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 ...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.展开更多
Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomi...Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomial urinary tract infections, surgical site infections and pneumonia in surgical clinic were studied. ESBL synthesis were observed 38.9% of E. coli strains obtained from urine, 92.3% of strains obtained from surgical site infections, and 50% of strains obtained from sputum. ESBL synthesis were observed 37.5% of K. pneumoniae strains obtained from urine, 85.7% of strains obtained from surgical site infections, and 60% of strains obtained from sputum. Different levels of ESBL synthesize of E. coli and K. pneumoniae strains isolated from different pattern is discussed. Conclusion. ESBL synthesis is common in E. coli and K. pneumoniae strains, which cause nosocomial infections. The frequency of occurrence of ESBL s synthesis among of these strains depends on clinical forms of nosocomial infections.展开更多
The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacteri...The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacterial control.The influence of some parameters in quantification and performance influencing of pathogen demobilization could be considered in disinfection of wastewater.The comparison of Polyvalent phage(NE1)versus Coliphage(NE4)in suppressing a bacterium Escherichia coli(NDM-1:b-lactam-resistant)with UV irradiation was observed the efficacy in reduction of cells in the disinfection and parameter process.The results with the effect of UV-C irradiation on NDM-1 infected with 1%of NE4 showed a decrease of cells from 8×10^(6)to 2×10^(5)in 60 min with UV-C dose.The NDM1(E.coli)was infected with 1%of NE4(Polyvalent Phage)under magnetic stirring for 1 h,the cells count was 8×10^(6).After 1 h in UV-C e×posure,the cells number reached 3×10^(5).The NDM1 that was e×posed in 1 h of UV-C irradiation and then was infected with 1%of NE4.Cells counting were done 24 h after this procedure.These cells were e×posed in UV-C and showed a reduction in the number of cells from 1×10^(8)to 4×10^(5)after 60 min.The results indicate that bacteriophages can mitigate bacteria species,and combined the conventional water disinfection technologies that can support the microbial safety control strategies.展开更多
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 s...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 × 10<sup>3</sup> to 3.044 × 10<sup>3</sup> 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 × 10<sup>6</sup><sup> </sup>CFU for Decatur silty loam and 6.3 × 10<sup>6</sup><sup> </sup>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.展开更多
BACKGROUND:The virulent factors of Escherichia coli(E.coli) play an important role in the process of pathopoiesis.The study aimed to compare drug-resistant genes and virulence genes between extended spectrum β-lactam...BACKGROUND:The virulent factors of Escherichia coli(E.coli) play an important role in the process of pathopoiesis.The study aimed to compare drug-resistant genes and virulence genes between extended spectrum β-lactamases(ESBLs)-producing E.coli and non-ESBLs-producing E.coli to provide a reference for physicians in management of hospital infection.METHODS: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,qacEA1-sull and 8 virulence genes(CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1) were tested by polymerase chain reaction(PCR).RESULTS:Among the 96 E.coli isolates,the ESBLs-producing E.coli comprised 46(47.9%)strains and the non-ESBLs-producing E.coli consisted of 50(52.1%) strains.The detection rates of multiple drug-resistant strain,qacEA1-sull,CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1 in 46ESBLs-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.coli strains,the positive rates of multiple drug-resistant strain,qacEA1-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.coli strains and the non-ESBLs-producing E.coli strains was statistically significant(P<0.05).CONCLUSION:The positive rate of multiple drug-resistant strains is higher in the ESBLsproducing 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.展开更多
Background:The independent and interactive effects of dietary fiber(DF)and threonine(Thr)were investigated in growing pigs challenged with either systemic E.coli lipopolysaccharide(LPS)or enteric Salmonella Typhimuriu...Background:The independent and interactive effects of dietary fiber(DF)and threonine(Thr)were investigated in growing pigs challenged with either systemic E.coli lipopolysaccharide(LPS)or enteric Salmonella Typhimurium(ST)to characterise their effect on intestinal barrier function.Results:In experiment 1,intestinal barrier function was assessed via oral lactulose and mannitol(L:M)gavage and fecal mucin analysis in pigs challenged with E.coli LPS and fed low fiber(LF)or high fiber(HF)diets with graded dietary Thr.Urinary lactulose recovery and L:M ratio increased(P<0.05)during the LPS inoculation period in LF fed pigs but not in HF fed pigs.Fecal mucin output was increased(P<0.05)in pigs fed HF compared to LF fed pigs.In experiment 2,RT-qPCR,ileal morphology,digesta volatile fatty acid(VFA)content,and fecal mucin output were measured in Salmonella Typhimurium challenged pigs,fed LF or HF diets with standard or supplemented dietary Thr.Salmonella inoculation increased(P<0.05)fecal mucin output compared to the unchallenged period.Supplemental Thr increased fecal mucin output in the HF-fed pigs(Fib×Thr;P<0.05).Feeding HF increased(P<0.05)VFA concentration in cecum and colon.No effect of either Thr or fiber on expression of gene markers was observed except a tendency(P=0.06)for increased MUC2 expression with the HF diet.Feeding HF increased goblet cell numbers(P<0.05).Conclusion:Dietary fiber appears to improve barrier function through increased mucin production capacity(i.e.,goblet cell numbers,MUC2 gene expression)and secretion(i.e.,fecal mucin output).The lack of effect of dietary Thr in Salmonella-challenged pigs provides further evidence that mucin secretion in the gut is conserved and,therefore,Thr may be limiting for growth under conditions of increased mucin production.展开更多
