Robenidine is a synthetic coccidiostat that is excreted from animals in its prototype form, leading to soil contamination. Despite its widespread use, comprehensive environmental risk assessments remain limited. Consequently, we initially constructed a manure-soil microcosm and investigated the degradation pattern of robenidine using a highly efficient HPLC-dSPE method. The degradation half-lives of robenidine in soil were 14.74 days at 0.8 mg/kg and 21.26 days at 8 mg/kg. Exposure to 8 mg/kg of robenidine significantly altered the soil microbial community, leading to a 140.0 % increase in the abundance of Proteobacteria. However, the Shannon index indicated that soil microbial diversity decreased by 32.4 % from 1 d to 60 d. Compared to the control check group, 8 mg/kg of robenidine significantly increased the abundance of harmful bacteria (e.g., unclassified_Intrasporangiaceae increased by 33.5 %) in the soil at 60 d, while simultaneously reducing the populations of beneficial bacteria such as Bacillaceae (decreased by 23.8 %), Pseudograilibacillus (decreased by 39.6 %), and Massilia (decreased by 31.7 %). Network correlation and FAPROTAX analyses indicated that long-term exposure to robenidine inhibited chitinolysis and aromatic compound degradation pathways. Furthermore, low-dose robenidine increased the activities of dehydrogenase, acid phosphatase, and β-glucosidase by 34.0 %, 24.7 %, and 21.6 % at 1 d, respectively, while these enzymes returned to control levels over time. These findings provide critical insights into the biological and metabolic impacts of robenidine exposure on soil microbial communities, which is crucial for clarifying the ecological concerns associated with robenidine.

The widespread of colistin resistance gens has aroused great public concern, and many efforts have been made to re-evaluate the application of colistin in veterinary medicines. Most of colistin is excreted with feces, while no literature has reported the determination of colistin in plants and its accumulation on the potential toxicity to plant life. In this study, a rapid and eco-friendly method using liquid chromatography tandem mass spectrometry (LC-MS/MS) based on dispersive solid-phase extraction was developed for detecting colistin in lettuce and was successfully applied to real samples. Furthermore, the toxic effects of colistin exposure on the growth, oxidative stress, and metabolism of lettuce were investigated. The LC-MS/MS results showed that the developed method had good linear correlation. Average recoveries of colistin at four spiked concentrations (10, 30, 100, and 300 µg/kg) ranged from 73.3

IntroductionThe pharmacokinetic profile and residue depletion of eugenol in carp (Cyprinus carpio) tissues and plasma were performed by a convenient and reliable high-performance liquid chromatography (HPLC) method.MethodsThe eugenol in carp tissues and plasma was extracted with a mixed solution of acetonitrile and methanol. N-hexane was used to remove lipid impurities. The method was successfully applied to the pharmacokinetic and residue elimination of eugenol in carp after the carp was administered a medicated bath.ResultsThe average recoveries of eugenol in tissues and plasma fortified with four concentration levels were 69.0–106.6% and 80.0–86.7%, respectively. The relative standard deviations were < 8.9%. The limit of detection (LOD) was 0.01 μg/g in tissue and 0.008 μg/ml in plasma, respectively. The pharmacokinetic parameter of Cmax for eugenol in plasma at the concentrations of 20, 35, and 75 mg/L were 10.86, 17.21, and 37.32 mg/L, respectively. The t1/2 values were 3.68, 4.22, and 9.31 h. After the investigation of the anesthetic effect, 35 mg/L of eugenol was the optimal concentration for anesthesia. The highest accumulation concentration of eugenol in carp is in the liver and the lowest is in the muscle. In addition, the eugenol in tissue was eliminated rapidly and at a lower level than the LOD at 48 h. According to the residue elimination, the withdrawal time of eugenol was suggested at 5.2 days.DiscussionThese results indicate that the developed method had good linearity and accuracy, and is sensitive enough for the monitoring of eugenol residue in carp. The half-life of eugenol decreased with the increase in drug concentration and the eugenol was eliminated rapidly in carp tissues. 35 mg/L eugenol was recommended as an anesthetic in carp due to its favorable anesthetic effect and no mortality. This study will contribute to the establishment of MRL regulation and setting a withdrawal period.

