摘要：
Xanthohumol (XTH, 1), a major prenylated chalcone in hops, has attracted considerable interests because of its pharmaceutical potency. To explore more related derivatives of XTH, its biotransformation was performed using the in vitro microbial model. Fungus Mucor sp. exhibited a robust biocatalytic feature to transform the substrate. Preparative fungi-mediated biotransformation led to the isolation of two new (2 and 5) and eight known (3, 4 and 6-11) metabolites. The two new metabolites were identified as (2 '' R)-dihydroxanthohumol B (2) and xanthohumol L 4 '-O-beta-D-glucopyranoside (5) based on the combined spectroscopic analysis. According to the cytotoxic activities of all metabolites, compounds 7 and 9 showed relatively sensitive cytotoxic activity against A375 and A549 cancer cell lines, respectively. These findings not only provided a biological approach to achieve the derivatives of XTH but also gave an information for the lead optimisation of XTH for the development of potential anti-cancer agents. [GRAPHICS] .
摘要：
Vibrio mimicus is a relatively rare food-borne pathogen in seafood and water. Rare reports have been published to investigate the biofilm of Vibrio mimicus. (-)-epigallocatechin-3-gallate (EGCG), the major polyphenolic cornponent of tea, can interfere with bacterial biofilm formation. This study showed that Vibrio mimicus was capable of forming high amounts of biofilms in various culture media. Sub-MICs of EGCG significantly reduced the biofilm production of Vibrio mimicus at 15 degrees C, 28 degrees C and 37 degrees C. Confocal laser-scanning microscope (CLSM) observation proved that the architecture of Vibrio mimicus biofilm was affected by EGCG at the concentration of 64 mu g/mL (1/4 MIC). EGCG reduced Vibrio mimicus autoaggregation and swimming motility. EGCG also increased membrane permeability and ROS production, caused cell membrane damage and led to potassium leakage. These may contribute to the antibiofilm efficacy of EGCG against Vthrio mimicus. Our work showed the inhibitory effects of sub-MICs of EGCG on Vibrio mimicus biofilm for the first time, supporting the potential application of EGCG as a natural antibiofilm agent in the food industry.
作者机构：
[李睿] School of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, 430023, China;Institute of Rural Energy and Environmental Protection, Chinese Academy of Agricultural Engineering, Beijing, 100121, China;Key Laboratory of Technologies and Models for Cyclic Utilization from Agricultural Resources, Ministry of Agriculture, Beijing, 100121, China;[刘烨] School of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, 430023, China<&wdkj&>Institute of Rural Energy and Environmental Protection, Chinese Academy of Agricultural Engineering, Beijing, 100121, China<&wdkj&>Key Laboratory of Technologies and Models for Cyclic Utilization from Agricultural Resources, Ministry of Agriculture, Beijing, 100121, China;[孟海波; 王健; 沈玉君; 丁京涛] Institute of Rural Energy and Environmental Protection, Chinese Academy of Agricultural Engineering, Beijing, 100121, China<&wdkj&>Key Laboratory of Technologies and Models for Cyclic Utilization from Agricultural Resources, Ministry of Agriculture, Beijing, 100121, China
摘要：
Listeria monocytogenes (L. monocytogenes) is a well-known food-borne pathogen that causes systemic listeriosis. Its biofilm-forming ability is known to be important for its antimicrobial resistance and persistence. Epigallocatechin-gallate (EGCG) is the highest component of tea polyphenols in tea extracts and has broad-spectrum antimicrobial activities. In this study, the efficacys of EGCG to inhibit biofilm formation and hemolytic activity of L. monocytogenes were determined. EGCG at 20 mu g/mL, 40 mu g/mL (less than compound's minimum inhibitory concentration, MIC) and 200 mu g/mL (1 MIC) were tested. Crystal violet staining showed that sub-MIC and MIC of EGCG could significantly reduce the biofilm formation by L. monocytogenes on polystyrene microtiter plates at three temperatures (15 degrees C, 30 degrees C and 37 degrees C). EGCG reduced the sessile cell numbers present in biofilm at those temperatures. EGCG also significantly inhibited hemolytic activity of L. monocytogenes as measured by sheep red blood cells. Real time PCR assay was used to investigate the relative gene expression of L monocytogenes grown at 37 degrees C and revealed that EGCG down-regulated virulence genes (inlA and hly), SOS response genes (recA and yneA) and quorum sensing gene (agrA). These results suggested the feasibility of using EGCG in food industry to control L monocytogenes biofilm formation. (C) 2017 Elsevier Ltd. All rights reserved.
