scholarly journals Mycotoxin degradation by microbial metabolites

2020 ◽  
Author(s):  
N. V. Statsyuk ◽  
L. A. Shcherbakova ◽  
O. D. Mikityuk ◽  
T. A. Nazarova ◽  
V. G. Dzhavakhiya
Keyword(s):  
Aflatoxin B1 ◽  
Gliocladium Roseum ◽  
Microbial Metabolites ◽  
Mycotoxin Degradation ◽  
Extracellular Metabolites ◽  
Optimum Ph ◽  
Enzymatic Nature ◽  
Optimum Ph And Temperature

Extracellular metabolites of Gliocladium roseum GRZ7 are able to destroy aflatoxin B1 and zearalenone (by 61.9 and 68%, respectively). The determined optimum pH and temperature confirm the enzymatic nature of these metabolites.

scholarly journals Immobilization of alpha-amylase produced by Bacillus circulans GRS 313

2003 ◽  
Vol 46 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Gargi Dey ◽  
Singh Bhupinder ◽  
Rintu Banerjee
Keyword(s):  
Calcium Alginate ◽  
Immobilized Enzyme ◽  
Fold Increase ◽  
Alginate Beads ◽  
Hydrolysis Kinetics ◽  
Initial Activity ◽  
Reaction Conditions ◽  
Bead Size ◽  
Optimum Ph ◽  
Optimum Ph And Temperature

A maltooligosaccharide-forming amylase from B circulans GRS 313 was immobilized by entrapment in calcium alginate beads. The immobilized activity was affected by the size of the bead and bead size of 2mm was found to be most effective for hydrolysis. Kinetics constants, Km and Vmax were estimated and were found to be affected by the bead size. The catalytic activity of the enzyme was studied in presence of various starchy residues and metal ions. HgCl2, CuSO4 and FeCl3 caused inhibition of the enzyme. The reaction conditions, pH and temperature, was optimized using response surface methodology. At the optimum pH and temperature of 4.9 and 57ºC, the apparent activity was 25.6U/g of beads, resulting in almost 2-fold increase in activity. The immobilized enzyme showed a high operational stability by retaining almost 85% of the initial activity after seventh use.

scholarly journals Purification and Characterization of a Feruloyl Esterase from the Intestinal Bacterium Lactobacillus acidophilus

2004 ◽  
Vol 70 (4) ◽  
pp. 2367-2372 ◽  
Author(s):  
Xiaokun Wang ◽  
Xin Geng ◽  
Yukari Egashira ◽  
Hiroo Sanada
Keyword(s):  
Lactobacillus Acidophilus ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Hydrophobic Interaction Chromatography ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Feruloyl Esterase ◽  
Intestinal Bacterium ◽  
Optimum Ph ◽  
Optimum Ph And Temperature

ABSTRACT Dietary ferulic acid (FA), a significant antioxidant substance, is currently the subject of extensive research. FA in cereals exists mainly as feruloylated sugar ester. To release FA from food matrices, it is necessary to cleave ester cross-linking by feruloyl esterase (FAE) (hydroxycinnamoyl esterase; EC 3.1.1.73). In the present study, the FAE from a human typical intestinal bacterium, Lactobacillus acidophilus, was isolated, purified, and characterized for the first time. The enzyme was purified in successive steps including hydrophobic interaction chromatography and anion-exchange chromatography. The purified FAE appeared as a single band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular mass of 36 kDa. It has optimum pH and temperature characteristics (5.6 and 37°C, respectively). The metal ions Cu2+ and Fe3+ (at a concentration of 5 mmol liter−1) inhibited FAE activity by 97.25 and 94.80%, respectively. Under optimum pH and temperature with 5-O-feruloyl-l-arabinofuranose (FAA) as a substrate, the enzyme exhibited a K m of 0.0953 mmol liter−1 and a V max of 86.27 mmol liter−1 min−1 mg−1 of protein. Furthermore, the N-terminal amino acid sequence of the purified FAE was found to be A R V E K P R K V I L V G D G A V G S T. The FAE released FA from O-(5-O-feruloyl-α-l-arabinofuranosyl)-(1→3)-O-β-d-xylopyranosyl-(1→4)-d-xylopyranose (FAXX) and FAA obtained from refined corn bran. Moreover, it released two times more FA from FAXX in the presence of added xylanase.

