Optimization of a bioactive exopolysaccharide production from endophytic Fusarium solani SD5

Exopolysaccharide from Leuconostoc mesenteroides XR1: Yield optimization, partial characterization and properties

The production conditions of exopolysaccharide (EPS) from Leuconostoc mesenteroides XR1 were optimized by response surface methodology (RSM). Maximum EPS yield was 56.59 ± 0.51 g/L under fermentation conditions with 2.6 g/L ammonium citrate, initial pH 6.5 and temperature 23 °C, which was 6.21-fold greater than the EPS yield before optimization. Characterization of the chain conformation using Congo red test and circular dichroism (CD) showed that EPS exhibited a random coil structure in aqueous solution. The CD results revealed that the EPS concentration altered its hydrogen-bond interactions and chirality, but did not change its chain conformation. The average polydispersity index (PDI) of the EPS solution was only 27.16 %, indicating that it was uniformly distributed in the aqueous solution with high stability. The degradation temperature of EPS was 253.11 °C, indicating high thermal stability. EPS possessed the ability to scavenge activities of free radicals and was protective against oxidative stress-induced plasmid DNA damage. In addition, stable hydrogels could be formed at EPS concentrations above 5 % (w/v). These results collectively showed that EPS can be used commercially as an antioxidant and drug delivery carrier.

Corrective role of endophytic exopolysaccharides from Clerodendrum infortunatum L. on arsenic-induced ovarian steroidogenic dysfunction and associated inflammatory responses

The present investigation aimed to evaluate the therapeutic potential of exopolysaccharides (EPSs) derived from endophytic fungi against arsenic [As(III)]-mediated metabolic and reproductive ailments. Two endophytic fungi, Diaporthe arengae (CleR1) and Fusarium proliferatum (CleR3), were isolated from Clerodendrum infortunatum (Cle), and used for the extraction of two types of EPSs. GC-MS analysis confirmed the presence of hydroxymethyl furfural (HMF) and α-d-glucopyranose in the EPS1 (CleR1) and EPS2 (CleR3), respectively. FTIR analysis revealed the potential As(III)-chelation properties of both EPSs. EPS1 and EPS2 significantly mitigated As(III)-induced oxidative stress and lipid peroxidation by restoring the activities of antioxidative enzymes. EPSs successfully corrected the gonadotropin imbalance and steroidogenic alterations. The downregulation of proinflammatory (NF-κB and TNF-α) and proapoptotic (BAX) mediators and the upregulation of antiapoptotic (Bcl-2) markers were also detected following the treatment with EPSs. Histomorphological restoration of reproductive and metabolic organs was also observed in both the EPS groups. Moreover, the As(III)-induced increase in the immunoreactivity of the androgen receptor (AR) was successfully reversed by these EPSs. Molecular docking predicted that HMF and α-d-glucopyranose of EPS1 and EPS2 interact with the active site of AR by limiting its activity. Hence, EPS could be effective for developing new therapeutic strategies for managing As(III) toxicity.

Polyphasic identification of Rhizopus oryzae and evaluation of physical fermentation parameters in potato starch processing liquid waste for β-glucan production

Β-glucans are polysaccharide macromolecules that can be found in the cell walls of molds, such as Rhizopus oryzae. They provide functional properties in food systems and have immunomodulatory activity, anticancer, and prebiotic effects; reduce triglycerides and cholesterol; and prevent obesity, among others benefits. Furthermore, potato starch production requires a large amount of water, which is usually discharged into the environment, creating problems in soils and bodies of water. The physical parameters to produce β-glucans were determined, liquid waste from potato starch processing was used and native Rhizopus oryzae was isolated and identified from cereal grains. The isolates grew quickly on the three types of agars used at 25 °C and 37 °C, and they did not grow at 45 °C. Rhizopus oryzae M10A1 produced the greatest amount of β-glucans after six days of culture at 30 °C, pH 6, a stirring rate of 150 rpm and a fermentation volume of 250 mL. By establishing the physical fermentation parameters and utilizing the liquid waste from potato starch, Rhizopus oryzae M10A1 yielded 397.50 mg/100 g of β-glucan was obtained.

