Concentrations Of Ammonium Chloride Research Articles

Conditional Optimization of Single Cell Protein Production from Crude Oil by <i>Pseudomonas aeruginosa</i>

The study was carried out to investigate the possible biodegradation of crude oil as a carbon by the bacterium <i>Pseudomonas aeruginosa</i> isolated from marine environment (Ras El-Menkar- Benghazi- Libya) using basal yeast extract protease peptone-3 (BYP) enriched medium. The isolated bacterium was identified and characterized according to its cultural condition and microbial biochemical properties. Different experiments were developed throughout this study to stimulate bacterial growth and production of single cell protein (SCP). The results show that the optimal concentration of crude oil as a carbon source for the highest bacterial growth (1.14g/l), and production of SCP (0.65g/l; 57.02% of the biomass dry weight) was 1%. This was required to utilize up to 50.6% of oil as a carbon source. As to the nitrogen source, the optimal concentration of ammonium chloride was 0.1%, in which the bacterial growth and SCP production increased to 1.23 g/l and 0.67 g/l respectively. The stimulating effects of organic and inorganic factors on the bacterial growth and SCP production was also tested. Addition of inorganic nutrients such as potassium phosphate (0.05%), magnesium sulphate (0.01%), and organic nutrient in the form of yeast extract (0.1%) to the fermentation medium slightly promoted the bacterial growth which reflected positively on SCP production and the percentage of the consumed crude oil, (>57%) at final pH value of 8.0. The obtained results indicated that the isolated<i> Pseudomonas aeruginosa</i> posses the ability to utilize the crude oil and use it as a carbon for bacterial growth and production of SCP.

Adaptation of Anaerobic Digestion Microbial Communities to High Ammonium Levels: Insights from Strain-Resolved Metagenomics.

Ammonia release from proteinaceous feedstocks represents the main inhibitor of the anaerobic digestion (AD) process, which can result in a decreased biomethane yield or even complete failure of the process. The present study focused on the adaptation of mesophilic AD communities to a stepwise increase in the concentration of ammonium chloride in synthetic medium with casein used as the carbon source. An adaptation process occurring over more than 20 months allowed batch reactors to reach up to 20 g of NH4+ N/L without collapsing in acidification nor ceasing methane production. To decipher the microbial dynamics occurring during the adaptation and determine the genes mostly exposed to selective pressure, a combination of biochemical and metagenomics analyses was performed, reconstructing the strains of key species and tracking them over time. Subsequently, the adaptive metabolic mechanisms were delineated by following the single nucleotide variants (SNVs) characterizing the strains and prioritizing the associated genes according to their function. An in-depth exploration of the archaeon Methanoculleus bourgensis vb3066 and the putative syntrophic acetate-oxidizing bacteria Acetomicrobium sp. ma133 identified positively selected SNVs on genes involved in stress adaptation. The intraspecies diversity with multiple coexisting strains in a temporal succession pattern allows us to detect the presence of an additional level of diversity within the microbial community beyond the species level.

Nile red-based lipid fluorometry protocol and its use for statistical optimization of lipids in oleaginous yeasts.

As lipogenic yeasts are becoming increasingly harnessed as biofactories of oleochemicals, the availability of efficient protocols for the determination and optimization of lipid titers in these organisms is necessary. In this study, we optimized a quick, reliable, and high-throughput Nile red-based lipid fluorometry protocol adapted for oleaginous yeasts and validated it using different approaches, the most important of which is using gas chromatography coupled to flame ionization detection and mass spectrometry. This protocol was applied in the optimization of the concentrations of ammonium chloride and glycerol for attaininghighest lipid titers in Rhodotorula toruloides NRRL Y-6987 and Yarrowia lipolytica W29 using response surface central composite design (CCD). Results of this optimization showed that the optimal concentration of ammonium chloride and glycerol is 4 and 123 g/L achieving a C/N ratio of 57 for R. toruloides, whereas for Y. lipolytica,concentrations are 4 and 139 g/L with a C/N ratio of 61 for Y. lipolytica. Outside the C/N of 33 to 74 and 45 to 75, respectively, for R. toruloides and Y. lipolytica, lipid productions decrease by more than 10%. The developed regression models and response surface plots show the importance of the careful selection of C/N ratio to attainmaximal lipid production. KEY POINTS: • Nile red (NR)-based lipid fluorometry is efficient, rapid, cheap, high-throughput. • NR-based lipid fluorometry can be well used for large-scale experiments like DoE. • Optimal molar C/N ratio for maximum lipid production in lipogenic yeasts is ~60.

