scholarly journals Transformation of Tetracycline by Manganese Peroxidase from Phanerochaete chrysosporium

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6803
Author(s):  
Xuemei Sun ◽  
Yifei Leng ◽  
Duanji Wan ◽  
Fengyi Chang ◽  
Yu Huang ◽  
...  
Keyword(s):  
Phanerochaete Chrysosporium ◽  
Manganese Peroxidase ◽  
Degradation Products ◽  
Degradation Mechanism ◽  
Transformation Products ◽  
Transformation Rate ◽  
Transformation Mechanism ◽  
Initial Concentration ◽  
Negative Impacts ◽  
High Level

The negative impacts on the ecosystem of antibiotic residues in the environment have become a global concern. However, little is known about the transformation mechanism of antibiotics by manganese peroxidase (MnP) from microorganisms. This work investigated the transformation characteristics, the antibacterial activity of byproducts, and the degradation mechanism of tetracycline (TC) by purified MnP from Phanerochaete chrysosporium. The results show that nitrogen-limited and high level of Mn2+ medium could obtain favorable MnP activity and inhibit the expression of lignin peroxidase by Phanerochaete chrysosporium. The purified MnP could transform 80% tetracycline in 3 h, and the threshold of reaction activator (H2O2) was about 0.045 mmol L−1. After the 3rd cyclic run, the transformation rate was almost identical at the low initial concentration of TC (77.05–88.47%), while it decreased when the initial concentration was higher (49.36–60.00%). The antimicrobial potency of the TC transformation products by MnP decreased throughout reaction time. We identified seven possible degradation products and then proposed a potential TC transformation pathway, which included demethylation, oxidation of the dimethyl amino, decarbonylation, hydroxylation, and oxidative dehydrogenation. These findings provide a novel comprehension of the role of MnP on the fate of antibiotics in nature and may develop a potential technology for tetracycline removal.

scholarly journals Hydrolysis and Photolysis Kinetics, and Identification of Degradation Products of the Novel Bactericide 2-(4-Fluorobenzyl)-5-(Methylsulfonyl)-1,3,4-Oxadiazole in Water

2018 ◽  
Vol 15 (12) ◽  
pp. 2741 ◽  
Author(s):  
Xingang Meng ◽  
Lingzhu Chen ◽  
Yuping Zhang ◽  
Deyu Hu ◽  
Baoan Song
Keyword(s):  
Degradation Product ◽  
High Performance ◽  
Degradation Products ◽  
Degradation Mechanism ◽  
The Novel ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
High Resolution Mass Spectrometer

Hydrolysis and photolysis kinetics of Fubianezuofeng (FBEZF) in water were investigated in detail. The hydrolysis half-lives of FBEZF depending on pH, initial concentration, and temperature were (14.44 d at pH = 5; 1.60 d at pH = 7), (36.48 h at 1.0 mg L−1; 38.51 h at 5.0 mg L−1; and 31.51 h at 10.0 mg L−1), and (77.02 h at 15 °C; 38.51 h at 25 °C; 19.80 h at 35 °C; and 3.00 h at 45 °C), respectively. The photolysis half-life of FBEZF in different initial concentrations were 8.77 h at 1.0 mg L−1, 8.35 h at 5.0 mg L−1, and 8.66 h at 10.0 mg L−1, respectively. Results indicated that the degradation of FBEZF followed first-order kinetics, as the initial concentration of FBEZF only had a slight effect on the UV irradiation effects, and the increase in pH and temperature can substantially accelerate the degradation. The hydrolysis Ea of FBEZF was 49.90 kJ mol−1, which indicates that FBEZF belongs to medium hydrolysis. In addition, the degradation products were identified using ultra-high-performance liquid chromatography coupled with an Orbitrap high-resolution mass spectrometer. One degradation product was extracted and further analyzed by 1H-NMR, 13C-NMR, 19F-NMR, and MS. The degradation product was identified as 2-(4-fluorobenazyl)-5-methoxy-1,3,4-oxadiazole, therefore a degradation mechanism of FBEZF in water was proposed. The research on FBEZF can be helpful for its safety assessment and increase the understanding of FBEZF in water environments.

scholarly journals Genomics Analysis and Degradation Characteristics of Lignin by Streptomyces Thermocarboxydus Strain DF3-3

2021 ◽  
Author(s):  
Fangyun Tan ◽  
Jun Cheng ◽  
Yu Zhang ◽  
Xingfu Jiang ◽  
Yueqiu Liu
Keyword(s):  
Energy Conversion ◽  
Manganese Peroxidase ◽  
Metabolic Pathways ◽  
Lignin Degradation ◽  
Degradation Products ◽  
Degradation Mechanism ◽  
Biomass Energy ◽  
Raw Material ◽  
Gas Chromatography Mass Spectrometry ◽  
Degradation Intermediates

