Fungus Flammulina Velutipes Research Articles

Biosorption of cadmium(II) and lead(II) from aqueous solutions by fruiting body waste of fungus Flammulina velutipes

The biosorption of Cd2+ and Pb2+ by fruiting body wastes of macrofungi Flammulina velutipes was studied. The factors affecting absorbtion including pH, initial metal concentration, biosorbent dosages and mutual competitive biosorption of both metal ions were focused. The sorption of Cd2+ and Pb2+ was increased with pH value from 2 to 6 and maximum biosorption was at pH 6. The quantity of Cd2+ and Pb2+ adsorbed increased with the initial concentration of metal ions and both metals removal gradually increased with the biosorbent dosage. There existed mutual competitive biosorption between Cd2+ and Pb2+ when they were in the same solution. The Langmuir isotherm model fitted both metal ions sorption data well in the experiment and the calculated maximum sorption capacity of Cd2+ and Pb2+ by F. velutipes was 8.4317 mg/g dry biomass with R 2 of 0.9228 and 18.3486 mg/g dry biomass with R 2 of 0.9280, respectively. Pseudo-first order equation fitted for adsorption data of Cd2+ with R 2 of 0.9504, while pseudo-second order equation more fitted for adsorption data of Pb2+ with R 2 of 0.9917.

Sphingolipid synthesis inhibitors affect growth, morphology and metabolism of basidial fungus Flammulina velutipes

Sphingolipid synthesis inhibitors affect growth, morphology and metabolism of basidial fungus Flammulina velutipes

Alterations in the composition of membrane glycero-and sphingolipids in the course of Flammulina velutipes surface culture development

Qualitative and quantitative characteristics of the alterations in the lipid composition of the membrane of the basidial fungus Flammulina velutipes in the course of surface culture development were investigated. Modifications of the lipid composition were shown to be timed to specific ontogeny stages, such as changes in the growth rate of the colonies, the appearance of differentiated vegetative cells, and the formation of generative structures. A slowdown of growth correlated with an alteration in the ratio of major classes of phospholipids, namely, with a decrease of phosphatidylcholine relative content and an increase in phosphatidylethanolamines. The differentiation of vegetative cells of the mycelium proceeded along with modifications of molecular composition of glycoceramides. In the course of the first week of growth, the surface culture of F. velutipes produced monohexosylceramides with epoxidized methyl sphingadienine as a sphingoid base. Later on, along with culture growth and specialization of mycelium cells, molecular species with methyl sphingadienine, common for basidiomycetes, start to prevail among the fungal glycoceramides. The formation of fruit bodies is accompanied by enrichment of molecules of phospholipids, mainly, the phosphatidylcholines, with unsaturated fatty acids.

Active site geometry of oxalate decarboxylase from Flammulina velutipes: Role of histidine-coordinated manganese in substrate recognition.

Oxalate decarboxylase (OXDC) from the wood-rotting fungus Flammulina velutipes, which catalyzes the conversion of oxalate to formic acid and CO(2) in a single-step reaction, is a duplicated double-domain germin family enzyme. It has agricultural as well as therapeutic importance. We reported earlier the purification and molecular cloning of OXDC. Knowledge-based modeling of the enzyme reveals a beta-barrel core in each of the two domains organized in the hexameric state. A cluster of three histidines suitably juxtaposed to coordinate a divalent metal ion exists in both the domains. Involvement of the two histidine clusters in the catalytic mechanism of the enzyme, possibly through coordination of a metal cofactor, has been hypothesized because all histidine knockout mutants showed total loss of decarboxylase activity. The atomic absorption spectroscopy analysis showed that OXDC contains Mn(2+) at up to 2.5 atoms per subunit. Docking of the oxalate in the active site indicates a similar electrostatic environment around the substrate-binding site in the two domains. We suggest that the histidine coordinated manganese is critical for substrate recognition and is directly involved in the catalysis of the enzyme.

Basidiomycetous fungus Flammulina velutipes harbors two linear mitochondrial plasmids encoding DNA and RNA polymerases

Basidiomycetous fungus Flammulina velutipes R15 strain had two linear plasmids in its mitochondria designated pFV1 and pFV2. They were double-stranded DNAs, whose sizes were 8.3 and 8.9 kb, respectively. Sequencing analysis of 7364 bases of the pFV1 and 6861 bases of the pFV2 revealed that the both plasmids had one set of two open reading frames (ORFs) each of that encoded putative DNA and RNA polymerases similar to those of mitochondrial plasmids in other filamentous fungi. In phylogenetic analysis of deduced amino acid sequences of the ORFs and counterparts of other filamentous fungi, the pFV2 was expectedly clustered with plasmids of basidiomycetous fungi, whereas the pFV1 with kalilo plasmid of ascomycetous fungus Neurospora intermedia.

Basidiomycetous fungus Flammulina velutipes harbors two linear mitochondrial plasmids encoding DNA and RNA polymerases.

Basidiomycetous fungus Flammulina velutipes R15 strain had two linear plasmids in its mitochondria designated pFV1 and pFV2. They were double-stranded DNAs, whose sizes were 8.3 and 8.9 kb, respectively. Sequencing analysis of 7364 bases of the pFV1 and 6861 bases of the pFV2 revealed that the both plasmids had one set of two open reading frames (ORFs) each of that encoded putative DNA and RNA polymerases similar to those of mitochondrial plasmids in other filamentous fungi. In phylogenetic analysis of deduced amino acid sequences of the ORFs and counterparts of other filamentous fungi, the pFV2 was expectedly clustered with plasmids of basidiomycetous fungi. whereas the pFV1 with kalilo plasmid of ascomycetous fungus Neurospora intermedia.

Gel formation of lignin and biodegradation of the lignin gels by microorganisms

The multifunctional, polyphenolic nature of isolated lignins invites practical applications in which lignin serves as the principal component of cross-linked network polymers. Unmodified kraft lignin was first condensated with phenols and then further condensated with resorcinol under alkaline conditions, to give lignin–phenol–resorcinol resin (LPR resin). Lignin gels were prepared from the methanol-diluted LPR resin with the use of organic cross-linking agent glutaraldehyde (GA) via reacting for 3 days at 25°C. The gel formation depended on the amounts of methanol, and not the amounts of GA. The lignin gel obtained exhibited a reversible expansion–contraction behavior when it was alternatively immersed in ethanol and in water. Degradation of cross-linked LPR–GA hydrogels by some microorganisms has been investigated. From the experimental results, the following findings were obtained. The lignin–GA gels are degraded by the four Basidiomycotia fungi examined. The most effective degradation of the lignin–GA gels was obtained with the fungus Flammulina velutipes. The present biodegradation results by wood-rotting fungi might give some clues as to future biotechnology of cross-linked lignin and lignin hydrogels.