scholarly journals Elevated Levels of an Enzyme Involved in Coenzyme B 12 Biosynthesis Kills Escherichia coli

mBio ◽  
2022 ◽  
Author(s):  
Victoria L. Jeter ◽  
Jorge C. Escalante-Semerena

E. coli is the best-studied prokaryote, and some strains of this bacterium are human pathogens. We show that when the level of the enzyme that catalyzes the penultimate step of vitamin B 12 biosynthesis is elevated, the viability of E. coli decreases.

2011 ◽  
Vol 77 (14) ◽  
pp. 4949-4958 ◽  
Author(s):  
C. Sekse ◽  
M. Sunde ◽  
B.-A. Lindstedt ◽  
P. Hopp ◽  
T. Bruheim ◽  
...  

ABSTRACTA national survey ofEscherichia coliO26 in Norwegian sheep flocks was conducted, using fecal samples to determine the prevalence. In total, 491 flocks were tested, andE. coliO26 was detected in 17.9% of the flocks. One hundred forty-twoE. coliO26 isolates were examined for flagellar antigens (H typing) and four virulence genes, includingstxandeae, to identify possible Shiga toxin-producingE. coli(STEC) and enteropathogenicE. coli(EPEC). Most isolates (129 out of 142) were identified asE. coliO26:H11. They possessedeaeand may have potential as human pathogens, although only a small fraction were identified as STEC O26:H11, giving a prevalence in sheep flocks of only 0.8%. Correspondingly, the sheep flock prevalence of atypical EPEC (aEPEC) O26:H11 was surprisingly high (15.9%). The genetic relationship between theE. coliO26:H11 isolates was investigated by pulsed-field gel electrophoresis (PFGE) and multilocus variable number tandem repeat analysis (MLVA), identifying 63 distinct PFGE profiles and 22 MLVA profiles. Although the MLVA protocol was less discriminatory than PFGE and a few cases of disagreement were observed, comparison by partition mapping showed an overall good accordance between the two methods. A close relationship between a few isolates of aEPEC O26:H11 and STEC O26:H11 was identified, but all theE. coliO26:H11 isolates should be considered potentially pathogenic to humans. The present study consisted of a representative sampling of sheep flocks from all parts of Norway. This is the first large survey of sheep flocks focusing onE. coliO26 in general, including results of STEC, aEPEC, and nonpathogenic isolates.


2013 ◽  
Vol 79 (15) ◽  
pp. 4613-4619 ◽  
Author(s):  
Patrick Studer ◽  
Werner E. Heller ◽  
Jörg Hummerjohann ◽  
David Drissner

ABSTRACTSprouts contaminated with human pathogens are able to cause food-borne diseases due to the favorable growth conditions for bacteria during germination and because of minimal processing steps prior to consumption. We have investigated the potential of hot humid air, i.e., aerated steam, to treat alfalfa and mung bean seeds which have been artificially contaminated withEscherichia coliO157:H7,Salmonella entericasubsp.entericaserovar Weltevreden, andListeria monocytogenesScott A. In addition, a recently collectedE. coliO178:H12 isolate, characterized by a reduced heat sensitivity, was exposed to the treatment described. Populations ofE. coliO157:H7 andS. entericaon alfalfa and mung bean seeds could be completely eliminated by a 300-s treatment with steam at 70 ± 1°C as revealed by enrichment studies.L. monocytogenesandE. coliO178:H12 could not be completely eliminated from artificially inoculated seeds. However, bacterial populations were reduced by more than 5 log CFU/g on alfalfa and by more than 4 log CFU/g on mung bean seeds. The germination rate of mung beans was not affected by the 300-s treatment compared to the germination rate of untreated seeds whereas that of alfalfa seeds was significantly lower by 11.9%. This chemical-free method is an effective alternative to the 20,000-ppm hypochlorite treatment presently recommended by the U.S. Food and Drug Administration (FDA).


2013 ◽  
Vol 79 (23) ◽  
pp. 7502-7509 ◽  
Author(s):  
Camilla Sekse ◽  
Marianne Sunde ◽  
Petter Hopp ◽  
Torkjel Bruheim ◽  
Kofitsyo Sewornu Cudjoe ◽  
...  

