microorganisms using agar well diffusion. Scavenging potentials of EPS was tested against 1, 1- diphenyl-2-picryhydrazyl (DPPH), hydroxyl (OH), iron (Fe2+) and nitric oxide (NO) radicals. In vitro prebiotic activity of EPS was carried out. The highest yield (5.60 g/L) of EPS was produced by P. pulmonarius in submerged culture supplemented with groundnut shell (20.0 g/L). The functional groups in EPS were hydroxyl (-OH), methyl (-CH3), ketone (-RCOH) and carbonyl group (-C=O). EPS displayed zones of inhibition (5.00-14.00 mm) against tested microorganisms. Scavenging activity of EPS ranged from 65.70-81.80% against DPPH. EPS supported the growth of Lactobacillus delbrueckii and Streptococcus thermophiles with values ranged from 3.04 × 104-3.40 × 104 cfu/ml and 2.50 × 104-2.81 × 104 cfu/ml, respectively. Submerged culture of P. pulmonarius with addition of agro-wastes enhanced yield of EPS. The EPS exhibited bio-functional properties like antimicrobial, antioxidant and prebiotic activities. Hence, agrowastes can be recycled in submerged fermentation with fungi to produce promising biomaterials for biopharmaceutical applications.

Exopolysaccharides from Lactobacillus kiferi as adjuvant enhanced the immuno-protective against Staphylococcus aureus infection

Exopolysaccharides from lactic acid bacteria (LAB) have gained more attention due to their health benefits. Most research on LAB EPS focuses on antitumor and antioxidant activities. To our knowledge, the immunoadjuvant activity of LAB EPS has not been thoroughly studied. In this study, the EPS produced by Lactobacillus kiferi WXD029 were purified by ethanol precipitation and column chromatography fractionation. The molecular weight of the EPS was 3.423 × 10⁵ Da and was mainly composed of Glu, GlcN, and GalN in a molar ratio of 3.1:1:1. In vitro, EPS could significantly enhance the proliferation and phagocytic activity as well as induce the production of NO, TNF-α, IL-1β, and IL-6 in RAW264.7 cells. In vivo, the EPS adjuvant could increase the titers of S.aureus antigen-specific antibodies and markedly enhanced T cell proliferation. Notably, EPS adjuvant also induced a strong potential Th1, Th2 and Th17-cell mixture responses. Furthermore, immunization with S.aureus antigen plus EPS adjuvant induced a protective effect when compared with S.aureus antigen alone in murine bacteremia, pneumonia and mastitis model. Collectively, these results suggest that EPS derived from probiotic Lactobacillus kiferi strain is promising as an efficient adjuvant candidate for the prevention of S. aureus infections.

Diversity and antimicrobial activity of endophytic fungi isolated from Securinega suffruticosa in the Yellow River Delta

Securinega suffruticosa (Pall.) Rehd is an excellent natural secondary shrub in the Shell Islands of Yellow River Delta. The roots of S. suffruticosa have high medicinal value and are used to treat diseases, such as neurasthenia and infant malnutrition. Any organism that is isolated from this species is of immense interest due to its potential novel bioactive compounds. In this research, the distribution and diversity of culturable endophytic fungi in S. suffruticosa were studied, and the endophytic fungi with antimicrobial activity were screened. A total of 420 endophytic fungi isolates were obtained from the S. suffruticosa grown in Shell Islands, from which 20 genera and 35 species were identified through morphological and internal transcribed spacer (ITS) sequence analyses. Chaetomium, Fusarium, Cladosporium, and Ceratobasidium were the dominant genera. The high species richness S (42), Margalef index D' (5.6289), Shannon-Wiener index H' (3.1000), Simpson diversity index Ds (0.9459), PIE index (0.8670), and evenness Pielou index J (0.8719) and a low dominant index λ (0.0541) indicated the high diversity of endophytic fungi in S. suffruticosa, the various species of endophytic fungi with obvious tissue specificity. The inhibition percentages of the 12 species of such endophytic fungi against Colletotrichum siamense were 3.6%-26.3%. C. globosum, Fusarium sp.3, and C. ramotenellum had a high antibacterial activity against Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) were between 0.5 mg/mL and 2 mg/mL. Alkaloid content detection indicated that endophytic fungi had a high alkaloid content, whereas the alkaloid contents of C. globosum and Fusarium sp.3 reached 0.231% and 0.170%, respectively. Members belonging to the endophytic fungal community in the S. suffruticosa of Shell Islands that may be used as antagonists and antibacterial agents for future biotechnology applications were identified for the first time.

Exopolysaccharides from the fungal endophytic Fusarium sp. A14 isolated from Fritillaria unibracteata Hsiao et KC Hsia and their antioxidant and antiproliferation effects

Exopolysaccharides (EPSs) are high-molecular-weight carbohydrates with a wide range of biophysiological activities, such as antioxidant activity, immunostimulatory activity, antitumor activity, hepatoprotective activity, and antifatigue effects. In the present work, two water-soluble EPSs, namely, A14EPS-1 and A14EPS-2, were isolated and purified from the fungal endophytic strain A14 using ethanol precipitation, DEAE-cellulose ion exchange chromatography and Sepharose G-150 gel filtration chromatography. A14EPS-1 (∼2.4 × 10⁴ Da, the major fraction) was mainly composed of mannose, rhamnose, glucose, galactose, xylose and arabinose with a molar ratio of 0.31:0.55:10.00:0.34:0.03:0.06. The major monosaccharide of A14EPS-1 was pyranose, which was connected by α-glycosidic linkages. And the side chains of A14EPS-1 may be composed of rhamnose, arabinose, glucose and galactose; moreover, the backbone of A14EPS-1 may be composed of rhamnose, xylose, arabinose and glucose. A14EPS-2 (∼0.5 × 10⁴ Da) was mainly composed of mannose, rhamnose, glucose, galactose, xylose and arabinose in a ratio of 0.16:0.88:10.00:0.39:0.06:0.06. Pyranose was observed in both the α- and β-configurations in A14EPS-2, and the α configuration was dominant. In addition, the results of the bioactivity assays indicated that both A14EPS-1 and A14EPS-2 had moderate antioxidant activity in vitro, and A14EPS-2 showed a moderate antiproliferation effect on human hepatocellular carcinoma HepG2 cells.