Synthesis of Cu and CuO nanoparticles from e-waste and evaluation of their antibacterial and photocatalytic properties

Waste printed circuit boards (WPCBs) contain a plethora of valuable metals, considered an attractive secondary resource. In the current research, a hydrometallurgical process combined ammonia/ammonium chloride leaching and reduction (using L-ascorbic acid) to recover copper and its oxide (CuO) as nanosized particles from WPCBs was investigated. The results of leaching indicated that 96.7% of copper could be recovered at a temperature of 35 °C for a leaching duration of 2 h with ammonium chloride and ammonia concentration of 2 mol/L at a solid:liquid ratio of 1:10 g/cm3. The synthesized particles exhibit spherical and distorted sphere morphology with average particle size of 460 nm and 50 nm for Cu and CuO NPs, respectively. The antibacterial activity of Cu, CuO, and a (1:1) blend of both (Cu/CuO) has been examined against five different bacterial and fungal strains. The highest zone of inhibition was measured as 21.2 mm for Cu NPs toward Escherichia coli and 16.7 mm for Cu/CuO blend toward Bacillus cereus bacteria. The highest zone of inhibition was measured as 13 mm and 13.8 mm for Cu/CuO blend toward Fusarium proliferatum and Penicillium verrucosum fungi. Cu/CuO blend showed notable photocatalytic activity towards Rhodamine B dye under visible light irradiation with 96% degradation rate within 120 min. Using the process developed in this study, copper and its oxide as nanoparticles can be produced from WPCBs and used for multifunctional applications.Graphical abstract

Effects of Ammonia on Juvenile Sunray Surf Clam (Mactra chinensis Philippi) in Laboratory Tests

The current study aimed to determine the acute and sub-chronic toxicity of ammonia to juvenile surf clams (Mactra chinensis Philippi). Acute toxicity tests were conducted with seven concentrations of ammonium chloride using a 96 h static-renewal approach. Sub-chronic ammonia exposure tests (20 d exposures) were conducted with 6 concentrations at 20 °C. The 96 h median lethal concentration (96 h LC50) was 11.1 (10.0; 12.0) mg/L total ammonia nitrogen (TAN) and 0.56 (0.50; 0.60) mg/L unionized ammonia (NH3). The relative growth rate was significantly reduced at concentrations higher than 1.6 mg/L TAN (0.075 mg/L NH3) in the 20 d tests. The estimated maximum acceptable toxicant concentration (MATC) based on the reduced growth of juvenile M. chinensis was between 0.8 and1.6 mg/L TAN (0.038–0.075 mg/L NH3). Histopathological changes were evaluated in the surviving clams after 20 days of exposure. Exposure to 14.1 mg/L TAN (0.661 mg/L NH3) resulted in changes in the mantle, foot and digestive diverticulum. We also examined the antioxidant enzyme activities of superoxide dismutase (SOD) and catalase (CAT) in 10 d and 20 d at 6 different levels (plus a control) of ammonia from 0.8 mg/L to 14.1 mg/L TAN. Ammonia exposure at 0.8 mg/L TAN (0.038 mg/L NH3) significantly affected SOD and CAT activities. The level of enzymic activity decreased with the increasing concentration of TAN. The results improved our understanding of oxidative damage under ammonia exposure and provided data for the aquaculture of sunray surf clams.

Evaluation of the Role of the Activating Application Method in the Cold Sintering Process of ZnO Ceramics Using Ammonium Chloride.

The influence of the method of applying the activating additive ammonium chloride and its concentration on the density and microstructure of zinc oxide ceramic obtained by cold sintering at 244 °C was investigated. The activating agent was applied by two methods: impregnation and subsequent autoclave treatment. When the powder was activated by the impregnation method, the crystal sizes remained at the initial level of 0.17-0.19 μm. After the autoclave treatment, the crystal sizes increased to 0.31-0.53 μm. Samples of cold sintering ZnO with relative density up to 0.96 and average grain sizes 0.29-0.86 μm were obtained. ZnO powders and ceramic samples were analyzed using SEM, TGA/DSC, and XRD to reveal the effect of the powder activation method and cold sintering conditions on the material microstructure. The effect of ammonium chloride concentration on grain growth and microstructure of ceramic samples is shown. It was found that the average grain size of ceramic samples with an increase in additive concentration passes through a minimum. In cold sintering of the autoclave activated powder, the effect of reducing the average grain size was observed. The results of this work are discussed on the basis of the idea of the solid-phase mobility of the crystal structure arising when interacting with an aqueous medium.