ABSTRACTThe investigation of an outbreak of hemorrhagic-uremic syndrome in Norway in 2006 indicated that the outbreak strainEscherichia coliO103:H25 could originate from sheep. A national survey of the Norwegian sheep population was performed, with the aim of identifying and describing a possible reservoir of potentially human-pathogenicE. coliO103, in particular of the H types 2 and 25. The investigation of fecal samples from 585 sheep flocks resulted in 1,222E. coliO103 isolates that were analyzed for the presence ofeaeandstxgenes, while a subset of 369 isolates was further examined for flagellar antigens (H typing),stxsubtypes,bfpA,astA, and molecular typing by pulsed-field gel electrophoresis (PFGE). The total ovineE. coliO103 serogroup was genetically diverse by numbers of H types, virulotypes, and PFGE banding patterns identified, although a tendency of clustering toward serotypes was seen. The flocks positive for potentially human-pathogenicE. coliO103 were geographically widely distributed, and no association could be found with county or geographical region. The survey showed thateae-negative,stx-negativeE. coliO103, probably nonpathogenic to humans, is very common in sheep, with 27.5% of flocks positive. Moreover, the study documented a low prevalence (0.7%) of potentially human-pathogenic Shiga toxin-producingE. coliO103:H2, while STEC O103:H25 was not detected. However, 3.1% and 5.8% of the flocks were positive for enteropathogenicE. coliO103 belonging to H types 2 and 25, respectively. These isolates are of concern as potential human pathogens by themselves but more importantly as possible precursors for human-pathogenic STEC.


2014 ◽  
Vol 59 (1) ◽  
pp. 152-158 ◽  
Author(s):  
Fatema Calcuttawala ◽  
Chellaram Hariharan ◽  
Gururaja P. Pazhani ◽  
Santanu Ghosh ◽  
Thandavarayan Ramamurthy

ABSTRACTColicin-mediated killing is an example of allelopathy, which has been found among several bacteria. Screening of 42 strains ofShigella sonneiisolated from diarrheal patients revealed that 39 (93%)S. sonneistrains were positive for colicin production againstEscherichia coliDH5α. In the PCR-based detection of the colicin types, 36 (92.3%) were identified as E3, 2 (5.1%) as E3 and E8, and 1 (2.6%) as E3 and E2. RepresentativeS. sonneistrains producing heterologous colicins exhibited antagonism against diarrheagenicEscherichia coli(DEC) groups. Although it is known that mutation in the colicin receptor renders the host resistant to colicin, there is a dearth of information on the genetic characterization of such mutants. In the fluctuation test, colicin-resistantE. colimutants were found to occur spontaneously at the rates of 2.51 × 10−8and 5.52 × 10−8per generation when exposed to colicins E3 and E8 and colicins E3 and E2, respectively. Genotypic characterization of colicin-resistantE. coli(ECCr) andS. sonnei(SSCr) strains displayed mutations in thebtuBgene, which encodes the receptor for vitamin B12uptake. This gene was interrupted by various insertion sequences, such as IS1, IS2, and IS911. Complementation of ECCrand SSCrwith plasmid-bornebtuB(pbtuB) accomplished restoration of the colicin-susceptible phenotype. The vitamin B12uptake assay gave an insight into the physiological relevance of thebtuBmutation. Our studies provide insights into the latent influence ofS. sonneicolicins in governing the existence of some of the shigellae and all of the DEC and the genetic mechanism underlying the emergence of resistance.


2020 ◽  
Vol 202 (12) ◽  
Author(s):  
Tomokazu Ito ◽  
Diana M. Downs

ABSTRACT Pyridoxal 5′-phosphate (PLP) is the biologically active form of vitamin B6 and an essential cofactor in all organisms. In Escherichia coli, PLP is synthesized via the deoxyxylulose 5-phosphate (DXP)-dependent pathway that includes seven enzymatic steps and generates pyridoxine 5′-phosphate as an intermediate. Additionally, E. coli is able to salvage pyridoxal, pyridoxine, and pyridoxamine B6 vitamers to produce PLP using kinases PdxK/PdxY and pyridox(am)ine phosphate oxidase (PdxH). We found that E. coli strains blocked in PLP synthesis prior to the formation of pyridoxine 5′-phosphate (PNP) required significantly less exogenous pyridoxal (PL) than strains lacking pdxH and identified the conversion of PL to pyridoxine (PN) during cultivation to be the cause. Our data showed that PdxI, shown to have PL reductase activity in vitro, was required for the efficient salvage of PL in E. coli. The pdxI+ E. coli strains converted exogenous PL to PN during growth, while pdxI mutants did not. In total, the data herein demonstrated that PdxI is a critical enzyme in the salvage of PL by E. coli. IMPORTANCE The biosynthetic pathway of pyridoxal 5′-phosphate (PLP) has extensively been studied in Escherichia coli, yet limited information is available about the vitamin B6 salvage pathway. We show that the protein PdxI (YdbC) is the primary pyridoxal (PL) reductase in E. coli and is involved in the salvage of PL. The orthologs of PdxI occur in a wide range of bacteria and plants, suggesting that PL reductase in the B6 salvage pathway is more widely distributed than previously expected.


