scholarly journals Characterization of dextransucrase from Leuconostoc mesenteroides T3, water kefir grains isolate

2017 ◽  
Vol 71 (4) ◽  
pp. 351-360 ◽  
Author(s):  
Miona Miljkovic ◽  
Sladjana Davidovic ◽  
Slavko Kralj ◽  
Slavica Siler-Marinkovic ◽  
Mirjana Rajilic-Stojanovic ◽  
...  
Keyword(s):  
Yeast Extract ◽  
Leuconostoc Mesenteroides ◽  
Divalent Cations ◽  
Sucrose Concentration ◽  
Maximum Activity ◽  
Promising Candidate ◽  
Polyethylene Glycol 400 ◽  
A Minor ◽  
Water Kefir

The production of dextransucrase (DS) by Leuconostoc mesenteroides T3, novel isolate from water kefir grain, was studied and optimized. Bacterial supernatant reached activity of 3.1 U/ml when the culture was grown at 23 ?C and under static culture condition using classical Tsuchiya medium for DS production. The increase of sucrose concentration to 7% led to an increase of DS activity by 52% compared to the control. Medium with 2% beef extract and 1% yeast extract resulted in 4.52 U/ml, which was 47% higher than in the control (with 2% yeast extract). Finally, the increase of K2HPO4 concentration from 2 to 3% resulted in the increased enzyme activity by 28%. Enzyme purified by polyethylene glycol 400 fractionation displayed maximum activity at 30?C and pH 5.4. Zymogram analysis confirmed the presence of DS of approximately 180 kDa. The addition of divalent cations Ca2+, Mg2+, Fe2+ and Co2+ led to a minor increase of DS activity, while the addition of Mn2+ was the most prominent with 73% increase. These findings classify dextransucrase from Leuconostoc mesenteroides T3 as promising candidate for production of dextran, which has numerous applications in various industries.

scholarly journals Characterization of medium-scale traveling ionospheric disturbances in the brazilian low latitude sector – Statistical Analysis of All-Sky Images of oi 630 nm airglow emission

2012 ◽  
Vol 30 (2) ◽  
Author(s):  
Danielle Cristina de Morais Amorim ◽  
Alexandre Alvares Pimenta ◽  
Aline Amorim de Almeida
Keyword(s):  
Statistical Analysis ◽  
Maximum Activity ◽  
Occurrence Rate ◽  
Ionospheric Disturbances ◽  
Low Latitude ◽  
Medium Scale ◽  
Airglow Emission ◽  
Traveling Ionospheric Disturbances ◽  
A Minor

In order to characterize the phenomenon known as Medium-Scale Traveling Ionospheric Disturbances (MSTIDs), we present in this paper the resultsobtained from the statistical analysis of 10.5 years all-sky images of OI 630 nm airglow emission over the Brazilian low latitude sector. The images, which were obtainedby an all-sky imager installed at Cachoeira Paulista (22.7◦S, 45◦W), show dark band structures propagating from southeast to northwest with velocities of 50-200 m/s.Our results show the greatest occurrence of MSTIDs during solar minimum and a minor occurrence rate during descending and ascending solar activity periods. Duringsolar maximum activity we have not detected MSTIDs signatures on all-sky images. In relation to seasonality, the greatest frequency of occurrence is during local winter.All detected events have occurred during geomagnetically quiet conditions (Kp<3). Possible mechanisms of generation of this phenomenon are discussed.

scholarly journals Functional and Molecular Characterization of the Halomicrobium sp. IBSBa Inulosucrase

2021 ◽  
Vol 9 (4) ◽  
pp. 749
Author(s):  
Gülbahar Abaramak ◽  
Jaime Ricardo Porras-Domínguez ◽  
Henry Christopher Janse van Rensburg ◽  
Eveline Lescrinier ◽  
Ebru Toksoy Öner ◽  
...  
Keyword(s):  
Molecular Characterization ◽  
Phylogenetic Analyses ◽  
Halophilic Archaea ◽  
Maximum Activity ◽  
Physiological Relevance ◽  
Health Related ◽  
Specific Alternative ◽  
Binding Groove ◽  
Native Host