Improved Itaconate Production with Ustilago cynodontis via Co-Metabolism of CO2-Derived Formate.

In recent years, it was shown that itaconic acid can be produced from glucose with Ustilago strains at up to maximum theoretical yield. The use of acetate and formate as co-feedstocks can boost the efficiency of itaconate production with Ustilaginaceae wild-type strains by reducing the glucose amount and thus the agricultural land required for the biotechnological production of this chemical. Metabolically engineered strains (U. cynodontis Δfuz7 Δcyp3 ↑Pria1 and U. cynodontis Δfuz7 Δcyp3 PetefmttA ↑Pria1) were applied in itaconate production, obtaining a titer of 56.1 g L-1 and a yield of 0.55 gitaconate per gsubstrate. Both improved titer and yield (increase of 5.2 g L-1 and 0.04 gitaconate per gsubstrate, respectively) were achieved when using sodium formate as an auxiliary substrate. By applying the design-of-experiments (DoE) methodology, cultivation parameters (glucose, sodium formate and ammonium chloride concentrations) were optimized, resulting in two empirical models predicting itaconate titer and yield for U. cynodontis Δfuz7 Δcyp3 PetefmttA ↑Pria1. Thereby, an almost doubled itaconate titer of 138 g L-1 was obtained and a yield of 0.62 gitaconate per gsubstrate was reached during confirmation experiments corresponding to 86% of the theoretical maximum. In order to close the carbon cycle by production of the co-feed via a "power-to-X" route, the biphasic Ru-catalysed hydrogenation of CO2 to formate could be integrated into the bioprocess directly using the obtained aqueous solution of formates as co-feedstock without any purification steps, demonstrating the (bio)compatibility of the two processes.

Molasses fermentation to produce low-cost carbon source for denitrification

In the present work, the fermentation of molasses using Saccharomyces cerevisiae was optimized in terms of denitrification efficiency, using the relative total nitrogen (TN) removal ratio and the C/N consumption ratio as the indicators. The denitrification efficiency in different wastewater was also measured in the presence of different carbon sources for denitrification, that is, fermentation broth, unfermented molasses, sodium acetate, ethanol and methanol. The results indicated that the optimal fermentation conditions were as follows: pH = 4.0; temperature, 33 °C; dilution rate, 0.15 h−1; sugar concentration, 13%; ammonium chloride concentration, 0.5 g/L; and air-flow rate in the reactor, 0.1 vvm for 30 min every 12 h. The relative TN removal ratio with the fermentation broth was 39% higher than that with unfermented molasses. However, the denitrification efficiency of the fermentation broth varied between landfill leachate, herbicide wastewater and brewing wastewater. The relative TN removal ratio was significantly higher only in the brewing wastewater, and the C/N consumption ratio was also significantly lower than that with methanol, ethanol and molasses. These results showed that the use of molasses fermentation broth as the carbon source for denitrification has advantages for specific sewage regarding effectiveness. The raw material cost of the fermentation broth was ca. 30% lower than sodium acetate. The results also suggested that the bacterial community structure had a significant impact on the denitrification efficiency of the fermentation broth.