2016 ◽  
Vol 60 (4) ◽  
pp. 2450-2455 ◽  
Author(s):  
Miaomiao Xie ◽  
Dachuan Lin ◽  
Kaichao Chen ◽  
Edward Wai Chi Chan ◽  
Wen Yao ◽  
...  

ABSTRACTA total of 55 cefotaxime-resistantEscherichia coliisolates were obtained from retail meat products purchased in Shenzhen, China, during the period November 2012 to May 2013. Thirty-seven of these 55 isolates were found to harbor ablaCTX-Mgene, with theblaCTX-M-1group being the most common type.blaCMY-2was detected in 16 isolates, alone or in combination with other extended-spectrum β-lactamase (ESBL) determinants. Importantly, thefosA3gene, which encodes fosfomycin resistance, was detected in 12 isolates, with several being found to reside in the conjugative plasmid that harbored theblaCTX-Mgene. The insertion sequence IS26was observed upstream of some of theblaCTX-M-55andfosA3genes. Conjugation experiments showed thatblaCTX-Mgenes from 15 isolates were transferrable, with Inc I1 and Inc FII being the most prevalent replicons. High clonal diversity was observed among theblaCTX-Mproducers, suggesting that horizontal transfer of theblaCTX-Mgenes amongE. colistrains in retail meats is a common event and that such strains may constitute an important reservoir ofblaCTX-Mgenes, which may be readily disseminated to other potential human pathogens.


2015 ◽  
Vol 81 (13) ◽  
pp. 4403-4410 ◽  
Author(s):  
Margaret A. Davis ◽  
William M. Sischo ◽  
Lisa P. Jones ◽  
Dale A. Moore ◽  
Sara Ahmed ◽  
...  

ABSTRACTEnterobacteriaceae-associatedblaCTX-Mgenes have become globally widespread within the past 30 years. Among isolates from Washington State cattle,Escherichia colistrains carryingblaCTX-M(CTX-ME. colistrains) were absent from a set of 2008 isolates but present in a set of isolates from 2011. On 30 Washington State dairy farms sampled in 2012, CTX-ME. coliprevalence was significantly higher on eastern than on northwestern Washington farms, on farms with more than 3,000 adult cows, and on farms that recently received new animals. The addition of fresh bedding to calf hutches at least weekly and use of residual fly sprays were associated with lower prevalence of CTX-ME. coli. In Washington State, the occurrence of human pathogens carryingblaCTX-Mgenes preceded the emergence ofblaCTX-M-associatedE. coliin cattle, indicating that these resistance determinants and/or their bacterial hosts may have emerged in human populations prior to their dissemination to cattle populations.


mBio ◽  
2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Grace Kwan ◽  
Amy O. Charkowski ◽  
Jeri D. Barak

ABSTRACTAlthough enteric human pathogens are usually studied in the context of their animal hosts, a significant portion of their life cycle occurs on plants. Plant disease alters the phyllosphere, leading to enhanced growth of human pathogens; however, the impact of human pathogens on phytopathogen biology and plant health is largely unknown. To characterize the interaction between human pathogens and phytobacterial pathogens in the phyllosphere, we examined the interactions betweenPectobacterium carotovorumsubsp.carotovorumandSalmonella entericaorEscherichia coliO157:H7 with regard to bacterial populations, soft rot progression, and changes in local pH. The presence ofP. carotovorumsubsp.carotovorumenhanced the growth of bothS. entericaandE. coliO157:H7 on leaves. However, in a microaerophilic environment,S. entericareducedP. carotovorumsubsp.carotovorumpopulations and soft rot progression by moderating local environmental pH. Reduced soft rot was not due toS. entericaproteolytic activity. Limitations onP. carotovorumsubsp.carotovorumgrowth, disease progression, and pH elevation were not observed on leaves coinoculated withE. coliO157:H7 or when leaves were coinoculated withS. entericain an aerobic environment.S. entericaalso severely undermined the relationship between the phytobacterial population and disease progression of aP. carotovorumsubsp.carotovorum budBmutant defective in the 2,3-butanediol pathway for acid neutralization. Our results show thatS. entericaandE. coliO157:H7 interact differently with the enteric phytobacterial pathogenP. carotovorumsubsp.carotovorum.S. entericainhibition of soft rot progression may conceal a rapidly growing human pathogen population. Whereas soft rotted produce can alert consumers to the possibility of food-borne pathogens, healthy-looking produce may entice consumption of contaminated vegetables.IMPORTANCESalmonella entericaandEscherichia coliO157:H7 may use plants to move between animal and human hosts. Their populations are higher on plants cocolonized with the common bacterial soft rot pathogenPectobacterium carotovorumsubsp.carotovorum, turning edible plants into a risk factor for human disease. We inoculated leaves withP. carotovorumsubsp.carotovorumandS. entericaorE. coliO157:H7 to study the interactions between these bacteria. WhileP. carotovorumsubsp.carotovorumenhanced the growth of bothS. entericaandE. coliO157:H7, these human pathogens affectedP. carotovorumsubsp.carotovorumfundamentally differently.S. entericareducedP. carotovorumsubsp.carotovorumgrowth and acidified the environment, leading to less soft rot on leaves;E. coliO157:H7 had no such effects. As soft rot signals a food safety risk, the reduction of soft rot symptoms in the presence ofS. entericamay lead consumers to eat healthy-looking butS. enterica-contaminated produce.


