Subhadip Mahapatra

Fungal Exopolysaccharide: Production, Composition and Applications

Fungal exopolysaccharides (EPSs) have been recognized as high value biomacromolecules for the last two decades. These products, including pullulan, scleroglucan, and botryosphaeran, have several applications in industries, pharmaceuticals, medicine, foods etc. Although fungal EPSs are highly relevant, to date information concerning fungal biosynthesis is scarce and an extensive search for new fugal species that can produce novel EPSs is still needed. In most cases, the molecular weight variations and sugar compositions of fungal EPSs are dependent to culture medium composition and different physical conditions provided during fermentation. An inclusive and illustrative review on fungal EPS is presented here. The general outline of the present work includes fungal EPS production, their compositions and applications. An emphasis is also given to listing out different fungal strains that can produce EPSs.

Fungal endophytes in three medicinal plants of Lamiaceae.

Three medicinal plants Ocimum sanctum, Ocimum bacilicum and Leucas aspera were screened to study endophytic diversity of the plants. Altogether 103 fungal endophytes belonging to fourteen genera were isolated. Leaves of all three medicinal plants were colonized by a great number of endophytic fungi. Leaves of O. sanctum were colonized by the most, that is, eleven endophytes. Highest Shannon-Wiener index (2.256) was exhibited by O. sanctum with the highest Simpsons diversity (0.8654) indicating great species specificity. O. bacilicum and L. aspera showed the highest similarity coefficient. Some fungal genera have been showed to be host specific. In the present study Curvularia sp., Hymenula sp., Tricoderma sp. and Tubercularia sp. exclusively colonized O. sanctum ; whereas Alternaria sp. and Spicaria sp. colonized only L. aspera .

Structural elucidation and bioactivity of a novel exopolysaccharide from endophytic Fusarium solani SD5

A bioactive exopolysaccharide [EPS (PS-I)], having Mw∼1.87×10(5) Da was produced by submerged culture of an endophytic fungus Fusarium solani SD5. Structural elucidation of the EPS (PS-I) was carried out by a series of experiments. Result indicates the presence of terminal α-L-rhamnopyranosyl, (1→2)-α-L-rhamnopyranosyl, (1→4)-β-D-galactopyranosyl, (1→4,6)-β-D-galactopyranosyl moieties in a molar ratio of nearly 1:1:3:1. TEM image showed fibril structure of the EPS with a diameter of approximately 1 nm. Melting point range of the EPS was found 172-178 °C. The isolated PS-I exhibit in vitro anti inflammatory and anti allergic activity. EPS (1000 μg/ml) protects 55% erythrocytes from hypotonic solution induced membrane lysis. Compound 48/80 induced mast cell degranulation was also protected by 56% with 100 μg/ml EPS.

Evaluation of in vitro antioxidant potency of exopolysaccharide from endophytic Fusarium solani SD5.

A potent endophytic fungus, Fusarium solani SD5 was used for exopolysaccharide (EPS) production. The isolated EPS were purified and major EPS fraction (PS-I); rhamno galactan was used to evaluate anti oxidant activities in vitro. EPS (PS-I) showed significant free radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl) and scavenging potency is indicated by IC(50) value 578.541 ± 33.256 μg/ml. EPS (PS-I) significantly induced antioxidant parameters of peritoneal macrophage cells at a concentration dependent manner and at 500 μg/ml it showed maximum protective effect against free radicals [malondialdehyde (MDA) 0.178 ± 0.015; super oxide dismutase (SOD) 41.287 ± 1.051; glutathione peroxidase (GPx) 30.182 ± 1.237; reduced glutathione (GSH) 56.892 ± 1.272; oxidized glutathione (GSSG) 8.458 ± 0.768]. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide] cytotoxicity assay indicated that EPS (PS-I) had no significant cytotoxic effect (concentration up to 500 μg/ml) on macrophage cells. Present findings suggested that the EPS (PS-I) may become a potential nontoxic exogenous antioxidant.