ВОССТАНОВЛЕНИЯ ДЕТАЛЕЙ СЕЛЬСКОХОЗЯЙСТВЕННОЙ ТЕХНИКИ НАНЕСЕНИЕМ КОМПОЗИЦИОННЫХ ПОКРЫТИЙ НА ОСНОВЕ ЖЕЛЕЗА

Great opportunities for increasing the resource of parts of agricultural machinery that require restoration are opened up by technologies for applying hardening coatings. Options for obtaining galvanic deposits in various electrolytes, which allow depositing metal coatings with various special properties that ensure reliable operation of restored units under appropriate conditions, are considered in the article. Solutions of sulphate, chloride, and hydroboric fluoride salts of divalent iron were used as the electrolyte. Methods of chemical analysis of galvanic deposits were used. The hardness of the deposited layers was determined using a PMT-3 instrument. The effect of various alloying additives on the quality of the precipitates obtained is analyzed depending on the concentration of inclusions. The boundaries of inclusion concentrations are determined. It has been established that for controlled deposition of a composite coating, the concentration of inclusions in the deposited iron-containing coating should not exceed 20 g/l. It has been found that even an insignificant presence of manganese inclusions in an iron-based composite coating, which is of the order of the measurement error, doubles its hardness. The dependence of the concentration of ammonium chloride, as the base material for the extraction of pure manganese, on the hardness of the deposited galvanic precipitate, was studied in the framework of the described study. The highest hardness was achieved at a concentration of NH4Cl in the range of 100–150 g/l, and manganese - 0.4% by weight. Graphical dependences of the main quality indicators of the resulting coatings on the type and composition of the electrolytes used were obtained. The influence of the electrolyte temperature and electrolysis regimes on the hardness of the deposited metal is analyzed.

Development of continuous compositional gradient Ni-W coatings utilizing electrodeposition for superior wear resistance under sliding contact

In the present work, the widely used ammonia-citrate bath for electrodeposition of homogeneous Ni-W coatings has been judiciously modified and a strategy has been developed to deposit dense nanocrystalline Ni-W coatings with continuous compositional gradient across the coating thickness. It was observed that the ammonium chloride, which is typically used to control the pH and increase the Faradaic efficiency of the bath, affects the compositional gradient profile in Ni-W coatings. The concentration of ammonium chloride has been optimised to obtain gradient Ni-W coatings with linear compositional variation in the W-content. Utilizing chemical stability diagrams and the existing theories, a plausible deposition mechanism for the influence of ammonium chloride has been proposed by correlating the W-content with the concentration of mixed metal complexes. The compositional gradient Ni-W coatings have demonstrated significantly lower residual stresses and superior scratch resistance compared to their homogeneous counter parts.

Hyperammonemia‐induced DNA‐damage Response Leads to the Acquisition of Cellular Senescence in Neurons after Chronic Liver Failure

BackgroundHepatic encephalopathy (HE) is a serious neuropsychiatric complication of chronic liver disease (Type C HE) that affects health‐related quality of life, clinical management, and patient survival. The current understanding of HE pathophysiology has centered around the synergistic actions of hyperammonemia with peripheral and central inflammation to precipitate HE. Furthermore, HE is associated with oxidative stress with consequences on lipid, protein and RNA structure, but the impact of these reactive species on DNA structure and function has not been analyzed and the implications of oxidative DNA lesions and the DNA damage response (DDR) has not been appreciated. In other organs, when DNA repair mechanisms fail, activation of the DDR may result in cellular senescence, a permanent cell cycle arrest with epigenetic alterations that promotes the production of a senescence‐associated phenotype (SASP) leading to the secretion of many factors including cytokines, chemokines, growth factors, proteases and insoluble extracellular matrix components13, In HE, senescent markers have been found in astrocytes, but research into neuronal senescence has been limited. The aim of this study is to assess the oxidative DNA lesions and DDR in HE.MethodsSD rats underwent bile duct ligation (BDL) surgery and C57BL/6 mice were treated with CCl4 for 16 wks to induce chronic liver failure. In parallel, human autopsy brain samples from patients with HE due to liver cirrhosis and age‐ and sex‐matched controls were used. In vitro, hippocampal neurons were treated with various concentrations of ammonium chloride (up to 5 mM) in the presence of the ATM inhibitor KU55933. Oxidative DNA lesions and double‐stranded DNA breaks were visualized by DNA comet assay (in vitro only), 8‐oxo‐2‐deoxyguanosinie (8‐oxoG) and g‐H2AX Immunofluorescence respectively. The DDR (phosphoATM, GADD45b) and markers of senescence (p16, p21, b‐Gal and SASPs; CCL2, TGFb1, IGFBP3, PAI‐1 and IL‐6) were assessed by IHC and qPCR.ResultsIn rodent models of HE and in human autopsy samples, oxidative DNA lesions and double‐stranded DNA breaks were evident in neurons of the CA1 and dentate gyrus in the hippocampus and in the purkinje cell layer in the cerebellum, regions known for their involvement in learning and memory and motor control. Evidence of these DNA lesions correlated with increased expression of markers of the DDR and cellular senescence in the same neuronal cell population. Treatment of hippocampal neurons with ammonia resulted in oxidative DNA lesions, double stranded DNA breaks, DDR activation and the acquisition of a senescent‐like phenotype. Inhibition of the DDR, in vitro attenuated the expression of markers of senescence.ConclusionHyperammonemia induces oxidative DNA damage and the subsequent activation of a DDR in neurons during Type C HE. Aberrant activation of the DDR promotes the hyperammonemia‐induced acquisition of a senescent‐like phenotype in neurons that may contribute to pathogenesis of Type C HE.

