Sequential use of ammonium and leucine as nitrogen sources during growth of Geotrichum candidum on a glucose based medium

Geotrichum candidum growth on ammonium and leucine as nitrogen sources and glucose as a carbon source was examined. A clear preference of G. candidum for ammonium over leucine as a nitrogen source was shown. Indeed, ammonium was completely exhausted at the end of exponential growth after less than 35 hrs of culture; in contrast only 5% of leucine was concomitantly assimilated. Growth continued at slower rates on glucose and leucine as carbon and nitrogen sources respectively, and at the end of culture (185 hrs), leucine was completely exhausted

The Effect of the Stationary Phase on Resolution in the HPLC-Based Separation of Racemic Mixtures Using Vancomycin as a Chiral Selector: A Case Study with Profen Nonsteroidal Anti-Inflammatory Drugs

\ua9 2023 by the authors.Chiral resolution is a technique of choice, making it possible to obtain asymmetric and enantiomerically pure compounds from a racemic mixture. This study investigated the behavior of vancomycin when used as a chiral additive in high-performance liquid chromatography (HPLC) to separate enantiomers of nonsteroidal anti-inflammatory drugs (NSAIDs), including ketoprofen, ibuprofen, flurbiprofen, and naproxen enantiomeric impurities. We compared two achiral stationary phases (C18 and NH2) to assess the impact of mobile phase composition and stationary phase on the vancomycin retention time in the racemic resolution of drug enantiomers. Our results demonstrated the successful enantioseparation of all drugs using vancomycin in the mobile phase (phosphate buffer 0.05 M/2-propanol, 50/50) with an NH2 column. This enhanced separation on the NH2 column resulted from the chromatography system’s efficiency and vancomycin dimers’ stereoselective interaction on the NH2 surface. This study underscores the importance of stationary phase selection in the chiral resolution of NSAIDs with vancomycin as a chiral additive. It offers valuable insights for future research and development of NSAID chiral separation methods, highlighting potential vancomycin applications in this context

Investigating the Efficacy of Oily Water Treatment at a De-Oiling Facility in the Northern Industrial Center of CINA - Hassi Messaoud: A Statistical Physics Assessment

Environmental protection is becoming a primary objective when choosing processes andtechnologies for treating oily waters resulting from hydrocarbon production. The focus of treatingoily waters is to eliminate contaminants from effluents before discharging them into the receivingenvironment while adhering to discharge standards. Our work aims to analyze the treatment processfor oily waters in the API unit of the North Industrial Center (CINA), which involves a physical–chemical treatment using activated silica and Kurifix. The study aims to improve the treatmentprocess used for oily water treatment to ensure water conservation for reuse. To enhance the CINAHMDoily water treatment process, we created coagulants with different doses (C1–C6) using sodiumsilicate, activated silicate (sodium silicate + sulfuric acid), distilled water, Kurifix, and an oxygenscavenger while measuring pH, HC (hydrocarbon), and SS (suspended solids) levels. Coagulationand flocculation processes were used to remove suspended solids and hydrocarbons from the water.The results show that the coagulant used reduces suspended matter and hydrocarbon content andincreases pH. The best treatment is achieved with a coagulant prepared with distilled water, 5%sodium silicate, and 2% sulfuric acid. The optimal dose of coagulant is 16 ppm. Automatic dosingprovides better efficiency than manual dosing. The study recommends continuous verification ofchemical preparation and injection, periodic cleaning of settling tanks, and monitoring of oily waterentering the station

Conserved presence of G-quadruplex forming sequences in the Long Terminal Repeat Promoter of Lentiviruses

G-quadruplexes (G4s) are secondary structures of nucleic acids that epigenetically regulate cellular processes. In the human immunodeficiency lentivirus 1 (HIV-1), dynamic G4s are located in the unique viral LTR promoter. Folding of HIV-1 LTR G4s inhibits viral transcription; stabilization by G4 ligands intensifies this effect. Cellular proteins modulate viral transcription by inducing/unfolding LTR G4s. We here expanded our investigation on the presence of LTR G4s to all lentiviruses. G4s in the 5'-LTR U3 region were completely conserved in primate lentiviruses. A G4 was also present in a cattle-infecting lentivirus. All other non-primate lentiviruses displayed hints of less stable G4s. In primate lentiviruses, the possibility to fold into G4s was highly conserved among strains. LTR G4 sequences were very similar among phylogenetically related primate viruses, while they increasingly differed in viruses that diverged early from a common ancestor. A strong correlation between primate lentivirus LTR G4s and Sp1/NF\u3baB binding sites was found. All LTR G4s folded: their complexity was assessed by polymerase stop assay. Our data support a role of the lentiviruses 5'-LTR G4 region as control centre of viral transcription, where folding/unfolding of G4s and multiple recruitment of factors based on both sequence and structure may take place