Abstract Background: Lignocellulose is an important raw material for biomass-to-energy conversion, and it exhibits a complex but inefficient degradation mechanism. Microbial degradation is promising due to its environmental adaptability and biochemical versatility, but the pathways used by microbes for lignin degradation have not been fully studied. Degradation intermediates and complex metabolic pathways require more study.Results: A novel actinomycete DF3-3, with the potential for lignin degradation, was screened and isolated. After morphological and molecular identification, DF3-3 was determined to be Streptomyces thermocarboxydus. The degradation of alkali lignin reached 31% within 15 days. Manganese peroxidase and laccase demonstrated their greatest activity levels, 1821.66 UL-1 and 1265.58 UL-1, respectively, on the sixth day. The highest lignin peroxidase activity was 480.33 UL-1 on the fourth day. A total of 19 lignin degradation intermediates were identified by gas chromatography-mass spectrometry (GC-MS), including 10 aromatic compounds. Genome sequencing and annotation identified 107 lignin-degrading enzyme-coding genes containing three core enzymatic systems for lignin depolymerization: laccases, peroxidases and manganese peroxidase. In total, 7 lignin metabolic pathways were predicted.Conclusions: Streptomyces thermocarboxydus strain DF3-3 has good lignin degradation ability. Degradation products and genomics analyses of DF3-3 show that it has a relatively complete lignin degradation pathway, including the β-ketoadipate pathway and peripheral reactions; gentisate pathway; anthranilate pathway; homogentisic pathway; and catabolic pathway for resorcinol. Two other pathways, the phenylacetate-CoA pathway and the 2,3-dihydroxyphenylpropionic acid pathway, are predicted based on genome data alone. This study provides the basis for future characterization of potential biotransformation enzyme systems for biomass energy conversion.

scholarly journals Degradation Products of Polychlorinated Biphenyls and Their In Vitro Transformation by Ligninolytic Fungi

Toxics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 81
Author(s):  
Kamila Šrédlová ◽  
Kateřina Šírová ◽  
Tatiana Stella ◽  
Tomáš Cajthaml
Keyword(s):  
Polychlorinated Biphenyls ◽  
Extracellular Enzymes ◽  
Degradation Products ◽  
Transformation Products ◽  
Irpex Lacteus ◽  
Chlorobenzoic Acid ◽  
Ligninolytic Fungi ◽  
Wide Range ◽  
Pcb Metabolites

Metabolites of polychlorinated biphenyls (PCBs)—hydroxylated PCBs (OH‑PCBs), chlorobenzyl alcohols (CB‑OHs), and chlorobenzaldehydes (CB‑CHOs)—were incubated in vitro with the extracellular liquid of Pleurotus ostreatus, which contains mainly laccase and low manganese-dependent peroxidase (MnP) activity. The enzymes were able to decrease the amount of most of the tested OH‑PCBs by > 80% within 1 h; the removal of more recalcitrant OH‑PCBs was greatly enhanced by the addition of the laccase mediator syringaldehyde. Conversely, glutathione substantially hindered the reaction, suggesting that it acted as a laccase inhibitor. Hydroxylated dibenzofuran and chlorobenzoic acid were identified as transformation products of OH‑PCBs. The extracellular enzymes also oxidized the CB‑OHs to the corresponding CB‑CHOs on the order of hours to days; however, the mediated and nonmediated setups exhibited only slight differences, and the participating enzymes could not be determined. When CB‑CHOs were used as the substrates, only partial transformation was observed. In an additional experiment, the extracellular liquid of Irpex lacteus, which contains predominantly MnP, was able to efficiently transform CB‑CHOs with the aid of glutathione; mono‑ and di-chloroacetophenones were detected as transformation products. These results demonstrate that extracellular enzymes of ligninolytic fungi can act on a wide range of PCB metabolites, emphasizing their potential for bioremediation.

Studies on Sporopollenin Biosynthesis in Cucurbita maxima I: The Substantial Labeling of Sporopollenin from Cucurbita maxima after Application of [14C]Phenylalanine

1993 ◽  
Vol 48 (1-2) ◽  
pp. 10-15 ◽  
Author(s):  
Sabine Gubatz ◽  
Rolf Wiermann
Keyword(s):  
Terephthalic Acid ◽  
Phthalic Acid ◽  
Degradation Products ◽  
Hydroxybenzoic Acid ◽  
Cucurbita Maxima ◽  
Purification Step ◽  
Decanedioic Acid ◽  
Octanedioic Acid ◽  
High Level ◽  
Tracer Experiments

The results of tracer experiments performed with anthers of Tulipa cv. Apeldoorn have already shown that a high level of incorporation into the sporopollenin fraction was achieved, when [14C]phenylalanine was applicated as a precursor. In order to investigate whether the substantial incorporation of [14C]phenylalanine is a unique phenomenon restricted to Tulipa, tracer experiments were carried out on anthers of Cucurbita maxima. The sporopollenin fraction was isolated and purified by a gentle method including extractions with various solvents, incubations with hydrolysing enzymes and fractionated saponifications. The remaining, as well as the released radioactivity, was determined after each purification step. After the application of [U-14C]phenylalanine, a substantial incorporation into the sporopollenin fraction was determined. The values were clearly higher than those obtained with [1-14C]glucose or those from corresponding experiments on Tulipa anthers. After potash fusion of sporopollenin fractions labeled via [U-14C]phenylalanine, p-hydroxybenzoic acid was shown to be the main com ponent among the ether soluble acids; moreover it showed the highest level of radioactivity. No radioactivity was detected in the degradation products oxalic acid, benzoic acid, phthalic acid and terephthalic acid or octanedioic acid- and decanedioic acid-dimethylester.