Optimization of Culture Medium for the Production of an Exopolysaccharide (p-CY02) with Cryoprotective Activity by Pseudoalteromonas sp. RosPo-2 from the Antarctic Sea

When cells are exposed to freezing temperatures, high concentrations of cryoprotective agents (CPA) prevent ice crystal formation, thus enhancing cell survival. However, high concentrations of CPAs can also cause cell toxicity. Exopolysaccharides (EPSs) from polar marine environments exhibit lower toxicity and display effects similar to traditional CPA. In this study, we sought to address these issues by i) selecting strains that produce EPS with novel cryoprotective activity, and ii) optimizing culture conditions for EPS production. Sixty-six bacteria producing mucous substances were isolated from the Ross Sea (Antarctic Ocean) using solid marine agar plates. Among them, Pseudoalteromonas sp. RosPo-2 was ultimately selected based on the rheological properties of the produced EPS (p-CY02). Cryoprotective activity experiments demonstrated that p-CY02 exhibited significantly cryoprotective activity at a concentration of 0.8% (w/v) on mammalian cells (HaCaT). This activity was further improved when combined with various concentrations of dimethyl sulfoxide (DMSO) compared to using DMSO alone. Moreover, the survival rate of HaCaT cells treated with 5% (v/v) DMSO and 0.8% (w/v) p-CY02 was measured at 87.9 ± 2.8% after freezing treatment. This suggests that p-CY02 may be developed as a more effective, less toxic, and novel non-permeating CPA. To enhance the production of EPS with cryoprotective activity, Response Surface Methodology (RSM) was implemented, resulting in a 1.64-fold increase in production of EPS with cryoprotective activity.

Optimizations of exopolysaccharide production by Fusarium nygamai strain AJTYC1 and its potential applications as an antioxidant, antimicrobial, anticancer, and emulsifier

BACKGROUND

Exopolysaccharides (EPSs) produced by microbes are recognized as biomacromolecules of great significance. EPSs from fungi are widely used in a variety of biotechnological fields, including medicine, bioremediation, and agriculture.

RESULTS

In this study, ten fungal isolates were isolated from Kafir El-Dair, Qalubia Governorate, Egypt. Isolate 5 produced more exopolysaccharides than the other examined fungi. According to microscopic morphological traits and genetic confirmation by the 18S rRNA gene, isolate 5 was identified as Fusarium nygamai strain AJTYC1. The present study showed that Czapek's broth media, which contains 6 g/100 ml of sucrose, 10 g/100 ml of peptone, pH 6, and 1.8 × 105 CFU/ml of inoculum size and is incubated at 30 °C for 9 days, was suitable for the production of EPSs from Fusarium nygamai strain AJTYC1 by using static conditions. Fourier transform infrared (FT-IR) was employed in the characterization of EPSs, which exhibited the presence of carboxyl groups, hydroxyl groups, carbonyl groups, and glycosidic bonds. High-performance liquid chromatography (HPLC) detected that EPSs consist of sucrose and glucose. The scavenging activity indicates that EPSs have good antioxidant activity. The partially purified exopolysaccharides produced from F. nygamai strain AJTYC1 exhibited excellent antioxidant and antimicrobial activity against gram positive, gram negative and fungal strains. The EPSs at a dose of 1000 µg/ml exhibited anticancer activity against colorectal colon cancer (HCT116), breast cancer (MCF7), and hepatocellular cancer cell lines. Moreover, EPSs is an effective emulsifier of a variety of vegetable oils, and the emulsion it produces is generally stable for up to 168 h.

CONCLUSIONS

The production of EPSs from F. nygamai strain AJTYC1 can be used as antioxidants, antimicrobials, anticancer, and emulsifiers.

Extraction and application of extracellular polymeric substances from fungi

Extracellular polymeric substances (EPS) are extracellular metabolites of microorganisms, highly associated with microbial function, adaptation, and growth. The main compounds in EPS have been revealed to be proteins, polysaccharides, nucleic acids, humic substances, lipids, etc. EPS are not only biomass, but also a biogenic material. EPS have high specific surface, abundant functional groups, and excellent degradability. In addition, they are more extensible to the environment than the microbial cells themselves, which exhibits their huge advantages. Therefore, they have been applied in many fields, such as the environment, ecosystem, basic commodities, and medicine. However, the functions of EPS highly depend on the suitable extraction process, as different extraction methods have different effects on their composition, structure, and function. There are many types of EPS extraction methods, in which physical and chemical methods have been widely utilized. This review summarizes the extraction methods and applications of EPS. In addition, it considers some important gaps in current knowledge, and indicates perspectives of EPS for their future study.

