Analysis of SARS-CoV-2 viral loads in stool samples and nasopharyngeal swabs from COVID-19 patients in the United Arab Emirates

Coronavirus disease 2019 (COVID-19) was first identified in respiratory samples and was found to commonly cause cough and pneumonia. However, non-respiratory symptoms including gastrointestinal disorders are also present and a big proportion of patients test positive for the virus in stools for a prolonged period. In this cross-sectional study, we investigated viral load trends in stools and nasopharyngeal swabs and their correlation with multiple demographic and clinical factors. The study included 211 laboratory-confirmed cases suffering from a mild form of the disease and completing their isolation period at a non-hospital center in the United Arab Emirates. Demographic and clinical information was collected by standardized questionnaire and from the medical records of the patient. Of the 211 participants, 25 % tested negative in both sample types at the time of this study and 53 % of the remaining patients had detectable viral RNA in their stools. A positive fecal viral test was associated with male gender, diarrhea as a symptom, and hospitalization during infection. A positive correlation was also observed between a delayed onset of symptoms and a positive stool test. Viral load in stools positively correlated with, being overweight, exercising, taking antibiotics in the last 3 months and blood type O. The viral load in nasopharyngeal swabs, on the other hand, was higher for blood type A, and rhesus positive (Rh factor). Regression analysis showed no correlation between the viral loads measured in stool and nasopharyngeal samples in any given patient. The results of this work highlight the factors associated with a higher viral count in each sample. It also shows the importance of stool sample analysis for the follow-up and diagnosis of recovering COVID-19 patients

Degradarea biomasei lignocelulozice de fungi filamentoase: rolul oxidoreductaselor, radicali liberi și protecția împotriva stresului oxidativ

ISSN 2066-2971International audienc

Fungal growth and enzyme production on alkali lignin from grasses

International audienc

Characterization of 2 novel H2O2 producing glyoxal oxidases from Pycnoporus cinnabarinus implicated in the breakdown of lignocelluloses

Lignin is one of the most abundant and recalcitrant natural polymers. Consequently, lignin degradation is important for completing the carbon cycle in forest ecosystems and a central challenge towards more environmentally-friendly and economically performing second-generation lignocellulosic-based biorefineries. The monokaryotic cell-line of the white-rot fungus Pycnoporus cinnabarinus BRFM 137 was shown to be an outstanding model to study the enzymatic machinery involved in the degradation and transformation of lignocellulosic materials [1]. Seven AA5_1 Carbohydrate-Active enzymes (Cazymes) have been identified including three glyoxal oxidases (GLOX) [2]. These GLOX are naturally secreted into the extracellular medium around the growing hyphal tip during fungal growth on lignin-rich substrates and acts as one of the sources of extracellular hydrogen peroxide that is mandatory for the oxidation reactions catalyzed by lignolytic peroxidases involved in lignin degradation [3]. In this work, two novel hydrogen peroxide-producing glyoxal oxidases from Pycnoporus cinnabarinus (PciGLOX1 and PciGLOX2) were for the first time cloned and successfully heterologously expressed in Aspergillus niger in Erlenmeyer flasks and in a 10 L bioreactor, and biochemically characterized. The wide variety of aldehydes that were oxidized makes these GLOX a promising tool not only for the deconstruction of plant biomass and the valorization of industrial lignin, but also for the production of valuable molecules for Green Chemistry applications. These enzymes and other oxidative enzymes produced in the framework of the EU-FP7 INDOX project will now be used simultaneously in order to study their synergistic interactions on lignocellulosic materials with the aim to get insights into the lignin-degrading strategies employed by Pycnoporus cinnabarinus

Pycnoporus cinnabarinus glyoxal oxidases display differential catalytic efficiencies on 5‑hydroxymethylfurfural and its oxidized derivatives

