scholarly journals Novel Mechanism and Kinetics of Tetramethrin Degradation Using an Indigenous Gordonia cholesterolivorans A16

2021 ◽  
Vol 22 (17) ◽  
pp. 9242
Author(s):  
Yuxin Guo ◽  
Yaohua Huang ◽  
Shimei Pang ◽  
Tianhao Zhou ◽  
Ziqiu Lin ◽  
...  
Keyword(s):  
Contaminated Soils ◽  
High Performance ◽  
Degradation Rate ◽  
Degradation Products ◽  
Living System ◽  
Gas Chromatography Mass Spectrometry ◽  
Synthetic Pyrethroids ◽  
Half Saturation Constant ◽  
Important Concern ◽  
Specific Degradation

Tetramethrin is a pyrethroid insecticide that is commonly used worldwide. The toxicity of this insecticide into the living system is an important concern. In this study, a novel tetramethrin-degrading bacterial strain named A16 was isolated from the activated sludge and identified as Gordonia cholesterolivorans. Strain A16 exhibited superior tetramethrin degradation activity, and utilized tetramethrin as the sole carbon source for growth in a mineral salt medium (MSM). High-performance liquid chromatography (HPLC) analysis revealed that the A16 strain was able to completely degrade 25 mg·L−1 of tetramethrin after 9 days of incubation. Strain A16 effectively degraded tetramethrin at temperature 20–40 °C, pH 5–9, and initial tetramethrin 25–800 mg·L−1. The maximum specific degradation rate (qmax), half-saturation constant (Ks), and inhibition constant (Ki) were determined to be 0.4561 day−1, 7.3 mg·L−1, and 75.2 mg·L−1, respectively. The Box–Behnken design was used to optimize degradation conditions, and maximum degradation was observed at pH 8.5 and a temperature of 38 °C. Five intermediate metabolites were identified after analyzing the degradation products through gas chromatography–mass spectrometry (GC-MS), which suggested that tetramethrin could be degraded first by cleavage of its carboxylester bond, followed by degradation of the five-carbon ring and its subsequent metabolism. This is the first report of a metabolic pathway of tetramethrin in a microorganism. Furthermore, bioaugmentation of tetramethrin-contaminated soils (50 mg·kg−1) with strain A16 (1.0 × 107 cells g−1 of soil) significantly accelerated the degradation rate of tetramethrin, and 74.1% and 82.9% of tetramethrin was removed from sterile and non-sterile soils within 11 days, respectively. The strain A16 was also capable of efficiently degrading a broad spectrum of synthetic pyrethroids including D-cyphenothrin, chlorempenthrin, prallethrin, and allethrin, with a degradation efficiency of 68.3%, 60.7%, 91.6%, and 94.7%, respectively, after being cultured under the same conditions for 11 days. The results of the present study confirmed the bioremediation potential of strain A16 from a contaminated environment.

scholarly journals Intracrystalline biomolecules in Recent and fossil brachiopod shells - the biochemistry of shell coloration

1992 ◽  
Vol 6 ◽  
pp. 59-59
Author(s):  
Heather Clegg ◽  
Gordon B. Curry
Keyword(s):  
Gas Chromatography ◽  
Carboxylic Acids ◽  
High Performance ◽  
Mass Spectra ◽  
Organic Molecules ◽  
Degradation Products ◽  
Polyacrylamide Gel Electrophoresis ◽  
Reference Points ◽  
Gas Chromatography Mass Spectrometry ◽  
Magnesium Calcite

The study of fossil biomolecules requires not only well preserved fossil samples, but abundant Recent material so that reference points can be established. Ideally it would also be possible to study the in situ decay of organic molecules in samples of different geological ages, and hence determine how degradation proceeds with time. The shells of brachiopods fulfill both these criteria, containing up to 1% organic components entombed within their shells, which are composed of highly stable, low magnesium calcite, that survives well in the fossil record for hundreds of millions of years.This particular study has concentrated on Plio-Pleistocene brachiopods from New Zealand. These fossils are the ancestors of living species, and hence it is possible to investigate intracrystalline biomolecules in modern day shells, as well as the degradation products of such biomolecules in fossil shells of the same species.Three of the species investigated have bright red shells in life, and during the study it became clear that this coloration was caused by a carotenoprotein which was embedded within, rather than around, the calcite fibres of the brachiopod shell. Carotenoproteins are composite molecules composed of a protein and a prosthetic carotenoid group. The protein has been characterised by hplc (high performance liquid chromatography) and SDS PAGE (sodium dodecylsulphate polyacrylamide gel electrophoresis), and the amino acids at the N-termini have been sequenced, demonstrating that this is a small protein which has a molecular weight of 6.5 kDa and is identical in all 3 species.At least two different types of carotenoids were detected after initial purification, and these were characterised using direct probe mass spectra, and hplc/mass spectra. Using these techniques the two carotenoids have been tentatively identified as canthaxanthin and the mono acetylenic analogue of asthaxanthin.In addition to the carotenoproteins, the calcite crystals of recent brachiopod shells contain lipids (carboxylic acids) and carbohydrates, which were characterised by gas chromatography (GC) and gas chromatography/mass spectrometry analyses (GC/MS).Fossil brachiopod shells could be distinguished from recent shells due to their lack of unsaturated acids and smaller amounts of carboxylic acids present. However there was no trend of decreasing quantities of fatty acid with increasing age.The presence of organic molecules such as carotenoproteins, lipids and carbohydrates within calcite crystals poses two questions. Firstly, are these compounds merely wastes metabolic products and are deposited within the shell during growth or, secondly, do they play an important role in the process of biomineralisation? At present these questions remain largely unanswered, because at present only the function of the carotenoprotein has been determined from the spectrum of biomolecules present within the shell (and the carotenoprotein may have other functions apart from coloration).

