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Enzyme and Microbial Technology

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https://www.readbyqxmd.com/read/29421043/influence-of-support-materials-on-continuous-hydrogen-production-in-anaerobic-packed-bed-reactor-with-immobilized-hydrogen-producing-bacteria-at-acidic-conditions
#1
Petra Muri, Romana Marinšek-Logar, Petar Djinović, Albin Pintar
This study assesses the impact of different support materials (Mutag BioChip™, expanded clay and activated carbon) on microbial hydrogen production in an anaerobic packed-bed reactor (APBR) treating synthetic waste water containing glucose as the main carbon source at low pH value. The APBRs were inoculated with acid pretreated anaerobic sludge and operated at pH value of 4±0.2 and hydraulic retention time (HRT) of 3h. The maximum hydrogen yield of 1.80mol H2/mol glucose was achieved for the APBR packed with Mutag BioChip™ (R1), followed by expanded clay (R2, 1...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421042/biosynthesis-of-gold-and-selenium-nanoparticles-by-purified-protein-from-acinetobacter-sp-sw-30
#2
Sweety A Wadhwani, Utkarsha U Shedbalkar, Richa Singh, Balu A Chopade
Synthesis of nanoparticles is an enzymatic reduction process in microorganisms. In the present study, a protein, lignin peroxidase has been purified by DEAE-Cellulose anion exchange chromatography and Biogel P-150 gel filtration chromatography from the cell suspension of Acinetobacter sp. SW30 responsible for the synthesis of gold nanoparticles (AuNP) and selenium nanoparticles (SeNP). The purified fraction has a specific activity of 29.4U/mg/min with 959 fold purification. Native and SDS PAGE confirmed that purified lignin peroxidase is monomeric enzyme with 97...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421041/characterization-of-a-topologically-unique-oxygenase-from-sphingobium-sp-pnb-capable-of-catalyzing-a-broad-spectrum-of-aromatics
#3
Pratick Khara, Madhumita Roy, Joydeep Chakraborty, Arindam Dutta, Tapan K Dutta
A Rieske non-heme iron ring-hydroxylating oxygenase (RHO) from Sphingobium sp. PNB involved in the initial oxidation of a wide range of low and high molecular weight polycyclic aromatic hydrocarbons (PAHs) was investigated. The RHO was shown to comprise of the gene products of distantly located ahdA1f-ahdA2f, ahdA3 and ahdA4 genes, which encoded the oxygenase α- and β-subunits, ferredoxin and reductase, respectively. In silico structural analysis of AhdA1f revealed a very large substrate-binding pocket, satisfying the spatial requirements to accommodate high molecular weight substrates...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421040/a-thermophilic-enzymatic-cocktail-for-galactomannans-degradation
#4
Martina Aulitto, Francesca Anna Fusco, Gabriella Fiorentino, Simonetta Bartolucci, Patrizia Contursi, Danila Limauro
The full utilization of hemicellulose sugars (pentose and exose) present in lignocellulosic material, is required for an efficient bio-based fuels and chemicals production. Two recombinant thermophilic enzymes, an endo-1,4-β-mannanase from Dictyoglomus turgidum (DturCelB) and an α-galactosidase from Thermus thermophilus (TtGalA), were assayed at 80 °C, to assess their heterosynergystic association on galactomannans degradation, particularly abundant in hemicellulose. The enzymes were tested under various combinations simultaneously and sequentially, in order to estimate the optimal conditions for the release of reducing sugars...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421039/aspergillus-niger-whole-cell-catalyzed-synthesis-of-caffeic-acid-phenethyl-ester-in-ionic-liquids
#5
Govindaraju Rajapriya, Vivek Kumar Morya, Ngoc Lan Mai, Yoon-Mo Koo
Synthesis of caffeic acid ester essentially requires an efficient esterification process to produce various kinds of medicinally important ester derivatives. In the present study, a comprehensive and comparative analysis of whole-cell catalyzed caffeic acid esters production in ionic liquids (ILs) media was performed. Olive oil induced mycelial mass of halotolerant Aspergillus niger (A.niger) EXF 4321 was freeze dried and used as a catalyst. To ensure maximum solubilization of caffeic acid for highest substrate loading several ILs were screened and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][Tf2N]) was found to have the maximum solubility and favoured for enzymatic activity of freeze dried mycelia...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421038/microbial-production-of-uracil-by-an-isolated-methylobacterium-sp-wj4-using-methanol
