iTRAQ-based proteomic profiling of Pycnoporus sanguineus in response to co-existed tetrabromobisphenol A (TBBPA) and hexavalent chromium.

In current study, we investigated the changes of proteome profiles of Pycnoporus sanguineus after a single exposure of Cr(VI), TBBPA and a combined exposure of TBBPA and Cr(VI), with the goal of illuminating the cellular mechanisms involved in the interactions of co-existed TBBPA and Cr(VI) with the cells of P. sanguineus at the protein level. The results revealed that some ATP-binding cassette (ABC) transporters were obviously induced by these pollutants to accelerate the transportation, transformation and detoxification of TBBPA and Cr(VI). Cr(VI) could inhibit the bioremoval of its organic co-pollutants TBBPA through suppressing the expression of several key proteins related to the metabolism of TBBPA by P. sanguineus, including two cytochrome P450s, pentachlorophenol 4-monooxygenase and glutathione S-transferases. Furthermore, Cr(VI) possibly reduced the cell vitality and growth of P. sanguineus by enhancing the expression of imidazole glycerol phosphate synthase as well as by decreasing the abundances of proteins associated with the intracellular metabolic processes, such as the tricarboxylic acid cycle, purine metabolism and glutathione biosynthesis, thereby adversely affecting the biotransformation of TBBPA. Cr(VI) also inhibited the expression of peptidyl prolyl cis/trans isomerases, thus causing the damage of cell membrane integrity. In addition, some important proteins participated in the resistance to Cr(VI) toxicity were observed to up-regulate, including heat shock proteins, 26S proteasome, peroxiredoxins and three critical proteins implicated in S-adenosyl methionine synthesis, which contributed to reducing the hazard of Cr(VI) to P. sanguineus. The results of this study provide novel insights into the physiological responses and molecular mechanism of white rot fungi P. sanguineus to the stress of concomitant TBBPA and Cr(VI).

Tannic extract potential as natural wood preservative of Acacia mearnsii.

High toxicity of the preservatives most frequently used in wood treatment and the resulting risks of handling pose a threat to small producers and to the environment. In an attempt to mitigate these problems, the present study was conducted with the objective of evaluating the preservative effect of tannic extract on biodeterioration of Acacia mearnsii wood. For this purpose, untreated and preserved specimens, some with tannin extract and some with a preservative mixture based on CCB (Chromated Copper Borate), were submitted to accelerated rotting trials with the fungus that causes white rot (Pycnoporus sanguineus) for 16 weeks. The evaluations were made with a basis on weight loss and chemical components analysis, and they showed that the natural resistance of Acacia wood is moderate when exposed to the white rot fungus. The tannin concentrations showed similar effects to those of the CBB mixture in all evaluations, i.e., they significantly increased the biological resistance of the material, which started to be classified as very resistant to the fungus. Overall, the results suggest that tannin can be considered as a potential natural preservative product.

Tannic extract potential as natural wood preservative of Acacia mearnsii

ABSTRACT High toxicity of the preservatives most frequently used in wood treatment and the resulting risks of handling pose a threat to small producers and to the environment. In an attempt to mitigate these problems, the present study was conducted with the objective of evaluating the preservative effect of tannic extract on biodeterioration of Acacia mearnsii wood. For this purpose, untreated and preserved specimens, some with tannin extract and some with a preservative mixture based on CCB (Chromated Copper Borate), were submitted to accelerated rotting trials with the fungus that causes white rot (Pycnoporus sanguineus) for 16 weeks. The evaluations were made with a basis on weight loss and chemical components analysis, and they showed that the natural resistance of Acacia wood is moderate when exposed to the white rot fungus. The tannin concentrations showed similar effects to those of the CBB mixture in all evaluations, i.e., they significantly increased the biological resistance of the material, which started to be classified as very resistant to the fungus. Overall, the results suggest that tannin can be considered as a potential natural preservative product.

Hexavalent chromium induced oxidative stress and apoptosis in Pycnoporus sanguineus.

White rot fungi have been proved to be a promising option for the removal of heavy metals, understanding their toxic response to heavy metals is conducive to developing and popularizing fungi-based remediation technologies so as to lessen the hazard of heavy metals. In this study, Cr(VI)-induced oxidative stress and apoptosis in Pycnoporus sanguineus, a species of white rot fungi were investigated. The results suggested that high level of Cr(VI) promoted the formation of ROS, including H2O2, O2•- and ·OH. With the increment of Cr(VI) concentration, the SOD and CAT activity along with GSH content increased within the first 24 h, but decreased afterward, companied with a significant enhancement of MDA content. Cr(VI)-induced oxidative damage further caused and aggravated apoptosis in P. sanguineus, especially at Cr(VI) concentrations above 20 mg/L. Cr(VI)-induced apoptosis was involved with mitochondrial dysfunction including mitochondrial depolarization, the enhancement of mitochondrial permeability and release of cytochrome c. The early and late apoptosis hallmarks, such as metacaspase activation, phosphatidylserine (PS) externalization, DNA fragmentation and the nuclear condensation and fragmentation were observed. Moreover, we also found disturbances of ion homeostasis, which was featured by K+ effluxes and overload of cytoplasmic and mitochondrial Ca2+.Based on these results, we suggest that Cr(VI) induced oxidative stress and apoptosis in white rot fungi, P. sanguineus.

Combination of steam explosion and laccase-mediator treatments prior to Eucalyptus globulus kraft pulping.

The effect of a pretreatment consisting of steam explosion (SE) followed by a laccase mediator system (LMS) stage on Eucalyptus globulus kraft pulping has been evaluated and compared with fungal pretreatments. Pretreatment with SE and LMS was more efficient than pretreatments using Pycnoporus sanguineus and Trametes sp. I-62. Steam explosion not only improved the enzyme penetration into the wood chips and shortened the pulping process by 60%, but also extracted around 50% of the hemicelluloses which could be converted into value-added products. The optimal conditions for the LMS treatment were 3h, 3UA/g and 40°C. Compared to SE, the SE/LMS treatment yielded an increase in delignification of 13.9% without affecting pulp properties, provided a similar screened kraft yield, and reduced consumption of chemical reagents Na(2)S and NaOH by 11.5% and 6.3%, respectively. Therefore, SE/LMS is a promising pretreatment for converting the pulp mill into a forest bio-refinery.

Production and characterization of a novel laccase with cold adaptation and high thermal stability from an isolated fungus.

A new white-rot fungus SYBC-L1, which could produce an extracellular laccase, was isolated from a decayed Elaeocarpus sylvestris. The strain was identified as Pycnoporus sp. SYBC-L1 according to the morphological characteristics and ribosomal ITS1-5.8S-ITS2 RNA genomic sequence analysis. The highest laccase activity of 24.1 U ml(-1), which was approximately 40-fold than that in basal medium, was achieved in optimal culture medium in submerged fermentation. The laccase produced by Pycnoporus sp. SYBC-L1 was not only a cold adaptation enzyme with a relative catalytic activity of 30.2% at 0 degrees C but also a high thermostable enzyme. The half-lives at 60, 70 and 80 degrees C were 85.5, 37.2, and 2.6 h, respectively. The laccase could effectively decolorize weak acid blue AS and diamond black PV up to 88% and 74.7%, respectively, within 2 h in the absence of any redox mediators. The results suggested Pycnoporus sp. SYBC-L1 was a potential candidate for laccase production and industrial application.