International audienceBackground: 5-Hydroxymethylfurfural (HMF), a major residual component of a lignocellulosic bio-refinery process, can be transformed into fundamental building blocks for green chemistry via oxidation. While chemical methods are well established, interest is also being directed into the enzymatic oxidation of HMF into the bio-plastic precursor 2,5-furandicarboxylic acid (FDCA). Results: We demonstrate that three glyoxal oxidases (PciGLOX) isoenzymes from the Basidiomycete fungus Pycnoporus cinnabarinus were able to oxidize HMF, with PciGLOX2 and PciGLOX3 being the most efficient. The major reaction product obtained with the three isoenzymes was 5-hydroxymethyl-2-furancarboxylic (HMFCA), a precursor in polyesters and pharmaceuticals production, and very little subsequent conversion of this compound was observed. However, small concentrations of FDCA, a substitute for terephthalic acid in the production of polyesters, were also obtained. The oxidation of HMF was significantly boosted in the presence of catalase for PciGLOX2, leading to 70% HMFCA yield. The highest conversion percentages were observed on 2,5-furandicarboxaldehyde (DFF), a minor product from the reaction of PciGLOX on HMF. To bypass HMFCA accumulation and exploit the efficiency of PciGLOX in oxidizing DFF and 5-formyl-2-furan carboxylic acid (FFCA) towards FDCA production, HMF was oxidized in a cascade reaction with an aryl alcohol oxidase (UmaAAO). After 2 h of reaction, UmaAAO completely oxidized HMF to DFF and further to FFCA, with FDCA only being detected when PciGLOX3 was added to the reaction. The maximum yield of 16% FDCA was obtained 24 h after the addition of PciGLOX3 in the presence of catalase. Conclusions: At least two conversion pathways for HMF oxidation can be considered for PciGLOX; however, the highest selectivity was seen towards the production of the valuable polyester precursor HMFCA. The three isoenzymes showed differences in their catalytic efficiencies and substrate specificities when reacted with HMF derivatives

Heterologous Production and Characterization of Two Glyoxal Oxidases from Pycnoporus cinnabarinus: Glyoxal Oxidases from Pycnoporus cinnabarinus

International audienceThe genome of the white rot fungus Pycnoporus cinnabarinus includes a large number of genes encoding enzymes implicated in lignin degradation. Among these, three genes are predicted to encode glyoxal oxidase, an enzyme previously isolated from Phanerochaete chrysosporium The glyoxal oxidase of P. chrysosporium is physiologically coupled to lignin-oxidizing peroxidases via generation of extracellular H2O2 and utilizes an array of aldehydes and α-hydroxycarbonyls as the substrates. Two of the predicted glyoxal oxidases of P. cinnabarinus, GLOX1 (PciGLOX1) and GLOX2 (PciGLOX2), were heterologously produced in Aspergillus niger strain D15#26 (pyrG negative) and purified using immobilized metal ion affinity chromatography, yielding 59 and 5 mg of protein for PciGLOX1 and PciGLOX2, respectively. Both proteins were approximately 60 kDa in size and N-glycosylated. The optimum temperature for the activity of these enzymes was 50°C, and the optimum pH was 6. The enzymes retained most of their activity after incubation at 50°C for 4 h. The highest relative activity and the highest catalytic efficiency of both enzymes occurred with glyoxylic acid as the substrate. The two P. cinnabarinus enzymes generally exhibited similar substrate preferences, but PciGLOX2 showed a broader substrate specificity and was significantly more active on 3-phenylpropionaldehyd

Does Learning a Skill with the Expectation of Teaching It Impair the Skill’s Execution Under Psychological Pressure If the Skill is Learned with Analogy Instructions?

Objective: Having learners practice a motor skill with the expectation of teaching it (versus an expectation of being tested on it) has been revealed to enhance skill learning. However, this improvement in skill performance is lost when the skill must be performed under psychological pressure due to ‘choking under pressure.’ The present study investigated whether this choking effect is caused by an accrual of declarative knowledge during skill practice and could be prevented if a technique (analogy instructions) to minimize the accrual of declarative knowledge during practice is employed. Design: We used a 2 (Expectation: teach/test) x 2 (Instructions: analogy/explicit) x 2 (Posttest: low-pressure/high-pressure) mixed-factor design, with repeated measures on the last factor. Methods: One-hundred fifty-six participants were quasi-randomly assigned (based on sex) to one of four groups. Participants in the teach/analogy and teach/explicit groups practiced golf putting with the expectation of teaching putting to another participant, and analogy instructions or explicit instructions, respectively. Participants in the test/analogy and test/explicit groups practiced golf putting with the expectation of being tested on their putting, and analogy instructions or explicit instructions, respectively. The next day all participants completed low- and high-pressure putting posttests, with their putting accuracy serving as the dependent variable. Results: We observed an Expectation x Instructions × Posttest interaction, such that a main effect of expectation was found in the low-pressure posttest, with the teach group exhibiting superior accuracy, and an Expectation × Instructions interaction was revealed for the high-pressure posttest. This interaction resulted from the teach group showing greater accuracy than the test group exclusively when receiving analogy instructions. Conclusion: Results show that participants who practiced with the expectation of teaching exhibited superior learning and indicate that they choked under pressure likely due to their accrual of declarative knowledge during practice, since the choking effect was prevented by having them practice with analogy instructions. Accordingly, having learners practice with the expectation of teaching and techniques that minimize the accrual of declarative knowledge is recommended

