1.Vanillic and syringic acids from biomass burning: Behaviour during Fenton-like oxidation in atmospheric aqueous phase and in the absence of light.
Santos GT1, Santos PS2, Duarte AC1. J Hazard Mater. 2016 Apr 7;313:201-208. doi: 10.1016/j.jhazmat.2016.04.006. [Epub ahead of print]
Biomass combustion is a threat to the environment since it emits to the atmosphere organic compounds, which may react and originate others more aggressive. This work studied the behaviours of vanillic and syringic acids, small aromatic tracers of biomass burning, during Fenton-like oxidation in aqueous phase and absence of light. For both compounds, the extent of oxidation increased with pH decrease from neutral to acid in atmospheric waters, but for vanillic acid the neutral pH was not able of promoting the oxidation. With the oxidation of both acids were formed chromophoric compounds, and the formation rate increased with the degree of electron-donator substituents in benzene ring. The initial and produced compounds were not totally degraded up to 24h of reaction at pH 4.5, suggesting that the night period may be not sufficient for their full degradation in atmospheric waters. The major compounds formed were the 3,4-dihydroxybenzoic acid for vanillic acid, and the 1,4-dihydroxy-2,6-dimethoxybenzene for syringic acid.
2.A Pycnoporus sanguineus laccase for denim bleaching and its comparison with an enzymatic commercial formulation.
Iracheta-Cárdenas MM1, Rocha-Peña MA2, Galán-Wong LJ3, Arévalo-Niño K4, Tovar-Herrera OE5. J Environ Manage. 2016 Apr 13;177:93-100. doi: 10.1016/j.jenvman.2016.04.008. [Epub ahead of print]
A laccase from the basidiomycete Pycnoporus sanguineus strain RVAN5 was evaluated for its ability to decolorize synthetic dyes and denim bleaching. Dye color reduction and denim bleaching were monitored at different dye concentrations and incubation times. Dye decolorization by Pycnoporus sanguineus fungal crude extract (FCE) ranged from 80 to 96% within 2-4 h at 25-65 °C. Comparable results were obtained when violuric acid (VA) was added as mediator to the FCE, however, the number of decolorized dyes increased significantly. Dye decolorization rates with VA varied of initial and final optical density (595 nm) values of 2.5-3.0 and 0.2-0.02, respectively. P. sanguineus FCE had no substantial effect on denim bleaching when used alone, notwithstanding, the mixture of FCE with VA (10 mM) showed significant denim color reduction values and considerably higher than those obtained with a bleaching enzyme from a commercial formulation; CIElab values obtained with FCE/VA mixture were of ΔL = 6.
3.Chlorination of oxybenzone: Kinetics, transformation, disinfection byproducts formation, and genotoxicity changes.
Zhang S1, Wang X1, Yang H2, Xie YF3. Chemosphere. 2016 Apr 13;154:521-527. doi: 10.1016/j.chemosphere.2016.03.116. [Epub ahead of print]
UV filters are a kind of emerging contaminant, and their transformation behavior in water treatment processes has aroused great concern. In particular, toxic products might be produced during reaction with disinfectants during the disinfection process. As one of the most widely used UV filters, oxybenzone has received significant attention, because its transformation and toxicity changes during chlorine oxidation are a concern. In our study, the reaction between oxybenzone and chlorine followed pseudo-first-order and second-order kinetics. Three transformation products were detected by LC-MS/MS, and the stability of products followed the order of tri-chloro-methoxyphenoyl > di-chlorinated oxybenzone > mono-chlorinated oxybenzone. Disinfection byproducts (DBPs) including chloroform, trichloroacetic acid, dichloroacetic acid and chloral hydrate were quickly formed, and increased at a slower rate until their concentrations remained constant.
4.The bile acid Deoxycholate Elicits defenses in Arabidopsis and reduces bacterial infection.
Zarattini M1,2, Launay A1,3, Farjad M1, Wénès E1, Taconnat L4, Boutet S1, Bernacchia G2, Fagard M1. Mol Plant Pathol. 2016 Apr 16. doi: 10.1111/mpp.12416. [Epub ahead of print]
Crop yield loss is significantly affected by disease. Considering that the worldwide demand for agricultural products is increasing, there is a need to pursue the development of new methods to protect crops from disease. One mechanism of plant protection is through the activation of its immune system. By exogenous application, "plant activator molecules" with elicitor properties, can be used to activate the plant immune system. These defense-inducing molecules represent a powerful and often environment-friendly toolset to fight pathogens. We show that the secondary bile acid deoxycholic acid (DCA) induces defense in Arabidopsis and reduces the proliferation of two bacterial phytopathogens, Erwinia amylovora and Pseudomonas syringae pv. tomato. We describe the global defense response triggered by this new plant activator in Arabidopsis at the transcriptional level. Several induced genes were selected for further analysis by qRT-PCR: we describe the kinetics of their induction and we show that abiotic stress, such as moderate drought or nitrogen limitation, does not impede DCA induction of defense.