为探讨超声、紫外线照射及加温等方法对质粒介导的黏菌素耐药基因mcr-1的影响,采用四因素三水平正交试验设计,以mcr-1阳性猪场废水样品为研究对象,采用实时荧光定量聚合酶链反应(qRT-PCR)测定mcr-1基因绝对丰度,以处理前后mcr-1基因绝对丰度变化率为指标,考察不同因素及水平对mcr-1基因含量的影响.结果表明,超声对mcr-1丰度有显著影响,其次是温度、加温时间,而紫外线照射对mcr-1的影响甚微.当依次将样品进行超声30 min、紫外线照射15 min、温度40℃作用30 min时,会使mcr-1含量比对照组高5倍多.而当超声时间为15 min、同时提高温度至50℃作用30 min和60℃作用5 min时,可使mcr-1的含量分别降低20.5％和30.6％.可见,不同因素及水平的组合可对mcr-1基因的含量造成相反的影响.因此,在实际中应筛选最佳的条件以尽可能地降低mcr-1基因的含量,减少mcr-1基因的进一步污染和扩散.

Altrenogest has been widely used in synchronization of estrus of pigs, but the existing preparations are inconvenient to use for they have to be administered individually. In order to simplify its administration and improve its stability, altrenogest microcapsules were successfully prepared by intra-liquid desiccation using ethyl cellulose as the capsule material in this study. The average particle size of the optimal altrenogest microcapslue was 76.8 mu m which is less than 200 mu m, so they are suitable for use in animal feed. The yields, encapsulation levels and drug loading capacity were 20 %, 84 % and 53 %, respectively. The drug release in artificial gastric juice was relatively rapid with 50 % in the first hour and 60 % by hour 2 and the release curve fit the power function equation. Extended exposure (10 d) to light (4500 lux), high humidity (95 %) and high temperature (60 celcius) did not change the concentration of encapsulated drug. The prepared altrenogest microcapsules are suitable as a feed additive and could simplify the use of this drug for the synchronization of estrus for swine production.

IntroductionTrifolium pratense L. has anti-inflammatory, antioxidant, cardiovascular disease prevention, and estrogen-like effects. The existing method for the assay of effective components is commonly based on a spectrophotometer, which could not meet the requirement of quality control. Furthermore, although there have been many studies on the anti-inflammation effect of red clover, a few have been reported on the regulatory effect of red clover isoflavones (RCI) on lipopolysaccharide (LPS)-induced inflammatory response in porcine alveolar macrophages (3D4/2 cells), and its mechanism of action is still unclear.MethodsThe main components of RCI including daidzein, genistein, and biochanin A were accurately quantified by high-performance liquid chromatography coupled with diode array detection (HPLC-DAD) after optimizing the extraction process through response surface methodology. The anti-inflammatory potential of RCI was carried out by detecting the level of inflammatory cytokines and mRNA expression of related genes. Furthermore, its anti-inflammatory mechanism was explored by investigating two signaling pathways (NF-κB and MAPK).ResultsThe optimal extraction conditions of RCI were as follows: the concentration of ethanol is 86% and the solid–liquid ratio is 1:29, with the herb particle size of 40 mesh sieve. Under the optimal conditions, the total extraction of target components of RCI was 2,641.469 μg/g. The RCI could significantly suppress the production and expression of many pro-inflammatory cytokines. The results of the Western blot revealed that RCI dramatically reduced the expression of p65, p-p65, IκB-α, p38, and p-p38. These results are associated with the suppression of the signal pathway of p38 MAPK, and on the contrary, activating the NF-κB pathway. Collectively, our data demonstrated that RCI reversed the transcription of inflammatory factors and inhibited the expression of p65, p-p65, IκB-α, and p38, indicating that RCI had excellent anti-inflammatory properties through disturbing the activation of p38 MAPK and NF-κB pathways.ConclusionThe extraction conditions of RCI were optimized by HPLC-DAD combined with response surface methodology, which will contribute to the quality control of RCI. RCI had anti-inflammatory effects on the LPS-induced 3D4/2 cells. Its mechanism is to control the activation of NF-κB and p38 MAPK pathways, thereby reducing the expression of inflammatory-related genes and suppressing the release of cytokines.