AIM: To study the effect of integration of tandem aroG-pheA genes into the tyrA locus of Corynebacterium glutamicum (C. glutamicum) on the production of L-phenylalanine.METHODS: By nitrosoguanidine mutagenesis, five p...AIM: To study the effect of integration of tandem aroG-pheA genes into the tyrA locus of Corynebacterium glutamicum (C. glutamicum) on the production of L-phenylalanine.METHODS: By nitrosoguanidine mutagenesis, five pfluorophenylalanine (FP)-resistant mutants of Cglutamicum FP were selected. The tyrA gene encoding prephenate dehydrogenase (PDH) of C.glutamicum was amplified by polymerase chain reaction (PCR) and cloned on the plasmid pPR. Kanamycin resistance gene (Km) and the PBF-aroGpheA-T (GA) fragment of pGA were inserted into tyrA gene to form targeting vectors pl-K and pTGAK, respectively. Then,they were transformed into C.glutamicum FP respectively by electroporation. Cultures were screened by a medium containing kanamycin and detected by PCR and phenotype analysis. The transformed strains were used for L-phenylalanine fermentation and enzyme assays.RESULTS: Engineering strains of C.glutamicum (Tyr-)were obtained. Compared with the original strain, the transformed strain C. glutamicum GAK was observed to have the highest elevation of L-phenylalanine production by a 1.71-fold,and 2.9-, 3.36-, and 3.0-fold in enzyme activities of chorismate mutase, prephenate dehydratase and 3-deoxy-Darabinoheptulosonate-7-phosphate synthase, respectively.CONCLUSION: Integration of tandem aroG-pheA genes into tyrA locus of C. glutamicum chromosome can disrupt tyrA gene and increase the yield of L-phenylalanine production.展开更多
Ciprofloxacin is a second-generation of fluoroquinolone,broad-spectrum antibiotic with bactericidal activity against Gram-positive and Gram-negative organisms.It is one of the most widely used antibiotics,because of i...Ciprofloxacin is a second-generation of fluoroquinolone,broad-spectrum antibiotic with bactericidal activity against Gram-positive and Gram-negative organisms.It is one of the most widely used antibiotics,because of its efficacy,safety,and relatively low cost.Ascorbic acid(vitamin C)is water-soluble monosaccharide antioxidant;it is essentially required by the body for its various biochemical and physiological processes.S.aureus is Gram-positive cocci;widely distributed in the environment,it is a member of the normal flora of the body.S.aureus is not always pathogenic;it is a common cause of skin infections including abscesses,respiratory infections such as sinusitis,and food poisoning.E.coli is Gram-negative bacteria,found in the environment,foods,and intestines.Most E.coli strains are harmless;it is part of the normal microbiota of the gut.However,some serotypes of E.coli cause serious food poisoning in their hosts;it can cause diarrhea,while others cause urinary tract infections,respiratory illness and pneumonia,and other illnesses.Method:Cup cut diffusion method was applied.Experiment I:is carried out to choose the concentration of vitamin C to be used in experiment II.The negative control is normal saline,added in cup in each plate,vitamin C(100 mg/mL,200 mg/mL,400 mg/mL)was added,the volume in each cup was 100μL.Experiment II:Eight groups of treatments were applied.The first is the negative control(1%normal saline),the second group is the positive control of vitamin C(200 mg/mL).The third,fourth and fifth groups are ciprofloxacin with different concentrations(10 mg/mL,20 mg/mL,40 mg/mL);the sixth,seventh and eighth are the combination of vitamin C with each concentration of ciprofloxacin(10 mg/mL,20 mg/mL,40 mg/mL).Each group includes six petri dishes.Bacterial plates were incubated at 37 oC for 24 h and 48 h.Zone of inhibition is measured in mm.Results and conclusion:Ciprofloxacin produces dose dependent increase in zone of inhibition of S.aureus and E.coli growth,after 24 and 48 hours incubation.While vitamin C in the concentration used produced inhibitory effect on the growth of S.aureus and E.coli,after 24 hours incubation,vitamin C effect was not changed after 48 hours incubation.After 24 hours incubation,vitamin C potentiated the effect of ciprofloxacin at low concentration(10 mg/mL);while vitamin C antagonized the effect of ciprofloxacin at higher concentrations(20 and 40 mg/mL)on S.aureus growth.In the same time,ciprofloxacin antagonized the inhibitory effect of vitamin C on S.aureus growth.After 48 hours incubation,S.aureus produced resistance against ciprofloxacin alone,and that combined with vitamin C compared to zone of inhibition after 24 hours.Ciprofloxacin produced dose dependent inhibition of E.coli growth after incubation for 24 and 48 hours.Vitamin C potentiated the inhibitory effect induced by ciprofloxacin(additive effect).The inhibitory effect of ciprofloxacin,vitamin C and the combination was not changed after 48 hours compared to 24 hours.展开更多
Objective To study MIC value of 7 boron derivatives namely [Boric acid (H3BO3), Anhydrous Borax (Na2B407), Sodium Borate (NaBO2), Diammonium Tetraborate (NH4)2B4O7, Sodium Perborate (NaBO3), Boron Trioxide ...Objective To study MIC value of 7 boron derivatives namely [Boric acid (H3BO3), Anhydrous Borax (Na2B407), Sodium Borate (NaBO2), Diammonium Tetraborate (NH4)2B4O7, Sodium Perborate (NaBO3), Boron Trioxide (B203), Potassium Tetraborate (K2B407)] on E. coil and P. aeruginosa and their effects on survival of bacteria in lake water and resistance against kanamycin antibiotic. Methods MIC values of Boron derivatives and antibiotic were studied by broth microdilution method. The effect of boron derivatives on survival of bacteria in lake water were also determined with plate count. Results Sodium perborate was determined as the substances. Effectiveness increased as temperature most effective substance among the studied increased. E. coil was more affected from P. aeruginosa in 8 mg/mL sodium perborate concentration in lake water. Moreover, it was determined that MIC value of kanamycin antibiotic decreased 200 times by especially treating P. aeruginosa with sodium perborate in lake water. However, it can be stated that this change in resistance did not arise from microorganisms. Conclusion Sodium perborate solution can be used supportedly in kanamycin antibiotic applications for P. aeruginosa. Future studies are necessary to explore the relation between sodium perborate and kanamycin which is effective on P. aeruginosa in lake water.展开更多