Biotech Application of Exopolysaccharides from Curvularia brachyspora: Optimization of Production, Structural Characterization, and Biological Activity

C. brachyspora, a widespread dematiaceous fungus, was evaluated in this study to optimize the production of exopolysaccharides (CB-EPS). Optimization was performed using response surface methodology, and the best production yielded 75.05% of total sugar at pH 7.4, with 0.1% urea, after 197 h. The obtained CB-EPS showed typical signals of polysaccharides, which was confirmed by FT-IR and NMR. The HPSEC analysis indicated a polydisperse polymer, showing a non-uniform peak, with an average molar mass (M_w) of 24,470 g/mol. The major monosaccharide was glucose (63.9 Mol%), followed by mannose (19.7 Mol%), and galactose (16.4 Mol%). Methylation analysis encountered derivatives that indicated the presence of a β-d-glucan and a highly branched glucogalactomannan. CB-EPS was tested on murine macrophages to verify its immunoactivity, and the treated cells were able to produce TNF-α, IL-6, and IL-10. However, the cells did not produce superoxide anions or nitric oxide nor stimulated phagocytosis. The results demonstrated an indirect antimicrobial activity of macrophages by stimulating cytokines, showing another biotech applicability for the exopolysaccharides produced by C. brachyspora.

Drought alleviation efficacy of a galactose rich polysaccharide isolated from endophytic Mucor sp. HELF2: A case study on rice plant

Endophytes play a vital role in plant growth under biotic and abiotic stress conditions. In the present investigation, a Galactose-Rich Heteropolysaccharide (GRH) with a molecular weight of 2.98 × 105 Da was isolated from endophytic Mucor sp. HELF2, a symbiont of the East Indian screw tree Helicteres isora. OVAT (One Variable at A Time) experiment coupled with RSM (Response Surface Methodology) study exhibited 1.5-fold enhanced GRH production (20.10 g L-1) in supplemented potato dextrose broth at a pH of 7.05 after 7.5 days of fermentation in 26°C. GRH has alleviated drought stress (polyethylene glycol induced) in rice seedlings (Oryza sativa ssp. indica MTU 7093 swarna) by improving its physicochemical parameters. It has been revealed that spray with a 50-ppm dosage of GRH exhibited an improvement of 1.58, 2.38, 3, and 4 times in relative water contents and fresh weight of the tissues, root length, and shoot length of the rice seedlings, respectively "in comparison to the control". Moreover, the soluble sugars, prolines, and chlorophyll contents of the treated rice seedlings were increased upto 3.5 (0.7 ± 0.05 mg/g fresh weight), 3.89 (0.57 ± 0.03 mg/g fresh weight), and 2.32 (1,119 ± 70.8 μg/gm of fresh weight) fold respectively, whereas malondialdehyde contents decreased up to 6 times. The enzymatic antioxidant parameters like peroxidase and superoxide dismutase and catalase activity of the 50 ppm GRH treated seedlings were found to be elevated 1.8 (720 ± 53 unit/gm/min fresh weight), 1.34 (75.34 ± 4.8 unit/gm/min fresh weight), and up to 3 (100 ppm treatment for catalase - 54.78 ± 2.91 unit/gm/min fresh weight) fold, respectively. In this context, the present outcomes contribute to the development of novel strategies to ameliorate drought stress and could fortify the agro-economy of India.

Potential functions and applications of diverse microbial exopolysaccharides in marine environments

Exopolysaccharides (EPSs) from microorganisms are essential harmless natural biopolymers used in applications including medications, nutraceuticals and functional foods, cosmetics, and insecticides. Several microbes can synthesize and excrete EPSs with chemical properties and structures that make them suitable for several important applications. Microbes secrete EPSs outside their cell walls, as slime or as a "jelly" into the extracellular medium. These EPS-producing microbes are ubiquitous and can be isolated from aquatic and terrestrial environments, such as freshwater, marine water, wastewater, and soils. They have also been isolated from extreme niches like hot springs, cold waters, halophilic environments, and salt marshes. Recently, microbial EPSs have attracted interest for their applications such as environmental bio-flocculants because they are degradable and nontoxic. However, further efforts are required for the cost-effective and industrial-scale commercial production of microbial EPSs. This review focuses on the exopolysaccharides obtained from several extremophilic microorganisms, their synthesis, and manufacturing optimization for better cost and productivity. We also explored their role and applications in interactions between several organisms.