为揭示不同环境下鸡粪中氯苯胍的残留降解规律,模拟不同环境状态,研究氯苯胍在不同起始浓度、温度和pH下的降解特征.鸡粪中氯苯胍经乙腈提取,正己烷除脂,分散固相萃取法进行净化,以C18色谱柱进行分离,高效液相色谱二极管阵列检测器进行检测.结果表明,氯苯胍在0.1～30μg/g浓度间呈线性相关,相关系数R2为0.999 6,检测限为0.03 μg/g,定量限为0.10 μg/g;鸡粪中氯苯胍在0.10、0.50、1.00 μg/g 3个添加水平下,外标法定量,回收率在83.81％～94.61％之间,批内相对标准偏差为2.74％～8.93％,批间相对标准偏差为7.62％～9.72％;鸡粪中氯苯胍降解速率受起始浓度、温度和pH影响,药物起始浓度越高,鸡粪中氯苯胍降解速率越慢,当药物起始浓度为10、40、200 μg/g时,在30 d内,氯苯胍降解速率分别为100％、100％和77.10％,半衰期分别为2.36 d、8.61 d和15.43 d;鸡粪中氯苯胍降解速率随温度升高而加快,当温度为4 ℃时,氯苯胍在30 d后降解速率为43.30％,而在25 ℃和45 ℃时完全降解;酸化或碱化后氯苯胍降解速率较未处理组明显加快,在试验期内均降解完全.因此,在进行粪便无害化处理时,可通过提高堆肥温度、将堆体酸化或碱化以提高氯苯胍降解速率,进而降低环境污染风险.

Using single factor experiments and response surface methodology, the extraction conditions of N~6-（2-hydroxyethyl） adenosine（HEA） from Cordyceps chanhua were optimized. Based on the results of the single factor experiments, a Box-Behnken surface response design was used to optimize liquid-to-material ratio,water bath temperature, and water bath time. The optimized conditions were as follows: ultrapure water as the solvent, liquid-to-material ratio 118∶1, ultrasonic time 25 min, water bath at 24 ℃ for 3.8 h. Using the optimized conditions, the resultant HEA content in the extract was（0.836 ± 0.030） mg·g -1 . HEA was further purified by macroporous resin, acidic alumina chromatography, semi-preparative high performance liquid chromatography（SP-HPLC） and then confirmed to be HEA by electrospray ionization mass spectrometry（ESI-MS） and proton nuclear magnetic resonance spectroscopy（~1H NMR）. The purity of HEA was determined to be 99.32% by high performance liquid chromatography（HPLC）.

A simple, sensitive, and efficient method based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the determination of 8 coccidiostats in chicken feces and environmental water (including sewage, pond water, and lake water) surrounding the farm. Target analytes in chicken feces were extracted with 2% acetic acid in acetonitrile solution, followed by a dispersive solid-phase extraction (DSPE) cleanup step using the mixture of PSA and C18 adsorbents. Environmental water samples were pretreated using a lyophilization approach. Analysis was carried out on a UPLC-MS/MS with the combination of methanol and 0.1% formic acid aqueous solution as the mobile phase under multiple reaction monitoring in positive and negative ionization modes. Results showed that 8 coccidiostats were linear with correlation coefficients higher than 0.99. Method validation was performed using fortified samples, reaching satisfactory recoveries of 75.9%-97.8% in chicken feces and 71.9%-108.2% in environmental water. Limits of detection for 8 analytes in chicken feces and environmental water were 0.03-2 mu g/kg and 0.005-1 mu g/L, respectively. Matrix effects were calculated and strong signal suppression (>50%) for some coccidiostats was observed. The developed method was successfully applied to analyze coccidiostats in chicken feces and environmental water collected from local chicken farms.

