Antibacterial mechanism of kojic acid and tea polyphenols against Escherichia coli O157:H7 through transcriptomic analysis

Escherichia coli O157:H7 is one of the major foodborne pathogenic bacterial that cause infectious diseases in humans.The previous found that a combination of kojic acid and tea polyphenols exhibited better activity against E.coli O157:H7 than using either alone.This study aimed to explore responses underlying the antibacterial mechanisms of kojic acid and tea polyphenols from the gene level.The functional enrichment analysis by comparing kojic acid and tea polyphenols individually or synergistically against E.coli O157:H7 found that acid resistance systems in kojic acid were activated,and the cell membrane and genomic DNA were destructed in the cells,resulting in“oxygen starvation”.The oxidative stress response triggered by tea polyphenols inhibited both sulfur uptake and the synthesis of ATP,which affected the bacteria's life metabolic process.Interestingly,we found that kojic acid combined with tea polyphenols hindered the uptake of iron that played an essential role in the synthesis of DNA,respiration,tricarboxylic acid cycle.The results suggested that the iron uptake pathways may represent a novel approach for kojic acid and tea polyphenols synergistically against E.coli O157:H7 and provided a theoretical basis for bacterial pathogen control in the food industry.

重组体pET-28a-alkB/E.coli降解页岩油泥石油烃的功能研究

为了降解页岩油泥中的石油烃,构建基因工程菌,表达石油烃降解关键酶以提高油泥的降解效果。以Pseudomonas qingdaonensis基因组为模板扩增alkB基因,连接至载体pET-28a,转化至E.coli BL21(DE3)中,SDS-PAGE和Western-blot鉴定表达的外源蛋白。pET-28a-alkB/E.coli处理原油和页岩油泥,采用气相色谱法评估降解效果。发现alkB基因在大肠杆菌中能表达外源蛋白,且14 d原油及页岩油泥的降解率分别为47.5%和47.1%,表明重组体pET-28a-alkB/E.coli具备降解页岩油泥石油烃的功能。

Comparison of extended spectrum β-lactamasesproducing Escherichia coli with non-ESBLsproducing E.coli:drug-resistance and virulence

The virulent factors of Escherichia coil （E.cofi） play an important role in the process of pathopoiesis. The study aimed to compare drug-resistant genes and virulence genes between extended spectrum β-1actamases （ESBLs）-producing E.coli and non-ESBLs-producing E.cofi to provide a reference for physicians in management of hospital infection. From October 2010 to August 2011,96 drug-resistant strains of E. coli isolated were collected from the specimens in Qingdao Municipal Hospital, Qingdao, China. These bacteria strains were divided into a ESBLs-producing group and a non-ESBLs-producing group. Drug sensitivity tests were performed using the Kirby-Bauer （K-B） method. Disinfectant gene, qacEAl-sull and 8 virulence genes （CNF2, hlyA, eaeA, VT1, est, bfpA, elt, and CNF1） were tested by polymerase chain reaction （PCR）. Among the 96 E.coli isolates, the ESBLs-producing E.coli comprised 46 （47.9%） strains and the non-ESBLs-producing E.cofi consisted of 50 （52.1%） strains. The detection rates of multiple drug-resistant strain, qacEAl-sull, CNF2, hlyA, eaeA,VT1, est, bfpA, elt, and CNF1 in 46 ESBLs-producing E.coli isolates were 89.1%, 76.1%, 6.5%, 69.6%, 69.6%, 89.1%, 10.9%, 26.1%, 8.7%, and 19.6%, respectively. In the non-ESBLs-producing E.cofi strains, the positive rates of multiple drug-resistant strain, qacEAl-sull, CNF2, hlyA, eaeA, VT1, est, bfpA, elt, and CNF1 were 62.0%, 80.0%, 16.0%, 28.0%, 64.0%, 38.0%, 6.0%, 34.0%, 10.0%, and 24.0%, respectively. The difference in the detection rates of multiple drug-resistant strain, hlyA and VT1 between the ESBLs-producing E.cofi strains and the non-ESBLs-producing E.cofi strains was statistically significant （P〈0.05）. The positive rate of multiple drug-resistant strains is higher in the ESBLs-producing strains than in the non-ESBLs-producing strains. The expression of some virulence genes hlyA and VT1 varies between the ESBLs-producing strains and the non-ESBLs-producing strains. Increased awareness of clinicians and enhanced testing by laboratories are required to reduce treatment failures and prevent the spread of multiple drug-resistant strains.