Broad-Spectrum Antimicrobial Action of Cell-Free Culture Extracts and Volatile Organic Compounds Produced by Endophytic Fungi Curvularia Eragrostidis

Endophytes are the mutualistic microorganisms that reside within the host plant and promote plant growth in adverse conditions. Plants and their endophytes are engaged in a symbiotic relationship that enables endophytes to access bioactive genes of the ethnomedicinal plants, and, as a result, endophytes are constantly addressed in the sector of pharmaceuticals and agriculture for their multidomain bio-utility. The gradual increase of antimicrobial resistance can be effectively countered by the endophytic metabolites. In these circumstances, in the present investigation, endophytic Curvularia eragrostidis HelS1 was isolated from an ethnomedicinally valuable plant Helecteris isora from East India's forests. The secondary volatile and non-volatile metabolites are extracted from HelS1 and are found to be effective broad-spectrum antimicrobials. A total of 26 secondary metabolites (9 volatiles and 17 non-volatiles) are extracted from the isolate, which exhibits effective antibacterial [against six Gram-positive and seven Gram-negative pathogens with a minimum inhibitory concentrations (MIC) value ranging from 12.5 to 400 μg ml-1] and antifungal (against seven fungal plant pathogens) activity. The secondary metabolite production was optimised by one variable at a time technique coupled with the response surface methodology. The results revealed that there was a 34% increase in antibacterial activity in parameters with 6.87 g L-1 of fructose (as a carbon source), 3.79 g L-1 of peptone (as a nitrogen source), pH 6.75, and an inoculation period of 191.5 h for fermentation. The volatile metabolite production was also found to be optimum when the medium was supplemented with yeast extract and urea (0.2 g L-1) along with dextrose (40 g L-1). Amongst extracted volatile metabolites, 1-H-indene 1 methanol acetate, tetroquinone, N, N-diphenyl-2-nitro-thio benzamide, Trans 1, 2-diethyl-trans-2-decalinol, naphthalene, and azulene are found to be the most effective. Our investigation opens up opportunities in the sector of sustainable agriculture as well as the discovery of novel antimicrobials against dreadful phyto and human pathogens.

Bioactivity study and metabolic profiling of Colletotrichum alatae LCS1, an endophyte of club moss Lycopodium clavatum L

Endophytes are silent microbial partners of green plants that ensure hosts' survival in odd conditions. They are known as the factories of multipotent metabolites with diverse bioactivities beneficial to modern pharmaceuticals industry. Endophytic fungi have been screened from a variety of plants and it is the first-time endophytes of club moss is being studied for production of antibacterial and antioxidative compounds. The present study reveals that Lycopodium clavatum L. harbors a potent niche of bioactive endophytic fungi and Colletotrichum alatae LCS1 was the prime producer of antibacterial and antioxidative compounds among them. The minimum inhibitory and bactericidal concentrations of ethyl- acetate culture extract ranged from 15.62 to 250 μg/mL against four Gram negative and three Gram positive microorganisms including methicillin resistant Staphylococcus aureus (ATCC-33591). Bio-autogram based screening followed by Gas chromatographic analysis confirmed the occurrence of 17 bioactive compounds and α-bisabolol is known to be the prime one. Alfa bisabolol is a unique and versatile bioactive essential oil and facilitates variety of functions. Killing kinetics data along with leakage of macromolecules into extracellular environment supports the cidal activity of the antibacterial principles at MBC values. Isolate C. alatae LCS1 was optimized by one variable at a time system coupled with response surface methodology for broad spectrum antibacterial production. The organism yielded maximum response (22.66±0.894 mm of zone of inhibition against MRSA) in 250 mL Erlenmeyer flask containing 50 mL potato dextrose broth supplemented with (g/L) glucose, 7.53; yeast extract concentration, 0.47; NaCl, 0.10 with medium pH 6.46; after 134 hours of incubation at 26°C. Optimized fermentation parameters enhanced antibacterial activity up-to more than 50% than the pre-optimized one (10.33±0.57 mm). Endophytic LCS1 was also efficient in free radical scavenging tested by DPPH, ABTS, H2O2 and FRAP assay with an IC50 values of 23.38±5.32 to 82.873±6.479 μg/mL.

