Termitomyces clypeatus

Abstract: The manuscript describes removal of chromium from aqueous solution by biomass of different moulds and yeasts. The biomass of Termitomyces clypeatus (TCB) is found to be the most effective of all the fungal species tested. The sorption of hexavalent chromium by live TCB depends on the pH of the solution, the optimum pH value being 3.0. The process follows Langmuir isotherm (regression coefficient 0.998, χ2-square 5.03) model with uniform distribution over the surface which gets strong support from the X-ray elemental mapping of chromium adsorbed biomass. The amino, carboxyl, hydroxyl, and phosphate groups of the biomass are involved in chemical interaction with the chromate ion forming a cage like structure depicted by scanning electron microscopic (SEM) and Fourier transform infrared spectroscopic (FTIR) results. Desorption and FTIR studies also exhibited that Cr6+ is reduced to trivalent chromium on binding to the cell surface. The level of chromium concentration present in the effluent of tannery industries’ is reduced to a permissible limit using TCB as adsorbent.

Abstract: Mechanism of Cr(VI) biosorption by heat inactivated fungal biomass of Termitomyces clypeatus was studied by analyzing its pH profile and surface chemistry. The biosorption efficiency enhanced with acid pretreatment and reduced by alkali. The pretreatment with CaCl2 increased the biosorption capacity but decreased with NaCl. Surface chemistry was characterized by potentiometric titration pH of zero charge and SEM–EDX analysis. The acidic and basic sites for the biomass were quantified as 7.75 and 3.25 mmol/g, respectively, and concluded that surface of the biomass was acidic. Acidic [carboxyl (pKa 3.45 and 4.29), imidazole (pKa 5.98), and phosphate (pKa 6.75)] and alkaline [amines (pKa 9.96, 11.92, and 12.47), sulfhydryl (thiol) (pKa 8.48), hydroxyl (pKa 11.12)] functional groups were identified and confirmed by FTIR analysis. The roles played by functional groups in chromium biosorption were found to be in the order: carboxyl > phosphates > lipids > sulfhydryl > amines. Integrative analysis of surface chemistry, functional group modification and FTIR showed that the Cr(VI) biosorption involved more than one mechanism such as physical adsorption, ion exchange, complexation and electrostatic attraction and followed in two subsequent steps – Cr2O72− biosorption at the protonated active sites (amino, carboxyl and phosphate groups) and reduction of Cr(VI) to Cr(III) by reductive groups (hydroxyl and carbonyl groups) on the biomass surface.

Abstract: Fruit bodies and mycelia of various higher Basidiomycetes were studied in search of biological effector molecules. In this study, we evaluated the antiproliferative and immunomodulatory properties of a protein fraction designated as Cibacron blue affinity eluted protein (CBAEP) isolated from five different species of edible mushrooms ( Termitomyces clypeatus , Pleurotus florida , Calocybe indica , Astraeus hygrometricus , and Volvariella volvacea ). This protein fraction (10–100 μg/ml) mediated antiproliferative activity on several tumor cell lines through the induction of apoptosis. Also the isolated protein fraction from all five mushrooms had a stimulatory effect on splenocytes, thymocytes and bone marrow cells. Further it enhanced mouse natural killer (NK) cell cytotoxicity and stimulated macrophages to produce nitric oxide (NO). The highest immunostimulatory activity was determined in the CBAEP from T. clypeatus and the highest antiproliferative activity from C. indica .

Abstract: An intra-cellular beta-glucosidase was purified to homogeneity by gel filtration, ion exchange chromatography and HPGPLC from mycelial extract of Termitomyces clypeatus in the presence of the glycosylation inhibitor 2-deoxy-d-glucose. CD spectroscopy demonstrated that the purified enzyme exhibited alpha-helical conformation. MALDI-TOF identified the enzyme's molecular weight as 6688Daltons, but SDS-PAGE and immunoblotting indicated that the enzyme formed aggregates. The enzyme also showed unique properties of co-aggregation with sucrase in the fungus. The enzyme showed around 80% stability up to 60 degrees C and residual activity was 80-100% between pH ranges 5-8. The enzyme had higher specific activity against p-nitrophenyl-d-glucopyranoside than cellobiose and HPLC showed that the enzyme possesses transglycosylation activity and synthesizes cello-oligosaccharides by addition of glucose. The enzyme will be useful in synthetic biology to produce complex bioactive glycosides and to avoid chemical hazards. This is the first report of a beta-glucosidase enzyme with such a low monomeric unit size.

Abstract: Biosorption of Cr(+6) by Termitomyces clypeatus has been investigated involving kinetics, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopic (FTIR) studies. Kinetics experiments reveal that the uptake of chromium by live cell involves initial rapid surface binding followed by relatively slow intracellular accumulation. Of the different chromate analogues tested, only sulfate ion reduces the uptake of chromium to the extent of approximately 30% indicating chromate ions accumulation into the cytoplasm using sulfate transport system. Metabolic inhibitors, e.g. N,N'-dicyclohexylcarbodiimide, 2,4-ditrophenol and sodium azide inhibit chromate accumulation by approximately 30% in live cell. This indicates that accumulation of chromium into the cytoplasm occurs through the active transport system. TEM-EDXA analysis reveals that the chromium localizes in the cell wall and also in the cytoplasm. Reduction of chromate ions takes place by chromate reductase activity of cell-free extracts of T. clypeatus. FTIR study indicates that chromate ions accumulate into the cytoplasm and then reduced to less toxic Cr(+3) compounds.