Degradation of triphenyltin compounds in sea water by pyoverdins from Pseudomonas chlororaphis

The yellow compound species pyoverdin was isolated from Pseudomonas chlororaphis. Degradation of triphenyltin (TPT) by pyoverdin (20 mg) was carried in distilled water (30 ml) containing a 6 µg l^?1 concentration of TPT at 20 °C for 96 h in aerobic conditions. The organotins in water and sea water were analyzed by gas chromatograph–mass spectrometry in selected ion mode. TPT and diphenyltin (DPT) in sea water were degraded to monophenyltin (MPT) with pyoverdins isolated from P. ­chlororaphis. Degradation of TPT in sea water increased with increasing temperature between 4 and 37 °C. Optimum degradation of TPT in sea water was at pH 7–8.5. Degradation of TPT and DPT in distilled water can be faster than in sea water. Also, degradation of TPT in both water and sea water was faster than that of DPT. Tributyltin, dibutyltin, monobutyltin and MPT in water and sea water were not degraded by pyoverdins isolated from P. chlororaphis. Copyright © 2001 John Wiley & Sons, Ltd.     

Effects of iron on the degradation of triphenyltin by pyoverdins isolated from Pseudomonas chlororaphis

The yellow compound pyoverdin was isolated from the bacteria Pseudomonas chlororaphis, isolated from mud in Japan. A study of the effects of iron, phosphorus, manganese and zinc on degradation of triphenyltin (TPT) by pyoverdin (20 mg) was carried out in distilled water (30 ml) containing 6 µg l^?1 concentration of TPT at 20 °C for 48 or 96 h. The organotins in water were analyzed by gas chromatograph–mass spectrometry in the selected ion mode. The degradation of TPT by pyoverdin decreased with increase of phosphorus at 0–35 mg l^?1 and Fe‐EDTA at 0–2 mg l^?1 concentrations. Also, degradation of diphenyltin by pyoverdin decreased with increase of Mn‐EDTA at 0–1 mg l^?1 and Zn‐EDTA at 0–1 mg l^?1. On the other hand, degradation of TPT by pyoverdin was found to be unaffected by manganese and zinc in water. Copyright © 2002 John Wiley & Sons, Ltd.     

Degradation of PCB by Bacteria Isolated from Long-Time Contaminated Soil

Abstract

Four bacterial isolates belonging to the genera Pseudomonas and Alcaligenes were obtained by the enrichment method, using biphenyl as the sole carbon source, from the soil, which underwent long-time contamination with technical mixtures of PCB. Kinetics of PCB degradation by individual isolates was measured using n-hexane extraction of the cultivation media in proper time intervals and analysed by congener specific gas chromatography with electron capture detection. All isolates exhibit interesting biodegradative potential. Specific degradation of individual congeners with respect to the number and position of chlorine substituents is discussed. The influence of glucose, biphenyl and 3-chlorobenzoic acid on the PCB degradation has been assessed.     

Degradation of tributyltin chloride in water photoinduced by iron(III)

The degradation of tributyltin chloride (TBT) photoinduced by iron(III) was investigated. Upon irradiation at λ_excitation >300 nm a photoredox process was observed, yielding iron(II) and ^·2OH radicals. The disappearance of TBT was proved to involve only an attack by ^·2OH radicals: the quantum yield of TBT disappearance was determined. A wavelength effect was observed; the shorter the excitation wavelength, the higher the rate of TBT disappearance. Most of the photoproducts were identified and the mechanism of degradation was elucidated. The main route to degradation is a stepwise debutylation of TBT to di‐ and mono‐butyltin with final formation of inorganic tin. The complete mineralization of TBT was achieved with long irradiation times, leading to innocuous inorganic tin. Copyright © 1999 John Wiley & Sons, Ltd.     

Fenton试剂降解水中的菲和芘

多环芳烃(PAHs)是最早发现且数量最多的致癌物[1],主要来源于人类活动和能源利用过程,如石油、煤等的燃烧、石油及石油化工产品生产、海上石油开发及石油运输中的溢漏等过程.     

Effects of exposure to dibutyltin dichloride on sperm density,viability and morphology in male mice

Experiments on the effects of 0.025–0.40 µg of dibutyltin dichloride (DBTCl) per kilogram body weight (kg bw), on sperm density, viability and morphology in mature mice were conducted by daily intraperitoneal injection for 7 days at 22 ± 2 °C and 12 h light–dark cycle conditions. The results demonstrated that DBTCl exhibited strong toxicity on sperm quality. Dosed with ≥ 0.05 µg DBTCl/kg bw groups, the testes weight, sperm density and the rate of survival of sperm decreased, whereas the rate of sperm abnormalities increased significantly. In addition, treatment with 0.05 µg DBTCl/kg bw resulted in increasing rate of sperm head abnormalities, whereas administration at 0.20 and 0.40 µg DBTCl/kg bw significantly increased the rate of sperm tail abnormalities. In the group treated at ≥ 0.10 µg DBTCl/kg bw, the mice body weights decreased. It appeared there was a noticeable dose–response relationship between DBTCl and the parameters studied. ED₅₀ values (7 days) of DBTCl for survival rate of sperm and density were 0.17 µg/kg bw and 0.19 µg/kg bw respectively. The present study provides a possibility for early diagnostic indicators and methods for sperm quality induced by organotin compounds (DBTCl) in mammals. Copyright © 2001 John Wiley & Sons, Ltd.     