scholarly journals Manganese Peroxidase from the Lignin-degrading Basidiomycete Phanerochaete chrysosporium

1989 ◽  
Vol 264 (6) ◽  
pp. 3335-3340 ◽  
Author(s):  
H Wariishi ◽  
H B Dunford ◽  
I D MacDonald ◽  
M H Gold
Keyword(s):  
Phanerochaete Chrysosporium ◽  
Manganese Peroxidase

scholarly journals Decision-making process for introduction of maternal vaccines in Kenya, 2017–2018

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Nancy A. Otieno ◽  
Fauzia A. Malik ◽  
Stacy W. Nganga ◽  
Winnie N. Wairimu ◽  
Dominic O. Ouma ◽  
...  
Keyword(s):  
Decision Making ◽  
Policy Development ◽  
Implementation Process ◽  
Policy Formulation ◽  
Advisory Group ◽  
Decision Making Process ◽  
Middle Income ◽  
Maternal Immunization ◽  
Negative Impacts ◽  
High Level

Abstract Background Maternal immunization is a key strategy for reducing morbidity and mortality associated with infectious diseases in mothers and their newborns. Recent developments in the science and safety of maternal vaccinations have made possible development of new maternal vaccines ready for introduction in low- and middle-income countries. Decisions at the policy level remain the entry point for maternal immunization programs. We describe the policy and decision-making process in Kenya for the introduction of new vaccines, with particular emphasis on maternal vaccines, and identify opportunities to improve vaccine policy formulation and implementation process. Methods We conducted 29 formal interviews with government officials and policy makers, including high-level officials at the Kenya National Immunization Technical Advisory Group, and Ministry of Health officials at national and county levels. All interviews were recorded and transcribed. We analyzed the qualitative data using NVivo 11.0 software. Results All key informants understood the vaccine policy formulation and implementation processes, although national officials appeared more informed compared to county officials. County officials reported feeling left out of policy development. The recent health system decentralization had both positive and negative impacts on the policy process; however, the negative impacts outweighed the positive impacts. Other factors outside vaccine policy environment such as rumours, sociocultural practices, and anti-vaccine campaigns influenced the policy development and implementation process. Conclusions Public policy development process is complex and multifaceted by its nature. As Kenya prepares for introduction of other maternal vaccines, it is important that the identified policy gaps and challenges are addressed.

In-Situ Study of Ti/TiN Stability under Nitrogen Anneal

1999 ◽  
Vol 564 ◽  
Author(s):  
P. W. DeHaven ◽  
K. P. Rodbell ◽  
L. Gignac
Keyword(s):  
Annealing Temperature ◽  
Time Range ◽  
Second Phase ◽  
Transformation Rate ◽  
Transformation Mechanism ◽  
Second Stage ◽  
Transmission Electron ◽  
Reaction Proceeds ◽  
Two Stages

AbstractThe effectiveness of a TiN capping layer to prevent the conversion of α-titantium to titanium nitride when annealed in a nitrogen ambient has been studied over the temperature range 300–700°C using in-situ high temperature diffraction and transmission electron microscopy. Over the time range of interest (four hours), no evidence of Ti reaction was observed at 300°C. At 450°C. nitrogen was found to diffuse into the Ti to form a Ti(N) solid solution. Above 500°C the titanium is transformed to a second phase: however this reaction follows two different kinetic paths, depending on the annealing temperature. Below 600°C. the reaction proceeds in two stages, with the first stage consisting of Ti(N) formation, and the second stage consisting of the conversion of the Ti(N) with a transformation mechanism characteristic of short range diffusion (grain edge nucleation). Above 600°C, a simple linear transformation rate is observed.

Studies on hydrolysis and radiolysis of N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide

2002 ◽  
Vol 90 (3) ◽  
Author(s):  
Y. Sugo ◽  
Y. Sasaki ◽  
S. Tachimori
Keyword(s):  
Gamma Irradiation ◽  
Room Temperature ◽  
Degradation Products ◽  
Liquid Waste ◽  
Amide Bond ◽  
Radioactive Liquid Waste ◽  
Ether Bond ◽  
Nuclear Fuel Reprocessing ◽  
High Level ◽  
Fuel Reprocessing

SummaryHydrolytic and radiolytic stabilities of a promising extractant, N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA), for actinides in high-level radioactive liquid waste from nuclear fuel reprocessing were investigated in air at room temperature. Hydrolysis by nitric acid was not observed, whereas radiolysis by gamma irradiation was notably observed. The radiolysis study showed that an amide-bond, an ether-bond, and a bond adjacent to the ether-bond tended to be broken by gamma irradiation, and dioctylamine and various N,N-dioctylmonoamides were identified as the main degradation products by GC/MS and NMR analyses. The

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