The kinetics of heparin adsorption with Dowex 1x1 ion exchange resin

The recovery of heparin from the porcine intestinal mucosa by using the ion exchange resin was studied. The procedure involved the following steps: alkaline hydrolysis, ion exchange resin adsorption, and elution. The activity of heparin was measured by an antifactor Xa assay. The ammonium chloride/ammonium hydroxide was used as a buffer, and the effect of salt concentration on the adsorption efficiency was evaluated. The results showed that the highest heparin yield (86.17%) was achieved at the lowest concentration of ammonium chloride. The pseudo-first-order model was shown as more adequate to describe heparin adsorption onto the resin.

Recovery of Vanadium by ammonium chloride precipitation method using response surface methodology

In this study, an attempt was made to recover vanadium from an alkaline solution using the precipitation process. A white salt ammonium metavanadate was obtained using the ammonium chloride precipitation method. Ammonium chloride was added directly to the alkaline liquor solution and the pH was adjusted approximately between 5 and 7 to form the white salt. The parameters affecting the recovery of vanadium, including the ammonium chloride concentration, the pH and the vanadium concentration in the caustic solution, were examined. The precipitation time had no significant influence on the vanadium recovery. The concentration of vanadium in the caustic solution and the concentration of ammonium chloride used for the precipitation were inversely related. It was found that a high recovery (over 90%) can be achieved with ammonium chloride and vanadium with concentrations over 4% (w / v) or 1000 mg L-1 (in the lye solution). It has also been observed that working in the pH range of 5 to 7 results in over 90% recovery. The influence of the parameters mentioned on the recovery of impurities was examined and the optimal values ​​determined. Ultimately, the maximum vanadium recovery (97.29%) was achieved at the optimal point obtained from the reaction surface methodology.

Electrochemical Preparation of Highly Oriented Microporous Structure Nickel Oxide Films as Promising Electrodes in Urea Oxidation

Abstract Highly oriented microporous nickel oxide films were prepared through the simple and fast anodization of nickel foils at 30 V, followed by calcination at 400 °C. Low concentrations of ammonium chloride and potassium hydroxide solutions, which were dispersed in ethylene glycol, were used as electrolytes. Microporous dimensions and large surface areas of the films were obtained by using both electrolytes. The ammonium chloride system provided a highly oriented microporous structure with excellent distribution of pores at the surface of nickel foil. On the contrary, it was not uniform in the potassium hydroxide system. Furthermore, cyclic voltammetry of the microporous films in alkaline solutions containing urea showed the highest oxidation currents at the nickel oxide films prepared in the ammonium chloride system. This nickel oxide film also showed excellent stability of the current responses, indicating that the method has potential to be applied in electrode preparation, especially urea oxidation.

Heterotrophically Ultrahigh-Cell-Density Cultivation of a High Protein-Yielding Unicellular Alga Chlorella With a Novel Nitrogen-Supply Strategy.

The unicellular green alga Chlorella is an ideal protein source. However, the high production cost and low production capability of the current main photoautotrophic culture mode limit its application especially as an alternative protein source for food and feed, which might be overcome through high-cell-density cultivation in fermenters. In this study, a Chlorella sorokiniana strain CMBB276 with high protein content was selected from five Chlorella strains by comprehensive evaluation of their growth rates, protein contents, and yields. The optimal cultural temperature, pH, and mole ratio of carbon and nitrogen (C/N) for C. sorokiniana CMBB276 growth were found to be 30°C, 6.5, and 18, respectively. Ammonium chloride was proved to be the best nitrogen (N) source for C. sorokiniana CMBB276 growth, whereas growth inhibition caused by the accumulation of salts was observed under fed-batch cultivation when maintaining a constant C/N ratio of 18 by controlling pH with sodium hydroxide solution. By simultaneously reducing the concentration of ammonium chloride in the feeding medium and controlling pH with ammonium hydroxide, we finally achieved the ultrahigh-cell-density cultivation of C. sorokiniana CMBB276. The highest biomass concentration and protein yield reached 232 and 86.55 g l−1, respectively, showing the great potential of culturing C. sorokiniana CMBB276 in fermenters for economic and large-scale protein source production.