Production of Bioactive Compounds with Broad Spectrum Bactericidal Action, Bio-Film Inhibition and Antilarval Potential by the Secondary Metabolites of the Endophytic Fungus Cochliobolus sp. APS1 Isolated from the Indian Medicinal Herb Andrographis paniculata

Endophytes, being the co-evolution partners of green host plants, are factories of pharmaceutically valuable novel natural products. Cochliobolus sp. APS1, an endophyte of Andrographis paniculata (Green Chiretta), produces a plethora of natural bioactive compounds and the multipotent alkaloid Aziridine, 1-(2-aminoethyl)-, is the prime one among them. The isolate exhibited antibacterial, anti-biofilm, and antilarval potency. The MIC and MBC values of the ethyl-acetate culture extract ranged from 15.62 to 250 µg/mL against ten pathogenic microorganisms (including MRSA and VRSA). Killing kinetics data along with the leakage of macromolecules into the extracellular environment supports the cidal activity of the antibacterial principles. The broad spectrum antibacterial activity of Aziridine, 1-(2-aminoethyl)-, was optimized by a one-variable-at-a-time system coupled with response surface methodology, which led to a 45% enhancement of the antibacterial activity. The maximum response (22.81 ± 0.16 mm of zone of inhibition against MRSA) was marked in 250 mL Erlenmeyer flask containing 90 mL potato dextrose broth supplemented with (g%/L) glucose, 9.7; urea concentration, 0.74; with medium pH 6.48; after 8.76 days of incubation at 26 °C. APS1 strongly inhibited biofilm formation in the tested pathogenic microorganisms and acts as a larvicidal agent against the Dengue-vector Aedes aegypti. This is probably the first report of Aziridine, 1-(2-aminoethyl)-, from any endophytic source. Cochliobolus sp. APS1 possesses industrial importance for the production of bioactive alkaloids.

Different techniques for concentration of extracellular biopolymers with herbicidal activity produced by Phoma sp

The natural ability of microorganisms to secrete high levels of bioactive compounds make them attractive hosts for producing novel compounds. Microbial biopolymers have potential applications in most of the sectors of the world economy. According to the physicochemical properties, they present some advantages, such as biodegradability, reproducibility, and stability. Based on this context, the objective of this work was to evaluate different methods for concentration and characterisation of extracellular biopolymers produced by Phoma sp. Extracellular biopolymers were produced by submerged fermentation and were concentrated by hollow fibre membranes and by adsorption. The structural characterisation of purified biopolymers was determined by Fourier Transform Infrared spectroscopy. Phytotoxic effects were assessed through absorption assays in detached leaves of Cucumis sativus and evaluated on the seventh day after application. The surface tension was evaluated for each sample. Hollow-fibre microfiltration membrane presented a higher purification factor than hollow-fibre ultrafiltration membrane. Extracellular biopolymers were identified in the permeate and retentate fractions, but in higher concentration in the retentate fractions. The adsorption process was efficient for recovering more than 88% of extracellular biopolymers from cell-free fermented broth. The best performance was obtained by using silica and activated carbon as adsorbent, with a recovery higher than 93%. The herbicidal activity was proportional to the concentration of biopolymers and the results are very promising for future applications because a concentrated solution of biopolymers can increase weed control. Membrane processes can be used to develop a liquid formulation of bioherbicide, whereas adsorption can be used to develop a solid formula.

Concentration of exopolysaccharides produced by Fusarium fujikuroi and application of bioproduct as an effective bioherbicide

Exopolysaccharides are secondary metabolites produced by microorganisms and are a subject of research in many fields of science and industry due to some of their confirmed properties, especially in the pharmaceutical and agrochemical areas. In this context, the objectives of this work were to evaluate the potential of Fusarium fujikuroi for producing exopolysaccharides and to concentrate such compounds in order to increase the herbicidal activity. Exopolysaccharides were produced by submerged fermentation and different concentration methods (membranes, lyophilization, and evaporation) were evaluated. The phytotoxic effects were assessed through absorption assays in detached leaves of Cucumis sativus and evaluated on the seventh day after application. The surface tension was evaluated for each concentration method. The production of exopolysaccharides in the crude broth without concentration was 5.94 g/L. When using the lyophilization method, a maximum yield of exopolysaccharides of 10.64 g/L was obtained. The membranes also presented satisfactory results of exopolysaccharides: 9.60 g/L. The increase of bioherbicidal activity and the lower surface tension are proportionally related to the increase of the concentration of exopolysaccharides.

Application of microbial extracellular carbohydrate polymeric substances in food and allied industries

Extracellular polymeric substances (EPS) are biopolymers, composed of polysaccharides, nucleic acids, proteins and lipids, which possess unique functional properties. Despite significant strides made in chemical production processes for polymers, the niche occupied by exopolysaccharides produced by bacteria, yeast or algae is steadily growing in its importance. With the availability of modern tools, a lot of information has been generated on the physico-chemical and biological properties using spectrometric tools, while advanced microscopic techniques have provided valuable insights into the structural-functional aspects. The size of EPS generally ranges between 10 and 10,000 kDa. The wide spectra of applications of EPS as adhesives, stabilizer, gelling, suspending, thickening agent, and surfactants in food and pharmaceutical industries are observed. The health benefits of these EPS enable the improvement of dual function, added value, and green products. This review summarizes previous work on the structural composition, rheological and thermal behaviour, and biosynthetic pathways of EPS and bioprocesses developed for their production. This review also considers each of the above factors and presents the current knowledge on the importance and refinement of available downstream protocols and genetic engineering towards specific food applications, which can help to diversify their prospects in different food and allied industries.