Study of degradation products and degradation pathways of sulfonated azo dyes under ultraviolet irradiation

2017 ◽  
Vol 89 (3) ◽  
pp. 322-334
Author(s):  
Jiangang Qu ◽  
Nannan Li ◽  
Chunmei Wang ◽  
Jinxin He
Keyword(s):  
Mass Spectrometry ◽  
Azo Dyes ◽  
Ultraviolet Irradiation ◽  
High Performance ◽  
Degradation Products ◽  
Inorganic Ions ◽  
Degradation Process ◽  
Gas Chromatography Mass Spectrometry ◽  
Ionization Mass ◽  
Degradation Pathways

Monitoring the light-induced decomposition course of azo dyes is essential to understand their degradation pathways and mechanisms. In this study, two model dyes are synthesized and used for stimulating the photodegradation processes of azo and hydrazone dyes, respectively. Their intermediates formed during initial and final fading processes are characterized by high-performance liquid chromatography-electrospray ionization-mass spectrometry, gas chromatography-mass spectrometry and ion chromatography. Results reveal that no dramatic differences are observed between the two dyes, although hydrazone dye would undergo a more complicated degradation process. Hydroxyl radicals are the dominant reactive species involved in the photodegradation of both model dyes under ultraviolet irradiation. In the initial steps, the intermediates are almost hydroxylated derivatives, while low-molecular-weight dicarboxylic acids and their hydroxylated and esterified derivatives, as well as non-volatile inorganic ions, are detected and evidenced in the final steps. Furthermore, photodegradation pathways and mechanisms for the two model dyes are proposed accordingly.

scholarly journals Formation of phthalates during the degradation of N-phenyl-2-naphthylamine by soil bacteria

2021 ◽  
Vol 11 (1) ◽  
pp. 107-115
Author(s):  
L. E. Makarova ◽  
A. S. Morits ◽  
N. A. Sokolova
Keyword(s):  
Ethyl Acetate ◽  
Pseudomonas Syringae ◽  
Soil Bacteria ◽  
High Performance ◽  
Rhizobium Leguminosarum ◽  
Culture Media ◽  
Degradation Products ◽  
Bacterial Species ◽  
Gas Chromatography Mass Spectrometry ◽  
Negative Effect

N-phenyl-2-naphthylamine (N-PNA) and phthalates are classified as antibiotic substances. The appearance and accumulation of these substances in the biosphere is associated with their technogenic and biogenic origin (metabolites of plants and bacteria). In this article, we compare the degrading action of such soil bacteria as Rhizobium leguminosarum bv. viceae, Bradyrhizobium japonicum, Pseudomonas syringae pv. pisi, Clavibacter michiganensis sps. Sepedonicus and Azotobacter chroococcum against N-PNA. These bacteria differ in their interaction with pea plants (Pisum sativum L.) synthesising N-PNA. The degradation products were studied using gas chromatography-mass spectrometry in ethyl acetate extracts obtained from culture liquid media, in which N-PNA at a concentration of 10 μM and the bacteria under study were introduced. The decrease in the N-PNA concentration in the extracts obtained using ethyl acetate from culture media, in which N-PNA had been added to a concentration of 100 μM, was monitored following two days of bacterial growth using the methods of high-performance liquid chromatography. It was shown that all the studied bacterial species are capable of degrading N-PNA with the formation of phthalates. The Rhizobium bacteria, endosymbionts of pea plants synthesising N-PNA, and free-living nitrogen-fixing bacteria of the Azotobacter genus showed the highest degrading activity. It was found that N-PNA reduced the viability of all types of bacteria, although to a varying degree. N-PNA had the most negative effect on the viability of the Azotobacter genus, although these bacteria showed a high degrading action against N-PNA. The dependence between the negative effect of NPNA on bacterial viability and the N-PNA concentration was mildly pronounced for Rhizobium and Pseudomonas, although being significant for Bradyrhizobium and Clavibacter.

