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Enzyme and Microbial Technology

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https://www.readbyqxmd.com/read/28284314/chitosan-based-biocatalytic-nanoparticles-for-pollutant-removal-from-wastewater
#1
Dulce A Alarcón-Payán, Rina D Koyani, Rafael Vazquez-Duhalt
Chitosan, a renewable biopolymer has the prospective applications in different fields due to its gelation capacity. Nanoconfiguration of chitosan through ionotropic gelation to encapsulate enzymatic activity offers numerous potential applications. In the present study, the preparation and characterization of chitosan nanoparticles loaded with versatile peroxidase are reported. Their performance in bioremediation process and the resistance enhancement against natural microbial biodegradation were studied. The average diameter of enzymatic nanoparticles was 120nm and showed a high enzyme loading capacity...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28284313/one-step-combined-focused-eppcr-and-saturation-mutagenesis-for-thermostability-evolution-of-a-new-cold-active-xylanase
#2
Juan Pablo Acevedo, Manfred T Reetz, Juan A Asenjo, Loreto P Parra
Enzymes active at low temperature are of great interest for industrial bioprocesses due to their high efficiency at a low energy cost. One of the particularities of naturally evolved cold-active enzymes is their increased enzymatic activity at low temperature, however the low thermostability presented in this type of enzymes is still a major drawback for their application in biocatalysis. Directed evolution of cold-adapted enzymes to a more thermostable version, appears as an attractive strategy to fulfill the stability and activity requirements for the industry...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28284312/combined-cross-linked-enzyme-aggregates-of-horseradish-peroxidase-and-glucose-oxidase-for-catalyzing-cascade-chemical-reactions
#3
Le Truc Nguyen, Kun-Lin Yang
Cascade reactions involved unstable intermediates are often encountered in biological systems. In this study, we developed combined cross-linked enzyme aggregates (combi-CLEA) to catalyze a cascade reaction which involves unstable hydrogen peroxide as an intermediate. The combi-CLEA contains two enzymes̶ glucose oxidase (GOx) and horseradish peroxidase (HRP) which are cross-linked together as solid aggregates. The first enzyme GOx catalyzes the oxidation of glucose and produces hydrogen peroxide, which is used by the second enzyme HRP to oxidize 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS)...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28284311/physico-cultural-parameters-during-agnps-biotransformation-with-bactericidal-activity-against-human-pathogens
#4
Gurusamy Raman, Seon Joo Park, Natarajan Sakthivel, Anil K Suresh
Production of AgNPs with desired morphologies and surface characteristics using facile, economic and non-laborious processes is highly imperative. Cell extract based syntheses are emerging as a novel technique for the production of diverse forms of NPs, and is assured to meet the requirements. Therefore, in order to have a better understanding, and to improvise and gain control over the NPs morphological and surface characteristics, the present investigation systematically evaluates the influence of various major physico-cultural parameters including diverse growth media, concentrations of precursor salts; pH and temperature on the biotransformation of ionic silver (Ag(+)) to nanopariculate silver nanoparticles (AgNPs), utilizing the cell free extract of the bacterium, P...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28284310/enzymatic-synthesis-of-phenethyl-ester-from-phenethyl-alcohol-with-acyl-donors
#5
Hyunah Kim, Chulhwan Park
Phenethyl ester is an important contributors to food, drinks, cosmetics and perfumery. Phenethyl acetate was synthesized enzymatically from phenethyl alcohol with acyl donors catalyzed by Novozym 435 from Candida antarctica lipase B. Through acyl donor screening, acetic anhydride and vinyl acetate were found to be the optimal acyl donors for the reaction. The effects of the molar ratio, temperature and solvents were investigated. The maximum conversion of phenethyl acetate were 99.12%, and 98.44%, using acetic anhydride and vinyl acetate as the acyl donors, respectively...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28284309/alleviation-of-metabolic-bottleneck-by-combinatorial-engineering-enhanced-astaxanthin-synthesis-in-saccharomyces-cerevisiae