#6
Wangjun Lee, Sangwoo Kim, Insu Song, Yuhyun Kwon, Soohyun Park, Byung-Keun Oh, Han Bin Oh, Jinwon Lee
In this study, we report the production of uracil from methanol by an isolated methylotrophic bacterium, Methylobacterium sp. WJ4. The use of methanol as alternative carbon feedstock is attractive option in biotechnology. As a feedstock of biotechnological processes, methanol has distinct advantages over methane. This is not only due to physical and chemical considerations, but also to the properties of the pertinent organisms. Besides, with a wide array of biological activities and synthetic accessibility, uracil is considered as privileged structures in drug discovery...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421037/essential-role-of-amino-acid-position-71-in-substrate-preference-by-meso-diaminopimelate-dehydrogenase-from-symbiobacterium-thermophilum-iam14863
#7
Yanan Zhang, Qinyuan Ma, Miaomiao Dong, Xianhai Zhang, Yichu Chen, Xiuzhen Gao, Yuanda Song
meso--Diaminopimelate dehydrogenase (meso-DAPDH) catalyzes the reversible oxidative deamination of the d-configuration of meso-2,6-diaminopimelate (meso-DAP) and is thought to have substrate specificity toward meso-DAP. The discovery of the meso-DAPDH from Symbiobacterium thermophilum IAM14863 (StDAPDH) revealed meso-DAPDH members with broad substrate specificity. In order to elucidate the substrate-preference mechanism of StDAPDH, it is necessary to identify the key residues related to this mechanism. Our previous work suggested that the non-active-site R71 of StDAPDH was related to substrate preference...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421036/enzymatically-and-chemically-oxidized-lignin-nanoparticles-for-biomaterial-applications
#8
Maija-Liisa Mattinen, Juan José Valle-Delgado, Timo Leskinen, Tuomas Anttila, Guillaume Riviere, Mika Sipponen, Arja Paananen, Kalle Lintinen, Mauri Kostiainen, Monika Österberg
Cross-linked and decolorized lignin nanoparticles (LNPs) were prepared enzymatically and chemically from softwood Kraft lignin. Colloidal lignin particles (CLPs, ca. 200 nm) in a non-malodorous aqueous dispersion could be dried and redispersed in tetrahydrofuran (THF) or in water retaining their stability i.e. spherical shape and size. Two fungal laccases, Trametes hirsuta (ThL) and Melanocarpus albomyces (MaL) were used in the cross-linking reactions. Reactivity of ThL and MaL on Lignoboost™ lignin and LNPs was confirmed by high performance size exclusion chromatography (HPSEC) and oxygen consumption measurements with simultaneous detection of red-brown color due to the formation of quinones...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421035/improvement-in-thermostability-of-xylanase-from-geobacillus-thermodenitrificans-c5-by-site-directed-mutagenesis
#9
Muhammad Irfan, Claudio F Gonzalez, Saad Raza, Muhamamd Rafiq, Fariha Hasan, Samiullah Khan, Aamer Ali Shah
Enzymes activity and stability at extreme temperature can be intensified by regularly applying protein engineering. In the present study, two amino acids were perceived to mark the temperature dependability of xylanase from Geobacillus thermodenitrificans C5. Six mutants of G. thermodenitrificans C5 were built through site-directed mutagenesis by interchanging the residue with proline and glutamic acid (R81P, H82E, W185P, D186E, double mutant W185P/D186E and triple mutant H82E/W185P/D186E). Both mutant and wild type enzymes were quantified in host E...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421034/stereoselective-hydroxylation-of-isophorone-by-variants-of-the-cytochromes-p450-cyp102a1-and-cyp101a1
#10
Shaghayegh Dezvarei, Joel H Z Lee, Stephen G Bell
