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Biosynthesis of acetylphloroglucinols found in Pseudomonas fluorescens Pf-5 was examined to identify the biosynthesis of phloroglucinol. Acetylphloroglucinols biosynthesis is encoded by a gene cluster consisting of phlACBD and a divergently transcribed phlF-encoded regulator.

In the present work, three-dimensional porous HxTiS2 nanosheet–polyaniline (PANI) nanocomposites were first synthesized by a two-step method. First, HxTiS2 ultrathin nanosheets were prepared by the lithium intercalation and exfoliation method, followed by the surface polymerization reactions of aniline. The influences of the amount of HxTiS2 nanosheets on the nanocomposite morphology and electrochemical performances of the nanocomposites modified glass carbon electrode (HxTiS2 nanosheet–PANI/GCE) were investigated. The results demonstrated that the incorporation of HxTiS2 nanosheets as a suitable substrate can regulate the growth of PANI, enhance the electrode stability and improve interfacial electron transfer rates. In addition, based on the nanocomposites, we developed a novel electrochemical sensor to directly detect trace Cu2+, and discovered that the coordination interaction between Cu2+ cations and the N atoms of the imine moieties in PANI endowed the electrochemical sensor with high selectivity. Because of the synergetic effects of HxTiS2 nanosheets and PANI, the as-prepared electrochemical sensor exhibited highly sensitive and selective assaying of Cu2+ with a detection limit of 0.7 nM (signal-to-noise ratio (S/N) equal to 3) and a linear range from 25 nM to 5 μM, under optimal conditions. [ABSTRACT FROM AUTHOR]

Membrane filtration provides effective solutions for removing contaminants, but achieving high permeability, good selectivity, and antifouling ability remains a great challenge for existing membrane filtration technologies. In this work, membrane filtration coupled with electrochemistry has been developed to enhance the filtration performance of a CNTs/Al2O3 membrane. The as-prepared CNTs/Al2O3 membrane, obtained by coating interconnected CNTs on an Al2O3 substrate, presented good pore-size tunability, mechanical stability, and electroconductivity. For the removal of a target (silica spheres as a probe) with a size comparable to the membrane pore size, the removal efficiency and flux at +1.5 V were 1.1 and 1.5 times higher, respectively, than those without electrochemical assistance. Moreover, the membrane also exhibited a greatly enhanced removal efficiency for contaminants smaller than the membrane pores, providing enhancements of 4 orders of magnitude and a factor of 5.7 for latex particles and phenol, respectively. These results indicated that both the permeability and the selectivity of CNTs/Al2O3 membranes can be significantly improved by electrochemical assistance, which was further confirmed by the removal of natural organic matter (NOM). The permeate flux and NOM removal efficiency at +1.5 V were about 1.6 and 3.0 times higher, respectively, than those without electrochemical assistance. In addition, the lost flux of the fouled membrane was almost completely recovered by an electrochemically assisted backwashing process. [ABSTRACT FROM AUTHOR]

Herein, we reported the assembly of colloidal graphene (CG) and microcystin (MC)-LR-DNA bioconjugates to develop a homogeneous competitive fluorescence-based immunoassay for rapid and sensitive detection of MC-LR in water samples. Initially, the MC-LR-DNA probe was quickly adsorbed onto the CG surface through the strong noncovalent Π-Π stacking interactions and can be effectively quenched benefiting from the high quenching efficiency of CG. In contrast, the competitive binding of anti-MC-LR with MC-LR-DNA destroyed the graphene/MC-LR-DNA interaction, thus resulting in the restoration of fluorescence signal. This signal transduction mechanism made it possible for analysis of the target MC-LR. Taking advantage of the colloidal nature of the as-prepared graphene, the assay was carried out in homogeneous solution throughout, which avoided numerous immobilization, incubation, and washing steps that were necessary to traditional heterogeneous immunoassays, thereby reducing the whole assay time (within less than 35 min) and allowing a much better antigen-antibody interaction. Moreover, due to the direct competitive mode, the assay did not involve any antibody labeling or modification process, which would be beneficial to preserve the binding affinity of antigen-antibody. Under optimal conditions, the proposed immunosensor can be applied for quantitative analysis of MC-LR with a detection limit of 0.14 μg/L, which satisfied the World Health Organization (WHO) provisional guideline limit of 1 μg/L for MC-LR in drinking water, thus providing a powerful tool for rapid and sensitive monitoring of MC-LR in environmental samples. [ABSTRACT FROM AUTHOR]

Chlorinated organic compounds are generally of great concern, but many uncertainties exist regarding how they are generated. To illustrate the possibility of photochemical formation of organochlorine compound in natural water, the phototransformation of bisphenol A (BPA) in aqueous saline solution containing Fe(III) and fulvic acid (FA), and in coastal seawater under simulated solar light irradiation was investigated. 2-(3-Chloro-4-hydroxyphenyl)-2-(4-hydroxyphenyl) propane (3-CIBPA) and 2,2-bis(3-chloro-4-hydroxyphenyl) propane (3,3- diCIBPA) were the main chlorinated derivatives during the processes. Laser flash photolysis (LFP) and electron spin resonance (ESR) results indicated that the chlorination of BPA was most likely due to the formation of CL•-2 radical as a consequence of Fe(III) irradiation, yielding Cl• and OH• radical species and finally forming Cl•-2 radical upon further reaction with chloride. The formation of Fe(III)-FA complex, which is a normal coexistence configuration of Fe(III) and FA in natural water, promoted the BPA chlorination through producing more Cl•-2 radical. Moreover, FA had two opposite effects: forming Fe(III)-FA complex to enhance Cl•-2 formation and competing radicals with BPA, which resulted in different overall effects at different concentrations: BRA chlorination was enhanced with the increasing of FA concentration ([FA]) when [FA] < 3.2 mg L-1, when the concentration of FA was as high as 10 mg L-1, it slowed down obviously. The described BPA photo-chlorination process took place from pH 63 to 8.5 and increased with the increasing of chloride concentration, indicating it could occur universally in natural saline surface water. These results propose a natural photochemical source for organochlorine compounds. [ABSTRACT FROM AUTHOR]