Preclinical and clinical evidence of the association of colibactinproducing Escherichia coli with anxiety and depression in colon cancer

BACKGROUND The association between the intestinal microbiota and psychiatric disorders is becoming increasingly apparent.The gut microbiota contributes to colorectal carcinogenesis(CRC),as demonstrated with colibactin-producing Escherichia coli(CoPEC).AIM To evaluate the association between CoPEC prevalence and anxiety-and depressive-like behaviors with both preclinical and clinical approaches.METHODS Patients followed after a CRC surgery and for whom the prevalence of CoPEC has been investigated underwent a psychiatric interview.Results were compared according to the CoPEC colonization.In parallel C57BL6/J wild type mice and mice with a CRC susceptibility were chronically infected with a CoPEC strain.Their behavior was assessed using the Elevated Plus Maze test,the Forced Swimming Test and the Behavior recognition system PhenoTyper®.RESULTS In a limited cohort,all patients with CoPEC colonization presented with psychiatric disorders several years before cancer diagnosis,whereas only one patient(17%)without CoPEC did.This result was confirmed in C57BL6/J wildtype mice and in a CRC susceptibility mouse model(adenomatous polyposis colimultiple intestinal neoplasia/+).Mice exhibited a significant increase in anxiety-and depressive-like behaviors after chronic infection with a CoPEC strain.CONCLUSION This finding provides the first evidence that CoPEC infection can induce microbiota-gut-brain axis disturbances in addition to its procarcinogenic properties.

The virulence regulator AbsR in avian pathogenic Escherichia coli has pleiotropic effects on bacterial physiology

Avian pathogenic Escherichia coli(APEC)belonging to extraintestinal pathogenic E.coli(ExPEC)can cause severe infections in extraintestinal tissues in birds and humans,such as the lungs and blood.MprA(microcin production regulation,locus A,herein renamed AbsR,a blood survival regulator),a member of the MarR(multiple antibiotic resistance regulator)transcriptional regulator family,governs the expression of capsule biosynthetic genes in human ExPEC and represents a promising druggable target for antimicrobials.However,a deep understanding of the AbsR regulatory mechanism as well as its regulon is lacking.In this study,we present a systems-level analysis of the APEC AbsR regulon using ChIP-Seq(chromatin immunoprecipitation sequencing)and RNA-Seq(RNA sequencing)methods.We found that AbsR directly regulates 99 genes and indirectly regulates 667 genes.Furthermore,we showed that:1)AbsR contributes to antiphagocytotic effects by macrophages and virulence in a mouse model for systemic infection by directly activating the capsular gene cluster;2)AbsR positively impacts biofilm formation via direct regulation of the T2SS(type II secretion system)but plays a marginal role in virulence;and 3)AbsR directly upregulates the acid tolerance signaling system EvgAS to withstand acid stress but is dispensable in ExPEC virulence.Finally,our data indicate that the role of AbsR in virulence gene regulation is relatively conserved in ExPEC strains.Altogether,this study provides a comprehensive analysis of the AbsR regulon and regulatory mechanism,and our data suggest that AbsR likely influences virulence primarily through the control of capsule production.Interestingly,we found that AbsR severely represses the expression of the type I-F CRISPR(clustered regularly interspaced short palindromic repeats)-Cas(CRISPR associated)systems,which could have implications in CRISPR biology and application.