The Ca. LSU intron flanking a 129 bp cxon upstream and a fOO bp exondownstream was inserted into the lacZ gene on pRS426 to transform E. coli. Northern blot analysisand RT-PCR showed that splicing of Ca. LSU in E. col...The Ca. LSU intron flanking a 129 bp cxon upstream and a fOO bp exondownstream was inserted into the lacZ gene on pRS426 to transform E. coli. Northern blot analysisand RT-PCR showed that splicing of Ca. LSU in E. coli is efficient upon inducible expression of theprecursor RNA, In contrast, co-lranscriptional self-splicing of the intron in vitro is much lessactive. Therefore, this E. coli splicing system can be used as a better model to investigate theeffect of the ribozyme inhibitors on Ca. LSUsplicing in living cell. We examined (he effects ofneomycin sulfatc and pentamidine on Ca. LSU splicing in E. coli, and found that these drugsdoes-dependently inhibit the intron splicing. However, heomycin is more potent than pentamidine inthis action.展开更多
Objective:Diarrhea is a leading cause of morbidity and mortality among children in developing countries.The bacterial pathogen most commonly associated with childhood diarrhea is Escherichia coli.A one-year prospectiv...Objective:Diarrhea is a leading cause of morbidity and mortality among children in developing countries.The bacterial pathogen most commonly associated with childhood diarrhea is Escherichia coli.A one-year prospective study was carried out in Sanandaj to determine the prevalence and roles of the different E.coli pathotypes in children less than five years of age with acute diarrhea.Methods:Rectal swab were collected prospectively from children with acute diarrhea and transported to the Department of Microbiology,School of Medicine, KUMS,Sanandaj during 2008.The study was approved by the institutional ethics committee.Results:During this study period,rectal swabs were investigated from a total of 466 children 1 to 144 months of age(mean, 29.97 months±S.D) with diarrhea.Among the children,191(41%,191/466) were girls,and 275 (59%,275/466) were boys.The age-specific incidence rates of acute diarrhea among children 13-24 and 1 - 12 months of age were 37.37%(37/99) and 26.26%(26/99),respectively,during the study period.A total of 99 strains of E.coli were detected.EPEC 59(59.59%) and EIEC 22(22.22%),were the most commonly found Escherichia coli strains detected in stools from children.Disk diffusion testing showed E.coli strains resistance to tetracycline(89.89%),chloramphenicol(88.88%),Ampicillin(79.79%),Amoxicillin (75.75%) and Ceficime(75.75%).Among risk factors like age,sex,haemoglubin,fathers and mothers education,food and weight of children only mother's education was significant(P =0.018).Conclusion: In most of the clinical laboratories in Iran,E.coli does not considered as an etiologic agent responsible for diarrhea. Results in this study revealed that E.coli should be considered as an etiologic agent causing acute diarrhea among children.We therefore,recommend the routine isolation and identification of E.coli strains in all the clinical laboratories in Sanandaj.Guidelines for appropriate use of antibiotics in Sanandaj need updating.展开更多
By using a yeast two-hybrid system,a yeast two-hybrid bait vector was constructed and identified for screening of the HPV18 E6-interacting proteins,and its effects on the growth of yeast cells and the activation of re...By using a yeast two-hybrid system,a yeast two-hybrid bait vector was constructed and identified for screening of the HPV18 E6-interacting proteins,and its effects on the growth of yeast cells and the activation of reporter genes were investigated.Total mRNA extracted from Hela cells was reversely transcribed into cDNA.Fragment of HPV18 E6 cDNA was amplified using RT-PCR and directly ligated to the pGBKT7 vector.The recombinant plasmid was confirmed by restriction endonuclease analysis and DNA sequencing.Th...展开更多
[Objectives] The study aimed to identify the pathogenic E. coli strain that caused diarrhea in foxes and to analyze its drug sensitivity.[Methods] A pathogenic E. coli strain was isolated from dead foxes with diarrhea...[Objectives] The study aimed to identify the pathogenic E. coli strain that caused diarrhea in foxes and to analyze its drug sensitivity.[Methods] A pathogenic E. coli strain was isolated from dead foxes with diarrhea. By conventional bacterial isolation and culture, morphological observation, pathogenicity test and K-B disc method, the isolated strain was identified as pathogenic E. coli .[Results] The isolated pathogen was highly sensitive to ceftriaxone, cefotaxime, ciprofloxacin and lincomycin, moderately sensitive to enrofloxacin, neomycin, gentamycin, spectinomycin, florfenicol, amikacin and polymyxin, and resistant to ampicillin, amoxicillin and doxycycline.[Conclusions] This study provided reference for the prevention and control of diarrheal diseases in foxes in Qinhuangdao region.展开更多
Astragalus membranaceus (huangqi), Allium sativum (garlic), Cinnamomum cassia (cinnamon), and Dolichos lablab L. (white hyacinth bean) are the traditional Chinese herbs that were used in prescriptions in treating diar...Astragalus membranaceus (huangqi), Allium sativum (garlic), Cinnamomum cassia (cinnamon), and Dolichos lablab L. (white hyacinth bean) are the traditional Chinese herbs that were used in prescriptions in treating diarrhea caused by bacterial infection. These herbs are relatively safe for use and investigation. This study aimed to investigate the effects of Astragalus membranaceus, Allium sativum, Cinnamomum cassia, and Dolichos lablab L. on the metabolism of Escherichia coli (E. coli). The growth rate of E. coli was monitored under the influence of each herb, revealing that Astragalus membranaceus and Allium sativum exhibited significant antibacterial activity, whereas Cinnamomum cassia and Dolichos lablab L. demonstrated moderate inhibitory effects on E. coli growth. Further inhibition zone testing allowed for the evaluation of each herb’s potency and the number of generations required for E. coli to develop resistance. Additionally, the impact of the four herbs on the expression of outer membrane protein A (OmpA) in E. coli was examined by using qPCR. The findings revealed that Astragalus membranaceus acted as a sustainable bactericide by inhibiting the growth and metabolism of E. coli MG1655 through the suppression of OmpA expression. These results suggest that Astragalus membranaceus has potential as a natural antimicrobial agent for treating E. coli infections.展开更多