scholarly journals Kinetics and New Mechanism of Azoxystrobin Biodegradation by an Ochrobactrum anthropi Strain SH14

2020 ◽  
Vol 8 (5) ◽  
pp. 625 ◽  
Author(s):  
Yanmei Feng ◽  
Wenping Zhang ◽  
Shimei Pang ◽  
Ziqiu Lin ◽  
Yuming Zhang ◽  
...  
Keyword(s):  
Contaminated Soils ◽  
Degradation Pathway ◽  
Order Kinetic ◽  
Ochrobactrum Anthropi ◽  
Strobilurin Fungicides ◽  
Residual Toxicity ◽  
Half Saturation Constant ◽  
Enhanced Biodegradation ◽  
Order Kinetic Model ◽  
Specific Degradation

Azoxystrobin is one of the most popular strobilurin fungicides, widely used in agricultural fields for decades.Extensive use of azoxystrobin poses a major threat to ecosystems. However, little is known about the kinetics and mechanism of azoxystrobin biodegradation. The present study reports a newly isolated bacterial strain, Ochrobactrum anthropi SH14, utilizing azoxystrobin as a sole carbon source, was isolated from contaminated soils. Strain SH14 degraded 86.3% of azoxystrobin (50 μg·mL−1) in a mineral salt medium within five days. Maximum specific degradation rate (qmax), half-saturation constant (Ks), and inhibition constant (Ki) were noted as 0.6122 d−1, 6.8291 μg·mL−1, and 188.4680 μg·mL−1, respectively.Conditions for strain SH14 based azoxystrobin degradation were optimized by response surface methodology. Optimum degradation was determined to be 30.2 °C, pH 7.9, and 1.1 × 107 CFU·mL−1 of inoculum. Strain SH14 degraded azoxystrobin via a novel metabolic pathway with the formation of N-(4,6-dimethoxypyrimidin-2-yl)-acetamide,2-amino-4-(4-chlorophenyl)-3-cyano-5,6-dimethyl-pyridine, and 3-quinolinecarboxylic acid,6,8-difluoro-4-hydroxy-ethyl ester as the main intermediate products, which were further transformed without any persistent accumulative product. This is the first report of azoxystrobin degradation pathway in a microorganism. Strain SH14 also degraded other strobilurin fungicides, including kresoxim-methyl (89.4%), pyraclostrobin (88.5%), trifloxystrobin (78.7%), picoxystrobin (76.6%), and fluoxastrobin (57.2%) by following first-order kinetic model. Bioaugmentation of azoxystrobin-contaminated soils with strain SH14 remarkably enhanced the degradation of azoxystrobin, and its half-life was substantially reduced by 95.7 and 65.6 days in sterile and non-sterile soils, respectively, in comparison with the controls without strain SH14. The study presents O. anthropi SH14 for enhanced biodegradation of azoxystrobin and elaborates on the metabolic pathways to eliminate its residual toxicity from the environment.

scholarly journals Synergistic Degradation of Chloramphenicol by an Ultrasound-Enhanced Fenton-like Sponge Iron System

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3561
Author(s):  
Xia Meng ◽  
Zhongming Liu ◽  
Shoujuan Wang ◽  
Fangong Kong
Keyword(s):  
Degradation Rate ◽  
Degradation Products ◽  
Iron Concentration ◽  
Sponge Iron ◽  
Degradation Efficiency ◽  
Gas Chromatography Mass Spectrometry ◽  
Oh Radicals ◽  
Surface Method ◽  
Synergistic Degradation ◽  
The Impact

In this study, an ultrasound Fenton-like sponge iron system was used to enhance the degradation efficiency for chloramphenicol (CAP). Three single-factor experiments of reaction pH, hydrogen peroxide (H2O2) concentration, and sponge iron (Fe) concentration were used to explore the impact on CAP degradation efficiency. The response surface method revealed the interactions between various factors. The degradation efficiency for CAP was as high as 99.97% at pH = 3, 3.19 mmol/L H2O2, and a sponge iron concentration of 2.26 g/L. The degradation rate for CAP was significantly reduced upon the addition of some inorganic salts, mainly due to the quenching of OH radicals. Gram-negative (G(−)) Escherichia coli and Gram-positive (G(+)) Staphylococcus aureus were used to evaluate the changes in the antibacterial activity of CAP. Finally, gas chromatography/mass spectrometry (GC-MS) was used to identify the degradation products and the degradation path for the products was proposed based on the detected products.

