scholarly journals Comparison of a Biosensor and a Commercial UV-Visible Method for Measuring Hexavalent Chromium in Liquid Medium

2021 ◽  
Author(s):  
Melany Avellaneda ◽  
Santiago Xavier Mafla ◽  
Moraima Mera
Keyword(s):  
Hexavalent Chromium ◽  
Gene Transformation ◽  
Coefficient Of Determination ◽  
Human Consumption ◽  
Allowable Limit ◽  
E Coli ◽  
Margin Of Error ◽  
Uv Visible ◽  
Bacteria Resistance

Abstract The objective of the research was to contrast two methods for the quantification of hexavalent chromium. The first method is the biosensor that from the gene transformation of the cells of Escherichia coli, was incorporated by electroporation the plasmid pTOP Blunt V2, synthesized with luxA genes that provides luminescence through the catalytic activity of the luciferase top and chr genes that give the bacteria resistance to chromium. The second method is the application of the UV-visible colorimetric technique. Chromium was analysed at different concentrations, from 0.05 mg l−1 (maximum allowable limit for human consumption); 0.1 mg l−1; 0.2 mg l−1; 0.4 mg l−1; 0.8 mg l−1 and 1 mg l−1 with 5 replicates, subsequent to this, the two methods of chromium analysis were applied in river samples, thus obtaining that the biosensor in concentrations of 2x106 CFU of E. coli, has a margin of error of 1.4%, a result derived from the coefficient of determination of the absorbance of chromium, unlike the UV-visible method with the colorimetric equipment, which presented a reading error of 3.9%.

scholarly journals Determination of Hexavalent Chromium (Cr(VI)) Concentrations via Ion Chromatography and UV-Vis Spectrophotometry in Samples Collected from Nacogdoches Wastewater Treatment Plant, East Texas (USA)

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Kefa K. Onchoke ◽  
Salomey A. Sasu
Keyword(s):  
Wastewater Treatment ◽  
Hexavalent Chromium ◽  
Ion Chromatography ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Standard Addition ◽  
Environmental Pollutant ◽  
Uv Visible ◽  
Wastewater Samples

The concentration of hexavalent chromium (Cr(VI)), a toxic environmental pollutant and carcinogen, was determined in samples collected from Nacogdoches Wastewater Treatment Plant (NWWTP) using ion chromatography and UV-visible spectrophotometry (IC, UV-Vis). On reaction with 1,5-diphenylcarbazide (DPC) Cr+6 forms a 1,5-diphenylcarbazide-Cr(VI) complex, which is then analyzed at 530 nm and 540 nm, respectively. Via ion chromatography Cr(VI) concentrations were in the range of 0.00190±0.0020 and 0.0010±0.0006 ppm at the influent and effluent, respectively. With the use of standard addition wastewater samples were spiked with a 0.5 ppm Cr(VI) standard of various amounts and subsequently analyzed with UV-Vis spectrophotometry. The spiked concentrations gave Cr(VI) concentrations in the range of 0.0090±0.0060 ppm and 0.0040±0.0061 ppm at the influent and influent wastewater, respectively. The determined Cr(VI) concentrations through the ion chromatography and UV-Vis spectrophotometry are below the maximum USEPA contaminant concentration of 0.1 ppm. From the analysis, the NWWTP efficiently removes Cr(VI) before discharge into the environment through La Nana Creek. The removal efficiency for Cr(VI) was determined to be ≥92.8% along the wastewater treatment stages from the influent (aeration stage) to the effluent stages prior to discharge into the La Nana Creek.

scholarly journals Selection conditions of the recombinant bovine α-interferon from E. coli inclusion bodies

2019 ◽  
Vol 64 (1) ◽  
pp. 7-17
Author(s):  
A. V. Zhydzetski ◽  
M. I. Patapovich ◽  
I. V. Kudina ◽  
U. A. Prakulevich ◽  
M. V. Sholukh
Keyword(s):  
Inclusion Bodies ◽  
Interferon Α ◽  
Target Cells ◽  
Homogeneous State ◽  
E Coli ◽  
Excellent Candidate ◽  
Infected Cells ◽  
Uv Visible ◽  
To Receive