#6
Pingping Zhou, Wenping Xie, Aipeng Li, Fan Wang, Zhen Yao, Qi Bian, Yongqiang Zhu, Hongwei Yu, Lidan Ye
Highly efficient biosynthesis of the commercially valuable carotenoid astaxanthin by microbial cells is an attractive alternative to chemical synthesis and microalgae extraction. With the goal of enhancing heterologous astaxanthin production in Saccharomyces cerevisiae, metabolic engineering and protein engineering were integrated to improve both the expression and activity of rate-limiting enzymes. Firstly, to increase the supply of β-carotene as a key precursor for astaxanthin, a positive mutant of GGPP synthase (CrtE03M) was overexpressed together with three other rate-limiting enzymes tHMG1, CrtI and CrtYB...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28284308/enzymatic-biosensor-based-on-entrapment-of-d-amino-acid-oxidase-on-gold-nanofilm-mwcnts-nanocomposite-modified-glassy-carbon-electrode-by-sol-gel-network-analytical-applications-for-d-alanine-in-human-serum
#7
Yalda Shoja, Amir Abbas Rafati, Javad Ghodsi
Sensing and determination of d-alanine is studied by using an enzymatic biosensor which was constructed on the basis of d-amino acid oxidase (DAAO) immobilization by sol-gel film onto glassy carbon electrode surface modified with nanocomposite of gold nanofilm (Au-NF) and multiwalled carbon nanotubes (MWCNTs). The Au-NF/MWCNT nanocomposite was prepared by applying the potentiostatic technique for electrodeposition of Au-NF on the MWCNT immobilized on glassy carbon electrode surface. The modified electrode is investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), linear sweep voltammetry (LSV) and cyclic voltammetry(CV) techniques...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28284307/changing-the-electron-donor-improves-azoreductase-dye-degrading-activity-at-neutral-ph
#8
Jingxian Qi, Caroline E Paul, Frank Hollmann, Dirk Tischler
The oxygen-insensitive azoreductase AzoRo originating from Rhodococcus opacus 1CP was found to be most active at low pH (ca. 4) and high temperature (ca. 50°C). AzoRo is not an efficient biocatalyst when used at low pH due to stability problems. To overcome this issue, we discovered that AzoRo accepts an alternative electron donor, 1-benzyl-1,4-dihydronicotinamide (BNAH), which allows fast turnover at neutral pH. In order to screen this nicotinamide coenzyme mimic as a source of electrons, AzoRo-catalysed reactions were run under neutral conditions, under which typically slow rates are observed with NADH...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28284306/an-improved-amperometric-triglyceride-biosensor-based-on-co-immobilization-of-nanoparticles-of-lipase-glycerol-kinase-and-glycerol-3-phosphate-oxidase-onto-pencil-graphite-electrode
#9
Vinay Narwal, C S Pundir
Nanoparticles (NPs) of commercial lipase from Candida rugosa, of glycerol kinase (GK) from Cellulomonas species, of glycerol-3- phosphate oxidase (GPO) from Aerococcus viridans were prepared, characterized and co-immobilized onto a pencil graphite (PG) electrode. The morphological and electrochemical characterization of PG electrode was performed by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) before and after co-immobilization of enzyme nanoparticles (ENPs)...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28284305/autodisplay-of-the-la-ssb-protein-on-lps-free-e-coli-for-the-diagnosis-of-sj%C3%A3-gren-s-syndrome
#10
Gu Yoo, Carina Dilkaute, Ji-Hong Bong, Hyun-Woo Song, Misu Lee, Min-Jung Kang, Joachim Jose, Jae-Chul Pyun
The objective of this study was to present an immunoassay for the diagnosis of Sjögren's syndrome based on the autodisplayed La/SSB protein on the outer membrane of intact E. coli (strain UT-5600) and LPS-free E. coli (ClearColi™). As the first step, an autodisplay vector (pCK002) was transfected into intact E. coli and LPS-free E. coli for comparison of efficiency of autdisplay of La/SSB. The maximal level of La/SSB expression was estimated to be similar for LPS-free E. coli and intact E. coli at different optimal induction periods...