Exploring the modulatory role of bovine lactoferrin on the microbiome and the immune response in healthy and Shiga toxin‑producing E.coli challenged weaned piglets

Background Post-weaned piglets suffer from F18+Escherichia coli(E.coli)infections resulting in post-weaning diar-rhoea or oedema disease.Frequently used management strategies,including colistin and zinc oxide,have contrib-uted to the emergence and spread of antimicrobial resistance.Novel antimicrobials capable of directly interacting with pathogens and modulating the host immune responses are being investigated.Lactoferrin has shown promising results against porcine enterotoxigenic E.coli strains,both in vitro and in vivo.Results We investigated the influence of bovine lactoferrin(bLF)on the microbiome of healthy and infected weaned piglets.Additionally,we assessed whether bLF influenced the immune responses upon Shiga toxin-producing E.coli(STEC)infection.Therefore,2 in vivo trials were conducted:a microbiome trial and a challenge infection trial,using an F18+STEC strain.BLF did not affect theα-andβ-diversity.However,bLF groups showed a higher relative abundance(RA)for the Actinobacteria phylum and the Bifidobacterium genus in the ileal mucosa.When analysing the immune response upon infection,the STEC group exhibited a significant increase in F18-specific IgG serum levels,whereas this response was absent in the bLF group.Conclusion Taken together,the oral administration of bLF did not have a notable impact on theα-andβ-diversity of the gut microbiome in weaned piglets.Nevertheless,it did increase the RA of the Actinobacteria phylum and Bifi-dobacterium genus,which have previously been shown to play an important role in maintaining gut homeostasis.Furthermore,bLF administration during STEC infection resulted in the absence of F18-specific serum IgG responses.

Impact of an oligosaccharide-based polymer on the metabolic profiles and microbial ecology of weanling pigs experimentally infected with a pathogenic E.coli

Background Our previous study has reported that supplementation of oligosaccharide-based polymer enhances gut health and disease resistance of pigs infected with enterotoxigenic E.coli(ETEC)F18 in a manner similar to carbadox.The objective of this study was to investigate the impacts of oligosaccharide-based polymer or antibiotic on the host metabolic profiles and colon microbiota of weaned pigs experimentally infected with ETEC F18.Results Multivariate analysis highlighted the differences in the metabolic profiles of serum and colon digesta which were predominantly found between pigs supplemented with oligosaccharide-based polymer and antibiotic.The relative abundance of metabolic markers of immune responses and nutrient metabolisms,such as amino acids and carbohydrates,were significantly differentiated between the oligosaccharide-based polymer and antibiotic groups(q<0.2 and fold change>2.0).In addition,pigs in antibiotic had a reduced(P<0.05)relative abundance of Lachnospiraceae and Lactobacillaceae,whereas had greater(P<0.05)Clostridiaceae and Streptococcaceae in the colon digesta on d 11 post-inoculation(PI)compared with d 5 PI.Conclusions The impact of oligosaccharide-based polymer on the metabolic and microbial profiles of pigs is not fully understood,and further exploration is needed.However,current research suggest that various mechanisms are involved in the enhanced disease resistance and performance in ETEC-challenged pigs by supplementing this polymer.

Prevalence of Drug Resistant Uropathogenic Escherichia coli from Immunocompromised Diabetic Patients Attending Selected Health Facilities in Benue State

Escherichia coli is the commonest bacterial uropathogen of UTIs, the commonest infections in immunocompromised diabetic patients. Better understanding of their main resistance mechanisms to commonly used antibacterial agents will help to reduce the burden of this infection. The prevalence of drug resistant uropathogenic Escherichia coli isolates from immunocompromised diabetic patients attending selected health facilities in Benue State was investigated. Two hundred and ninety-six midstream urine samples were collected for both study and control diabetic patients. Bacterial isolation was done using semi-quantitative method. Drug resistant Escherichia coli were identified as multidrug resistant (MDR), extensive drug resistant (XDR) and pan-drug resistant organisms (PDR). Statistical significance was considered at p E. coli isolates from the study and control subjects with overall prevalence of 20.9% and 8.4% respectively. The isolates were highly resistant to penicillin (ampicillin), monobactam (aztreonam), older quinolone (nalidixic acid) whereas the majority of them showed high susceptibility to aminoglycoside (streptomycin), cephalosporin (cefotaxime) and carbapenem (imipenem). None showed complete susceptibility to all the tested antibiotics. Twenty-five E. coli were identified in this MDR, eight, XDR while 5 were PDR. High numbers of drug resistant E. coli isolates were identified in the study group of which 25 were MDR, 8 XDR while 5 were PDR isolates. High prevalence of UTI and drug resistant isolates occur in diabetic patients with hyperglycemic condition.