摘要：
Paenibacterin is a novel antimicrobial lipopeptide produced by Paenibacillus thiaminolyticus. The present study assesses the efficacy of paenibacterin in inhibiting Listeria monocytogenes biofilm formation and removing established biofilm. Paenibacterin at 1.7 mu g/mL (less than compound's minimum inhibitory concentration, MIC) and higher concentrations (3.4 mu g/mL, 6.8 mu g/mL) were tested. Concentrations greater than the lipopeptide's MIC significantly inhibited the formation of L. monocytogenes biofilm on polystyrene microtiter plates at 30 degrees C and 37 degrees C. Paenibacterin also was added to established biofilm and its structure or removal was monitored by fluorescence microscopes after appropriate staining. Results show that paenibacterin could eliminate established biofilms formed at 30 degrees C for 72 h, whereas it could not disrupt stronger biofilms formed at 37. degrees C for 72 h. Motility of L. monocytogenes is important for its ability to form biofilm. Swimming assay confirmed that paenibacterin suppressed L. monocytogenes motility. Real time quantitative PCR data revealed that paenibacterin down-regulated L. monocytogenes critical biofilm-associated genes, prfA, agrA, flail, fliG and flgE. These results suggested the feasibility of using paenibacterin in food processing environments to control L. monocytogenes growth and biofilm formation, or even for removal of some established biofilms. (C) 2017 Elsevier Ltd. All rights reserved.
作者机构：
[谈笑; 陈颖; 王娉] Agro-Product Safety Research Center, Chinese Academy of Inspection and Quarantine, Beijing, 100176, China;[李睿; 谈笑] College of Biological and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, 430023, China
摘要：
Shiga toxin-producing Escherichia coli (STEC) strains are one of the most important recently emerged groups of food borne pathogens. This study investigated the prevalence of molecular markers for STEC and characteristics of E. coli O157 isolates from foods sold at retail markets in Wuhan, China. A total of 489 samples (350 meat products and 139 raw vegetables) were purchased from 22 large scale markets between July of 2011 and September of 2013. The meat samples consisted of frozen chicken products, raw pork, raw beef, frozen fish products and processed duck products. The raw vegetable samples consisted of lettuce, bok choy, radish, spinach, cucumber, and tomato. Shiga toxin genes (stx1 and stx2) and an O-group marker of the seven main pathogenic STEC serogroups (O157, O26, O45, O103, O111, O121, and O145) were detected in the samples by using PCR. 100% agreement was obtained between the results of the PCR targeting for wzy(O157) and the PCR targeting for rfbE(O157) gene. The result demonstrated that PCR assay targeting for wzy(O157) gene can be employed as an effective screening method for E. coli O157 in food sample. In the study, E. coli O157 and non-O157 STEC were detected in 55 (11.2%) and 75 (153%) samples by PCR screening, respectively. There was significant difference in the occurrence of STEC contamination between supermarkets (19/127, 15.0%) and open markets (111/362, 30.7%) (P < 0.05). Out of 489 samples, 5 samples carried O45, 1 sample carried O145 and 1 sample carried O111. Markers for O103, O26 and O121 were not detected. This result differed from other reports. Immunomagnetic separation based cultivation technique was used to isolate E. coli O157 from 27 food samples collected in 2013. Finally 7 E. coli O157 isolates were obtained. Among the 7 isolates, the prevalent six genotype was stx(1a) and stx(2a). Four E. coli O157 strains exhibited toxic effects on Vero cells, while 3 isolates had no detectable cytotoxicity effects even though they contained sty genes. All E. coli O157 isolates were sensitive to the 12 antimicrobials tested except for roxithromycin. There are some inconsistencies between the PCR screening and culture results. Characteristics of STEC isolates should be evaluated and considered for monitoring STEC contamination in foods. (c) 2015 Elsevier Ltd. All rights reserved.
作者：
Liu Zhiguo;Fu Yunjie;Li Qi;Li Kui;Chen Jiangyuan;...
期刊：
ITME 2011 - Proceedings: 2011 IEEE International Symposium on IT in Medicine and Education,2011年2:628-632
通讯作者：
Liu, Z.(Zhiguo_1@126.com)
作者机构：
[Liu Zhiguo; Fu Yunjie; Li Qi; Li Kui; Chen Jiangyuan; Zhou Guoping; Li Rui; Liu Lieju] School of Biological and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, China
会议名称：
2011 IEEE International Symposium on IT in Medicine and Education
会议时间：
December 2011
会议地点：
Cuangzhou
会议论文集名称：
2011 IEEE International Symposium on IT in Medicine and Education