May 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28193334/glutamate-dehydrogenase-rocg-in-bacillus-licheniformis-wx-02-enzymatic-properties-and-specific-functions-in-glutamic-acid-synthesis-for-poly-%C3%AE-glutamic-acid-production
#11
Guangming Tian, Qin Wang, Xuetuan Wei, Xin Ma, Shouwen Chen
Poly-γ-glutamic acid (γ-PGA), a natural biopolymer, is widely used in cosmetics, medicine, food, water treatment, and agriculture owing to its features of moisture sequestration, cation chelation, non-toxicity and biodegradability. Intracellular glutamic acid, the substrate of γ-PGA, is a limiting factor for high yield in γ-PGA production. Bacillus subtilis and Bacillus licheniformis are both important γ-PGA producing strains, and B. subtilis synthesizes glutamic acid in vivo using the unique GOGAT/GS pathway...
April 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28193333/heterologous-expression-of-%C3%AE-glutamyl-transpeptidase-from-bacillus-atrophaeus-gs-16-and-its-application-in-the-synthesis-of-%C3%AE-d-glutamyl-l-tryptophan-a-known-immunomodulatory-peptide
#12
Meenu Saini, Shruti Bindal, Rani Gupta
Gamma-glutamyl transpeptidase from a mesophilic bacterium Bacillus atrophaeus GS-16 (BaGGT) was expressed heterologously in E. coli using pET-51b vector. Maximum production of BaGGT was obtained at 16°C after 16h of IPTG induction and the protein, in its native conformation, was active as a heterooctamer which was composed of four heterodimeric units combined together. One heterodimeric unit constituted two subunits with molecular masses of 45kDa and 21kDa, respectively. The recombinant enzyme was purified by one step His-tag affinity purification protocol with a specific activity of 90U/mg and 5...
April 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28193332/analysis-of-agaricus-meleagris-pyranose-dehydrogenase-n-glycosylation-sites-and-performance-of-partially-non-glycosylated-enzymes
#13
Christoph Gonaus, Daniel Maresch, Katharina Schropp, Peter Ó Conghaile, Dónal Leech, Lo Gorton, Clemens K Peterbauer
Pyranose Dehydrogenase 1 from the basidiomycete Agaricus meleagris (AmPDH1) is an oxidoreductase capable of oxidizing a broad variety of sugars. Due to this and its ability of dioxidation of substrates and no side production of hydrogen peroxide, it is studied for use in enzymatic bio-fuel cells. In-vitro deglycosylated AmPDH1 as well as knock-out mutants of the N-glycosylation sites N(75) and N(175), near the active site entrance, were previously shown to improve achievable current densities of graphite electrodes modified with AmPDH1 and an osmium redox polymer acting as a redox mediator, up to 10-fold...
April 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28193331/colorimetric-enumeration-of-bacterial-contamination-in-water-based-on-%C3%AE-galactosidase-gold-nanoshell-activity
#14
Fouzia Tanvir, Atif Yaqub, Shazia Tanvir, William A Anderson
In this study we report a method for the rapid and sensitive estimation of bacterial cell concentration in solution based on a colorimetric enzyme/gold nanoshells conjugate system. The CTAB capped gold nanoshells are electrostatically attracted by both the bacterial surface and the enzyme β-galactosidase. The preferential binding of cationic (CTAB)-functionalized gold nanoshells to the more negative bacterial surfaces leaves active β-galactosidase in solution, providing an enzyme-amplified colorimetric response of the binding event...
April 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28193330/conversion-of-cysteine-to-3-mercaptopyruvic-acid-by-bacterial-aminotransferases
#15
Christina Andreeßen, Vanessa Gerlt, Alexander Steinbüchel
3-Mercaptopyruvate (3MPy), a structural analog of 3-mercaptopropionic acid, is a precursor compound for biosynthesis of polythioesters in bacteria. The cost-effectiveness and sustainability of the whole process could be greatly improved by using the cysteine degradation pathway for an intracellular supply of 3MPy. Transamination of cysteine to its corresponding α-keto acid 3MPy is catalyzed by cysteine aminotransferases (CAT). However, CAT activity has so far not been described for bacterial aminotransferases (AT), and it was unknown whether they can be applied for the conversion of cysteine to 3MPy...