2014 ◽  
Vol 80 (7) ◽  
pp. 2166-2175 ◽  
Author(s):  
R. P. Johnson ◽  
B. Holtslander ◽  
A. Mazzocco ◽  
S. Roche ◽  
J. L. Thomas ◽  
...  

ABSTRACTVerotoxin-producingEscherichia coli(VTEC) strains are the cause of food-borne and waterborne illnesses around the world. Traditionally, surveillance of the human population as well as the environment has focused on the detection ofE. coliO157:H7. Recently, increasing recognition of non-O157 VTEC strains as human pathogens and the German O104:H4 food-borne outbreak have illustrated the importance of considering the broader group of VTEC organisms from a public health perspective. This study presents the results of a comparison of three methods for the detection of VTEC in surface water, highlighting the efficacy of a direct VT immunoblotting method without broth enrichment for detection and isolation of O157 and non-O157 VTEC strains. The direct immunoblot method eliminates the need for an enrichment step or the use of immunomagnetic separation. This method was developed after 4 years of detecting low frequencies (1%) ofE. coliO157:H7 in surface water in a Canadian watershed, situated within one of the FoodNet Canada integrated surveillance sites. By the direct immunoblot method, VTEC prevalence estimates ranged from 11 to 35% for this watershed, andE. coliO157:H7 prevalence increased to 4% (due to improved method sensitivity). This direct testing method provides an efficient means to enhance our understanding of the prevalence and types of VTEC in the environment. This study employed a rapid evidence assessment (REA) approach to frame the watershed findings with watershedE. coliO157:H7 prevalences reported in the literature since 1990 and the knowledge gap with respect to VTEC detection in surface waters.


2015 ◽  
Vol 81 (14) ◽  
pp. 4720-4727 ◽  
Author(s):  
Attila Nagy ◽  
Joseph Mowery ◽  
Gary R. Bauchan ◽  
Lili Wang ◽  
Lydia Nichols-Russell ◽  
...  

ABSTRACTInfection by human pathogens through the consumption of fresh, minimally processed produce and solid plant-derived foods is a major concern of the U.S. and global food industries and of public health services. EnterohemorrhagicEscherichia coliO157:H7 is a frequent and potent foodborne pathogen that causes severe disease in humans. Biofilms formed byE. coliO157:H7 facilitate cross-contamination by sheltering pathogens and protecting them from cleaning and sanitation operations. The objective of this research was to determine the role that several surface structures ofE. coliO157:H7 play in adherence to biotic and abiotic surfaces. A set of isogenic deletion mutants lacking major surface structures was generated. The mutant strains were inoculated onto fresh spinach and glass surfaces, and their capability to adhere was assessed by adherence assays and fluorescence microscopy methods. Our results showed that filament-deficient mutants bound to the spinach leaves and glass surfaces less strongly than the wild-type strain did. We mimicked the switch to the external environment—during which bacteria leave the host organism and adapt to lower ambient temperatures of cultivation or food processing—by decreasing the temperature from 37°C to 25°C and 4°C. We concluded that flagella and some other cell surface proteins are important factors in the process of initial attachment and in the establishment of biofilms. A better understanding of the specific roles of these structures in early stages of biofilm formation can help to prevent cross-contaminations and foodborne disease outbreaks.


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