Objective To explore the genotyping characteristics of human fecal Escherichia coli(E. coli) and the relationships between antibiotic resistance genes(ARGs) and multidrug resistance(MDR) of E. coli in Miyun District, ...Objective To explore the genotyping characteristics of human fecal Escherichia coli(E. coli) and the relationships between antibiotic resistance genes(ARGs) and multidrug resistance(MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data.Methods Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs,multilocus sequence typing(MLST), and polymorphism trees were analyzed using whole-genome sequencing data(WGS).Results This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal(49/70) and healthy groups(15/24).Conclusion We developed a random forest(RF) prediction model of TEM.1 + baeR + mphA + mphB +QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.展开更多
This study aims to generate data which can be used as a potential starting point for the updating of the Philippine Water Quality Criteria and the determination of the true impact of land use to the fecal contaminatio...This study aims to generate data which can be used as a potential starting point for the updating of the Philippine Water Quality Criteria and the determination of the true impact of land use to the fecal contamination of the Pampanga River Basin (PRB), the largest subwatershed of Manila Bay. Levels of fecal indicator bacteria (FIB) were determined in the selected tributaries of the PRB, representing three land use categories, namely, the forest/woodland (control), agricultural and residential lands. FIB were quantified in order to investigate the potential contribution of the selected areas in the fecal contamination of the PRB. The study was conducted in 2021 covering March, May, June, July, and September to represent the dry (March and May) and wet (June, July, and September) seasons. Counts of FIB, namely thermotolerant coliform, E. coli, and enterococci were qualitatively correlated with the results of the ocular survey and key informant interview based on known fecal contributors and their relevant rainfall data. FIB counts of water bodies in the selected agricultural and residential land use categories had Geometric Mean (GM) counts that are statistically greater than those of bodies of water near the representative forest/woodland (control), and exceeded the acceptable GM limits for all FIB, regardless of the season. Notably, the GM values recorded for the waters near the selected forest/woodland (control) passed the water quality criteria for all measured FIB parameters for both seasons. Furthermore, enterococci levels in the control site were statistically lower during the wet season. These initial findings suggest that agricultural and residential land use categories could be major contributors to the unacceptable water quality of tributaries of the Pampanga River Basin. The prevalence of thermotolerant coliforms and E. coli was noted regardless of rainfall and land use, indicating these FIB may not be adequate as water quality indicators. With their ability to survive and persist in fecally contaminated sediments in water bodies and in nutrient-poor environments, enterococci could be more definitive indicators of fecal contamination and microbiological quality of environmental waters.展开更多
Escherichia coli has become one of the most important causes of calf diarrhea.The aim of this study is to determine the patterns of antimicrobial resistance of E.coli isolates from six cattle farms and to identify pro...Escherichia coli has become one of the most important causes of calf diarrhea.The aim of this study is to determine the patterns of antimicrobial resistance of E.coli isolates from six cattle farms and to identify prominent resistance genes and virulence genes among the strains isolated from the diarrhea of calves.Antimicrobial susceptibility tests were performed using the disk diffusion method,and PCR was used to detect resistance and virulence genes.The prevalence of multidrug resistant(MDR)E.coli was 77.8%in dairy cattle and 63.6%in beef cattle.There were high resistance rates to penicillin(100%,100%)and ampicillin(96.3%,86.4%)in E.coli from dairy cattle and beef cattle.Interestingly,resistance rate to antimicrobials and distribution of resistance genes in£coli isolated from dairy cattle were higher than those in beef cattle.Further analysis showed that the most prevalent resistance genes were blojm and oodAl in dairy cattle and beef cattle,respectively.Moreover,seven diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,F41,K99 and STa)were present in the isolates from dairy cattle,with a prevalence ranging from 3.7%to 22.22%.Six diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,hylA and F41)were identified in the isolates from beef cattle,with a prevalence ranging from 2.27%to 63.64%.Our results provide important evidence for better exploring their interaction mechanism.Further studies are also needed to understand the origin and transmission route of£coli in cattle to reduce its prevalence.展开更多
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 w...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.展开更多
基金supported by Pancosma SA,Geneva,Switzerland,Jastro & Shields Graduate Research Awardthe United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA),multistate projects W4002 and NC1202
文摘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.