Differences in Production, Composition, and Antioxidant Activities of Exopolymeric Substances (EPS) Obtained from Cultures of Endophytic Fusarium culmorum Strains with Different Effects on Cereals

Exopolymeric substances (EPS) can determine plant-microorganism interactions and have great potential as bioactive compounds. The different amounts of EPS obtained from cultures of three endophytic Fusarium culmorum strains with different aggressiveness-growth promoting (PGPF), deleterious (DRMO), and pathogenic towards cereal plants-depended on growth conditions. The EPS concentrations (under optimized culture conditions) were the lowest (0.2 g/L) in the PGPF, about three times higher in the DRMO, and five times higher in the pathogen culture. The EPS of these strains differed in the content of proteins, phenolic components, total sugars, glycosidic linkages, and sugar composition (glucose, mannose, galactose, and smaller quantities of arabinose, galactosamine, and glucosamine). The pathogen EPS exhibited the highest total sugar and mannose concentration. FTIR analysis confirmed the β configuration of the sugars. The EPS differed in the number and weight of polysaccharidic subfractions. The EPS of PGPF and DRMO had two subfractions and the pathogen EPS exhibited a subfraction with the lowest weight (5 kDa). The three EPS preparations (ethanol-precipitated EP, crude C, and proteolysed P) had antioxidant activity (particularly high for the EP-EPS soluble in high concentrations). The EP-EPS of the PGPF strain had the highest antioxidant activity, most likely associated with the highest content of phenolic compounds in this EPS.

Fermentation conditions optimization, purification, and antioxidant activity of exopolysaccharides obtained from the plant growth-promoting endophytic actinobacterium Glutamicibacter halophytocola KLBMP 5180

In this study, an endophytic actinobacterium Glutamicibacter halophytocola KLBMP 5180, was investigated for the production and antioxidant activity of exopolysaccharides (EPSs). First, the suitable fermentation time, temperature, inoculation volume, pH value, and the carbon and nitrogen sources for EPSs production were obtained using the one variable at a time method (OVAT). Then, a central composition design was used for fermentation conditions optimization to obtain the maximum EPS yield. The optimal medium and condition were as follows: 100 mL broth in 250 mL Erlenmeyer flasks, including 3.65 g/L maltose, 9.88 g/L malt extract, 3.40 g/L yeast extract, 1.41 g/L MnCl₂, pH 7.5, culture temperature 28 °C, and 200 rpm for 7 days, which increased the yield of EPSs to 2.89 g/L. Two purified EPSs, 5180EPS-1 (MW 58.9 kDa) and 5180EPS-2 (10.5 kDa), comprising rhamnose, galacturonic acid, glucose, glucuronic acid, xylose, and arabinose, were obtained for chemical analysis and antioxidant evaluation. The scavenging ability and reducing power of the superoxide anion and hydroxyl radicals demonstrated the moderate in vitro antioxidant activities of the two EPSs, thus indicating their potential to be a new source of natural antioxidants. However, further structure elucidation and functional studies need to be continued.

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.

Chemical characterization and antioxidant properties of exopolysaccharides from mangrove filamentous fungi Fusarium equiseti ANP2

A filamentous fungi F. equiseti strain ANP2 with good exopolysaccharide (EPS) yield, apparent viscosity was screened and isolated from Krishna estuarine mangrove sediments. Based on molecular characteristics the selected strain was confirmed as F. equiseti, yielded EPS (4.9 ± 0.25 g/L) and whole cell biomass (3.5 ± 0.2 g/L) in MSM during early stationary phase. The crude EPS was purified by chromatography of Q-Sepharose and Superdex-75, affording Ms and MF-1 fractions were obtained, respectively. Chemical analyses revealed that EPS is primarily composed of neutral sugars and proteins. FTIR-spectroscopy revealed presence of hydroxyl, carbonyl groups and glycosidic bonds which correspond to typical heteropolysaccharide. GC analysis demonstrated that MF-1 mainly consist of mannose (72.6%) and glucose (27.3%). Viscosity studies exhibited typical non-Newtonian pseudoplastic behaviour with high viscosity. The scavenging ability on hydroxyl radicals, indicate that MF-1-EPS has good antioxidant activity. Current study demonstrated that MF-1 differed from previously characterized Fusarium sp., and can serve as potential antioxidant.