Impact of Genetic Diversity of Uropathogenic Escherichia coli and Klebsiella pneumoniae Strains on the Dissemination of Extended Spectrum Beta-Lactam Resistance Genes in Côte d’Ivoire

The increase and spread of bacterial resistance to extended-spectrum beta-lactam antibiotics are reported in many infections and are a real public health problem worldwide. Drug pressure is a factor that favors the emergence of a population of better adapted bacteria. However, there is no literature highlighting the genetic diversity and evolutionary structure of E. coli and K. pneumoniae in an environment with high selection pressure in Côte d’Ivoire. The objective of this study was to evaluate the genetic diversity of E. coli and K. pneumoniae strains circulating at the HKB Hospital in Abobo and at the Daloa Regional Hospital and its impact on the dissemination of extended spectrum beta-lactam resistance genes. A total of 39 strains isolated from the urinary tract of infected patients, including 30 strains of E. coli and 9 strains of K. pneumoniae were studied. A total of 39 strains isolated from the urinary tract of infected patients, including 30 strains of E. coli and 9 strains of K. pneumoniae were studied. From genomic DNA extracts, ESBL resistance genes were amplified by PCR and sequenced, in addition to genetic typing by ERIC-PCR. The data obtained were submitted to genetic and bioinformatics analyses. The results have shown a genetic diversity important in E. coli and K. pneumoniae with diversity indexs (SID) ranging from 0.5 to 0.77. The genetic structure of the bacterial species studied has shown a clonal distribution of strains with clones expressing TEM-9 and CTX-M-15 variants. Also, this clonal structure was correlated with the spread of resistance genes in E. coli and K. pneumoniae. The spread of resistant clones is a factor that might limit the fight against antibiotic resistance.

Phytochemicals of Aloe barbadensis miller as Potential Inhibitors of Uropathogenic Escherichia coli for Urinary Tract Infection Therapy: An in Silico Approach

Urinary tract infections (UTIs) are common infections caused by normal skin or rectum bacteria that get into the urethra and infect the urinary tract. Although the infection can affect various parts of the tract, bladder infections are the most prevalent kind. Uropathogenic Escherichia Coli (UPEC) is the most common pathogen associated with UTI development. Therefore, inhibiting the UPEC protein target (PDB ID: 8BVD) appears to be a promising therapeutic strategy. Therefore, in this study, molecular docking and dynamics were conducted to examine the antibacterial activity of Aloe barbadensis miller against UPEC bacteria. The Aloe barbadensis miller natural compounds licochalcone A, palmidin B and palmidin C were downloaded from PubChem with amoxicillin, which was used as a control drug and studied against the target molecule. The potential parameters examined were the docking scores, absorption, distribution, metabolism, excretion, toxicity (ADMET), bioavailability, root mean square deviation (RMSD), root mean square fluctuation (RMSF), hydrogen bonding, radius of gyration, and potential energy of the system. Docking scores showed that all ligands demonstrated an admirable candidature as an inhibitor to 8BVD molecule, and the score hierarchy is licochalcone A (-6.4 kcal/mol), palmidin C (-6.1 kcal/mol), palmidin B (-6.0 kcal/mol), and amoxicillin (-5.9 kcal/mol). All ligands appeared to have good drug-like properties and oral bioavailability. Molecular dynamic studies showed that all ligands exhibited an excellent nominee as inhibitors in their vicinity at 20 ns. However, there is a relatively high fluctuation of palmidin B compared with other compounds, which seems to be more stable. This work suggests that the selected phytoconstituents could be used as inhibitors of the 8BVD protein in the fight against UTIs. However, further investigation on the clinical and experimental validation of UTI treatment’s specific mechanisms and effects is still welcomed.