Fructans are fructose-based (poly)saccharides with inulin and levan being the best-known ones. Thanks to their health-related benefits, inulin-type fructans have been under the focus of scientific and industrial communities, though mostly represented by plant-based inulins, and rarely by microbial ones. Recently, it was discovered that some extremely halophilic Archaea are also able to synthesize fructans. Here, we describe the first in-depth functional and molecular characterization of an Archaeal inulosucrase from Halomicrobium sp. IBSBa (HmcIsc). The HmcIsc enzyme was recombinantly expressed and purified in Escherichia coli and shown to synthesize inulin as proven by nuclear magnetic resonance (NMR) analysis. In accordance with the halophilic lifestyle of its native host, the enzyme showed maximum activity at very high NaCl concentrations (3.5 M), with specific adaptations for that purpose. Phylogenetic analyses suggested that Archaeal inulosucrases have been acquired from halophilic bacilli through horizontal gene transfer, with a HX(H/F)T motif evolving further into a HXHT motif, together with a unique D residue creating the onset of a specific alternative acceptor binding groove. This work uncovers a novel area in fructan research, highlighting unexplored aspects of life in hypersaline habitats, and raising questions about the general physiological relevance of inulosucrases and their products in nature.

scholarly journals Characterization of Two NMN Deamidase Mutants as Possible Probes for an NMN Biosensor

2021 ◽  
Vol 22 (12) ◽  
pp. 6334
Author(s):  
Alessandra Camarca ◽  
Gabriele Minazzato ◽  
Angela Pennacchio ◽  
Alessandro Capo ◽  
Adolfo Amici ◽  
...  
Keyword(s):  
Enzymatic Reaction ◽  
Promising Candidate ◽  
Beneficial Effects ◽  
Steady State Fluorescence ◽  
Nicotinamide Mononucleotide ◽  
Recognition Elements ◽  
Steady State Fluorescence Spectroscopy ◽  
Similar Affinity ◽  
Micromolar Range

Nicotinamide mononucleotide (NMN) is a key intermediate in the nicotinamide adenine dinucleotide (NAD+) biosynthesis. Its supplementation has demonstrated beneficial effects on several diseases. The aim of this study was to characterize NMN deamidase (PncC) inactive mutants to use as possible molecular recognition elements (MREs) for an NMN-specific biosensor. Thermal stability assays and steady-state fluorescence spectroscopy measurements were used to study the binding of NMN and related metabolites (NaMN, Na, Nam, NR, NAD, NADP, and NaAD) to the PncC mutated variants. In particular, the S29A PncC and K61Q PncC variant forms were selected since they still preserve the ability to bind NMN in the micromolar range, but they are not able to catalyze the enzymatic reaction. While S29A PncC shows a similar affinity also for NaMN (the product of the PncC catalyzed reaction), K61Q PncC does not interact significantly with it. Thus, PncC K61Q mutant seems to be a promising candidate to use as specific probe for an NMN biosensor.

scholarly journals Bioprocess development for enhanced endoglucanase production by newly isolated bacteria, purification, characterization and in-vitro efficacy as anti-biofilm of Pseudomonas aeruginosa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Atef M. Ibrahim ◽  
Ragaa A. Hamouda ◽  
Noura El-Ahmady El-Naggar ◽  
Fatma M. Al-Shakankery
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Yeast Extract ◽  
Statistical Design ◽  
Life Time ◽  
Maximum Activity ◽  
Bioprocess Development ◽  
Ammonium Sulfate Precipitation ◽  
Face Centered ◽  
Central Composite

AbstractEndoglucanase producing bacteria were isolated from Egyptian soils and the most active bacterial strain was identified as Bacillus subtilis strain Fatma/1. Plackett–Burman statistical design was carried out to assess the effect of seven process variables on endoglucanase production. Carboxymethyl cellulose (CMC), yeast extract and peptone were the most significant variables that enhanced the endoglucanase production and thus were selected for further optimization using face-centered central composite design. The highest yield of endoglucanase (32.37 U/mL) was obtained in run no. 9, using 18 g/L CMC, 8 g/L peptone, 7 g/L yeast extract and 0.1 g/L FeSO4.7H2O. The optimized medium showed about eightfold increase in endoglucanase production compared to the unoptimized medium. The produced crude enzyme was further purified by ammonium sulfate precipitation, then DEAE-Sepharose CL6B column. The purified enzyme was shown to have a molecular weight of 37 kDa. The enzyme showed maximum activity at pH 8.0, temperature of 50 °C, incubation time of 60 min. The half-life time (T1/2) was 139.53 min at 50 °C, while being 82.67 min at 60 °C. Endoglucanase at concentration of 12 U/mL effectively removed 84.61% of biofilm matrix of Pseudomonas aeruginosa with marked reduction in carbohydrate content of the biofilm from 63.4 to 7.9 μg.