Production of bioproducts by endophytic fungi: chemical ecology, biotechnological applications, bottlenecks, and solutions

Endophytes are microorganisms that colonize the interior of host plants without causing apparent disease. They have been widely studied for their ability to modulate relationships between plants and biotic/abiotic stresses, often producing valuable secondary metabolites that can affect host physiology. Owing to the advantages of microbial fermentation over plant/cell cultivation and chemical synthesis, endophytic fungi have received significant attention as a mean for secondary metabolite production. This article summarizes currently reported results on plant-endophyte interaction hypotheses and highlights the biotechnological applications of endophytic fungi and their metabolites in agriculture, environment, biomedicine, energy, and biocatalysts. Current bottlenecks in industrial development and commercial applications as well as possible solutions are also discussed.

Yield enhancement strategies of rare pharmaceutical metabolites from endophytes

Endophytes are barely untapped as vital sources in the medicine. They are microorganisms which mostly exist in plants. As they are exploited, it is accepted that endophytes can produce active metabolites that possess same function as their hosts such as taxol, podophyllotoxin, hypericin, and azadirachtin. These metabolites have been promising potential usefulness in safety and human health concerns. We are supposed to adopt measures to raise production for the low yield of metabolites. This paper summarizes the latest advances in various bioprocess optimization strategies. These techniques can overcome the limitations associated with rare pharmaceutical metabolite-producing endophytic fungi. These strategies include strain improvement, genome shuffling, medium optimization, fermentation conditions optimization, addition of specific factor, addition of solid sorbent, and co-culturing. It will enable endophytes to produce high and sustainable production of rare pharmaceutical metabolites.

β-(1→6)-D-glucan secreted during the optimised production of exopolysaccharides by Paecilomyces variotii has immunostimulatory activity

Paecilomyces variotii is a filamentous fungus that occurs worldwide in soil and decaying vegetation. Optimization of the fermentation process for exopolysaccharide (EPS) production from the fungus P. variotii, structure determination and immuno-stimulating activity of EPS were performed. Response surface methodology (RSM) coupled with central composite design (CCD) was used to optimize the physical and chemical factors required to produce EPS in submerged fermentation. Preliminary investigations to choose the three factors for the present work were made using a factorial experimental design. Glucose, ammonium nitrate (NH₄NO₃) and pH were used as variables for which, with constant temperature of 28 °C and agitation of 90 rpm, the optimal process parameters were determined as glucose values of 0.96%, NH₄NO₃ 0.26% and pH 8.0. The three parameters presented significant effects. In this condition of culture, the main composition of the isolated EPS was a linear β-(1 → 6)-linked-D-glucan, as determined by Nuclear Magnetic Resonance (NMR) and methylation analysis. This polysaccharide is a very unusual as an EPS from fungi, especially a filamentous fungus such as P. variotii. Murine peritoneal macrophages cultivated with β-glucan for 6 and 48 h showed an increase in TNF-α, IL-6 and nitric oxide release with increased polysaccharide concentrations. Therefore, we conclude that the β-(1 → 6)-linked-D-glucan produced in optimised conditions of P. variotii cultivation has an immune-stimulatory activity on murine macrophages.

Immunomodulatory Properties of Filamentous Fungi Cultivated through Solid-State Fermentation on Rapeseed Meal

Water extracts from solid-state fermentation (SSF) on rapeseed meal using filamentous fungi exhibit interesting immunomodulatory activities in vitro. Immunomodulation was determined by the capacity of the compounds to activate blood neutrophils and to influence cytokine production in human peripheral blood mononuclear cells (PBMC) and mouse bone marrow-derived macrophages (BMDM). Among the strains tested, Aspergillus sojae mycelium and SSF extracts were the most promising in terms of enhancing the immune response. The filamentous fungus was also successfully cultivated in a pre-pilot bioreactor with forced aeration. The results indicated that the extracts not only activated blood neutrophils but also significantly modulated IL-1β cytokine levels with lipopolysaccharide (LPS)-stimulated PBMC and BMDM without any cytotoxicity in immune cells. IL-1β was down-regulated in a dose-dependent manner in the presence of A. sojae crude mycelium and SSF extract with PBMC, which indicated that there was an anti-inflammatory activity, whereas IL-1β secretion was up-regulated in the presence of stimulated BMDM with the highest concentration that was tested (100 μg/mL). The non-fermented rapeseed had no effect at the same concentration. SSF culture, as a natural product, may be a good source for the development of functional feed with an immunostimulating effect or could potentially be used in medicinal applications.