文摘Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomial urinary tract infections, surgical site infections and pneumonia in surgical clinic were studied. ESBL synthesis were observed 38.9% of E. coli strains obtained from urine, 92.3% of strains obtained from surgical site infections, and 50% of strains obtained from sputum. ESBL synthesis were observed 37.5% of K. pneumoniae strains obtained from urine, 85.7% of strains obtained from surgical site infections, and 60% of strains obtained from sputum. Different levels of ESBL synthesize of E. coli and K. pneumoniae strains isolated from different pattern is discussed. Conclusion. ESBL synthesis is common in E. coli and K. pneumoniae strains, which cause nosocomial infections. The frequency of occurrence of ESBL s synthesis among of these strains depends on clinical forms of nosocomial infections.
基金Fundação de Amparo a Pesquisa do Estado de São Paulo(FAPESP)and the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq),São Paulo,Brazil for PhD scholarship(Process N°.141086/2015-7)financial support(Process No.870243/1997-7).
文摘The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacterial control.The influence of some parameters in quantification and performance influencing of pathogen demobilization could be considered in disinfection of wastewater.The comparison of Polyvalent phage(NE1)versus Coliphage(NE4)in suppressing a bacterium Escherichia coli(NDM-1:b-lactam-resistant)with UV irradiation was observed the efficacy in reduction of cells in the disinfection and parameter process.The results with the effect of UV-C irradiation on NDM-1 infected with 1%of NE4 showed a decrease of cells from 8×10^(6)to 2×10^(5)in 60 min with UV-C dose.The NDM1(E.coli)was infected with 1%of NE4(Polyvalent Phage)under magnetic stirring for 1 h,the cells count was 8×10^(6).After 1 h in UV-C e×posure,the cells number reached 3×10^(5).The NDM1 that was e×posed in 1 h of UV-C irradiation and then was infected with 1%of NE4.Cells counting were done 24 h after this procedure.These cells were e×posed in UV-C and showed a reduction in the number of cells from 1×10^(8)to 4×10^(5)after 60 min.The results indicate that bacteriophages can mitigate bacteria species,and combined the conventional water disinfection technologies that can support the microbial safety control strategies.
文摘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 × 10<sup>3</sup> to 3.044 × 10<sup>3</sup> 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 × 10<sup>6</sup><sup> </sup>CFU for Decatur silty loam and 6.3 × 10<sup>6</sup><sup> </sup>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.
文摘BACKGROUND:The virulent factors of Escherichia coli(E.coli) play an important role in the process of pathopoiesis.The study aimed to compare drug-resistant genes and virulence genes between extended spectrum β-lactamases(ESBLs)-producing E.coli and non-ESBLs-producing E.coli to provide a reference for physicians in management of hospital infection.METHODS: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,qacEA1-sull and 8 virulence genes(CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1) were tested by polymerase chain reaction(PCR).RESULTS:Among the 96 E.coli isolates,the ESBLs-producing E.coli comprised 46(47.9%)strains and the non-ESBLs-producing E.coli consisted of 50(52.1%) strains.The detection rates of multiple drug-resistant strain,qacEA1-sull,CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1 in 46ESBLs-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.coli strains,the positive rates of multiple drug-resistant strain,qacEA1-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.coli strains and the non-ESBLs-producing E.coli strains was statistically significant(P<0.05).CONCLUSION:The positive rate of multiple drug-resistant strains is higher in the ESBLsproducing 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.
基金Funding for this project was provided by Alberta Agriculture and Forestry Strategic Research and Development Section,Evonik Nutrition&Care GmbH,and Mitacs Accelerate.
文摘Background:The independent and interactive effects of dietary fiber(DF)and threonine(Thr)were investigated in growing pigs challenged with either systemic E.coli lipopolysaccharide(LPS)or enteric Salmonella Typhimurium(ST)to characterise their effect on intestinal barrier function.Results:In experiment 1,intestinal barrier function was assessed via oral lactulose and mannitol(L:M)gavage and fecal mucin analysis in pigs challenged with E.coli LPS and fed low fiber(LF)or high fiber(HF)diets with graded dietary Thr.Urinary lactulose recovery and L:M ratio increased(P<0.05)during the LPS inoculation period in LF fed pigs but not in HF fed pigs.Fecal mucin output was increased(P<0.05)in pigs fed HF compared to LF fed pigs.In experiment 2,RT-qPCR,ileal morphology,digesta volatile fatty acid(VFA)content,and fecal mucin output were measured in Salmonella Typhimurium challenged pigs,fed LF or HF diets with standard or supplemented dietary Thr.Salmonella inoculation increased(P<0.05)fecal mucin output compared to the unchallenged period.Supplemental Thr increased fecal mucin output in the HF-fed pigs(Fib×Thr;P<0.05).Feeding HF increased(P<0.05)VFA concentration in cecum and colon.No effect of either Thr or fiber on expression of gene markers was observed except a tendency(P=0.06)for increased MUC2 expression with the HF diet.Feeding HF increased goblet cell numbers(P<0.05).Conclusion:Dietary fiber appears to improve barrier function through increased mucin production capacity(i.e.,goblet cell numbers,MUC2 gene expression)and secretion(i.e.,fecal mucin output).The lack of effect of dietary Thr in Salmonella-challenged pigs provides further evidence that mucin secretion in the gut is conserved and,therefore,Thr may be limiting for growth under conditions of increased mucin production.