The stereoselective oxidation of hydrocarbons is an area of research where enzyme biocatalysis can make a substantial impact. The cyclic ketone isophorone was stereoselectively hydroxylated (≥95%) by wild-type CYP102A1 to form (R)-4-hydroxyisophorone, an important chiral synthon and flavour and fragrance compound. CYP102A1 variants were also selective for 4-hydroxyisophorone formation and the product formation rate increased over the wild-type enzyme by up to 285-fold, with the best mutants being R47L/Y51F/I401P and A74G/F87V/L188Q...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421033/biodegradation-of-fibrillated-oil-palm-trunk-fiber-by-a-novel-thermophilic-anaerobic-xylanolytic-bacterium-caldicoprobacter-sp-cl-2-isolated-from-compost
#11
Erma Widyasti, Ayumi Shikata, Rokiah Hashim, Othman Sulaiman, Kumar Sudesh, Edi Wahjono, Akihiko Kosugi
Oil palm trunk (OPT) is one of the most promising lignocellulosic bioresources. To develop effective biodegradation, thermophilic, anaerobic microorganisms were screened from bovine manure compost using fibrillated OPT (f-OPT) pretreated by wet disk milling as the substrate. One thermophilic, anaerobic bacterium, strain CL-2, whose 16S rDNA gene has 98.6% sequence identity with that of Caldicoprobacter faecale DSM 20678T, exhibited high degradation activity (32.7% reduction in total dry solids of f-OPT). Strain CL-2 did not use cellulose as a carbon source, but used hemicelluloses such as xylan, arabinoxylan, starch and pectin at 70 °C...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421032/producing-functional-recombinant-human-keratinocyte-growth-factor-in-pichia-pastoris-and-investigating-its-protective-role-against-irradiation
#12
Zahra Bahadori, Hamid Reza Kalhor, Seyed Javad Mowla
Keratinocyte Growth Factor (KGF) is a paracrine-acting, epithelial mitogen that plays a prominent role in the regeneration of damaged epithelial tissues. In spite of different attempts to produce recombinant human KGF in many organisms, including bacteria, mammalian cells, plant cells and insect cells; production of recombinant form suffers from lower yields and recovery relative to other recombinant proteins of similar size and properties. Due to many advantages of Pichia pastoris expression systems for producing industrial enzymes and pharmaceutical proteins, in this study P...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29421031/an-enzymatic-alternative-for-the-synthesis-of-nucleoside-5-monophosphates
#13
Esteban D Gudiño, Julia Y Santillán, Luis E Iglesias, Adolfo M Iribarren
A new procedure was carried out for the synthesis of nucleoside 5'-monophosphates, involving the use of two enzymes. The first step applied phospholipase D from Streptomyces netropsis and phosphatidylcholine as phosphatidyl donor, to give 5'-(3-sn-phosphatidyl) nucleosides (C, U, A, I). These were selectively hydrolysed in the second step by the action of phospholipase C from Bacillus cereus to produce the respective 5'-nucleotides. Application of this methodology on a preparative scale conducted to 5'-adenosine monophosphate in 63% overall yield from adenosine...
April 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29310860/kinetic-resolution-of-sec-alcohols-catalysed-by-candida-antarctica-lipase-b-displaying-pichia-pastoris-whole-cell-biocatalyst
#14
Kun Zhang, Zhiyou Pan, Zhoujian Diao, Shuli Liang, Shuangyan Han, Suiping Zheng, Ying Lin
Kinetic resolution of sec-alcohols is a green process with biocatalyst. Candida antarctica lipase B (CALB) displayed on Pichia pastoris cell-surface (Pp-CALB) was characterized in kinetic resolution of sec-alcohols with different structures. The reaction parameters including acyl donors, molar ratio of substrates, solvents and temperatures were examined with 2-octanol as model substrate. 47.4% molar conversion of 2-octanol and 99.7% eep were obtained after a 5h reaction with Pp-CALB, and 90% of its original activity still remained after being reused for 10 cycles...
March 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29310859/maximize-rhamnolipid-production-with-low-foaming-and-high-yield
#15
Maysam Sodagari, Krutika Invally, Lu-Kwang Ju
Rhamnolipids are well-known microbial surfactants with many potential applications. Their production cost, however, remains high due to the severe foaming tendency in aerobic fermentation and the relatively low productivity and yield. In this study, we assessed the boundaries set by these constraints after optimization of basic parameters such as dissolved oxygen concentration (DO), pH and carbon sources. DO 10% and pH 5.5-5.7 were found optimal; cell growth and/or rhamnolipid production were slower at lower DO (5%) or pH (5...