Multi-Response Optimization of Granaticinic Acid Production by Endophytic Streptomyces thermoviolaceus NT1, Using Response Surface Methodology

Streptomyces thermoviolaceus NT1, an endophytic isolate, was studied for optimization of granaticinic acid production. It is an antimicrobial metabolite active against even drug resistant bacteria. Different media, optimum glucose concentration, initial media pH, incubation temperature, incubation period, and inoculum size were among the selected parameters optimized in the one-variable-at-a-time (OVAT) approach, where glucose concentration, pH, and temperature were found to play a critical role in antibiotic production by this strain. Finally, the Box–Behnken experimental design (BBD) was employed with three key factors (selected after OVAT studies) for response surface methodological (RSM) analysis of this optimization study.RSM analysis revealed a multifactorial combination; glucose 0.38%, pH 7.02, and temperature 36.53 °C as the optimum conditions for maximum antimicrobial yield. Experimental verification of model analysis led to 3.30-fold (61.35 mg/L as compared to 18.64 mg/L produced in un-optimized condition) enhanced granaticinic acid production in ISP2 medium with 5% inoculum and a suitable incubation period of 10 days. So, the conjugated optimization study for maximum antibiotic production from Streptomyces thermoviolaceus NT1 was found to result in significantly higher yield, which might be exploited in industrial applications.

Extracellular polysaccharides from Ascomycota and Basidiomycota: production conditions, biochemical characteristics, and biological properties

Fungal polysaccharides (PSs) are the subject of research in many fields of science and industry. Many properties of PSs have already been confirmed and the list of postulated functions continues to grow. Fungal PSs are classified into different groups according to systematic affinity, structure (linear and branched), sugar composition (homo- and heteropolysaccharides), type of bonds between the monomers (β-(1 → 3), β-(1 → 6), and α-(1 → 3)) and their location in the cell (cell wall PSs, exoPSs, and endoPSs). Exopolysaccharides (EPSs) are most frequently studied fungal PSs but their definition, classification, and origin are still not clear and should be explained. Ascomycota and Basidiomycota fungi producing EPS have different ecological positions (saprotrophic and endophytic, pathogenic or symbiotic-mycorrhizae fungi); therefore, EPSs play different biological functions, for example in the protection against environmental stress factors and in interactions with other organisms. EPSs obtained from Ascomycota and Basidiomycota fungal cultures are known for their antioxidant, immunostimulating, antitumor, and antimicrobial properties. The major objective of the presented review article was to provide a detailed description of the state-of-the-art knowledge of the effectiveness of EPS production by filamentous and yeast Ascomycota and Basidiomycota fungi and techniques of derivation of EPSs, their biochemical characteristics, and biological properties allowing comprehensive analysis as well as indication of similarities and differences between these fungal groups. Understanding the role of EPSs in a variety of processes and their application in food or pharmaceutical industries requires improvement of the techniques of their derivation, purification, and characterization. The detailed analyses of data concerning the derivation and application of Ascomycota and Basidiomycota EPSs can facilitate development and trace the direction of application of these EPSs in different branches of industry, agriculture, and medicine.

Water soluble exo-polysaccharide from Syncephalastrum racemosum, a strong inducer of plant defence reactions

This study examines the production, characterization and bioactivity on plant cell cultured in vitro of exopolysaccharides (EPS) from Syncephalastrum racemosum CBS 443.59. Firstly, the influence of the fungus culture condition in shake flasks (pH, temperature and different carbon and nitrogen sources) on EPS and biomass production was evaluated. In order to enhance EPS production, a new protocol based on two-stage pH fermentation in a 3 L stirred fermentor was developed. Under this condition, EPS production increased by 3.55 times, compared to a constant pH process, reaching a maximal EPS concentration of 2.62 g/L. Structurally, the EPS contains a polyglucuronic acid backbone, linked essentially with mannose and fucose units and some galactose and glucose units. The bioactivity of EPS as inducer of defence reactions in plant suspension-cultured cells was also studied. Our results show, for first time, that EPS from S. racemosum CBS 443.59 induces, depending on the concentration, PAL activation and H2O2 synthesis in Arabidopsis thaliana cell suspensions.