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Xu G.,Northeast Agricultural University | An W.,Inspection and Quarantine Technical Center | Wang H.,Northeast Agricultural University | Zhang X.,Northeast Agricultural University
Frontiers in Microbiology

Objectives: The purpose of this study was to investigate the prevalence of extended spectrum β-lactamase (ESBL) genes in Escherichia coli isolated from post-weaning diarrhea (PWD) piglets in Heilongjiang province, China. Methods: Of 458 E. coli isolated from 589 fecal samples from PWD piglets, a total of 198 isolates were confirmed as ESBL producers by the double-disk synergy test (DDST). Polymerase chain reaction (PCR) and sequencing were performed to identify genes for ESBL, plasmid-mediated quinolone resistance (PMQR), and integrons. Results: Of the 198 isolates, blaCTX-M and blaTEM were detected in 191 and 149 isolates, respectively. Sequencing revealed that 10 blaCTX-M subtypes were detected, and blaCTX-M-14 was the most prevalent, followed by blaCTX-M-55 and blaCTX-M-65. Of the 149 TEM-positive strains, four were blaTEM-52 and the rest were blaTEM-1. Among the 198 ESBL-positive isolates, 173 isolates were found to harbor at least one PMQR gene, with oqxAB, qnrS, qnrB, qepA, and aac(6')-Ib-cr being detected alone or in combination in 125, 114, 26, 24, and 45 strains, respectively. One hundred and fifty-five ESBL-positive isolates were also positive for class I integron (int1), and eight different gene cassette arrays were confirmed in 110 isolates by restriction fragment length polymorphism (RFLP) and DNA sequencing analyses, with predominance of dfrA17-aadA5, dfrA12-orfF-aadA2, and dfrA1-aadA1 arrays. Conclusion: To the best of our knowledge, this is the first report of the blaTEM-52 gene in pig E. coli isolates in China and this is also the first description of the coexistence of the qnrB, qnrS, aac(6')-Ib-cr, qepA, and oqxAB genes in one E. coli strain. © 2015 Xu, An, Wang and Zhang. Source

Zhang M.-S.,Zhangzhou Normal University | Huang J.-R.,Zhangzhou Entry exit Inspection and Quarantine Bureau | Zheng X.-H.,Inspection and Quarantine Technical Center | Xie Q.-F.,Zhangzhou Normal University
Chemical Research in Chinese Universities

A new liquid-liquid microextraction method based on the solidification of floating organic drops coupled with gas chromatography was developed for the determination of trace benzene, toluene and xylene(BTX) in water samples. In the microextraction procedure, a microdrop of n-decanol was delivered to the surface of the analytes' solution, and stirred for a desired time. Following the absolute extraction, the sample vial was cooled in an ice bath for 10 min. The solidified n-decanol was then transferred into a plastic tube and melted naturally; and 1 μL of it was injected into gas chromatography for analysis. Factors relevant to the extraction efficiency were studied and optimized. The optimal experimental conditions were: 15 μL of n-decanol as extractive solvent, 30 mL of solution containing analytes, no salt, the stirring rate 400 r/min, the extraction temperature 30 °C, and the extraction time 30 min. Under those optimized conditions, the detection limit(LOD) of analytes was in a range of 0.05-0.10 ng/mL by the developed method. A good linearity(r>0.99) in a calibration range of 0.01-100 μg/mL was obtained. The recoveries of the real samples at different spiked levels of BTX were in the range from 92.2% to 103.4%. Source

Song J.,Beijing Normal University | Li X.,Inspection and Quarantine Technical Center | Zeng L.,Beijing Normal University | Liu H.,Beijing Normal University | Xie M.,Beijing Normal University
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment

A method for the determination of cyanidin-3-glucoside (red kernel colour, RKC) in various matrices, including carbonated soft drinks, fruit-based soft drinks, sugar confectionery and milk-based drinks, by high performance liquid chromatography (HPLC) based on UV-Vis detection (at 520 nm) have been developed. Pre-treatment procedures for various matrices have been optimised. For soft drinks, the pH values were adjusted to 2.0, and sugar confectionery and milk-based drinks were extracted with 30 and 50% methanol in 0.1% formic acid (pH ~ 2.5) aqueous solutions, respectively. The limits of detection for the established methods ranged from 0.2 mg/kg for soft drinks to 2.0 mg/kg for the sugar confectionery and milk-based drinks with the relative standard deviations lower than 7%, which satisfy the method performance requirements for quality control for the beverages. The stability of the colourant RKC under various thermal and pH conditions was investigated by quadruple time-of-flight mass spectrometry (Q-TOF-MS). The main colourant component of RKC, cyanidin-3-glucoside (Cyd-3-Glu), lost the glucose entity under thermal treatment. A new component was identified when RKC degraded under various pH conditions and a degradation pathway is proposed. The results will assist in understanding the degradation mechanism of the colourant Cyd-3-Glu. © 2011 Copyright Taylor and Francis Group, LLC. Source

Cai H.,Jimei University | You M.,Fujian Agriculture and forestry University | Ryall K.,Natural Resources Canada | Li S.,Natural Resources Canada | Wang H.,Inspection and Quarantine Technical Center
Agronomy Journal

The physiological indices of Chinese cabbage(Brassica chinensis L.) grown under different intercropping systems used for this study included total soluble protein content, soluble sugar content, reducing sugar content, nitrate content, and pigment concentration. The objective of the present study is to discover the physiological level changes in Chinese cabbage in intercropping systems. The intercropping systems studied involved Chinese cabbage- garlic (Allium sativum L.) (CG), and Chinese cabbage-lettuce (Lactuca sativa L.) (CL). Chinese cabbage monoculture served as control (CK). Overall, higher mean soluble protein content and nitrate content were found in Chinese cabbage grown in the intercropping systems than those in CK. Significantly higher chlorophyll a content was found in cabbages from CL than CK during the latter half of the growing season. No significant difference in soluble sugar concentrations was found in CG and CL, as compared with CK. Reducing sugar content varied over the growing period of the Chinese cabbage in CG and CL. These results suggest that Chinese cabbage intercropped with noncrucifer plants increase the plant nutrient content. © 2011 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. Source

Zhang M.,Zhangzhou Normal University | Huang J.,Zhangzhou Entry exit Inspection and Quarantine Bureau | Zheng X.,Inspection and Quarantine Technical Center | Wu L.,Zhangzhou Normal University

A novel analytical technique termed ultrasonic-assisted drop-to-drop solvent microextraction (USA-DDSME) in a capillary tube was developed to determine trace benzene, toluene, xylene in one drop of a water sample, which was combined with gas chromatography-flame ionization detection (GC-FID). The advantages of this method are rapidity, convenience, ease of operation, simplicity of the device, and extremely little solvent and sample consumption. Extraction conditions including the type of extraction solvent, the volume of extraction solvent, the volume of sample, extraction time and effect of salt concentration were optimized. The best optimum parameters for extraction were achieved with 3 μL of extraction solvent. Chloroform was divided into four equal divisions in 20 μL water sample (without salt addition) in a capillary tube and ultrasonicated for 10 min, centrifugated at 2,500 rpm for 5 min to let the extraction solvent settle at the bottom of the capillary tube, then 1 μL of the separated extraction solvent was injected into the GC-FID for analysis. Linearity of the method was determined by analyzing spiked water samples over a concentration range of 0.1-50 μg mL-1. Correspondingly, the LOD values were 0.01 μg mL-1. All calibration curves were found to have good linearity with correlation coefficients (r 2) > 0.995. The precision (RSD) of the system, measured by six repeated determinations of the analytes at 1 μg mL-1 were in the range of 1.6-3.5%. © 2010 Vieweg+Teubner Verlag | Springer Fachmedien Wiesbaden GmbH. Source

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