Glyoxal Oxidases from Pycnoporus Cinnabarinus for Green Chemistry Applications

Glyoxal Oxidases from Pycnoporus Cinnabarinus for Green Chemistry Applications . International Symposium on Green Chemistry (2017

A Putative Lignin Copper Oxidase from Trichoderma reesei

International audienceThis article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY)The ability of Trichoderma reesei, a fungus widely used for the commercial production of hemicellulases and cellulases, to grow and modify technical soda lignin was investigated. By quantifying fungal genomic DNA, T. reesei showed growth and sporulation in solid and liquid cultures containing lignin alone. The analysis of released soluble lignin and residual insoluble lignin was indicative of enzymatic oxidative conversion of phenolic lignin side chains and the modification of lignin structure by cleaving the β-O-4 linkages. The results also showed that polymerization reactions were taking place. A proteomic analysis conducted to investigate secreted proteins at days 3, 7, and 14 of growth revealed the presence of five auxiliary activity (AA) enzymes in the secretome: AA6, AA9, two AA3 enzymes), and the only copper radical oxidase encoded in the genome of T. reesei. This enzyme was heterologously produced and characterized, and its activity on lignin-derived molecules was investigated. Phylogenetic characterization demonstrated that this enzyme belonged to the AA5_1 family, which includes characterized glyoxal oxidases. However, the enzyme displayed overlapping physicochemical and catalytic properties across the AA5 family. The enzyme was remarkably stable at high pH and oxidized both, alcohols and aldehydes with preference to the alcohol group. It was also active on lignin-derived phenolic molecules as well as simple carbohydrates. HPSEC and LC-MS analyses on the reactions of the produced protein on lignin dimers (SS ββ, SS βO4 and GG β5) uncovered the polymerizing activity of this enzyme, which was accordingly named lignin copper oxidase (TrLOx). Polymers of up 10 units were formed by hydroxy group oxidation and radical formation. The activations of lignin molecules by TrLOx along with the co-secretion of this enzyme with reductases and FAD flavoproteins oxidoreductases during growth on lignin suggest a synergistic mechanism for lignin breakdown

Enzyme Activities of Two Recombinant Heme-Containing Peroxidases, TvDyP1 and TvVP2, Identified from the Secretome of Trametes versicolor

Trametes versicolor is a wood-inhabiting agaricomycete known for its ability to cause strong white-rot decay on hardwood and for its high tolerance of phenolic compounds. The goal of the present work was to gain insights into the molecular biology and biochemistry of the heme-including class II and dye-decolorizing peroxidases secreted by this fungus. Proteomic analysis of the secretome of T. versicolor BRFM 1218 grown on oak wood revealed a set of 200 secreted proteins, among which were the dye-decolorizing peroxidase TvDyP1 and the versatile peroxidase TvVP2. Both peroxidases were heterologously produced in Escherichia coli, biochemically characterized, and tested for the ability to oxidize complex substrates. Both peroxidases were found to be active against several substrates under acidic conditions, and TvDyP1 was very stable over a relatively large pH range of 2.0 to 6.0, while TvVP2 was more stable at pH 5.0 to 6.0 only. The thermostability of both enzymes was also tested, and TvDyP1 was globally found to be more stable than TvVP2. After 180 min of incubation at temperatures ranging from 30 to 50°C, the activity of TvVP2 drastically decreased, with 10 to 30% of the initial activity retained. Under the same conditions, TvDyP1 retained 20 to 80% of its enzyme activity. The two proteins were catalytically characterized, and TvVP2 was shown to accept a wider range of reducing substrates than TvDyP1. Furthermore, both enzymes were found to be active against two flavonoids, quercetin and catechin, found in oak wood, with TvVP2 displaying more rapid oxidation of the two compounds. They were tested for the ability to decolorize five industrial dyes, and TvVP2 presented a greater ability to oxidize and decolorize the dye substrates than TvDyP1