Enhancement of laccase production from a newly isolated Trichoderma harzianum S7113 using submerged fermentation: Optimization of production medium via central composite design and its application for hydroquinone degradation

Trichoderma harzianum S7113 as an efficient fungal isolate for laccase production was identified using the 18S rRNA sequencing. T. harzianum S7113 attained its maximal laccase production level on the 14th day of static incubation at 28 °C and pH 5.0 using the inoculum size of 5 discs (14 mm), according to the one factor per time (OFT) method. The most appropriate carbon, organic and inorganic nitrogen sources to promote maximal laccase synthesis were glucose (15 g/L), beef extract (5 g/L), and ammonium chloride (4 g/L), respectively. Results of Response Surface Methodology (RSM) revealed that glucose, meat extract, and ammonium chloride concentrations of 17.54, 7.17, and 4.36 g/L respectively, at a pH value of 6.74 are the favorite conditions for high titer production. The ANOVA analysis highlighted an excellent match between the actual experimental results and the model predicted laccase production levels. The biodegradation of hydroquinone (HQ) by T. harzianum S7113 laccase was most efficient in the pH range of 5.0 to 6.5. The increase in laccase concentration led to a significant increase in the HQ conversion to get a biodegradation rate of 92 ± 2.6% with a laccase concentration of 0.75 U/mL after 3 h of reaction.

Evaluation of Fed-Batch Fermentation for Production of Polyhydroxybutyrate With a Banana Pulp Juice Substrate From an Agro Industrial By-Product

Pollution resulting from the persistence of plastics in the environment has driven the development of substitutes for these materials through fermentation processes using agro-industrial wastes. Polyhydroxybutyrate (PHB) is a rapidly biodegradable material with chemical and mechanical properties comparable to those of some petroleum-derived plastics. PHB accumulates intracellularly as an energy reserve in a wide variety of microorganisms exposed to nutritionally imbalanced media. The objective of this study was to evaluate the use of a banana waste product as a carbon source for PHB production. PHB was extracted by acid methanolysis and detected by gas chromatography-mass spectrometry. Eleven bacterial strains with potential for PHB production were evaluated by in vitro fermentation in a culture broth containing fructose as the carbon source and limited nitrogen. A 22 central composite rotational design was applied to optimize the concentrations of banana juice and ammonium chloride needed to maximize the PHB-producing biomass concentration. The process was then carried out in a 3 L fed-batch fermentation system that included an initial stage of biomass growth. Banana juice was used as the carbon source and fructose pulses were added to maintain the test sugar concentrations of 30, 40, and 50 g/L. The control strain, Cupriavidus necator (ATCC 17699), produced 2.816 g/L of PHB, while productivity of the most promising isolate, C. necator (CR-12), was 0.495 g/L. Maximum biomass production was obtained using 5% banana juice and 2 g/L ammonium chloride. PHB production was not detected in fed-batch fermentations supplemented with 30 or 40 g/L of fructose, while the mean PHB production in fermentations with 50 g/L of fructose was 1.3 g/L.

Large-Scale Preparation of Highly Stable Recombinant Human Acidic Fibroblast Growth Factor in Escherichia coli BL21(DE3) plysS Strain.

In this study, the optimum human aFGF gene encoding haFGF135 was cloned in pET3c and transferred to Escherichia coli BL21(DE3) plysS. To enhance the yield of fermentation and the expression level of the target protein, the fermentation parameters, including temperature, pH, dissolved oxygen, glucose concentration, ammonium chloride concentration, induction time, and inducer (IPTG) concentration, were optimized. The optimized fermentation parameters were used in large-scale fermentation (30 L). Ion-exchange and heparin-affinity column chromatography techniques were used for separation and purification of rhaFGF135 protein. HPLC, isoelectric focusing electrophoresis, and mass spectrometry were used to detect the purity, isoelectric point, and molecular weight and peptide map of rhaFGF135 protein, respectively. Mitogenic activity of rhaFGF135 protein was detected in NIH-3T3 cells and a full-thickness injury wound diabetic rat model. The production and expression level of rhaFGF135 in the 30-L scale fermentation reached 80.4 ± 2.7 g/L culture and 37.8% ± 1.8%, respectively. The RP-HPLC and SDS-PAGE purity of the final rhaFGF135 product almost reached 100%, and the final pure protein yield was 158.6 ± 6.8 mg/L culture. Finally, the cell and animal experiments showed that rhaFGF135 retained a potent mitogenic activity. The large-scale process of rhaFGF135 production reported herein is relatively stable and time-saving, and thus, it can be used as an efficient and economic strategy for the synthesis of rhaFGF135 at the industrial level.