G-Quadruplex Visualization in Cells via Antibody and Fluorescence Probe

G-quadruplexes (G4s) are noncanonical nucleic acids structures involved in key regulatory and pathological roles in eukaryotes, prokaryotes, and viruses: the development of specific antibodies and fluorescent probes represent an invaluable tool to understand their biological relevance. We here present three protocols for the visualization of G4s in cells, both uninfected and HSV-1 infected, using a specific antibody and a fluorescent G4 ligand, and the effect of the fluorescent ligand on a G4 binding protein, nucleolin, upon binding of the molecule to the nucleic acids structure

Methyl orange removal from aqueous solutions by natural and treated skin almonds

International audienceThe aim of this study was to explore the feasibility of using skin almonds (SA), a new agricultural sorbent, for the removal of hazardous dye methyl orange (MO). The fi rst objective of this work was to examine the infl uence of different chemical treatments on the adsorption capacity of SA. The treatment of SA with alkaline solution as well as with salt solution decreased the sorption ability for MO, whereas the acidic treatment increased markedly the sorption ability for the anionic dye. The next objective was to evaluate the properties of the adsorbent, the effect of the contact time, the temperature, the dye concentration and the particles size. Adsorption of the dye on both adsorbents (natural and treated) has been monitored through the Langmiur, Freundlich and Redlich-Peterson adsorption isotherm models and it was shown that the adsorption process followed as Freundlish isotherm, which led to the higher correlation coefficient. Two kinetic models, pseudo-second order and Elovich equation were employed to analyze kinetics data. It was found that the pseudo second-order was the most relevant to describe the adsorption behavior. In addition, the activation energy was also determined based on the pseudo-second order rate constants

Biodegradation of p-cresol by Pseudomonas spp.

International audiencePhenols are toxic to several biochemical reactions. However, biological transformation of phenols to nontoxic entities exists in specialized microbes, owing to enzymatic potential involving enzymes of aromatic catabolic pathways. In this study, a series of experiments were performed to examine the effects of the mineral medium composition and the pH on p-cresol removal. In this purpose, p-cresol biodegradation was carried out in a batch reactor containing mixed bacteria; the temperature (30°C), the stirring velocity (200 rpm), the KH2PO4 concentration (1.5 g/L), the K2HPO4 concentration (2 g/L), and p-cresol concentration (100 mg/L) were kept constants. The initial pH was varied in the range 5–9 and the mineral components were tested in the following concentration ranges: 0–2 g/L for Nitrogen sources (NH4Cl, KNO3, and NH4NO3), 0–0.5 g/L for NaCl, and 0–0.2 g/L for MgSO4. Their effects on p-cresol biodegradation and specific growth rate were examined. The shorter biodegradation time of p-cresol was 30.5 h for NH4Cl, NaCl, and MgSO4 concentrations of 1, 0.3, and 0.1 g/L, respectively. Maximum specific growth rate (0.34 h−1) and total p-cresol removal were recorded for an optimal pH value of 8

Response surface methodology for the optimization of the electrochemical degradation of phenol on Pb/PbO2 electrode.

International audiencehe electrochemical oxidation of phenol on Pb/PbO2 electrode was carried out in order to develop a predictive model. A central composite design (CCD) was employed for the screening of significant operating parameters and to identify their most relevant interactions. The model equation obtained led to a classification of these parameters based on their level of significance, namely the current density, the temperature, the initial phenol concentration, and the agitation speed. In addition, three relevant interactions were found, current density--temperature, initial phenol concentration--current density and initial phenol concentration--temperature. After performing a screening of the various factors, response surface analysis led to the following optimal conditions for the yield of phenol degradation: 189 ≤ [pOH]0 ≤ 200 mg L−1, 19.66 ≤ i ≤ 25 mA cm−2, 600 rpm, and 60°C for the initial phenol concentration, the current density, the agitation speed, and the temperature , respectively. Under these conditions, the obtained phenol degradation yield was 71% and the chemical oxygen demand (COD) was reduced more than 45%

Alachlor dechlorination prior to an electro-Fenton process Influence on the biodegradability of the treated solution

International audienceThis study investigates alachlor herbicide removal by electro-Fenton (EF) process with and without a previous dechlorination step by electro-reduction (ER-EF). The objective is to evaluate the relevance of dechlorination before electro-Fenton according to the biodegradability evolution and the energy consumption. The influence of the applied current, the ferrous ions concentration and the air flow rate on the production of hydrogen peroxide and on the general behavior of alachlor removal by EF oxidation was studied and optimized EF conditions were chosen. Scavenger tests were performed to determine the contribution of hydroxyl radicals (•OH), superoxide radicals (•O2-) and sulfate radicals (• SO4-) during alachlor degradation. Some intermediate products formed during degradation by EF of alachlor and of the electroreduced solution were identified and the evolution of small organic acids was examined. Possible pathways of alachlor degradation and of deschloroalachlor, the mean byproduct from ER, were proposed on the basis of the EF reaction. EF treatment significantly improved the biodegradability of electrolyzed solutions with BOD5/COD ratio increasing from 0 to 0.4 after 0.5 h oxidation and can be further enhanced by the application of ER prior to EF, leading to a maximum value for the BOD5/COD ratio of 0.7 that can be due to the absence of chloroacetic acid found during the EF treatment. The energy consumption of the different electrochemical processes was also evaluated