Influence of co-existed tetrabromobisphenol A (TBBPA) and hexavalent chromium on the cellular characteristics of Pycnoporus sanguineus during their removal and reduction.

Simultaneous TBBPA removal and Cr(VI) reduction by Pycnoporus sanguineus together with the effect of these co-existed pollutants on the fungal cellular characteristics were investigated in this study, aiming at illuminating the mechanism involved in the interactions between contaminants and microbial cells. The results revealed that Cr(VI) reduction and TBBPA removal declined from 92.5%, 75.4-30.6%, 44.8% when Cr(VI) concentration increased from 5 to 40mg/L, respectively. The removal efficiencies for Cr(VI) and TBBPA reached 61.4% and 94% separately under the optimum concentration of TBBPA at 10mg/L. Subsequent analyses indicated that the negative effect of Cr(VI) of high concentrations on Cr(VI) reduction and TBBPA removal was mainly attributed to the inhibition of fungal growth, intracellular proteins synthesis, cell viability and ATP enzyme activity. Compared with the moderate impact of TBBPA, the cell membrane of P. sanguineus was impaired severely and the surface morphology and intracellular structure changed dramatically in the presence of high concentration of Cr(VI) (above 10mg/L). This study also suggested that high level of TBBPA (15 and 20mg/L) promoted the synthesis of intracellular proteins and improved ATP enzyme activity within the first 48h of the reaction for enhancing the transportation and transformation of TBBPA.

Bioreduction of Precious Metals by Microorganism: Efficient Gold@N-Doped Carbon Electrocatalysts for the Hydrogen Evolution Reaction.

The uptake of precious metals from electronic waste is of environmental significance and potential commercial value. A facile bioreductive synthesis is described for Au nanoparticles (ca. 20 nm) supported on N-doped carbon (Au@NC), which was derived from Au/Pycnoporus sanguineus cells. The interface and charge transport between Au and N-doped carbon were confirmed by HRTEM and XPS. Au@NC was employed as an electrocatalyst for the hydrogen evolution reaction (HER), exhibiting a small onset potential of -54.1 mV (vs. RHE), a Tafel slope of 76.8 mV dec(-1) , as well as robust stability in acidic medium. Au@NC is a multifunctional electrocatalyst, which demonstrates high catalytic activity in the oxygen reduction reaction (ORR), as evidenced by an onset potential of +0.97 V, excellent tolerance toward methanol, and long-term stability. This work exemplifies dual recovery of precious Au and fabrication of multifunctional electrocatalysts in an environmentally benign and application-oriented manner.

Growth inhibition and antioxidative response of wood decay fungi exposed to plant extracts of Casearia species.

UNLABELLED: Ligninolytic fungi take part in critical processes in ecosystems such as nutrient recycling; however, some fungal species can be pathogenic to forest and urban trees and deteriorate wood products. The tropical flora is an important source of antimicrobial compounds environmentally safer than traditional wood preservatives. Therefore, this study aimed to evaluate the inhibitory activity of ethanol plant extracts of Casearia sylvestris and Casearia decandra on the white-rot wood decay basidiomycetes Trametes villosa and Pycnoporus sanguineus. In addition, the effect of the extracts on the fungal antioxidative metabolism was studied. Among the different substances present in the extracts, the phytochemical analyses identified a clerodane diterpenoid (C. sylvestris) and cinnamic acid, hydroquinone and ß-sitosterol (C. decandra). The extracts inhibited the fungi up to 70% and caused hyphal morphology changes. The extracts triggered oxidative stress process as indicated by the increased levels of the antioxidant enzymes catalase and glutathione reductase. Therefore, the Casearia extracts are a potential source of natural biocides to control wood decay fungi, and one of the mechanisms of action is the oxidative stress. SIGNIFICANCE AND IMPACT OF THE STUDY: The Casearia plant extracts exhibited important antifungal activity on wood decay fungi and triggered oxidative stress process, an inhibitory mechanism rarely studied in filamentous fungi exposed to plant extracts. Therefore, a starting point was provided for the development of natural compounds-based products as an alternative to chemical fungicides. In addition, subsidies were given to further studies in order to elucidate in more detail how compounds present in extracts of native tropical plants affect the physiology of fungi.