Putative hydrophobins of black poplar mushroom (Agrocybe cylindracea).

Hydrophobin proteins were extracted from Agrocybe cylindracea mycelia, the culture media (potato dextrose broth, PDB), and fruiting bodies. The putative hydrophobins obtained showed approximate sizes ranging from 8.0 to 25.0 kDa, dependent on their source. Multiple hydrophobin protein bands were detected in fruiting bodies. The hydrophobin yielded from aerial mycelia, or fruiting bodies, was approximately 6 mg/g dried weight. The crude extracts were examined for their properties in regards to surface modification, emulsification, and surface activity. Coating of hydrophobic Teflon sheet with crude extract made the surface significantly hydrophilic, whereas exposure of glass surfaces to extracts resulted in enhanced hydrophobicity. Crude extracts from culture media of A. cylindracea displayed emulsifying activity when mixed with hexane and could significantly reduce the surface tension of 60% ethanol and deionised water. The putative hydrophobin protein band from culture media (9.6 kDa), as analysed using LC-MS/MS, contained an amino acid fragment structurally similar to class I hydrophobin proteins from Basidiomycetes.

Biodegradation of polycyclic aromatic hydrocarbons by a thermotolerant white rot fungus Trametes polyzona RYNF13.

The biodegradation of three polycyclic aromatic hydrocarbons (PAHs), phenanthrene, fluorene, and pyrene, by a newly isolated thermotolerant white rot fungal strain RYNF13 from Thailand, was investigated. The strain RYNF13 was identified as Trametes polyzona, based on an analysis of its internal transcribed spacer sequence. The strain RYNF13 was superior to most white rot fungi. The fungus showed excellent removal of PAHs at a high concentration of 100 mg·L-1. Complete degradation of phenanthrene in a mineral salt glucose medium culture was observed within 18 days of incubation at 30°C, whereas 90% of fluorene and 52% of pyrene were degraded under the same conditions. At a high temperature of 42°C, the strain RYNF13 was still able to grow, and degraded approximately 68% of phenanthrene, whereas 48% of fluorene and 30% of pyrene were degraded within 32 days. Thus, the strain RYNF13 is a potential fungus for PAH bioremediation, especially in a tropical environment where the temperature can be higher than 40°C. The strain RYNF13 secreted three different ligninolytic enzymes, manganese peroxidase, laccase, and lignin peroxidase, during PAH biodegradation at 30°C. When the incubation temperature was increased from 30°C to 37°C and 42°C, only two ligninolytic enzymes, manganese peroxidase and laccase, were detectable during the biodegradation. Manganese peroxidase was the major enzyme produced by the fungus. In the culture containing phenanthrene, manganese peroxidase showed the highest enzymatic activity at 179 U·mL-1. T. polyzona RYNF13 was determined as a potential thermotolerant white rot fungus, and suitable for application in the treatment of PAH-containing contaminants.

Investigation of damaged interior walls using synchrotron-based XPS and XANES.

Evidence of internal sulfate attack in field exposure was demonstrated by the damaged interior wall of a three-year-old house situated in Nakhon Ratchasima Province, Thailand. Partial distension of the mortar was clearly observed together with an expansion of a black substance. Removal of the black substance revealed a dense black layer. This layer was only found in the vicinity of the damaged area, suggesting that this black material is possibly involved in the wall cracking. By employing synchrotron-based X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) techniques, the unknown sample was chemically identified. The S 2p and O 1s XPS results mutually indicated the existence of sulfate species in the materials collected from the damaged area. The XANES results indicated the presence of ferrous (II) sulfate, confirming sulfate-induced expansion and cracking. The sulfate attack in the present case appeared to physically affect the structure whereas the chemical integrity at the molecular level of the calcium silicate hydrate phase was retained since there was a lack of spectroscopic evidence for calcium sulfate. It was speculated that internal sulfate probably originated from the contaminated aggregates used during the construction. The current findings would be beneficial for understanding the sulfate-attack mechanism as well as for future prevention against sulfate attack during construction.

Mesoscale crystallization of calcium phosphate nanostructures in protein (casein) micelles.

Aqueous micelles of the multi-protein calcium phosphate complex, casein, were treated at 60°C and pH 7 over several months. Although partial dissociation of the micelles into 12 nm sized amorphous calcium phosphate (ACP)/protein nanoparticles occurred within a period of 14 days, crystallization of the ACP nanoclusters into bundles of hydroxyapatite (HAP) nanofilaments was not observed until after 12 weeks. The HAP nanofilaments were formed specifically within the partially disrupted protein micelles suggesting a micelle-mediated pathway of mesoscale crystallization. Similar experiments using ACP-containing synthetic micelles prepared from ß-casein protein alone indicated that co-aligned bundles of HAP nanofilaments were produced within the protein micelle interior after 24 hours at temperatures as low as 35°C. The presence of Mg²(+) ions in the casein micelles, as well as a possible synergistic effect associated with the multi-protein nature of the native aggregates, could account for the marked inhibition in mesoscale crystallization observed in the casein micelles compared with the single-component b-casein constructs.

Photodegradation of phenanthrene by N-doped TiO2 photocatalyst.

The photodegradation of phenanthrene has been catalyzed by nanostructures of TiO2 doped with nitrogen, N-doped TiO2. The N-doped TiO2 was prepared from the sol-gel reaction of Titanium(IV) bis(ethyl acetoacetato)diisopropoxide with 25% ammonia solution. The N-doped TiO2 was calcined at various temperatures from 300 to 700 degrees C. X-ray diffraction (XRD) results showed that N-doped TiO2 remained amorphous at 300 degrees C but anatase-to-rutile transformation started at 400 degrees C and was complete at 700 degrees C. The average particle size calculated from Scherrer's equation was in the range of 9-51 nm with surface area (S(BET)) of 253.7-4.8 m2/g. X-ray photoelectron spectroscopy (XPS) results confirmed the incorporation of nitrogen atoms (Ti-N bond) in the N-doped catalyst. Moreover, the percentage of nitrogen determined by Elemental analysis was 0.236% of N-doped calcined at 400 degrees C. UV-Vis reflection spectra indicated that N-doped TiO2 calcined at 400 degrees C shifted to the higher absorption edge in the range of visible light. N-doped TiO2 calcined at 400 degrees C successfully catalyzed the photodegradation of phenanthrene (80% conversion) whereas N-doped TiO2 calcined at 500 degrees C and P25 TiO2 failed as catalysts.

Immobilisation and encapsulation of functional protein-inorganic constructs.

Self-assembly methods for the immobilisation or encapsulation of the positively charged redox protein, cytochrome c (cyt c), in layered organoclays or silica nanoparticles, respectively, are described and contrasted. Protein-polymer-organoclay nanocomposites are produced by spontaneous restacking of delaminated aminopropyl-functionalised magnesium phyllosilicate sheets in the presence of an aqueous solution of poly(sodium 4-styrene sulfonate) (PSS) and cyt c. In contrast, single molecules of cyt c are encapsulated in silica nanoparticles by sol-gel reactions at the oil-water interface of microemulsion water droplets. In both cases, the protein molecules remain structurally intact after entrapment, are accessible to small molecule redox agents, exhibit excellent peroxidase activity in the presence of hydrogen peroxide, and show enhanced stability and catalytic properties under adverse conditions of pH. The ability to prepare functional protein-inorganic conjugates in general could significantly extend the technological scope of biological products and processes, and should therefore be an important adjunct in the translation of synthetic biology to real-life applications.