[目的]考察蝉拟青霉5704s菌丝体提取液的降血糖作用,探索发挥降血糖作用的主要功能组分.[方法]制备蝉拟青霉5704s菌丝体提取液,分离提取液中峰1、峰2蛋白,采用小鼠试验和体外试验测定菌丝体提取液以及不同活性组分的降血糖作用,SDS-PAGE电泳测定主要降血糖组分分子量.[结果]蝉拟青霉5704s菌丝体提取液具有较好的降血糖作用,血糖下降率为36.85％;体外试验中,提取液峰1蛋白的α-糖苷酶抑制率为71.23％,峰2蛋白的抑制率为63.17％;小鼠试验中,提取液峰1蛋白的血糖下降率为40.23％,峰2蛋白的血糖下降率为25.70％;体外试验和小鼠试验均表明提取液峰1蛋白的降血糖效果优于峰2蛋白,峰1蛋白的分子量为57 781 Da.[结论]确定蝉拟青霉5704s菌丝体提取液中发挥主要降血糖功效的组分是峰1蛋白.

[目的]观察长期添加阿朴酯颗粒剂对昆明小鼠肝脏、肾脏组织结构与功能及其体液免疫水平的影响,系统评价其安全性,为阿朴酯在畜禽生产中的科学应用提供参考依据.[方法]通过急性毒性试验测定阿朴酯颗粒剂对昆明小鼠的半数致死量(LD50),然后设50％LD50(1.4 g/kg)和80％LD50(2.2 g/kg)作剂量组,以等量生理盐水为空白对照.单次灌胃1.4 g/kg阿朴酯悬浊液后,于灌胃后第4、12、36和60 h及第7和14 d进行眼球采血,用于测定血常规指标;按1.4和2.2 g/kg的剂量分别连续灌胃阿朴酯悬浊液21 d后,分析小鼠体重增重、血清生化指标、尿常规指标及免疫指标的变化情况,并采集小鼠肝脏和肾脏制作石蜡切片进行组织学观察.[结果]阿朴酯颗粒剂对昆明小鼠的LD50为2.74 g/kg,95％置信限为2.69～3.41 g/kg.依据WHO毒性分级标准,阿朴酯颗粒剂属低毒级物质.按1.4 g/kg的剂量单次灌胃阿朴酯悬浊液后,昆明小鼠血液中性粒细胞数量在灌胃后第4 h显著升高(P<0.05,下同),白细胞总数在灌胃后第12和36 h显著升高,淋巴细胞数量在灌胃后第4和12 h极显著升高(P<0.01,下同),红细胞总数和平均红细胞血红蛋白含量在灌胃后第36 h显著升高.以2.2 g/kg的剂量连续灌胃阿朴酯悬浊液21 d后,昆明小鼠的体重增重和平均日增重极显著降低,血清中的碱性磷酸酶活性和尿素含量极显著升高、而谷草转移酶活性和肌酐含量极显著降低;尿液中白细胞数量及蛋白、微白蛋白和酮体含量显著上升;肝脏黄染、淤血,肝索与肝窦紊乱不清,肝细胞碎裂溶解,发生肿胀或坏死;肾脏明显肿大、黄染,肾小体破损消亡,髓质部呈弥漫性出血;血清免疫细胞因子IL-1β、TNF-α和IL-10水平显著或极显著升高,而免疫球蛋白IgM和SIgA浓度显著下降.[结论]阿朴酯颗粒剂属低毒级物质,但高剂量使用可快速升高血细胞数量,破坏小鼠肝肾组织结构并引起功能障碍,且对体液免疫有抑制作用.因此,建议在家禽生产中不可超量或长期添加,尤其拌料时需保证均匀,避免误食高剂量阿朴酯而造成肝肾功能损伤.