E.coli HPI通过NLRP3/caspase-1信号通路诱导细胞焦亡而促进肠道炎症

目的:探究大肠埃希菌(Escherichia coli,E.coli)强毒力岛(high-pathogenicity island,HPI)对细胞焦亡及肠道炎症的影响。方法:用含HPI的E.coli株(HPI+)、HPI缺失的E.coli株(△HPI)和脂多糖(lipopolysaccharide,LPS)分别处理昆明小鼠和IPEC-J2细胞(猪小肠上皮细胞)。测定小鼠肠道乳酸脱氢酶(lactate dehydrogenase,LDH)活性、超氧化物歧化酶(superoxide dismutase,SOD)活性、IgA表达和分泌性IgA(secretory IgA,SIgA)含量;HE和TUNEL染色观察肠道损伤;RT-qPCR、免疫组织化学染色和Western blot检测小鼠肠组织和IPEC-J2细胞中核苷酸结合寡聚化结构域样受体蛋白3(nucleotide-binding oligomerization domain-like receptor protein 3,NLRP3)/caspase-1信号通路关键调控点的表达;ELISA检测小鼠血清和IPEC-J2细胞培养上清液中白细胞介素1β(interleukin-1β,IL-1β)和IL-18含量;共聚焦显微镜观察NLRP3与caspase-1的共定位。siRNA沉默IPEC-J2细胞的NLRP3,验证NLRP3在E.coli HPI感染中的关键调控功能。结果:相对于△HPI感染,E.coli HPI显著降低小鼠肠道SOD活性,增加IgA+B细胞,并促进LDH的释放和SIgA的分泌;ELISA、HE染色和TUNEL染色结果显示,E.coli HPI促进了小鼠肠道上皮细胞DNA断裂、组织损伤和炎症;Western blot结果显示,相对于△HPI,E.coli HPI感染使得小鼠肠道消皮素D的N端片段(gasdermin D N-terminal fragment,GSDMD-N)蛋白水平显著升高;RT-qPCR和免疫组织化学染色结果显示,E.coli HPI显著促进了小鼠肠道和IPEC-J2细胞中NLRP3、含caspase募集结构域的凋亡相关斑点样蛋白(apoptosis-associated speck-like protein containing a caspase recruitment domain,ASC)、caspase-1、GSDMD、IL-1β和IL-18的mRNA和蛋白表达,IL-1β和IL-18分泌增加;共聚焦显微镜观察发现,相对于△HPI感染,E.coli HPI显著促进了NLRP3炎症小体的组装,使得NLRP3与caspase-1发生共定位;此外,在NLRP3沉默的IPEC-J2细胞中观察到E.coli HPI诱导的细胞炎症、细胞损伤及NLRP3/caspase-1信号通路的激活被缓解。结论:HPI的存在增强了E.coli的毒力水平,促进肠道炎症;NLRP3/caspase-1信号通路调控的细胞焦亡参与了E.coli HPI诱导的肠道损伤。

Multidrug-Resistant of Escherichia coli and Salmonella spp. Strains in Chicken Feces Intended for Consumption in Open Spaces of Ouagadougou, Burkina Faso

Resistant bacteria can be transmitted to humans through feces or contaminated meat from local chickens. Bacterial strains were isolated from the intestinal contents of 400 local chicken samples from various sales sites. These strains were then characterized using bacteriological and biochemical methods to identify resistant strains. In a study conducted in Ouagadougou, we systematically collected chicken fecal samples from 20 locations across the city, followed by isolation and identification of Salmonella spp. using specific enrichment and culture methods, as well as Escherichia coli. Bacterial strains were characterized using antibiotic resistance profiles were determined through agar diffusion tests, revealing sensitivity or resistance to a range of antibiotics based on established scientific criteria. The results showed that out of the 400 samples collected, 81.25% and 63.5% were contaminated by Escherichia coli and Salmonella spp., respectively. Among these, 86.15% of identified Escherichia coli and 50.78% of Salmonella spp. displayed resistance to at least one tested antibiotic. Among 280 Escherichia coli isolates identified resistant to at least one antibiotic, 31.07% were resistant to cefotaxime (CTX), 20.35% to ceftazidime (CAZ), 21.07% to ceftriaxone (CTR), 75% to amoxicillin clavulanic acid (AMC), 23.57% aztreoname (ATM) and 27.14% were resistant to imipenem (IMP). In the case of the 129 Salmonella spp. isolates resistant to at least one tested antibiotic, 34.88% were resistant to CTX;41.08% to CAZ;35.65% to CTR, 92% to AMC, 39.53% to ATM and finally 47.28% were resistant to IMP. Our study revealed high prevalence of resistance in bacterial strains isolated from local chickens sold outdoors in Ouagadougou. These findings raise significant public health concerns, due to the possible transmission of these resistant strains to humans through the consumption of contaminated meat, thus complicating the treatment of bacterial infections.

