Use of Biochar from Rice Husk Pyrolysis: Part A: Recovery as an Adsorbent in the Removal of Emerging Compounds.

One of the main products of pyrolysis is char. For the better performance and improvement of its physicochemical properties, it is necessary to make temperature changes. In this study, different temperatures have been tested for the pyrolysis of rice husk, and the biochar obtained from the process went through an evaluation to test its yield in the removal of emerging compounds such as azithromycin (AZT) and erythromycin (ERY). For this, pyrolysis of rice husk has been carried out at temperatures of 450, 500, 550, and 600 °C, and the biochars have been characterized by ultimate analysis and proximate analysis, as well as specific surface area tests. Then, different adsorption tests have been carried out with a 200 mg L-1 drug (AZT and ERY) solution prepared in the laboratory. All biochars have been found to present removal percentages higher than 95%. Therefore, obtaining biochar from rice husk at any temperature and using it in the removal of high-molecular-weight compounds are quite suitable.

Novel bacterial taxa in a minimal lignocellulolytic consortium and their potential for lignin and plastics transformation.

The understanding and manipulation of microbial communities toward the conversion of lignocellulose and plastics are topics of interest in microbial ecology and biotechnology. In this study, the polymer-degrading capability of a minimal lignocellulolytic microbial consortium (MELMC) was explored by genome-resolved metagenomics. The MELMC was mostly composed (>90%) of three bacterial members (Pseudomonas protegens; Pristimantibacillus lignocellulolyticus gen. nov., sp. nov; and Ochrobactrum gambitense sp. nov) recognized by their high-quality metagenome-assembled genomes (MAGs). Functional annotation of these MAGs revealed that Pr. lignocellulolyticus could be involved in cellulose and xylan deconstruction, whereas Ps. protegens could catabolize lignin-derived chemical compounds. The capacity of the MELMC to transform synthetic plastics was assessed by two strategies: (i) annotation of MAGs against databases containing plastic-transforming enzymes; and (ii) predicting enzymatic activity based on chemical structural similarities between lignin- and plastics-derived chemical compounds, using Simplified Molecular-Input Line-Entry System and Tanimoto coefficients. Enzymes involved in the depolymerization of polyurethane and polybutylene adipate terephthalate were found to be encoded by Ps. protegens, which could catabolize phthalates and terephthalic acid. The axenic culture of Ps. protegens grew on polyhydroxyalkanoate (PHA) nanoparticles and might be a suitable species for the industrial production of PHAs in the context of lignin and plastic upcycling.

Use of biochar from rice husk pyrolysis: assessment of reactivity in lime pastes.

Biochar has unique properties such as its porous structure, specific surface area, and stable chemical properties. The rice husk is characterized by its high content of silica, and that during the pyrolysis process it generates a considerable amount of biochar that can be used in different processes. The aim of this work is to evaluate several biochars from the pyrolysis process in the reactivity of lime pastes. For this, biochar has been obtained at four different temperatures (450, 500, 550 and 600 °C), and they have been characterized by XRF, XRD, ICP-EOS, and particle size distribution, to determine their phases and their chemical composition. Biochar has been replaced in lime pastes in different proportions (5, 10, 15, 20, 25 and 30%), and exposed to different curing times (1, 3, 7, 14, 28, 56, 90 and 180 days). It has been found that all the replacements show reactivity within the lime pastes and that the percentage of 25% in all the biochar tested could be an adequate replacement.

Dexibuprofen ameliorates peripheral and central risk factors associated with Alzheimer's disease in metabolically stressed APPswe/PS1dE9 mice.

BACKGROUND: Several studies stablished a relationship between metabolic disturbances and Alzheimer´s disease (AD) where inflammation plays a pivotal role. However, mechanisms involved still remain unclear. In the present study, we aimed to evaluate central and peripheral effects of dexibuprofen (DXI) in the progression of AD in APPswe/PS1dE9 (APP/PS1) female mice, a familial AD model, fed with high fat diet (HFD). Animals were fed either with conventional chow or with HFD, from their weaning until their sacrifice, at 6 months. Moreover, mice were divided into subgroups to which were administered drinking water or water supplemented with DXI (20 mg kg-1 d-1) for 3 months. Before sacrifice, body weight, intraperitoneal glucose and insulin tolerance test (IP-ITT) were performed to evaluate peripheral parameters and also behavioral tests to determine cognitive decline. Moreover, molecular studies such as Western blot and RT-PCR were carried out in liver to confirm metabolic effects and in hippocampus to analyze several pathways considered hallmarks in AD. RESULTS: Our studies demonstrate that DXI improved metabolic alterations observed in transgenic animals fed with HFD in vivo, data in accordance with those obtained at molecular level. Moreover, an improvement of cognitive decline and neuroinflammation among other alterations associated with AD were observed such as beta-amyloid plaque accumulation and unfolded protein response. CONCLUSIONS: Collectively, evidence suggest that chronic administration of DXI prevents the progression of AD through the regulation of inflammation which contribute to improve hallmarks of this pathology. Thus, this compound could constitute a novel therapeutic approach in the treatment of AD in a combined therapy.

Reaction mechanism of glutathione synthetase from Arabidopsis thaliana: site-directed mutagenesis of active site residues.

Glutathione is essential for maintaining the intracellular redox environment and is synthesized from gamma-glutamylcysteine, glycine, and ATP by glutathione synthetase (GS). To examine the reaction mechanism of a eukaryotic GS, 24 Arabidopsis thaliana GS (AtGS) mutants were kinetically characterized. Within the gamma-glutamylcysteine/glutathione-binding site, the S153A and S155A mutants displayed less than 4-fold changes in kinetic parameters with mutations of Glu-220 (E220A/E220Q), Gln-226 (Q226A/Q226N), and Arg-274 (R274A/R274K) at the distal end of the binding site resulting in 24-180-fold increases in the K(m) values for gamma-glutamylcysteine. Substitution of multiple residues interacting with ATP (K313M, K367M, and E429A/E429Q) or coordinating magnesium ions to ATP (E148A/E148Q, N150A/N150D, and E371A) yielded inactive protein because of compromised nucleotide binding, as determined by fluorescence titration. Other mutations in the ATP-binding site (E371Q, N376A, and K456M) resulted in greater than 30-fold decreases in affinity for ATP and up to 80-fold reductions in turnover rate. Mutation of Arg-132 and Arg-454, which are positioned at the interface of the two substrate-binding sites, affected the enzymatic activity differently. The R132A mutant was inactive, and the R132K mutant decreased k(cat) by 200-fold; however, both mutants bound ATP with K(d) values similar to wild-type enzyme. Minimal changes in kinetic parameters were observed with the R454K mutant, but the R454A mutant displayed a 160-fold decrease in k(cat). In addition, the R132K, R454A, and R454K mutations elevated the K(m) value for glycine up to 11-fold. Comparison of the pH profiles and the solvent deuterium isotope effects of A. thaliana GS and the Arg-132 and Arg-454 mutants also suggest distinct mechanistic roles for these residues. Based on these results, a catalytic mechanism for the eukaryotic GS is proposed.