发根农杆菌浸染植物后产生的发根可合成高水平次生代谢产物,这种代谢增强作用是由rol基因诱导激发的,因此可利用rol基因提高颠茄中托品烷生物碱(tropane alkaloids,TAs)的合成能力.本研究以颠茄为实验材料,将发根农杆菌pRiA4质粒上的rolC基因通过CaMV35S启动子驱动,导入颠茄中超表达.分析转基因颠茄的表型、TAs含量以及TAs合成途径关键酶基因转录表达水平表化.结果 表明,转基因颠茄表现出根系发达、雄性不育、雄蕊柱长高于雌蕊、提前开花、节间缩短、花小且多、腋芽和侧芽增多、顶端优势下降和叶片狭长等表型;转基因颠茄的TAs含量均显著高于对照,莨菪碱、山莨菪碱和东莨菪碱含量最高可达对照的2.58、3.59和15.77倍;TAs合成途径中的3个关键酶基因腐胺N-甲基转移酶(PMT)、托品酮还原酶Ⅰ(TRI)和莨菪碱6-β-羟化酶(H6H)的表达量与对照相比表达上调.以上研究表明rolC基因通过上调颠茄TAs合成关键酶基因的表达提高了颠茄中TAs的合成能力,为利用rolC基因进行高TAs含量的颠茄分子育种奠定了基础.

为研究记忆训练功能是否与小鼠海马区c-FOS蛋白有关,并探究胆碱能受体激动剂和阻断剂与小鼠海马区c-fos基因转录和c-FOS蛋白表达之间是否存在相关性.以小鼠水迷宫学习记忆测试平台为基础,将小鼠随机分为空白组、模型组、逃生组,应用实时荧光定量PCR方法,观察逃生记忆结果与小鼠中枢海马区c-fos基因表达水平变化的相关性.并通过小鼠尾静脉注入毛果芸香碱和阿托品后,测定小鼠海马区c-fos基因转录水平和c-FOS蛋白表达量的变化,探讨对记忆功能有影响的胆碱受体激动剂和抑制剂对记忆的影响是否与c-FOS蛋白表达有关.结果表明:经7 d逃生训练试验后小鼠逃生速度极显著大于对照组(P＜0.01),且逃生训练组小鼠c-fos基因转录水平极显著高于空白组和模型组(P＜0.01),提示小鼠c-fos基因可能与小鼠逃生记忆产生有关.毛果芸香碱可升高小鼠海马区c-fos基因转录水平、阿托品可降低小鼠海马区c-fos基因转录水平,在2.5 h达到作用峰值(P＜0.01),且具有较好的量效关系;毛果芸香碱可极显著地升高海马区的c-FOS蛋白含量(P＜0.01),且此升高作用与捉持和尾静脉注射处理行为无关.从以上结果推测小鼠海马c-FOS蛋白可能与小鼠记忆形成有关.

