Evaluation of a new high-throughput method for identifying quorum quenching bacteria

Quorum sensing (QS) is a population-dependent mechanism for bacteria to synchronize social behaviors such as secretion of virulence factors. The enzymatic interruption of QS, termed quorum quenching (QQ), has been suggested as a promising alternative anti-virulence approach. In order to efficiently identify QQ bacteria, we developed a simple, sensitive and high-throughput method based on the biosensor Agrobacterium tumefaciens A136. This method effectively eliminates false positives caused by inhibition of growth of biosensor A136 and alkaline hydrolysis of N-acylhomoserine lactones (AHLs), through normalization of beta-galactosidase activities and addition of PIPES buffer, respectively. Our novel approach was successfully applied in identifying QQ bacteria among 366 strains and 25 QQ strains belonging to 14 species were obtained. Further experiments revealed that the QQ strains differed widely in terms of the type ofQQenzyme, substrate specificity and heat resistance. The QQ bacteria identified could possibly be used to control disease in aquaculture

Dimethyl­ammonium tetra­chloridoferrate(III) 18-crown-6 clathrate

The reaction of dimethyl­amine hydro­chloride, 18-crown-6 and ferric chloride in ethanol yields the title compound, (C2H8N)[FeCl4]·C12H24O6, which exhibits an unusual supramolecular structure. The protonated dimethyl­amine contains one NH2 + group, resulting in a 1:1 supra­molecular rotator–stator structure (CH3—NH2 +—CH3)(18-crown-6), through N—H⋯O hydrogen-bonding inter­actions between the ammonium group of the cation and the O atoms of the crown ether. In the crystal, all three components lie on a common crystallographic mirror plane normal to [010]

Bis(4-fluoro­anilinium) tetra­chloridocuprate(II)

The crystal structure of the title compound, (C6H7FN)2[CuCl4], consists of parallel two-dimensional perovskite-type layers of corner-sharing CuCl6 octa­hedra. These are bonded together via N—H⋯Cl hydrogen bonds from the 4-fluoro­anilinium chains, which are almost perpendicular to the layers. The CuCl4 dianions have two short Cu—Cl bonds [2.2657 (15) and 2.2884 (13) Å] and two longer bonds [2.8868 (15) Å], giving highly Jahn–Teller-distorted CuCl6 octa­hedra. The Cu atoms are situated on crystallographic centers of inversion