The study of biological activity of transformation products of diclofenac and its interaction with chlorogenic acid

In the present work we compared the biological activity of DCF,4’-OHDCF and 5-OHDCF as molecules of most biodegradation pathways of DCF and selected transformation products(2-hydroxyphenylacetic acid;2,5-dihydroxyphenylacetic acid and 2,6-dichloroaniline)which are produced during AOPs,such as ozonation and UV/H2 O2.We also examined the interaction of DCF with chlorogenic acid(CGA).CGA is commonly used in human diet and entering the environment along with waste mainly from the processing and brewing of coffee and it can be toxic for microorganisms included in activated sludge.In the present experiment the evaluation of following parameters was performed:E.coli K-12 cells viability,growth inhibition of E.coli K-12 culture,LC50 and mortality of Chironomus aprilinus,ge no toxicity,sodA promoter induction and ROS generation.In addition the reactivity of E.coli SM recA:luxCDABE biosensor strain in wastewater matrices was measured.The results showed the influence of DCF,4’-OHDCF and 5-OHDCF on E.coli K-12 cells viability and bacteria growth,comparable to AOPs by-products.The highest toxicity was observed for selected,tested AOPs by-products,in comparison to the DCF,4’-OHDCF and 5-OHDCF.Genotoxicity assay indicated that 2,6-dichloroaniline(AOPs by-product)had the highest toxic effect.The oxidative stress assays revealed that the highest level of ROS generation and sodA promoter induction were obtained for DCF,4’-OHDCF and 5-OHDCF,compared to other tested compounds.We have also found that there is an interaction between chlorogenic acid and DCF,which resulted in increased toxicity of the mixture of the both compounds to E.coli K-12,comparable to parent chemicals.The strongest response of E.coli SM biosensor strain with recA:luxCDABE genetic construct in filtered treated wastewaters,comparable to control sample was noticed.It indicates,that E.coli SM recA:luxCDABE biosensor strains is a good tool for bacteria monitoring in wastewater environment.Due to toxicity and biological activity of tested DCF transformation products,there is a need to use additional wastewater treatment systems for wastewater contaminated with pharmaceutical residues.

An ethanol biosensor based on a bacterial cell-immobilized eggshell membrane

An ethanol biosensor was fabricated based on a Methylobacterium organophilium-immobilized eggshell membrane and an oxygen（O2） electrode.A linear response for ethanol was obtained in the range of 0.050-7.5 mmol/L with a detection limit of 0.025 mmol/L（S/N= 3） and a R.S.D.of 2.1%.The response time was less than 100 s at room temperature and ambient pressure. The optimal loading of bacterial cells on the biosensor membrane is 40 mg（wet weight）.The optimal working conditions for the microbial biosensor are pH 7.0 phosphate buffer（50 mmol/L） at 20-25℃.The interference test,operational and storage stability of the biosensor are studied in detail.Finally,the biosensor is applied to determine the ethanol contents in various alcohol samples and the results are comparable to that obtained by gas chromatographic method and the results are satisfactory.Our proposed biosensor provides a convenient,simple and reliable method to determine ethanol content in alcoholic drinks.

Immobilisation of electrochemically active bacteria on screen-printed electrodes for rapid in situ toxicity biosensing

are time-consuming and not sensitive enough.However,bacteria typically connect to electrodes through biofilm formation,leading to problems due to lack of uniformity or long device production times.A suitable immobilisation technique can overcome these challenges.Still,they may respond more slowly than biofilm-based electrodes because bacteria gradually adapt to electron transfer during biofilm formation.In this study,we propose a controlled and reproducible way to fabricate bacteria-modified electrodes.The method consists of an immobilisation step using a cellulose matrix,followed by an electrode polarization in the presence of ferricyanide and glucose.Our process is short,reproducible and led us to obtain ready-to-use electrodes featuring a high-current response.An excellent shelf-life of the immobilised electrochemically active bacteria was demonstrated for up to one year.After an initial 50% activity loss in the first month,no further declines have been observed over the following 11 months.We implemented our bacteria-modified electrodes to fabricate a lateral flow platform for toxicity monitoring using formaldehyde(3%).Its addition led to a 59% current decrease approximately 20 min after the toxic input.The methods presented here offer the ability to develop a high sensitivity,easy to produce,and long shelf life bacteria-based toxicity detectors.