Direct Electrochemical Sensing of Phenazine‐1‐carboxylic Acid Secreted by Pseudomonas chlororaphis subsp. aureofaciens BCRC 11057T Using Disposable Screen‐printed Carbon Electrode

A novel electrochemical approach for direct recognition of antibiotic phenazine‐1‐carboxylic acid (PCA) was developed. PCA was electropolymerized on preanodized screen‐printed carbon electrode (SPCE*‐PCA) through repetitive cyclic voltammetry and characterized by XPS and FESEM. Electron transfer involved intermediate phenomenon of diffusion‐controlled redox process and surface bound redox reaction. At pH 8 (optimum), SPCE*‐PCA had a detection limit of 0.51±0.04 μM, a quantification limit of 1.7±0.13 μM, linearity of up to 50 µM, a repeatability of 15.5 % and a reproducibility of 1.7 %. PCA secreted by Pseudomonas chlororaphis subsp. aureofaciens BCRC 11057^T was investigated successfully using present single run approach.     

Degradation of thiram in water, soil and plants: a study by high-performance liquid chromatography

A comprehensive study was conducted to evaluate the persistence of thiram in water and soil under controlled conditions and on two plants, namely tomato and radish, in field conditions. In order to follow the decay of the pesticide, an HPLC procedure was developed employing an octadecyl endcapped RP-C18 column using a mixture of acetonitrile and water as the mobile phase and an ultraviolet detector. Studies conducted in water at different temperature, pH and organic content revealed that the persistence of the pesticide decreases with the increase in all the three variables. In the three different types of soils studied, the effect of pH was more or less apparent on a similar line. On average a slower decay was observed in the case of plants than in water and soil.     

Effect of Catalase on Biocatalytic Synthesis of Pyruvate by Enzymes from Pseudomonas sp.

Pyruvate was produced from DL-lactate by a kind of green-chemical biocatalyst --cell-free extract from bacterial strain Pseudomonas sp. SM-6. Catalase in cell-free extract, whichcould stabilize the pyruvate formed by lactate oxidase, played an important role in pyruvatepreparation. The effect of catalase in conversion process was evaluated.     

Comparative study of biosurfactant produced by microorganisms isolated from formation water of petroleum reservoir

Biosurfactant produced by Pseudomonas aeruginosa, Bacillus subtilis and Rhodococcus erythropolis that isolated from the formation water of Chinese petroleum reservoir has been compared in surface abilities and oil recovery. Maximum biosurfactant production reached to about 2.66 g/l and the surface tension of liquid decreased from 71.2 to 22.56 mN/m using P. aeruginosa. Three strains exhibited a good ability to emulsify the crude oil, and biosurfactant of P. aeruginosa attained an emulsion index of 80% for crude oil which was greater than other strains. Stability studies were carried out under the extreme environmental conditions, such as high temperature, pH, salinity and metal ions. Results showed an excellent resistance of all biosurfactants to retain their surface-active properties at extreme conditions. It was found that the biosurfactants from three isolated bacteria showed a good stability above pH of 5, but at lower pH (from 1 to 5) they will harmfully be affected. They were able to support the condition up to 20 g/l salinity. P. aeruginosa biosurfactant was even stable at the higher salinity. Regarding temperature, all produced biosurfactants demonstrated a good stability in the temperature up to 120 °C. But stability of three biosurfactants was affected by monovalent and trivalent ions. Oil recovery experiments in physical simulation showed 7.2-14.3% recovery of residual oil after water flooding when the biosurfactant of three strains was added. These results suggest that biosurfactants of these indigenous isolated strains are appropriate candidates for enhanced oil recovery with a preference to biosurfactant of P. aeruginosa.     

Atomic absorption spectrometric/hydride generation determination of tributyltin and dibutyltin in sea water at the nanogram per litre level

A relatively simple system is described for the determination of tributyltin and dibutyltin in sea water at the ng l^?1 level. It is based on hydride generation followed by cryogenic trapping on a silanized glass wool column, transport to a quartz cuvette atomizer, and detection by atomic absorption spectrometry. Detection limits (3σ) of 2 ng Sn l^?1 are obtained for both species.     