April 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28193329/characterization-and-crystal-structure-of-a-thermostable-glycoside-hydrolase-family-45-1-4-%C3%AE-endoglucanase-from-thielavia-terrestris
#16
Jian Gao, Jian-Wen Huang, Qian Li, Weidong Liu, Tzu-Ping Ko, Yingying Zheng, Xiansha Xiao, Chih-Jung Kuo, Chun-Chi Chen, Rey-Ting Guo
1,4-β-Endoglucanase is one of the most important biocatalysts in modern industries. Here, a glycoside hydrolase (GH) family 45 endoglucanase from thermophilic fungus Theilavia terrestris (TtCel45A) was expressed in Pichia pastoris. The recombinant protein shows optimal activity at 60°C, pH 4-5. The enzyme exhibits extraordinary thermostability that more than 80% activity was detected after heating at 80°C for 2.5h. The high resolution crystal structures of apo-form enzyme and that in complex with cellobiose and cellotetraose were solved to 1...
April 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28193328/engineering-neurospora-crassa-for-cellobionate-production-directly-from-cellulose-without-any-enzyme-addition
#17
Hui Lin, Amanda Hildebrand, Takao Kasuga, Zhiliang Fan
In a cellulosic biorefinery, the cellulase enzymes needed for hydrolysis are one of the major contributors to high processing costs, while the hydrolysis product, cellobiose, has strong inhibition to the cellulases. In this study, we report engineering recombinant Neurospora crassa strains which are able to produce cellobionate, an organic acid, from cellulose without any enzyme addition. Recombinant strains were constructed by heterologously expressing laccase genes from different sources under different promoters in N...
April 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28193327/cloning-expression-and-biochemical-characterization-of-a-novel-nadp-dependent-7%C3%AE-hydroxysteroid-dehydrogenase-from-clostridium-difficile-and-its-application-for-the-oxidation-of-bile-acids
#18
Daniel Bakonyi, Werner Hummel
A gene encoding a novel 7α-specific NADP(+)-dependent hydroxysteroid dehydrogenase from Clostridium difficile was cloned and heterologously expressed in Escherichia coli. The enzyme was purified using an N-terminal hexa-his-tag and biochemically characterized. The optimum temperature is at 60°C, but the enzyme is inactivated at this temperature with a half-life time of 5min. Contrary to other known 7α-HSDHs, for example from Clostridium sardiniense or E. coli, the enzyme from C. difficile does not display a substrate inhibition...
April 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28193326/properties-of-a-novel-thermostable-glucose-isomerase-mined-from-thermus-oshimai-and-its-application-to-preparation-of-high-fructose-corn-syrup
#19
Dong-Xu Jia, Lin Zhou, Yu-Guo Zheng
Glucose isomerase (GI) is used in vitro to convert d-glucose to d-fructose, which is capable of commercial producing high fructose corn syrup (HFCS). To manufacture HFCS at elevated temperature and reduce the cost of enriching syrups, novel refractory GIs from Thermoanaerobacterium xylanolyticum (TxGI), Thermus oshimai (ToGI), Geobacillus thermocatenulatus (GtGI) and Thermoanaerobacter siderophilus (TsGI) were screened via genome mining approach. The enzymatic characteristics research showed that ToGI had higher catalytic efficiency and superior thermostability toward d-glucose among the screened GIs...
April 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/28110669/in-vitro-screening-and-in-silico-validation-revealed-key-microbes-for-higher-production-of-significant-therapeutic-enzyme-l-asparaginase
#20
Archana Vimal, Awanish Kumar
l-asparaginase is an enzyme of medical prominence and reputable as a chemotherapeutic agent. It also has immense potential to cure autoimmune and infectious diseases. The vast application of this enzyme in healthcare sector increases its market demand. However, presently the huge market demand is not achieved completely. This serves the basis to explore better producer microbial strains to bridge the gap between huge demand and supply of this therapeutic enzyme. The present study deals with the successful screening of potent microorganisms producing l-asparaginase...
March 2017: Enzyme and Microbial Technology
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