The Transport and Persistence of Escherichia coli in Leachate from Poultry Litter Amended Soils

Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay soil and Hartsells Sandy soil was conducted using soil columns and simulated groundwater leaching. Enumeration of initial E. coli was determined to range from 2.851 × 103 to 3.044 × 103 CFU per gram of soil. These results have been used in a batch study to determine the persistence rate of E. coli in Decatur silty Clay soil and Hartsells Sandy soil. Results prove that E. coli survival growth rate increases for clay soil later than and at a higher rate than sandy soil. The column study has determined that E. coli was transported at a rate of 3.7 × 106 CFU for Decatur silty loam and 6.3 × 106 CFU for Hartsells sandy per gram of soil. Further, linear regression analysis predictions show higher porosity and soil moisture content affect transport, and Hartsells sandy soil has higher transport of E. coli due to its higher porosity and lower volumetric water content.

Growth Inhibition of Escherichia coli and Staphylococcus epidermidis from Various Types of Honey

Honey has long been considered a wound treatment used to keep cuts and other epidermal injuries clean. This study tested that claim by comparing manuka honey used in medicine today, local unprocessed honey taken straight from a hive, and pasteurized honey found at a store, on strains of E. coli and S. epidermidis. The study evaluated the effects these honeys had on bacterial growth to determine which had the greatest inhibition of bacterial growth. To determine this, plates streaked with strains of E. coli or S. epidermidis bacteria and agar wells filled with one of the honeys were incubated and subsequently the diameter of the zone of inhibition was measured. After 20 trials using each honey and bacteria type, manuka and unprocessed were shown to have a statistically significant advantage over the pasteurized honey at inhibiting the growth of E. coli and S. epidermidis, though it was variable whether manuka had an advantage over the unprocessed honey.

Evaluating the Potential of Nitrofurantoin and Fosfomycin for E.coli UTIs: A Susceptibility Study

This study was designed to find the susceptibility of Nitrofurantoin and Fosfomycin among urinary isolates of Escherichia.coli.Four hundred(400)urine samples were collected for susceptibility of nitrofurantoin and fosfomycin among urinary isolates of E.coli.All indoor and outdoor patients'urinary samples yielded growth of E.coli.Mid-stream urine specimens were inoculated on blood agar and CLED agar and incubated at 35±2°C.Growth was observed,and Escherichia coli was identified by Gram staining,Catalase,Motility test and API 20E(Bio murex)as per standard procedure.Antimicrobial susceptibility testing of isolates for nitrofurantoin and fosfomycin was carried out by the modified Kirby-Bauer disc diffusion method according to CLSI guidelines ATCC 25922.E.coli was used as a quality control strain.A total of 400 samples were tested susceptibility of nitrofurantoin and fosfomycin among urinary isolates of E.coli during this period.A total of 400 samples yielded the growth of E.coli,out of which 178(44.5%)were male and 222(55.5%)were female samples.Among males,18(10%)were tolerant to nitrofurantoin,and 2(1.1%)were tolerant to fosfomycin.Among females,9(4.09%)were susceptible to nitrofurantoin while 6(2.72%)were susceptible to fosfomycin.Among age groups below 45 years old,6(4.76%)were tolerant to nitrofurantoin,and 2(1.58%)were sensitive to fosfomycin.Between 46-66 years old,4(2.81%)were sensitive to nitrofurantoin,and 3(2.11%)were sensitive to fosfomycin.Between 67-90 years old,17(12.87%)were sensitive to nitrofurantoin,and 4(3.03%)were tolerant to fosfomycin.Fosfomycin and nitrofurantoin showed good susceptibility in urinary isolates of E.coli and can be used empirically in our setup.