结合分子模拟探讨PC脂肪酶催化PBS基共聚物降解的主链异构效应

采用固定化洋葱假单胞菌脂肪酶(Pseudomonas cepacia lipase,PC脂肪酶)为催化剂,在有机溶剂体系中研究了环己烷二甲醇和环己烷二甲酸对聚丁二酸丁二醇酯(PBS)的改性共聚物,即聚(丁二酸丁二醇-co-丁二酸环己烷二甲醇酯)(PBS-co-CHDMS)和聚(丁二酸丁二醇-co-环己烷二甲酸丁二醇酯)(PBS-co-BCHDA)的降解规律及其差异性.通过共聚物降解率随时间的变化、降解产物的MALDI-TOF-MS分析研究了共聚物降解规律,并以分子模拟分别研究了降解差异性和PC脂肪酶与底物的结合机制.研究结果表明,PC脂肪酶均可催化PBS基共聚物降解;在降解60 h后,相比较于PBS-co-BCHDA,PBS-co-CHDMS降解率均更大;其中PBS-co-10%CHDMS降解率最大,为85%.共聚物降解不仅生成了线型小分子,还产生了部分环状低聚物;此外,PBS-co-CHDMS降解产生的低聚物种类比PBS-co-BCHDA的要多.分子对接模拟结果表明,在氯仿中,PC脂肪酶与底物结合自由能的大小顺序为CMSCMBSCMBCABBSB,即含有丁二酸环己烷二甲醇酯(CHDMS)单元的底物与PC脂肪酶活性位点的对接更为稳定.     

Biocatalytic Synthesis of Pyruvate from DL-lactate with Enzymes in Pseudomonas sp.

Pyruvate has received increasing attention in recent years as a potential precursor for the synthesis of L-amino acids1. Compared with other small non-chiral building blocks, pyruvate is relatively expensive. Conventional processes for preparing pyruvate include a process comprising reacting sodium cyanide and acetyl chloride to synthesize acetyl cyanide and hydrolyzing the acetyl cyanide, and a process comprising reacting tartaric acid and potassium hydrogen sulfate. These processes not on…     

Immobilization of heavy metals by Pseudomonas putida CZ1/goethite composites from solution

Bacterial–mineral composites are important in the retention of heavy metals due to their large sorption capacity under a wide range of environmental conditions. This study provides the first quantitative comparison of the metal-binding capacities of P. putida CZ1–goethite composite to its individual components. When the same amount (on a dry weight basis) of living and nonliving cells of P. putida CZ1, goethite or their composites was separately exposed to solutions of 0.5 mM Cu(II) and Zn(II) in 0.01 M KNO₃, the living cells removed the largest quantity of heavy metals. The results of calculated metal retention values indicated that the adsorption of goethite to bacteria has not mask or neutralize chemically reactive adsorption sites normally available to metal ions. Moreover, the nonliving cells–goethite composite retained approximately 82% more Zn than that predicted by their individual behavior. The preferential association of Zn with P. putida CZ1 was observed by TEM and EDS analyses of a mixture consisting of the bacteria and goethite. Desorption of Cu and Zn with 1.0 M CH₃COOK solution from P. putida CZ1 and goethite indicated the differences in the functional groups able to bind heavy metals.     

Screening and Comparison of Lignin Degradation Microbial Consortia from Wooden Antiques

Lignin, which is a component of wood, is difficult to degrade in nature. However, serious decay caused by microbial consortia can happen to wooden antiques during the preservation process. This study successfully screened four microbial consortia with lignin degradation capabilities (J-1, J-6, J-8 and J-15) from decayed wooden antiques. Their compositions were identified by genomic sequencing, while the degradation products were analyzed by GC-MS. The lignin degradation efficiency of J-6 reached 54% after 48 h with an initial lignin concentration of 0.5 g/L at pH 4 and rotation speed of 200 rpm. The fungal consortium of J-6 contained Saccharomycetales (98.92%) and Ascomycota (0.56%), which accounted for 31% of the total biomass. The main bacteria in J-6 were Shinella sp. (47.38%), Cupriavidus sp. (29.84%), and Bosea sp. (7.96%). The strongest degradation performance of J-6 corresponded to its composition, where Saccharomycetales likely adapted to the system and improved lignin degradation enzymes activities, and the abundant bacterial consortium accelerated lignin decomposition. Our work demonstrated the potential utilization of microbial consortia via the synergy of microbial consortia, which may overcome the shortcomings of traditional lignin biodegradation when using a single strain, and the potential use of J-6 for lignin degradation/removal applications.     