基金Supported by the National Natural Science Foundation of China,No.30070020
文摘AIM: To study the effect of integration of tandem aroG-pheA genes into the tyrA locus of Corynebacterium glutamicum (C. glutamicum) on the production of L-phenylalanine.METHODS: By nitrosoguanidine mutagenesis, five pfluorophenylalanine (FP)-resistant mutants of Cglutamicum FP were selected. The tyrA gene encoding prephenate dehydrogenase (PDH) of C.glutamicum was amplified by polymerase chain reaction (PCR) and cloned on the plasmid pPR. Kanamycin resistance gene (Km) and the PBF-aroGpheA-T (GA) fragment of pGA were inserted into tyrA gene to form targeting vectors pl-K and pTGAK, respectively. Then,they were transformed into C.glutamicum FP respectively by electroporation. Cultures were screened by a medium containing kanamycin and detected by PCR and phenotype analysis. The transformed strains were used for L-phenylalanine fermentation and enzyme assays.RESULTS: Engineering strains of C.glutamicum (Tyr-)were obtained. Compared with the original strain, the transformed strain C. glutamicum GAK was observed to have the highest elevation of L-phenylalanine production by a 1.71-fold,and 2.9-, 3.36-, and 3.0-fold in enzyme activities of chorismate mutase, prephenate dehydratase and 3-deoxy-Darabinoheptulosonate-7-phosphate synthase, respectively.CONCLUSION: Integration of tandem aroG-pheA genes into tyrA locus of C. glutamicum chromosome can disrupt tyrA gene and increase the yield of L-phenylalanine production.
文摘Ciprofloxacin is a second-generation of fluoroquinolone,broad-spectrum antibiotic with bactericidal activity against Gram-positive and Gram-negative organisms.It is one of the most widely used antibiotics,because of its efficacy,safety,and relatively low cost.Ascorbic acid(vitamin C)is water-soluble monosaccharide antioxidant;it is essentially required by the body for its various biochemical and physiological processes.S.aureus is Gram-positive cocci;widely distributed in the environment,it is a member of the normal flora of the body.S.aureus is not always pathogenic;it is a common cause of skin infections including abscesses,respiratory infections such as sinusitis,and food poisoning.E.coli is Gram-negative bacteria,found in the environment,foods,and intestines.Most E.coli strains are harmless;it is part of the normal microbiota of the gut.However,some serotypes of E.coli cause serious food poisoning in their hosts;it can cause diarrhea,while others cause urinary tract infections,respiratory illness and pneumonia,and other illnesses.Method:Cup cut diffusion method was applied.Experiment I:is carried out to choose the concentration of vitamin C to be used in experiment II.The negative control is normal saline,added in cup in each plate,vitamin C(100 mg/mL,200 mg/mL,400 mg/mL)was added,the volume in each cup was 100μL.Experiment II:Eight groups of treatments were applied.The first is the negative control(1%normal saline),the second group is the positive control of vitamin C(200 mg/mL).The third,fourth and fifth groups are ciprofloxacin with different concentrations(10 mg/mL,20 mg/mL,40 mg/mL);the sixth,seventh and eighth are the combination of vitamin C with each concentration of ciprofloxacin(10 mg/mL,20 mg/mL,40 mg/mL).Each group includes six petri dishes.Bacterial plates were incubated at 37 oC for 24 h and 48 h.Zone of inhibition is measured in mm.Results and conclusion:Ciprofloxacin produces dose dependent increase in zone of inhibition of S.aureus and E.coli growth,after 24 and 48 hours incubation.While vitamin C in the concentration used produced inhibitory effect on the growth of S.aureus and E.coli,after 24 hours incubation,vitamin C effect was not changed after 48 hours incubation.After 24 hours incubation,vitamin C potentiated the effect of ciprofloxacin at low concentration(10 mg/mL);while vitamin C antagonized the effect of ciprofloxacin at higher concentrations(20 and 40 mg/mL)on S.aureus growth.In the same time,ciprofloxacin antagonized the inhibitory effect of vitamin C on S.aureus growth.After 48 hours incubation,S.aureus produced resistance against ciprofloxacin alone,and that combined with vitamin C compared to zone of inhibition after 24 hours.Ciprofloxacin produced dose dependent inhibition of E.coli growth after incubation for 24 and 48 hours.Vitamin C potentiated the inhibitory effect induced by ciprofloxacin(additive effect).The inhibitory effect of ciprofloxacin,vitamin C and the combination was not changed after 48 hours compared to 24 hours.