Hydrothermal Treatment of Liquid Crystal Using a Batch Reactor

2014 ◽  
Vol 878 ◽  
pp. 563-568
Author(s):  
Xu Ning Zhuang ◽  
Ying Ying Ye ◽  
Wen Zhi He ◽  
Guang Ming Li ◽  
Ju Wen Huang
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Reaction Time ◽  
Reaction Temperature ◽  
High Performance ◽  
Degradation Rate ◽  
Degradation Products ◽  
Liquid Crystal Display ◽  
Batch Reactor ◽  
Tube Reactor

Liquid crystals, contained in Liquid Crystal Display (LCD), would cause undesirable impacts on the environment and human health if not treated properly. Converting the waste liquid crystal into harmless product has aroused worldwide attention. In the present work, hydrothermal technology was applied to treat the liquid crystal of 4-octoxy-4'-cyanobiphenyl, which is one of the most common used liquid crystals in LCDs. The experiment was carried out in a 5.7 mL stainless tube reactor and heated by an oven. The effect of reaction temperature and reaction time on degradation rate was evaluated and the analysis was conducted with High Performance Liquid Chromatography (HPLC). The degradation products in liquid phase were analyzed with Gas Chromatography/Mass Spectrometer (GC/MS). Results indicate that the degradation rate improved along with the increase of reaction temperature and reaction time. At 300 C and with the reaction time of 90 min, 99.8% of 4-octoxy-4'-cyanobiphenyl could be degraded into simple and environmental innocuous products and its environmental risks were finally eliminated.

scholarly journals Anaerobic-Aerobic Process for Microbial Degradation of Tetrabromobisphenol A

2000 ◽  
Vol 66 (6) ◽  
pp. 2372-2377 ◽  
Author(s):  
Zeev Ronen ◽  
Aharon Abeliovich
Keyword(s):  
Contaminated Soils ◽  
High Performance ◽  
Culture Medium ◽  
Gas Chromatography Mass Spectrometry ◽  
Tetrabromobisphenol A ◽  
Circuit Boards ◽  
Industry Waste ◽  
Aerobic Process ◽  
Yeast Extract Medium ◽  
Bacterium Strain

ABSTRACT Tetrabromobisphenol A (TBBPA) is a flame retardant that is used as an additive during manufacturing of plastic polymers and electronic circuit boards. Little is known about the fate of this compound in the environment. In the current study we investigated biodegradation of TBBPA, as well as 2,4,6-tribromophenol (TBP), in slurry of anaerobic sediment from a wet ephemeral desert stream bed contaminated with chemical industry waste. Anaerobic incubation of the sediment with TBBPA and peptone-tryptone-glucose-yeast extract medium resulted in a 80% decrease in the TBBPA concentration and accumulation of a single metabolite. This metabolite was identified by gas chromatography-mass spectrometry (GC-MS) as nonbrominated bisphenol A (BPA). On the other hand, TBP was reductively dehalogenated to phenol, which was further metabolized under anaerobic conditions. BPA persisted in the anaerobic slurry but was degraded aerobically. A gram-negative bacterium (strain WH1) was isolated from the contaminated soil, and under aerobic conditions this organism could use BPA as a sole carbon and energy source. During degradation of BPA two metabolites were detected in the culture medium, and these metabolites were identified by GC-MS and high-performance liquid chromatography as 4-hydroxybenzoic acid and 4-hydroxyacetophenone. Both of those compounds were utilized by WH1 as carbon and energy sources. Our findings demonstrate that it may be possible to use a sequential anaerobic-aerobic process to completely degrade TBBPA in contaminated soils.

The Influence of Some Factors on Spirolactone Stability in Solution

2008 ◽  
Vol 59 (7) ◽  
Author(s):  
Daniela Lucia Muntean ◽  
Silvia Imre ◽  
Cosmina Voda
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Uv Irradiation ◽  
High Performance ◽  
Degradation Products ◽  
Simultaneous Action ◽  
Ethanolic Solution ◽  
Degradation Processes ◽  
Stable Solutions ◽  
Preformulation Study

The influence of some factors on spironolactone stability in solution was studied, by applying high-performance liquid chromatography, as a part of a pharmaceutical preformulation study in order to obtain a spironolactone solution for alopecia treatment. Solutions of 1 mg/ml spironolactone in aqueous ethanolic solution 1 : 1 and in 20 mM cyclodextrines solutions (b-, hydroxi-b- and methyl-b-cyclodextrine) was used, maintained at 8 and 22 �C, protected from light and after UV irradiation at 254 nm. The main degradation products were 7a-thiospirolactone and canrenone. The most stable solutions were the alcoholic ones and with methyl-beta-cyclodextrine, but the simultaneous action of temperature and UV irradiation allowed degradation processes after one hour of exposure, more aggressive in the presence of methyl-beta-cyclodextrine. In conclusion, for alopecia treatment with spironolactone a 1 mg/mL ethanolic solution could be used and it is recommendable the protection of treated zone.

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