The combined contamination of heavy metals and microplastics is widespread in freshwater environments. However, there are few researches on their combined effects on aquatic plants. In this study, the effects of single and combined stress of 0.01 mg L-1 cadmium (Cd), 50 mg L-1 polyethylene and 50 mg L-1 polypropylene for 15 days on the physiological response, ultrastructure and rhizosphere microbial community of duckweed were investigated. The results showed that Cd and microplastics single or combined stress inhibited the growth of duckweed, shortened the root length and decreased the chlorophyll content. Compared with single Cd treatments, the combination of microplastics and Cd increased duckweed growth rate and increased superoxide dismutase activity and malondialdehyde content and reduced chloroplast structural damage, indicating that the combined stress could reduce the toxicity of heavy metals to duckweed. Through the study of rhizosphere microbial diversity, 1381 Operational Taxonomic Unit (OTUs) were identified and rich microbial communities were detected in the duckweed rhizosphere. Among them, the main microbial communities were Proteobacteria, Bacteroidetes, and Cyanobacteria. Compared with Cd single stress, the ACE and chao index of rhizosphere microbial community increased under combined stress, indicating that the diversity and abundance of microbial communities were improved after combined stress treatment. Our study revealed the effects of heavy metals and microplastics on aquatic plants, providing a theoretical basis for duckweed applications in complex water pollution.

为调查贵州省浮萍种间亲缘关系及变异情况,研究在贵州省辖9个地级行政区的多处水环境中共采集到41份浮萍种质,通过形态鉴定这些种质中33个属于绿萍属(Lemna),6个属于紫萍属(Spirodela),2个属于斑萍属/兰氏萍属(Landoltia).利用叶绿体atpF-atpH间隔序列和rpS16内含子序列进行分子生物学分析和鉴定,41份浮萍种质聚类到Lemna aequinoctialis、Lemna minor、Spirodela polyrhiza和Landoltia punctata 4个种.atpF-atpH间隔序列和rpS16内含子序列的单倍型多样性分别为0.98700和0.64700,群体突变率分别为0.15380和0.14334,平均每kb核苷酸差异数为47.20000和61.72200,核苷酸多态性分别为0.08725和0.09158.研究讨论了中国亚热带温润季风地区浮萍的遗传多样性,为浮萍亲缘关系分析提供了依据,也为亚热带湿润季风气候地区植物的种属鉴定及资源化利用奠定了基础.

近年来,水体镉污染日益严峻,筛选超富集植物用于其治理具有重要意义.本研究以90个浮萍株系为实验材料,采用30mg·L-1的镉处理7d,获得7个镉耐受优势株系.通过Blast比对和构建系统发育树鉴定该7个浮萍株系的种属,确定为 Spirodelapolyrhiza、Lemnajaponica、Lemna minor 和 Landoltiapunctata.通过低质量浓度(0.5mg·L-1)和高质量浓度(10mg·L-1)镉处理7d,进一步比较和研究了 7个优势株系对镉的富集效果.结果表明,低浓度镉处理后,5个株系的镉富集量超过100 mg·kg-1;高浓度镉处理后,7个浮萍株系的镉富集量超过1 200mg·kg-1,生物富集系数大于120,对水体中镉的去除率高于70％.其中,4号株系(L.japonica)为本次筛选出的最佳株系,其镉富集量、生物富集系数和对水体中镉的去除率分别达到2 834.30 mg·kg-1、283.43和82.50％.

为探索恢复细菌对抗菌药物敏感性的方法,文章通过设计单因素试验分别研究了营养条件、传代次数与耐药菌敏感性恢复之间的关系.结果显示,对环丙沙星高度耐药的大肠杆菌菌株[MIC(最小抑菌浓度)=128μg/mL]在稀释8、16和32倍的培养基中传代培养210代后,恢复为敏感菌株(MIC=0.25μg/mL);对环丙沙星高度耐药的大肠杆菌在正常培养基中传代培养210代后,其MIC值为16μg/mL.表明对环丙沙星高度耐药的大肠杆菌在较低的营养条件下可以恢复为敏感菌株,较低的营养条件有利于细菌对药物敏感性的恢复.