Like other proteins of the cytokine family, bovine α-interferon activates and modulates antiviral state of the target cells and inhibits division and growth of the infected cells which makes it an excellent candidate as a new antiviral therapeutic agent.This study is concerned with the determination of the optimal isolation, purification and refolding conditions of the recombinant bovine interferon-α (rbIFN-α) from inclusion bodies (IBs). Main methods used were UV/Visible spectroscopy, electrophoresis, liquid chromatography and refolding by dilution.It was found that two step IBs washing with solutions containing 50 mmol/l Tris, 50 mmol/l NaCl and 3.5 mol/l urea and their subsequent solubilization in 50 mmol/l Tris-HCl, pH 9.8 mol/l Urea and 20 mmol/l β-mercaptoethanol allow us to receive the target protein in monomeric form and 53.18 ± 9.3 % purity. Further application of the anion-exchange tandem chromatography on DE 52 cellulose and toyopearl DEAE-650 M gives a possibility to remove the major impurities and obtain rbIFN-α with 80.7 ± 8.6 % purity. Refolding by dilution in the buffer containing 20 mmol/l NaPB, рН 7.4, 0.4 mol/l sucrose, 1 mmol/l L-Cys, 0.1 mmol/l L-Cystine, 1 mmol/l EDTA, 0.05 % Kolliphor EL at 10 °C followed by the protein collection allows to get the recombinant rbIFN-α in homogeneous state, with 98.43 % purity and antiviral activity about (5 ± 3.6)•106 U/mg.

Determination of Aflatoxins in Edible Oils from China and Ethiopia Using Immunoaffinity Column and HPLC-MS/MS

2019 ◽  
Vol 102 (1) ◽  
pp. 149-155 ◽  
Author(s):  
Lingyun Chen ◽  
Alemu Eshetie Molla ◽  
Kassa Metsehet Getu ◽  
Ande Ma ◽  
Chengsong Wan
Keyword(s):  
Edible Oils ◽  
Total Concentration ◽  
Edible Oil ◽  
Sub Saharan Africa ◽  
National Standard ◽  
Human Consumption ◽  
Immunoaffinity Column ◽  
Allowable Limit ◽  
Policy Makers

Abstract Background: Aflatoxin (AF) ingestion through contaminated foodstuffs causes at least 250 000 deaths every year from hepatocellular carcinoma in China and sub-Saharan Africa. Objective: The main objective of the study was to determine the aflatoxin levels of oils in South Gondar, Ethiopia, and oils purchased from retail markets in Guangzhou, China. Methods: We used a rapid, sensitive, and selective HPLC-tandem mass spectrometry (MS/MS) method for the determination of aflatoxins in edible oils from China and Ethiopia using immunoaffinity column cleaning. Results: The level of contamination for Ethiopian oils ranged between 0.07 and 145.59 μg/kg for total aflatoxins. Of the 27 edible oil samples from Guangzhou, China, the total concentration of aflatoxins (AFB1 + AFB2 + AFG1 + AFG2) ranged between 0.03 and 2.23 μg/kg. Conclusions: The study concluded that the peanut oils from Ethiopia were contaminated with aflatoxins higher than the allowable limit set by many countries while the oils from China were safe for human consumption. Highlights: We first describe an HPLC-MS/MS method for the determination of aflatoxins in 48 edible oil samples from China and Ethiopia using immunoaffinity column cleaning. This is the first preliminary study done on Ethiopian edible oils, giving policy-makers and future researchers baseline data. It is also used to assess the aflatoxin levels of the Chinese edible oils from Guangzhou. Therefore, conducting a comparative study points out the severity of the problem and helps to formulate a new national standard for policy-makers, making this study imperative.

scholarly journals MICROBIAL FOOD SAFETY OF STREET FOODSAROUND THE VICINITY OF LSPU - SCCREGINA

2020 ◽  
Vol 8 (12) ◽  
pp. 75-80
Author(s):  
Regina E. Gloria ◽  
◽  
Ph. D Mary Jane D. Fuentes ◽  
DPA Zenaida O. Vitasa Ed. D. ◽  
◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Human Consumption ◽  
E Coli ◽  
Descriptive Research ◽  
A Value ◽  
Pathogenic Microbes ◽  
The Mean ◽  
High Level

