Quaternary ammonium biocides promote conjugative transfer of antibiotic resistance gene in structure- and species-dependent manner.

The linkage between biocides and antibiotic resistance has been widely suggested in laboratories and various environments. However, the action mechanism of biocides on antibiotic resistance genes (ARGs) spread is still unclear. Thus, 6 quaternary ammonium biocides (QACs) with different bonded substituents or alkyl chain lengths were selected to assess their effects on the conjugation transfer of ARGs in this study. Two conjugation models with the same donor (E. coli DH5α (RP4)) into two receptors, E. coli MG1655 and pathogenic S. sonnei SE6-1, were constructed. All QACs were found to significantly promote intra- and inter-genus conjugative transfer of ARGs, and the frequency was highly impacted by their structure and receptors. At the same environmental exposure level (4 × 10-1 mg/L), didecyl dimethyl ammonium chloride (DDAC (C10)) promoted the most frequency of conjugative transfer, while benzathine chloride (BEC) promoted the least. With the same donor, the enhanced frequency of QACs of intra-transfer is higher than inter-transfer. Then, the acquisition mechanisms of two receptors were further determined using biochemical combined with transcriptome analysis. For the recipient E. coli, the promotion of the intragenus conjugative transfer may be associated with increased cell membrane permeability, reactive oxygen species (ROS) production and proton motive force (PMF)-induced enhancement of flagellar motility. Whereas, the increase of cell membrane permeability and decreased flagellar motility due to PMF disruption but encouraged biofilm formation, maybe the main reasons for promoting intergenus conjugative transfer in the recipient S. sonnei. As one pathogenic bacterium, S. sonnei was first found to acquire ARGs by biocide exposure.

Preparation of a broad-spectrum anti-zearalenone and its primary analogues antibody and its application in an indirect competitive enzyme-linked immunosorbent assay.

A broad-spectrum monoclonal antibody (mAb)-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) has been developed for rapidly screening zearalenone (ZEN) and its primary analogues in various samples using an easy sample preparation procedure. Primarily, a group-specific mAb, 6C2, was produced, which had IC50 values for ZEN, α-zearalenol, ß-zearalenol, α-zearalanol, ß-zearalanol and zearalanone of 114.0, 127.4, 290.4, 114.9, 205.6 and 257.1 ng L-1, respectively. The limit of detection and limit of quantitation of this method for ZEN and its five primary analogues in various matrix samples ranged from 114.2 to 812.3 ng L-1 and 237.1 to 1653.9 ng L-1, respectively. The recoveries of the above samples spiked with ZEN and its five primary analogues were in the range of 62.9-113.6%. The CVs were less than 13.2%. A good correlation (R2 = 0.995) between the ic-ELISA results and the HPLC-MS/MS results for swine feeds supported the reliability of the developed ic-ELISA.

[Determination of inorganic elements in five kinds of Mongolia medicines by high pressure sealed microwave digestion-ICP-AES].

Five kinds of Mongolia medicines, Eridun-Urile, Deduhonghuaqiweiwan, Tonglage-5, Uzhumu-7 and Geiwang-9 are digested with HNO3-HClO4 system by high pressure system-sealed Microwave Digestion. The 17 inorganic elements content of magnesium, aluminum, calcium, chromium, manganese, ferrum, cobalt, nickel, copper, zincum, arsenic, selenium, strontium, molybdenum, silver, cadmium, plumbum in the solution are determined by ICP-AES. The results are proved to be reliable by adding standard recovery experiment. The recovery is 97.48%-103.01% for Mg, 102.71%-105.60% for Al, 102.00%-105.53% for Ca, 98.78%-100.34% for Cr, 101.93%-104.65% for Mn, 100.34%-104.51% for Fe, 103.13%-105.46% for Co, 100.07%-103.22% for Ni, 97.25%-99.06% for Cu, 98.57%-100.10% for Zn, 102.35%-105.37% for As, 100.24%-104.59% for Se, 99.19%-102.70% for Sr, 103.35%-105.78% for Mo, 99.65%-101.32% for Ag, 102.73%-105.32% for Cd, and 104.76%-106.35% for Pb by this method. The relative standard deviation is less than 3.3% for all the elements. And the method has high accuracy and good precision The determination results indicate that the content of element in Five Kinds of Mongolia Medicines is 0-15 microg x g(-1) for Cd, Ag, As, Pb, Co, Ni, Cu; 15-100 microg x g(-1) for Mo, Se, Zn, Cr; 100-3 000 microg x g(-1) for Mn, Sr, Fe, Mg, Al; 3 000-8 000 microg x g(-1) for Ca. Among of the five kinds of mongolia medicines, the content of elements has great differences. The order is Ca > Mg > Al > Fe > Mn > Sr > Se > Zn > Mo > Cu > Pb > As >Cr > Ni > Co > Cd > Ag for Eridun-Urile; Ca > Al > Fe > Mg > Mn > Sr > Se > Mo > Zn > Ni > Cr > Cu > Pb > As > Co > Cd > Ag for Deduhonghuaqiweiwan; Ca > Fe > Mg > Al > Mn > Sr > Se > Zn > Mo > Cr > Ni > Cu > Pb > As > Co > Cd > Ag for Tonglage-5, Ca > Al > Mg > Fe > Sr > Mn > Se > Zn > Co > Mo > Cr > Cu > Pb > As > Ag > Ni > Cd for Uzhumu-7 and Mg > Ca > Al > Fe > Se > Mn > Zn > Sr > Mo > Cu > Cr > Pb >As > Ag > Co = Cd = Ni for Geiwang-9. The content of common elements Ca, Mg, Fe, Mn, Zn, Cu are higher. These results provide theoretical basis for developing quality control, improving the potency of Mongolia medicines and developing new Mongolia medicines.