Life‐cycle toxicity of dibutyltin to the sheepshead minnow (Cyprinodon variegatus) and implications of the ubiquitous tributyltin impurity in test material

Dibutyltin (DBT) is used in the plastics polymerization process as a catalyst in polyvinyl chloride (PVC) products and is the primary degradation product of tributyltin (TBT), an antifoulant in marine paint. DBT and other organotin compounds make their way into the environment through antifoulants, PVC processing plants, and PVC products maintained in water and water‐handling systems. A flow‐through saltwater life‐cycle toxicity test was conducted to determine the chronic effect of DBT to the sheepshead minnow (Cyprinodon variegatus Lacepede), an estuarine species. Embryos were monitored through hatch, maturation, growth, and reproduction in DBT concentrations of 158, 286, 453, 887, and 1510 µg l^?1. Progeny were monitored for survival as embryos and fry/juveniles, and growth for 30 days post‐isolation. Mean length of parental generation fish was significantly reduced on day 30 at DBT concentrations ≥887 µg l^?1, setting the lowest observable effect concentration (LOEC) at 887 µg l^?1 and the no observable effect concentration (NOEC) at 453 µg l^?1. Fecundity, as egg viability, was significantly reduced at the LOEC. Survival of parental and progeny generation embryos and mean length, wet weight and dry weight of progeny generation juveniles were not significantly affected at concentrations ≤LOEC. TBT, a toxic impurity in DBT reversibly produced in DBT by the process of comproportionation, was also monitored throughout this study. Comparing measured levels of TBT in this study with levels exerting toxic effects in an earlier TBT life‐cycle study with C. variegatus suggests biological responses in this study were likely due to the TBT impurity and not to DBT alone. Results indicate that TBT impurity as low as 0.1% may have a significant influence on the perceived toxicity of DBT and that spontaneous production of TBT in DBT may be the major source of biological toxicity of DBT. Copyright © 2003 John Wiley & Sons, Ltd.     

Effect of Pseudomonas moorei KB4 Cells’ Immobilisation on Their Degradation Potential and Tolerance towards Paracetamol

Pseudomonas moorei KB4 is capable of degrading paracetamol, but high concentrations of this drug may cause an accumulation of toxic metabolites. It is known that immobilisation can have a protective effect on bacterial cells; therefore, the toxicity and degradation rate of paracetamol by the immobilised strain KB4 were assessed. Strain KB4 was immobilised on a plant sponge. A toxicity assessment was performed by measuring the concentration of ATP using the colony-forming unit (CFU) method. The kinetic parameters of paracetamol degradation were estimated using the Hill equation. Toxicity analysis showed a protective effect of the carrier at low concentrations of paracetamol. Moreover, a pronounced phenomenon of hormesis was observed in the immobilised systems. The obtained kinetic parameters and the course of the kinetic curves clearly indicate a decrease in the degradation activity of cells after their immobilisation. There was a delay in degradation in the systems with free cells without glucose and immobilised cells with glucose. However, it was demonstrated that the immobilised systems can degrade at least ten succeeding cycles of 20 mg/L paracetamol degradation. The obtained results indicate that the immobilised strain may become a useful tool in the process of paracetamol degradation.     

Degradation of ROMP-based bio-renewable polymers by UV radiation

The degradation of a bio-renewable polymer under UV exposure was studied using various methods. Degradation of the bio-renewable polymer increased with increasing exposure time. Enhanced cross-link density in the early stage of degradation was confirmed by Soxhlet extraction. Tensile testing showed a transition from ductile failure to brittle fracture. Surface cracks and embrittlement were primary reasons for most reductions in mechanical properties, such as tensile strength and breaking strain. The effects of degradation were confined to the surface of thick bio-based polymer specimens, confirmed by both SEM and PAS-FTIR. Depth profile studies of degraded samples showed that the concentration of oxidation products, such as hydroxyl and carbonyl groups, varied with depth depending on the diffusion of oxygen.     

Anti-infective potential of caffeic acid and epicatechin 3-gallate isolated from methanol extract of Euphorbia hirta (L.) against Pseudomonas aeruginosa

Euphorbia hirta (L.) plant is traditionally used in Malaysia for the treatment of gastrointestinal, bronchial and respiratory ailments caused by nosocomial infectious agents. Bioactivity-guided fractionation of the methanol extract of the aerial parts of E. hirta and analysis using high-performance liquid chromatography have led to the isolation of two antibacterial compounds. These compounds were identified as caffeic acid (CA) and (–)-epicatechin 3-gallate (ECG) based on spectroscopic analyses and comparison with previously published data. Using broth microdilution method, both ECG and CA had demonstrated significant minimum inhibitory concentration of 15.6 and 31.3 μg/mL respectively, against Pseudomonas aeruginosa. Time-kill assessment of ECG and CA displayed bactericidal effect on P. aeruginosa cells.