Characteristics of the major DNA polymerases found during early and late maize germination

1988 ◽  
Vol 66 (6) ◽  
pp. 1186-1191 ◽  
Author(s):  
Alejandra Vazquez ◽  
Jorge Vazquez-Ramos
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerases ◽  
Absolute Requirement ◽  
Optimum Ph ◽  
Embryo Axes ◽  
The Difference ◽  
Alpha Type ◽  
Degree Of Purification ◽  
Optimum Ph And Temperature

Two types of DNA synthesis have been detected during maize germination (0–24 h). To determine if the difference in these two types of synthesis was due to the presence of distinct DNA polymerases, we partially isolated and characterized the enzymes present at 3 (early) and 24 (late) h of germination. The material used was embryo axes. The result indicates that at both 3 and 24 h, enzymes are similar with regard to optimum pH and temperature, absolute requirement of Mg2+ (12 mM), and stimulation by KCl (50 mM). They are also equally inhibited by N-ethylmaleimide and cytosine-β-D-arabinofuranoside. These facts would classify the enzymes as alpha type; however, the enzymes differ in their sensitivity to aphidicolin and the degree of purification. The nature of the enzymes is discussed.

A new method for the adaptive determination of optimum pH and temperature

1989 ◽  
Vol 33 (11) ◽  
pp. 1419-1424 ◽  
Author(s):  
Jeff. L Harmon ◽  
Gerasimos Lyberatos ◽  
Spyros A. Svoronos
Keyword(s):  
New Method ◽  
Optimum Ph ◽  
Optimum Ph And Temperature

Characteristics of Spore-Bound Laccase from Bacillus subtilis WD23 and its Use in Dye Decolorization

2010 ◽  
Vol 113-116 ◽  
pp. 226-230 ◽  
Author(s):  
Chun Lei Wang ◽  
Min Zhao ◽  
Xing Dong Wei ◽  
Tai Lun Li ◽  
Lei Lu
Keyword(s):  
Bacillus Subtilis ◽  
Dye Decolorization ◽  
Luria Bertani ◽  
Biochemical Tests ◽  
16S Rdna Sequence ◽  
16S Rdna Sequence Analysis ◽  
Optimum Ph ◽  
Ph Range ◽  
Physiological And Biochemical ◽  
Optimum Ph And Temperature

Treatment of xenobiotic compounds such as textile dyes with bacterial laccases is limited to the acid pH range and moderate temperatures. A bacterial strain, designated as WD23, was isolated from forest soil using Luria-Bertani medium supplemented with 0.4 mmol/L Cu2+. The isolated strain was identified as Bacillus subtilis by physiological and biochemical tests and 16S rDNA sequence analysis. Here we charactered the spore-bound laccase of B. subtilis WD23 and used the laccase to decolorize dyes. The spores of the strain showed laccase-like activity, oxidizing syringaldazine, 2,6-dimethoxyphenol and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonate acid)(ABTS). The optimum pH and temperature for the spore-bound laccase were 6.8 and 60°C, respectively. It also showed higher stabilities over a broad pH range, the pH half-life was more than 6 months at pH 6.8. The spore laccase could efficiently decolorize 50~90% of anthraquinone and azo dyes in 24 h. The spore laccase can play an important role in bioremediation.

Study on the Optimum Condition for Immobilization and Properties of Laccase on Coordinated Chitosan-Cu2+

2013 ◽  
Vol 864-867 ◽  
pp. 1262-1265 ◽  
Author(s):  
Bo Yang ◽  
Xu Ming Wang
Keyword(s):  
Optimum Condition ◽  
Heat Resistance ◽  
High Activity ◽  
Storage Stability ◽  
Optimal Conditions ◽  
Immobilized Laccase ◽  
Complex Time ◽  
Optimum Ph ◽  
Polymeric Coordination ◽  
Optimum Ph And Temperature

Coordinated chitosan-Cu2+ as a carrier, the laccase was immobilized on it by polymeric coordination method. In this study, the optimal conditions for immobilization and properties of laccase were investigated. The optimal conditions for immobilization were: CuSO4 (0.05 mol/L), complex time (7 h), laccase concentration (250 U/mL), immobilization time (8 h). Under this condition, the activity of immobilized laccase can reach 820 U/g. In comparison with the free laccase, the optimum pH and temperature of immobilized laccase have a little change, while the heat resistance and pH stability were improved. After the immobilized laccase was stored in the refrigerator at 4 °C for 25 days, the activity of it remained 69.5 % of the original, it illustrates the immobilized laccase has a good storage stability. The laccase immobilized with chitosan-Cu2+ has high activity and has potential to use in industry as a biocatalyst.