E.coli O78和LAB对牦牛肠道上皮细胞MAPK/Zonulin通路的影响

为探究牦牛致病性大肠杆菌(E.coli O78)和乳酸杆菌(LAB)对牦牛肠道上皮屏障MAPK/Zonulin通路的影响作用,采用牦牛上皮细胞作为实验模型,Transwell构建单层上皮细胞屏障,设立阴性对照组(Control组)、阳性对照组(Model组,加入1×10^(5)CFU E.coli O78)、低剂量组乳酸杆菌组(LLAB组,加入1×10^(5)CFU E.coli O78和1×10^(5)CFU LAB)、高剂量乳酸杆菌组(HLAB组,加入加入1×10^(5)CFU E.coli O78和1×10^(7)CFU LAB),采用RT-qPCR和Western-blot技术测定各组P38、ERK、JNK、Zonulin的基因和蛋白表达水平。结果:与Control组相比,Model组的P38、ERK、JNK、Zonulin的基因表达水平极显著上升(P<0.01),而其蛋白表达水平呈现显著上升的趋势(P<0.05);与Model组相比,LLAB组P38的基因表达水平极显著下降(P<0.01),ERK、JNK、Zonulin的基因表达水平表现显著下降的趋势(P<0.05),P38、ERK、Zonulin的蛋白表达水平则呈现极显著下降的趋势(P<0.01),JNK的蛋白表达水平表现为显著下降(P<0.05);与Model组相比,HALB组P38、ERK、JNK的基因的表达水平表现为显著下降(P<0.05),Zonulin的基因表达水平表现为极显著下降(P<0.01),P38、ERK、JNK、Zonulin的蛋白表达水平呈现极显著下降的趋势(P<0.01)。结论:E.coli O78可通过上调MAPK通路关键基因P38、ERK、JNK的基因表达水平,同时上调Zonulin蛋白使肠道屏障受损;LAB可以减轻E.coli O78引起的肠道屏障受损,这一作用是通过下调MAPK通路关键基因P38、ERK、JNK的基因表达水平,同时下调Zonulin蛋白表达水平来实现的。

Survey of O-islands in Escherichia coli O157 and Other Enteric Pathogens——O-islands of E.coli O157∶H7

The genome of the enterohemorrhagic Escherichia coli O157∶H7 EDL933 contains 177 “O”-islands (OIs). To study their potential contribution to the O157-specific pathogenicity, we surveyed the distribution of 22 OIs by PCR and DNA hybridization in 17 isolates of Shiga toxin producing (Stx-positive) E.coli O157∶H7, and compared with their distribution in 21 isolates of Stx-negative E.coli O157 and 21 isolates of non-O157 enteric pathogens. Fourteen of 22 OIs were present in non-O157 entericpathogens analyzed. Eight of 22 OIs were found only in the 17 Shiga toxin- (Stx) positive E.coli O157∶H7 isolates, but they were absent from the 21 Stx-negative E.coli O157∶NM and O157︰Hund isolates tested. Among the 8 OIs, only OI43 or OI48 were exclusively detected in Stx-positive E.coli O157∶H7, absent from neither of Stx-negative E.coli O157 and non-O157 enteric pathogens, such as Salmonella, Shigella, Citrobacter, Vibrio cholera, enteropathogenic E.coli (EPEC), enteroadherent E.coli (EAEC), enteroinvasive E.coli (EIEC) and enterotoxingenic E.coli (ETEC). The OI43 and OI48 are 83 kb in size and identical in DNA sequences, which encode genes for urease, tellurite resistance and adherence. By analyzing their junction genes with PCR and DNA hybridization, we found that 21 Chinese isolates have OI48 only. However, for 7 Japanese patient isolates, 4 have OI43 and 3 have OI48; for American isolates, 2 have both of OI43 and OI48, 2 have OI48 only. These data confirmed the highly plasticity of the pathogenic E.coli genome. The unique presence of OI43/OI48 in Stx-positive E.coli O157∶H7 denotes its critical role in the pathogenicity specific to this pathogen.