March 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29310858/influence-of-the-metal-ion-on-the-enzyme-activity-and-kinetics-of-pepa-from-lactobacillus-delbrueckii
#16
Jacob Ewert, Claudia Glück, Henry Strasdeit, Lutz Fischer, Timo Stressler
The aminopeptidase A (PepA; EC 3.4.11.7) belongs to the group of metallopeptidases with two bound metal ions per subunit (M1M2(PepA)) and is specific for the cleavage of N-terminal glutamic (Glu) and aspartic acid (Asp) and, in low amounts, serine (Ser) residues. Our group recently characterized the first PepA from a Lactobacillus strain. However, the characterization was performed using synthetic para-nitroaniline substrates and not original peptide substrates, as was done in the current study. Prior to the characterization using original peptide substrates, the PepA purified was converted to its inactive apo-form and eight different metal ions were tested to restore its activity...
March 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29310857/a-conserved-residue-of-l-alanine-dehydrogenase-from-bacillus-pseudofirmus-lys-73-participates-in-the-catalytic-reaction-through-hydrogen-bonding
#17
Guangzheng He, Shujing Xu, Shanshan Wang, Qing Zhang, Dong Liu, Yuling Chen, Jiansong Ju, Baohua Zhao
A multiple protein sequence alignment of l-alanine dehydrogenases from different bacterial species revealed that five highly conserved amino acid residues Arg-15, Lys-73, Lys-75, His-96 and Asp-269 are potential catalytic residues of l-alanine dehydrogenase from Bacillus pseudofirmus OF4. In this study, recombinant OF4Ald and its mutants of five conserved residues were constructed, expressed in Escherichia coli, purified by His6-tag affinity column and gel filtration chromatography, structure homology modeling, and characterized...
March 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29310856/chemoenzymatic-synthesis-of-sucuronic-acid-using-d-glucurono-6-3-lactone-and-sucrose-as-raw-materials-and-properties-of-the-product
#18
Hiroki Hosaka, Saori Mizoguchi, Mitsuru Tashiro, Takashi Fujimoto, Takako Hirano, Wataru Hakamata, Toshiyuki Nishio
Using d-glucurono-6,3-lactone (GlcL) and sucrose (Suc) as raw materials, we synthesized sucuronic acid (SucA), in which the d-glucose (Glc) residue of Suc was replaced with d-glucuronic acid, by a three-step chemoenzymatic method. In the 1st chemical step, methyl d-glucuronate (GlcAM) was synthesized by treating GlcL with a strong base anion exchange resin, Amberlite IRA402BL OH AG, in anhydrous methanol. In the 2nd step, which included an enzyme reaction, methyl sucuronate (SucAM) was synthesized from GlcAM and fructose by exploiting the transfructosylation activity of the Microbacterium saccharophilum K-1 β-fructofuranosidase, a reaction that is suppressed in the presence of high-concentration Glc...
March 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29310855/identification-of-r-selective-%C3%AF-aminotransferases-by-exploring-evolutionary-sequence-space
#19
Eun-Mi Kim, Joon Ho Park, Byung-Gee Kim, Joo-Hyun Seo
Several (R)-selective ω-aminotransferases (R-ωATs) have been reported. The existence of additional R-ωATs having different sequence characteristics from previous ones is highly expected. In addition, it is generally accepted that R-ωATs are variants of aminotransferase group III. Based on these backgrounds, sequences in RefSeq database were scored using family profiles of branched-chain amino acid aminotransferase (BCAT) and d-alanine aminotransferase (DAT) to predict and identify putative R-ωATs. Sequences with two profile analysis scores were plotted on two-dimensional score space...
March 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29310854/stabilization-of-dimeric-%C3%AE-glucosidase-from-aspergillus-niger-via-glutaraldehyde-immobilization-under-different-conditions
#20
Perla Guadalupe Vazquez-Ortega, Maria Teresa Alcaraz-Fructuoso, Juan A Rojas-Contreras, Javier López-Miranda, Roberto Fernandez-Lafuente
The dimeric enzyme β-glucosidase from Aspergillus niger has been immobilized on different amino-agarose beads at pH 5 and 7, exploiting the versatility of glutaraldehyde. The stability of the free enzyme depended on enzyme concentration. Immobilization via ion exchange improved enzyme stability/activity, depending on the immobilization pH. However, the enzyme was desorbed in 75 mM NaCl at pH 7 and some stability/enzyme concentration dependence still existed. TREATMENT: of these biocatalysts with glutaraldehyde increased enzyme stability (e...
March 2018: Enzyme and Microbial Technology
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