scholarly journals Partial purification and biochemical characterization of a new highly acidic NYSO laccase from Alcaligenes faecalis

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Soad A. Abdelgalil ◽  
Ahmad R. Attia ◽  
Reyed M. Reyed ◽  
Nadia A. Soliman
Keyword(s):  
Enzyme Activity ◽  
Sodium Dodecyl ◽  
Alcaligenes Faecalis ◽  
Maximum Activity ◽  
Sodium Oxalate ◽  
Partial Purification ◽  
Bromophenol Blue ◽  
Bromocresol Purple ◽  
Laccase Enzyme

Abstract Background Due to the multitude industrial applications of ligninolytic enzymes, their demands are increasing. Partial purification and intensive characterization of contemporary highly acidic laccase enzyme produced by an Egyptian local isolate designated Alcaligenes faecalis NYSO were studied in the present investigation. Results Alcaligenes faecalis NYSO laccase has been partially purified and intensively biochemically characterized. It was noticed that 40–60% ammonium sulfate saturation showed maximum activity. A protein band with an apparent molecular mass of ~ 50 kDa related to NYSO laccase was identified through SDS-PAGE and zymography. The partially purified enzyme exhibited maximum activity at 55 °C and pH suboptimal (2.5–5.0). Remarkable activation for enzyme activity was recognized after 10-min exposure to temperatures (T) 50, 60, and 70 °C; time elongation caused inactivation, where ~ 50% of activity was lost after a 7-h exposure to 60 °C. Some metal ions Cu2+, Zn2+, Co2+, Ni2+, Mn2+, Cd2+, Cr2+, and Mg2+ caused strong stimulation for enzyme activity, but Fe2+ and Hg2+ reduced the activity. One millimolar of chelating agents [ethylenediamine tetraacetic acid (EDTA), sodium citrate, and sodium oxalate] caused strong activation for enzyme activity. Sodium dodecyl sulfate (SDS), cysteine-HCl, dithiothreitol (DTT), β-mercaptoethanol, thioglycolic acid, and sodium azide caused strong inhibition for NYSO laccase activity even at low concentration. One millimolar of urea, imidazole, kojic acid, phenylmethylsulfonyl fluoride (PMSF), H2O2, and Triton X-100 caused activation. The partially purified NYSO laccase had decolorization activity towards different dyes such as congo red, crystal violet, methylene blue, fast green, basic fuchsin, bromophenol blue, malachite green, bromocresol purple eriochrome black T, and Coomassie Brilliant Blue R-250 with various degree of degradation. Also, it had a vast range of substrate specificity including lignin, but with high affinity towards p-anisidine. Conclusion The promising properties of the newly studied laccase enzyme from Alcaligenes faecalis NYSO strain would support several industries such as textile, food, and paper and open the possibility for commercial use in water treatment. It will also open the door to new applications due to its ligninolytic properties in the near future.

scholarly journals Characterization of Phospholipase Activity of the Pseudomonas aeruginosa Type III Cytotoxin, ExoU

2005 ◽  
Vol 187 (3) ◽  
pp. 1192-1195 ◽  
Author(s):  
Hiromi Sato ◽  
Jimmy B. Feix ◽  
Cecilia J. Hillard ◽  
Dara W. Frank
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Substrate Specificity ◽  
Yeast Extract ◽  
Enzyme Activation ◽  
Phospholipase Activity ◽  
Eukaryotic Protein ◽  
Type Iii

ABSTRACT Recombinant ExoU (rExoU) and yeast extract were used to optimize an in vitro phospholipase assay as a basis for identifying the mechanism for enzyme activation and substrate specificity. Our results support a model in which a eukaryotic protein cofactor or complex facilitates the interaction of rExoU with phospholipid substrates.

scholarly journals Occurrence of fatty acid epoxide hydrolases in soybean (Glycine max). Purification and characterization of the soluble form

1992 ◽  
Vol 282 (3) ◽  
pp. 711-714 ◽  
Author(s):  
E Blée ◽  
F Schuber
Keyword(s):  
Glycine Max ◽  
Gel Filtration ◽  
Soluble Form ◽  
Soluble Enzyme ◽  
Purification And Characterization ◽  
Epoxide Hydrolases ◽  
Major Activity ◽  
Apparent Homogeneity ◽  
A Minor

Epoxide hydrolases catalysing the hydration of cis-9,10-epoxystearate into threo-9,10-dihydroxystearate have been detected in soybean (Glycine max) seedlings. The major activity was found in the cytosol, a minor fraction being strongly associated with microsomes. The soluble enzyme, which was purified to apparent homogeneity by (NH4)2SO4 fractionation, hydrophobic, DEAE- and gel-filtration chromatographies, has a molecular mass of 64 kDa and a pI of 5.4.