Effect of Ammonium Salts on the Decarboxylation of Oxaloacetic Acid in Atmospheric Particles

Oxaloacetic acid (OAA) is a 3-oxocarboxylic acid formed from the oxidation of succinic acid. OAA and other 3-oxocarboxylic acids experience a decarboxylation reaction in aqueous solutions, which can be catalyzed by ammonium and amines. This catalysis has not been studied under atmospherically relevant conditions despite previous interest in OAA in the atmosphere. To address this, 1 mM solutions of OAA were prepared with varying concentrations of ammonium sulfate, ammonium bisulfate, ammonium chloride, and sodium sulfate to simulate various atmospheric conditions. The extent of the decarboxylation was monitored using UV–visible absorption spectroscopy. OAA’s uncatalyzed decarboxylation lifetime was around 5 h. Under moderately acidic conditions representative of aerosol particles (pH = 3–4), the decarboxylation rate increased linearly with ammonium concentration up to about 2.7 M, after which additional ammonium had no effect. The effective lifetime of OAA reduced to approximately 1 h under these conditions. Density functional theory calculations support the proposed catalytic mechanism, predicting the free energy barrier height for decarboxylation to be approximately 21 kcal/mol lower after OAA has reacted with ammonium. In more acidic solutions (pH < 1), OAA’s decarboxylation was suppressed, with lifetimes of tens of hours, even in the presence of ammonium. A comparison of the decarboxylation rate with the expected rate of oxidation by OH suggests that decarboxylation will be the dominant loss mechanism for OAA, and presumably other 3-oxocarboxylic acids, in aerosol particles and cloud/fog droplets. This result explains why OAA is hard to detect in field measurements even though it is a known oxidation product of succinic acid.

The Impact of Zeolite on Ammonia Toxicity, Growth Performance and Physiological Status of the Nile Tilapia (Oreochromius niloticus)

Environmental pollution adversely affects fish growth and health. Thus, the search for agents that have a protective role against pollutants’ toxicity is worthwhile; especially those with the potential natural biological occurrence and no side effects. Hence, an investigation was undertaken to examine the opposing effect of zeolite against ammonia toxicity which induced perturbations in some hematological, biochemical parameters and poor growth in Nile tilapia (O. niloticus). Moreover, an evaluation of the efficiency of chelating zeolite to counteract the toxicity of two levels of ammonium chloride (18 and 1.8 mg NH4cl/l) was conducted. Fingerlings Nile tilapia, with weight ranges from 9.1 - 9.4 g, were assigned to five groups with three replicates. The first group was determined as control with zero additions. The 2nd and the 4th were exposed to 18 and 1.8 mg NH4Cl/l, respectively. In addition, the 3rd and the 5th groups were exposed to the same concentration of ammonium chloride with 6g Zeolite /l, respectively. As result, congruent with an increase in ammonia, a significant decrease was detected in growth performance, feed intake, feed conversion ratio, erythrocyte count (RBCS), hemoglobin content (HB), hematocrit value (Hct) and total protein in fish exposed to doses of ammonia. Moreover, the addition of zeolite enhanced the blood parameter and growth in fish exposed to a low concentration of ammonia, recording values close to those of the control fish. On the other hand, the glucose concentration, alanine aminotransferase activity (ALT), alkaline phosphatase (ALK), total lipid profile and kidney function increased significantly, particularly in fish exposed to the two levels of ammonia toxicity. Whereas, its values in a fish group exposed to a low concentration of ammonia with 6g of zeolite became similar to those of the control. Thus, the addition of zeolite to ammonia in a contaminated medium is recommended to reduce ammonia concentration in aquaculture, improve growth performance and physiological function and activities in fish.