scholarly journals STUDY OF AFLATOXIN B1-DESTROYING ACTIVITY OF Gliocladium roseum AND Trichoderma viride AND THEIR АNTAGONISM TOWARD TOXIGENIC Aspergillus flavus

2016 ◽  
Vol 51 (6) ◽  
pp. 946-950 ◽  
Author(s):  
L.A. Shcherbakova ◽  
◽  
O.D. Mikityuk ◽  
T.A. Nazarova ◽  
V.G. Dzhavakhiya ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Trichoderma Viride ◽  
Gliocladium Roseum

scholarly journals Inhibition of the biosynthesis of polyketide mycotoxins by microbial metabolites

2020 ◽  
Author(s):  
D. V. Erokhin ◽  
O. D. Mikityuk ◽  
L. A. Shcherbakova ◽  
V. G. Dzhavakhiya
Keyword(s):  
Secondary Metabolite ◽  
Aflatoxin B1 ◽  
Microbial Metabolites

6-Demethylmevinoliin, a secondary metabolite of Penicillum citrinum, is able to efficiently inhibit the biosynthesis of two polypeptide mycotoxins, aflatoxin B1 and zearalenone, by 92 and 78% of the control, respectively.

scholarly journals Characterization of amylase and protease activity in the digestive tract of two teleosts (Labeo rohita and Anabas testudineus) with different feeding habits

2021 ◽  
Vol 64 (2) ◽  
pp. 173-179
Author(s):  
Sanjeet Debnath ◽  
Surjya Kumar Saikia
Keyword(s):  
Digestive Tract ◽  
Protease Activity ◽  
Specific Activity ◽  
Labeo Rohita ◽  
Feeding Habits ◽  
Anabas Testudineus ◽  
Pyloric Caeca ◽  
Optimum Ph ◽  
Optimum Ph And Temperature

Two teleosts (Rohu, Labeo rohita and Koi, Anabas testudineus), both with contrasting feeding habits (herbivorous versus carnivorous) were studied for amylase and protease activity concerning different regions of their digestive tracts. Significant differences in enzymatic activity across different regions of the digestive tracts were observed. Rohu, with three equal regions of the stomachless gut, showed the highest amylolytic activity at the posterior digestive tract but the highest proteolytic activity is limited to mid region. Contrary to such observation, Koi with three distinct regions of the digestive tract (stomach, pyloric caeca and intestine), the pyloric caeca exhibited the highest specific activity for both amylase and total protease. The optimum pH and temperature conditions were determined concerning the activity for both amylase and protease.

scholarly journals Efficient Degradation of Aflatoxin B1 and Zearalenone by Laccase-like Multicopper Oxidase from Streptomyces thermocarboxydus in the Presence of Mediators

Toxins ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 754
Author(s):  
Xing Qin ◽  
Yanzhe Xin ◽  
Jiahuan Zou ◽  
Xiaoyun Su ◽  
Xiaolu Wang ◽  
...  
Keyword(s):  
Aflatoxin B1 ◽  
Degradation Products ◽  
Copper Ion ◽  
Blue Color ◽  
Multicopper Oxidases ◽  
Simultaneous Reduction ◽  
Mycotoxin Degradation ◽  
Bivalent Copper ◽  
Encoding Gene ◽  
Degradation Ability

Multicopper oxidases (MCOs) are a diverse group of enzymes that could catalyze the oxidation of different xenobiotic compounds, with simultaneous reduction in oxygen to water. Aside from laccase, one member of the MCO superfamily has shown great potential in the biodegradation of mycotoxins; however, the mycotoxin degradation ability of other MCOs is uncertain. In this study, a novel MCO-encoding gene, StMCO, from Streptomyces thermocarboxydus, was identified, cloned, and heterologously expressed in Escherichia coli. The purified recombinant StMCO exhibited the characteristic blue color and bivalent copper ion-dependent enzyme activity. It was capable of oxidizing the model substrate ABTS, phenolic compound DMP, and azo dye RB5. Notably, StMCO could directly degrade aflatoxin B1 (AFB1) and zearalenone (ZEN) in the absence of mediators. Meanwhile, the presence of various lignin unit-derived natural mediators or ABTS could significantly accelerate the degradation of AFB1 and ZEN by StMCO. Furthermore, the biological toxicities of their corresponding degradation products, AFQ1 and 13-OH-ZEN-quinone, were remarkably decreased. Our findings suggested that efficient degradation of mycotoxins with mediators might be a common feature of the MCOs superfamily. In summary, the unique properties of MCOs make them good candidates for degrading multiple major mycotoxins in contaminated feed and food.

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