基金supported by 2009--0214 numbered project of National Boron Research Institute(BOREN)-Turkey
文摘Objective To study MIC value of 7 boron derivatives namely [Boric acid (H3BO3), Anhydrous Borax (Na2B407), Sodium Borate (NaBO2), Diammonium Tetraborate (NH4)2B4O7, Sodium Perborate (NaBO3), Boron Trioxide (B203), Potassium Tetraborate (K2B407)] on E. coil and P. aeruginosa and their effects on survival of bacteria in lake water and resistance against kanamycin antibiotic. Methods MIC values of Boron derivatives and antibiotic were studied by broth microdilution method. The effect of boron derivatives on survival of bacteria in lake water were also determined with plate count. Results Sodium perborate was determined as the substances. Effectiveness increased as temperature most effective substance among the studied increased. E. coil was more affected from P. aeruginosa in 8 mg/mL sodium perborate concentration in lake water. Moreover, it was determined that MIC value of kanamycin antibiotic decreased 200 times by especially treating P. aeruginosa with sodium perborate in lake water. However, it can be stated that this change in resistance did not arise from microorganisms. Conclusion Sodium perborate solution can be used supportedly in kanamycin antibiotic applications for P. aeruginosa. Future studies are necessary to explore the relation between sodium perborate and kanamycin which is effective on P. aeruginosa in lake water.
基金Supported by the National Natural Science Foundation of China (30170213) and the Foundation of Wuhan University(0000028)
文摘The Ca. LSU intron flanking a 129 bp cxon upstream and a fOO bp exondownstream was inserted into the lacZ gene on pRS426 to transform E. coli. Northern blot analysisand RT-PCR showed that splicing of Ca. LSU in E. coli is efficient upon inducible expression of theprecursor RNA, In contrast, co-lranscriptional self-splicing of the intron in vitro is much lessactive. Therefore, this E. coli splicing system can be used as a better model to investigate theeffect of the ribozyme inhibitors on Ca. LSUsplicing in living cell. We examined (he effects ofneomycin sulfatc and pentamidine on Ca. LSU splicing in E. coli, and found that these drugsdoes-dependently inhibit the intron splicing. However, heomycin is more potent than pentamidine inthis action.
基金The autors are thankful to Kurdistan Digestive,Liver Research Center which is affiliated to Kurdistan University of Medical Sciences,Sanandaj,for providing the financial support and necessary facilities
文摘Objective:Diarrhea is a leading cause of morbidity and mortality among children in developing countries.The bacterial pathogen most commonly associated with childhood diarrhea is Escherichia coli.A one-year prospective study was carried out in Sanandaj to determine the prevalence and roles of the different E.coli pathotypes in children less than five years of age with acute diarrhea.Methods:Rectal swab were collected prospectively from children with acute diarrhea and transported to the Department of Microbiology,School of Medicine, KUMS,Sanandaj during 2008.The study was approved by the institutional ethics committee.Results:During this study period,rectal swabs were investigated from a total of 466 children 1 to 144 months of age(mean, 29.97 months±S.D) with diarrhea.Among the children,191(41%,191/466) were girls,and 275 (59%,275/466) were boys.The age-specific incidence rates of acute diarrhea among children 13-24 and 1 - 12 months of age were 37.37%(37/99) and 26.26%(26/99),respectively,during the study period.A total of 99 strains of E.coli were detected.EPEC 59(59.59%) and EIEC 22(22.22%),were the most commonly found Escherichia coli strains detected in stools from children.Disk diffusion testing showed E.coli strains resistance to tetracycline(89.89%),chloramphenicol(88.88%),Ampicillin(79.79%),Amoxicillin (75.75%) and Ceficime(75.75%).Among risk factors like age,sex,haemoglubin,fathers and mothers education,food and weight of children only mother's education was significant(P =0.018).Conclusion: In most of the clinical laboratories in Iran,E.coli does not considered as an etiologic agent responsible for diarrhea. Results in this study revealed that E.coli should be considered as an etiologic agent causing acute diarrhea among children.We therefore,recommend the routine isolation and identification of E.coli strains in all the clinical laboratories in Sanandaj.Guidelines for appropriate use of antibiotics in Sanandaj need updating.
基金supported by grants from National Natural Sciences Foundation of China(No.30672227,30600668)"973"Program of China(No.2009CB521800)Joint Research Fund for Overseas Chinese,Hong Kong and Macao Young Scholars(No.30628029)
文摘By using a yeast two-hybrid system,a yeast two-hybrid bait vector was constructed and identified for screening of the HPV18 E6-interacting proteins,and its effects on the growth of yeast cells and the activation of reporter genes were investigated.Total mRNA extracted from Hela cells was reversely transcribed into cDNA.Fragment of HPV18 E6 cDNA was amplified using RT-PCR and directly ligated to the pGBKT7 vector.The recombinant plasmid was confirmed by restriction endonuclease analysis and DNA sequencing.Th...
基金Supported by Project of Hebei Education Department(ZD2017234)Project of Science and Technology Bureau of Shijiazhuang(171500953A)Project of Science and Technology Bureau of Qinhuangdao(201602A046)
文摘[Objectives] The study aimed to identify the pathogenic E. coli strain that caused diarrhea in foxes and to analyze its drug sensitivity.[Methods] A pathogenic E. coli strain was isolated from dead foxes with diarrhea. By conventional bacterial isolation and culture, morphological observation, pathogenicity test and K-B disc method, the isolated strain was identified as pathogenic E. coli .[Results] The isolated pathogen was highly sensitive to ceftriaxone, cefotaxime, ciprofloxacin and lincomycin, moderately sensitive to enrofloxacin, neomycin, gentamycin, spectinomycin, florfenicol, amikacin and polymyxin, and resistant to ampicillin, amoxicillin and doxycycline.[Conclusions] This study provided reference for the prevention and control of diarrheal diseases in foxes in Qinhuangdao region.