Optimization of a bioactive exopolysaccharide production from endophytic Fusarium solani SD5

Endophytic fungi were less investigated for exopolysaccharide production. In this study endophytic Fusarium solani SD5 was used for optimization of exopolysaccharide production. One variable at a time method and response surface methodology were employed to explore the optimum medium compositions and fermentation conditions. The organism produced maximum exopolysaccharide after 13.68 days of incubation at 28 °C in potato dextrose broth supplemented with (g%/l) glucose, 9.8; yeast extract, 0.69; KCl, 0.05; KH₂PO₄, 0.05 with medium pH 6.46. Use of 50 ml medium in 250 ml Erlenmeyer flask gives highest exopolysaccharide production. The organism produced more than two times higher exopolysaccharide (2.276 ± 0.032 g/l EPS) at optimized condition compared to pre-optimized condition (0.96 ± 0.021). In vivo toxicity test established nontoxic nature of the EPS (≤400 mg EPS/Kg of body weight). The EPS slightly altered intestinal indigenous bacteria and influenced the growth of beneficial Lactobacillus spp.

Diversity and screening for antimicrobial activity of endophytic fungi from Alstonia scholaris

Endophytic fungi of three tissues (petiole, bark and leaf) of Alstonia scholaris were assessed. A total number of 1,152 endophytic fungi were isolated from 1,002 different plant segments of seven different localities of Paschim Medinipur, West Bengal, India. The isolated fungi belong to nineteen genera, including four unidentified fungi and yeast. Colletotrichum sp. (20.39%) and Sordaria sp. (29.68%) were most commonly isolated from this plant. Hyalopus sp., Fusarium sp. and Curvularia sp. were also isolated. The colonization frequency of endophytic fungi is much higher in leaves (44.66%) in comparison to petioles (32.16%) and barks (23.17%). The study provided evidence for tissue specificity of endophytic fungi. The endophytic fungal species diversity was higher in plant segments collected from Gopegarh and Khoirullahchak, while diversity was the lowest in Rice mill area. Screenings of antimicrobial activity of these isolated endophytic fungi were done. Eight endophytic fungi showed antimicrobial activity. Among them Curvularia sp., Aspergillus sp. and one unidentified fungus showed maximum activity against test pathogens.

Production and structural elucidation of exopolysaccharide from endophytic Pestalotiopsis sp. BC55

There is a little information on exopolysaccharide production by endophytic fungi. In this investigation endophytic Pestalotiopsis sp. BC55 was used for optimization of exopolysaccharide production. One variable at a time method and response surface methodology were adopted to find out the best culture conditions and medium compositions for maximum exopolysaccharide production. The organism produced maximum exopolysaccharide (4.320 ± 0.022 g/l EPS) in 250 ml Erlenmeyer flask containing 75 ml potato dextrose broth supplemented with (g%/l) glucose, 7.66; urea, 0.29; CaCl2, 0.05 with medium pH 6.93; after 3.76 days of incubation at 24°C. Exopolysaccharide [EPS (EP-I)] produced by this organism have Mw ∼2×10(5)Da with a melting point range of 122-124°C. Structural elucidation of the EPS (PS-I) was carried out after a series of experiments. Result indicated the presence of only (1→3)-linked β-d-glucopyranosyl moiety. The structure of the repeating unit was established as - →3)-β-d-Glcp-(1→.

Effects of Standardized Wrightia tinctoria and Stereospermum suaveolens Extracts on Various Immuno-Inflammatory Parameters

Effects of standardized Wrightia tinctoria seeds extract (WTSE) and Stereospermum suaveolens root extract (SSRE) on erythrocyte membrane stabilization, mast cell protection, nitric oxide, and pro-inflammatory cytokines production were evaluated by in vitro methods. WTSE and SSRE were standardized against chlorogenic acid and lapachol, respectively, using reverse-phase high-performance liquid chromatography. Standardized WTSE and SSRE inhibited erythrocyte membrane lysis, mast cell degranulation, and LPS-stimulated nitric oxide and pro-inflammatory cytokine (IL-β, IL-6 and TNF-α) production by RAW 264.7 macrophage cells in a dose-dependent manner.