Facile Synthesis of Cu2O Nanocubes in Triblock Copolymer Solutions

2007 ◽  
Vol 121-123 ◽  
pp. 275-278
Author(s):  
Jin Hua Jiang ◽  
Qiu Ming Gao
Keyword(s):  
Triblock Copolymer ◽  
Solar Spectrum ◽  
Blue Shift ◽  
Edge Length ◽  
Promising Candidate ◽  
Organic Species ◽  
Transmission Electron ◽  
Ft Ir ◽  
Average Edge Length

Cuprous oxide and related materials in nanosizes are of much interest and investigated extensively recently. It is reported here that cubic Cu2O nanocubes were synthesized successfully in aqueous solutions at room temperature in air condition. Copper (II) salts in water were reduced with ascorbate acid in air, using the nonionic pluronic amphiphilic triblock copolymer EO20PO70EO20 (P123) as the template-directing and protecting agent. The average edge length of the cubes varied from 50 to 100 nm. Transmission electron microscopy (TEM) has been used for the shape and structural characterization of the obtained Cu2O nanocubes. The UV-Vis spectra showed an obvious blue-shift (0.53 eV), compared to the band gap of the bulk Cu2O crystal, which makes it a promising candidate in solar energy conversion since this sample can make use of higher energy visible rays of solar spectrum. In the FT-IR spectra the peak of Cu-O bond for the Cu2O is clearly distinguished and several weak peaks of the C-H, C-C and C=O bonds for the organic species can also be detectable, implying a little P123 residua in the products. The effect of the triblock copolymer P123 on the growth of the Cu2O nanocubes is discussed.

Identification and functional characterization of levS, a gene encoding for a levansucrase from Leuconostoc mesenteroides NRRL B-512 F

Gene ◽  
2006 ◽  
Vol 376 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Sandra Morales-Arrieta ◽  
Maria Elena Rodríguez ◽  
Lorenzo Segovia ◽  
Agustín López-Munguía ◽  
Clarita Olvera-Carranza
Keyword(s):  
Leuconostoc Mesenteroides ◽  
Functional Characterization ◽  
Gene Encoding

scholarly journals Characterization of a Cytotoxic Factor in Culture Filtrates of Serratia marcescens

2002 ◽  
Vol 70 (3) ◽  
pp. 1121-1128 ◽  
Author(s):  
Kent B. Marty ◽  
Christopher L. Williams ◽  
Linda J. Guynn ◽  
Michael J. Benedik ◽  
Steven R. Blanke
Keyword(s):  
Cytotoxic Activity ◽  
Serratia Marcescens ◽  
Mammalian Cells ◽  
Divalent Cations ◽  
Recombinant Expression ◽  
Cytotoxic Factor ◽  
Culture Filtrates ◽  
Type Strains

ABSTRACT Serratia marcescens culture filtrates have been reported to be cytotoxic to mammalian cells. Using biochemical and genetic approaches, we have identified a major source of this cytotoxic activity. Both heat and protease treatments abrogated the cytotoxicity of S. marcescens culture filtrates towards HeLa cells, suggesting the involvement of one or more protein factors. A screen for in vitro cytotoxic activity revealed that S. marcescens mutant strains that are deficient in production of a 56-kDa metalloprotease are significantly less cytotoxic to mammalian cells. Cytotoxicity was significantly reduced when culture filtrates prepared from wild-type strains were pretreated with either EDTA or 1,10-phenanthroline, which are potent inhibitors of the 56-kDa metalloprotease. Furthermore, cytotoxic activity was restored when the same culture filtrates were incubated with zinc divalent cations, which are essential for enzymatic activity of the 56-kDa metalloprotease. Finally, recombinant expression of the S. marcescens 56-kDa metalloprotease conferred a cytotoxic phenotype on the culture filtrates of a nonpathogenic Escherichia coli strain. Collectively, these data suggest that the 56-kDa metalloprotease contributes significantly to the in vitro cytotoxic activity commonly observed in S. marcescens culture filtrates.

Sign in / Sign up

Export Citation Format

Share Document