Since antimicrobials were banned as feed additives, coccidiostats with favorable anticoccidial action and growth promotion have been widely used in the breeding industry. The monitoring of coccidiostats in feed is necessary, while the current methods based on mass-spectrometer analysis have limited applicability and matrix effects could interfere with the results. Accordingly, in the present paper, a rapid analytical strategy for the simultaneous determination of six synthetic coccidiostats in feed using high-performance liquid chromatography coupled with diode-array detection was developed. Coccidiostats in chicken feeds were extracted with the trichloroacetic acid–acetonitrile solution. The cleanup was performed by dispersive solid-phase extraction after the optimization of the response surface methodology. The method exhibited good linearity for target coccidiostats within the range of 0.05~20 µg/mL. Recoveries for six compounds in fortified feed samples were from 67.2% to 107.2% with relative standard deviations less than 9.6%. The limit of detection was 0.2~0.3 mg/kg. The successful application of the method in commercial feed verified that it is effective and sensitive for the rapid determination of multiple coccidiostats in chicken feeds.

为了研究金银花提取物对细菌内毒素的清除效果,分别采用水、乙醇和石油醚提取得到金银花提取物,再分别与大肠杆菌标准内毒素作用后,通过鲎试验法检测3种提取物中细菌内毒素残留量,对比分析3种金银花提取物清除细菌内毒素的作用.结果表明:金银花水提物、乙醇提取物、石油醚提取物中绿原酸含量分别为11.536±0.036、12.347±0.099、11.752±0.047μg/mL,说明乙醇提取物中绿原酸含量最高;与标准细菌内毒素作用后,金银花水提物、乙醇提取物、石油醚提取物中内毒素残留量分别为0.799±0.005、0.164±0.001、0.175±0.002 EU/mL,即水提取液、乙醇提取液、石油醚提液对细菌内毒素的清除率分别为84.02％±0.10％、96.71％±0.02％、96.50％±0.04％.说明金银花乙醇提取物对细菌内毒素的清除效果最佳.本试验结果可为后续金银花抗细菌内毒素的作用机制研究提供前期基础.

[目的]探究环境胁迫因子对猪源多重耐药大肠杆菌生存适应性的影响,为创造多重耐药菌株带来高适应代价的环境及加速降低种群耐药水平提供理论依据.[方法]以分离自贵州省规模化猪场的多重耐药大肠杆菌QL15为研究对象,以大肠杆菌质控(敏感)菌株ATCC25922为对照,经体外竞争试验测定不同环境(培养基浓度、碳源、氮源、pH和温度)胁迫下耐药菌株QL15相对于敏感菌株ATCC25922的适应性,并通过重测序变异位点和实时荧光定量PCR测定分析耐药基因表型及外排泵和外膜孔道蛋白基因表达与细菌适应性代价的关系.[结果]耐药菌株QL15在体外独立及混合培养时,除在稀释LB培养基(1/4、1/8和1/16)中的长势较敏感菌株ATCC25922低外,在低碳源(0.1％和0.5％)、低氮源(0.01％和0.05％)、酸碱性(pH=5.0、pH=6.0和pH=8.0)及低温(20℃)和高温(42℃)胁迫下的生长均优于敏感菌株ATCC25922,且混合培养结果优于独立培养.将耐药菌株QL15基因组序列与敏感菌株ATCC25922基因组序列进行比对,共检测到509个InDel突变位点,其中Delete突变位点233个、Insert突变位点276个;共注释到71个功能基因,以细胞壁与细胞膜相关基因突变最多(10个),占14.1％.与敏感菌株ATCC25922相比,耐药菌株QL15在不同环境胁迫下其外排泵与外膜孔道蛋白相关基因emrB、acrB、tolC和ompC呈下调表达,而ompF基因呈上调表达.[结论]多重耐药大肠杆菌耐药性的获得促使其具有更强的适应性,但对可直接利用营养物质的获取弱于敏感菌株,即处于竞争劣势.耐药大肠杆菌的多重耐药性主要是由多种外排泵和外膜孔道蛋白介导完成,其中,ompF基因在pH胁迫、全营养胁迫和高、低温胁迫下均处于上调表达状态,故推测ompF基因的高表达有利于大肠杆菌在上述胁迫条件下生长.