Knowing the number of pathogenic microbes in the street foods such as Escherichia coli, coliform, and molds present in street foods around the vicinity of LSPU – SCC was the focused of the study. Determination of the quality of the street foods such as banana cue, kikiam, kwek – kwek, minane, and siomai of which has a high level of safety in the street food around the vicinity of LSPU – SCC were considered. This study utilized the Descriptive research design and the mean in testing and gathering of data. The results reveled that all the street foods tested were safe from E. coli with the mean of ocfu/g and all at lss than 10 cfu/g or 0 count which gathered Satisfactory remarks. However, the findings revealed that the banana cue, minane and siomai were safe from coliform while kwek and kikiam were not with a value of 2800 cfu/g. In addition, all the street foods tested were safe from molds and the total mean of all the microbes present were 987.47 cfu/g which means that the street foods were Unsatisfactory level with 100cfu/g and above count and revealed that only banana cue, minane, and siomai are safe for human consumption while large amount of microbes were found in kikiam, and kwek -kwek which means that they are not safe for human and may cause disease.

Concentration determination of chromatin in unstained resin-embedded sections by means of Z-contrast in STEM

1990 ◽  
Vol 48 (2) ◽  
pp. 186-187
Author(s):  
M. Haider ◽  
B. Bohrmann
Keyword(s):  
Energy Loss ◽  
Freeze Substitution ◽  
Biological Macromolecules ◽  
Local Concentration ◽  
E Coli ◽  
Concentration Determination ◽  
Phosphorous Content ◽  
Z Contrast ◽  
Electron Energy Loss

The technique of Z-contrast in STEM offers the possibility to determine the local concentration of macromolecules like lipids, proteins or DNA. Contrast formation depends on the atomic composition of the particular structure. In the case of DNA, its phosphorous content discriminates it from other biological macromolecules. In our studies, sections of E. coli, the dinoflagellate Amphidinium carterae and Euglena spec. cells were used which were obtained by cryofixation followed by freeze-substitution into acetone with 3% glutaraldehyde. The samples were then embedded either in Lowicryl HM20 at low temperature or in Epon at high temperature. Sections were coated on both sides with 30Å carbon.The DF- and the inelastic image have been recorded simultaneously with a Cryo-STEM. This Cryo-STEM is equipped with a highly dispersive Electron Energy Loss Spectrometer. With this instrument pure Z-contrast can be achieved either with a Filtered DF-image divided by the inelastic image or, as is used in this paper, by dividing the conventional DF-image by an inelastic image which has been recorded with an inelastic detector whose response is dependent on the total energy loss of the inelastically scattered electrons.

Co-expression of recombinant single chain variable fragment recognizing blood antigen fused with sumo and chaperones in Escherichia coli

2018 ◽  
Vol 40 (4) ◽  
Author(s):  
Dang Thi Ngoc Ha ◽  
Le Thi Thu Hong ◽  
Truong Nam Hai
Keyword(s):  
Recombinant Antibody ◽  
Blood Type ◽  
Soluble Form ◽  
Supernatant Fraction ◽  
Blood Group Antigens ◽  
Single Chain ◽  
E Coli ◽  
Recombinant Scfv ◽  
Single Chain Variable Fragments

Single chain variable fragments (scFv) have widely been used in research, diagnosis and treatment, but the scFv is considered as difficult protein for expression in E. coli. In previous studies, we expressed a construction of recombinant single chain variable fragments again antigen specific for blood type A (antiA-scFv) individually or fused with Trx or SUMO. However, soluble fraction was low abandant and only approximately 40% when fused with Trx, the other cases were expressed in form of inclusion body. Therefore, it was difficult for purification, refolding and activity assesment. In thispaper, we demonstrated a suitable construction for soluble production of antiA-scFv fused with SUMO (SM/antiA-scFv) in presence of chaparones. Under fermentation with 0.1 mM IPTG at 20oC, the SM/antiA-scFv was entirely expressed in soluble form. Importantly, after cleavage from SUMO with SUMOprotease, antiA-scFv was still maintained in the supernatant fraction. Therefore, it can help ensure bioactivity and is useful for purification process. To the best of our knowledge, this is the first report showing soluble recombinant scFv fused with SUMO in presence of chaperone for determination of blood group antigens. Thus, this result facilitates the optimal study of soluble expression, purification and bioactivity determination of the antiA-scFv recombinant antibody. 

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