Sterilization Effects of Bacterial Inhibitor on Escherichia coli in Cattle Manure Compost

[Objective] The aim of this study was to explore the sterilization effects on Escherichia coli by adding bacterial inhibitor(CaCN2)during the process of cattle manure composting so as to provide a theoretical basis for cattle manure harmless treatment.[Method] Both experimental groups supplemented with 2.0% bacterial inhibitor and control groups without bacterial inhibitor were cultured under different temperatures(20,30,37,50,60 ℃)to determine the optimal composing temperature.Under 30 ℃,different bacterial inhibitor doses(0,2.0%,2.5%,3.0%)were added into the compost to obtain the optimal bacterial inhibitor addition dose.[Result] 30,50 and 60 ℃ were ideal temperatures for sterilization of E.coli.Under 30 ℃,E.coli couldn't be detected in 2.5% dose group and 3.0% dose group after culture for 48 h,demonstrating no less than 2.5% bacterial inhibitor should be added.[Conclusion] It has an important significance to enhance the sterilization effects on E.coli by adding CaCN2 into cattle manure compost especially in winter.

口服益生菌Escherichia coli Nissle 1917调控断奶仔猪空肠黏膜屏障功能的机理研究

旨在探讨口服益生菌Escherichia coli(E.coli)Nissle 1917调控病原菌E.coli Abbottstown攻毒或未攻毒21d断奶仔猪肠道屏障功能的机理。将20头21d断奶仔猪((6.35±0.38)kg)随机分为4组:(1)饲喂基础日粮的对照组(CON);(2)正试期口服E.coli Nissle 1917组(EcN);(3)预试期E.coli Abbottstown攻毒组(EcA);(4)预试期E.coli Abbottstown攻毒和正试期口服E.coli Nissle 1917组(EcN+EcA)。每个处理5个重复,每个重复1头仔猪。试验分为3d预试期和21d正试期。预试期EcA和EcN+EcA组的断奶仔猪接种5×10~9E.coli Abbottstown。正试期EcN和EcN+EcA组仔猪每天每头口服1×10~10E.coli Nissle 1917。试验结果表明,未攻毒的断奶仔猪中,与CON相比,口服1×10~10E.coli Nissle 1917能显著改善生长性能(P<0.05),降低腹泻率,提高oCcludin蛋白水平(P<0.05),显著降低空肠黏膜calprotectin蛋白水平(P<0.05),显著下调空肠黏膜蛋白激酶R(Protein kinase R,PKR)、toll样受体-2(Toll-like receptor-2,TLR-2)和真核起始因子-5A(eukaryotic initiation factor-5A,eIF-5A)mRNA的相对表达丰度(P<0.05),上调空肠黏膜内皮生长因子(Endothelial growth factor,EGF)、肝细胞生长因子(Hepatocyte growth factor,HGF)、胰岛素样生长因子(Insulin-like growth factor,IGF-I)、三叶肽因子-3(trefoil peptide factor-3,TFF-3)mRNA的相对表达丰度(P<0.05);在E.coli Abbottstown攻毒的断奶仔猪中,与EcA组相比,口服1×10~10E.coli Nissle 1917能显著改善生长性能(P<0.05),降低腹泻率,降低血清二胺氧化酶(DAO)活性(P<0.05)和一氧化氮(NO)含量(P<0.05),下调空肠黏膜PKR、eIF-5A和TLR-2 mRNA相对表达丰度(P<0.05),显著降低空肠黏膜calprotectin蛋白水平和淋巴细胞数量(P<0.05),显著提高空肠黏膜oCcludin蛋白水平(P<0.05),上调空肠黏膜IGF-I、HGF、TFF-3和EGF mRNA相对表达丰度(P<0.05)。本试验结果提示,口服1×10~10E.coli Nissle 1917能降低病原大肠杆菌攻毒或未攻毒21日龄断奶仔猪空肠黏膜屏障功能的损伤。

重组E.coli工程菌高密度培养生产人源型胶原蛋白

Several technical parameters were studied during the fermentation of recombinant E.coli for the production of collagen-like biopolymer.The effects of dissolved oxygen as well as glucose concentration on fermentation were observed.The OD 600 value could reach 98 when dissolved oxygen was controlled at 50% and glucose around 1%.The production of human-like collagen with a yield of 29.4% was obtained.