文摘Astragalus membranaceus (huangqi), Allium sativum (garlic), Cinnamomum cassia (cinnamon), and Dolichos lablab L. (white hyacinth bean) are the traditional Chinese herbs that were used in prescriptions in treating diarrhea caused by bacterial infection. These herbs are relatively safe for use and investigation. This study aimed to investigate the effects of Astragalus membranaceus, Allium sativum, Cinnamomum cassia, and Dolichos lablab L. on the metabolism of Escherichia coli (E. coli). The growth rate of E. coli was monitored under the influence of each herb, revealing that Astragalus membranaceus and Allium sativum exhibited significant antibacterial activity, whereas Cinnamomum cassia and Dolichos lablab L. demonstrated moderate inhibitory effects on E. coli growth. Further inhibition zone testing allowed for the evaluation of each herb’s potency and the number of generations required for E. coli to develop resistance. Additionally, the impact of the four herbs on the expression of outer membrane protein A (OmpA) in E. coli was examined by using qPCR. The findings revealed that Astragalus membranaceus acted as a sustainable bactericide by inhibiting the growth and metabolism of E. coli MG1655 through the suppression of OmpA expression. These results suggest that Astragalus membranaceus has potential as a natural antimicrobial agent for treating E. coli infections.
基金funded by the National Pathogen Identification Network project and Research on Key Technologies of Intelligent Monitoring,Early Warning and Tracing of Infectious Diseases in Miyun。
文摘Objective To explore the genotyping characteristics of human fecal Escherichia coli(E. coli) and the relationships between antibiotic resistance genes(ARGs) and multidrug resistance(MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data.Methods Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs,multilocus sequence typing(MLST), and polymorphism trees were analyzed using whole-genome sequencing data(WGS).Results This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal(49/70) and healthy groups(15/24).Conclusion We developed a random forest(RF) prediction model of TEM.1 + baeR + mphA + mphB +QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.
文摘This study aims to generate data which can be used as a potential starting point for the updating of the Philippine Water Quality Criteria and the determination of the true impact of land use to the fecal contamination of the Pampanga River Basin (PRB), the largest subwatershed of Manila Bay. Levels of fecal indicator bacteria (FIB) were determined in the selected tributaries of the PRB, representing three land use categories, namely, the forest/woodland (control), agricultural and residential lands. FIB were quantified in order to investigate the potential contribution of the selected areas in the fecal contamination of the PRB. The study was conducted in 2021 covering March, May, June, July, and September to represent the dry (March and May) and wet (June, July, and September) seasons. Counts of FIB, namely thermotolerant coliform, E. coli, and enterococci were qualitatively correlated with the results of the ocular survey and key informant interview based on known fecal contributors and their relevant rainfall data. FIB counts of water bodies in the selected agricultural and residential land use categories had Geometric Mean (GM) counts that are statistically greater than those of bodies of water near the representative forest/woodland (control), and exceeded the acceptable GM limits for all FIB, regardless of the season. Notably, the GM values recorded for the waters near the selected forest/woodland (control) passed the water quality criteria for all measured FIB parameters for both seasons. Furthermore, enterococci levels in the control site were statistically lower during the wet season. These initial findings suggest that agricultural and residential land use categories could be major contributors to the unacceptable water quality of tributaries of the Pampanga River Basin. The prevalence of thermotolerant coliforms and E. coli was noted regardless of rainfall and land use, indicating these FIB may not be adequate as water quality indicators. With their ability to survive and persist in fecally contaminated sediments in water bodies and in nutrient-poor environments, enterococci could be more definitive indicators of fecal contamination and microbiological quality of environmental waters.
基金This study was supported by the National Science and Technology Ministry(2014BAD13B03-1)the project supported by the Heilongjiang Province Farms General Administration of China(HNK135-04-03)This work was supported by a grant from the Heilongjiang Bayi Agricultural University Support Program for San Heng San Zong(TDJH202002).
文摘Escherichia coli has become one of the most important causes of calf diarrhea.The aim of this study is to determine the patterns of antimicrobial resistance of E.coli isolates from six cattle farms and to identify prominent resistance genes and virulence genes among the strains isolated from the diarrhea of calves.Antimicrobial susceptibility tests were performed using the disk diffusion method,and PCR was used to detect resistance and virulence genes.The prevalence of multidrug resistant(MDR)E.coli was 77.8%in dairy cattle and 63.6%in beef cattle.There were high resistance rates to penicillin(100%,100%)and ampicillin(96.3%,86.4%)in E.coli from dairy cattle and beef cattle.Interestingly,resistance rate to antimicrobials and distribution of resistance genes in£coli isolated from dairy cattle were higher than those in beef cattle.Further analysis showed that the most prevalent resistance genes were blojm and oodAl in dairy cattle and beef cattle,respectively.Moreover,seven diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,F41,K99 and STa)were present in the isolates from dairy cattle,with a prevalence ranging from 3.7%to 22.22%.Six diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,hylA and F41)were identified in the isolates from beef cattle,with a prevalence ranging from 2.27%to 63.64%.Our results provide important evidence for better exploring their interaction mechanism.Further studies are also needed to understand the origin and transmission route of£coli in cattle to reduce its prevalence.
文摘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.