scholarly journals Studies on the lipid content and phosphate requirement of glucose- and acetate-grown Escherichia coli

1968 ◽  
Vol 110 (4) ◽  
pp. 775-781 ◽  
Author(s):  
A. P. Damoglou ◽  
E A Dawes
Keyword(s):  
Escherichia Coli ◽  
Energy Source ◽  
Carbon Source ◽  
Lipid Content ◽  
Dry Weight ◽  
The Other ◽  
Ammonium Salts ◽  
Phosphate Limitation ◽  
E Coli ◽  
High Phosphate

1. The phosphate requirement, i.e. the concentration of inorganic orthophosphate that just ceases to be limiting for growth, of Escherichia coli N.C.T.C. 5928 was determined for growth in ammonium–salts media containing glucose or acetate as the carbon and energy source, and compared with that of six other strains of E. coli. 2. The phosphate requirement for E. coli N.C.T.C. 5928 growing on acetate was about ten times that for growth on glucose, but this difference was not observed with any of the other strains. 3. After about 40 generations' growth on acetate with phosphate limitation in a chemostat, the phosphate requirement of the cells gradually decreased until it was equivalent to that of the glucose-grown organism; a single passage through glucose batch culture sufficed to restore the original high phosphate requirement, indicating a permeability phenomenon. 4. The lipid content of E. coli N.C.T.C. 5928 grown on glucose or acetate was measured isotopically by fractionation of cells grown on inorganic [32P]orthophosphate and gravimetrically after extraction from the cells by three different methods; change of carbon source from glucose to acetate did not affect the lipid content, which remained constant at 8–9% of the bacterial dry weight.

Some biochemical effects of 4-deoxy-4-fluoro-D-glucose on Escherichia coli

1977 ◽  
Vol 55 (8) ◽  
pp. 911-915 ◽  
Author(s):  
N. F. Taylor ◽  
Li-Yu Louie
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Catabolite Repression ◽  
Dry Weight ◽  
Resting Cells ◽  
Phosphotransferase System ◽  
E Coli ◽  
Biochemical Effects ◽  
Inhibition Of Growth ◽  
Uncompetitive Inhibitor

The uptake of 4-deoxy-4-fluoro-D-glucose (4FG), without subsequent catabolism, by resting cells of Escherichia coli (ATCC 11775) is 0.06 mg/mg dry weight. In frozen–thawed cells of this organism, 4FG is a substrate for the phosphoenolpyruvate phosphotransferase system with a rate of phosphorylation twice that found for the isomeric 3-deoxy-3-fluoro-D-glucose. 4FG is not a carbon source for growth of this organism and it inhibits the extent of growth of cells in the presence of glucose. The inhibition of growth of E. coli K12 on lactose by 4FG is also observed and this is considered to be consistent with the fact that 4FG is an uncompetitive inhibitor of β-galactosidase (EC 3.2.1.23) activity and that 4FG or 4-deoxy-4-fluoro-D-glucose-6-phosphate repress β-galactosidase synthesis. These results support the view that catabolite repression may be produced by compounds which are not necessarily metabolised further than hexose-6-phosphates.

scholarly journals Escherichia coli O157:H7 SURVIVAL IN TRADITIONAL AND LOW LACTOSE YOGURT DURING FERMENTATION AND COOLING PERIODS

2017 ◽  
Vol 18 (0) ◽  
Author(s):  
Camila Sampaio Cutrim ◽  
Raphael Ferreira de Barros ◽  
Robson Maia Franco ◽  
Marco Antonio Sloboda Cortez
Keyword(s):  
Escherichia Coli ◽  
The Other ◽  
Lactose Hydrolysis ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Gas Formation ◽  
Whole Milk ◽  
Milk Contamination ◽  
Different Types ◽  
Fermentation Period

Abstract The purpose of this study was to evaluate the behavior of E. coli O157:H7 during lactose hydrolysis and fermentation of traditional and low lactose yogurt. It also aimed to verify E. coli O157:H7 survival after 12 h of storage at 4 ºC ±1 ºC. Two different types of yogurts were prepared, two with whole milk and two with pre-hydrolyzed whole milk; in both groups one yogurt was inoculated with E. coli O157:H7 and the other one was not inoculated. The survival of E. coli and pH of yogurt were determined during fermentation and after 12-h refrigeration. The results showed that E. coli O157:H7 was able to grow during the fermentation period (from 4.34 log CFU.mL-1 to 6.13 log CFU.mL-1 in traditional yogurt and 4.34 log CFU.mL-1 to 6.16 log CFU.mL-1 in low lactose yogurt). The samples with E. coli O157:H7 showed gas formation and syneresis. Thus, E. coli O157:H7 was able to survive and grow during fermentation of traditional and low lactose yogurts affecting the manufacture technology. Moreover, milk contamination by E. coli before LAB addition reduces the growth of L. bulgaricus and S. thermophilus especially when associated with reduction of lactose content.

scholarly journals Heterologous Production of 6-Deoxyerythronolide B in Escherichia coli through the Wood Werkman Cycle

Metabolites ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 228
Author(s):  
R. Axayacatl Gonzalez-Garcia ◽  
Lars K. Nielsen ◽  
Esteban Marcellin
Keyword(s):  
Escherichia Coli ◽  
Natural Products ◽  
Carbon Source ◽  
Sole Carbon Source ◽  
Structural Diversity ◽  
Heterologous Production ◽  
E Coli ◽  
Anticancer Properties ◽  
Defined Media ◽  
Extender Unit

Polyketides are a remarkable class of natural products with diverse functional and structural diversity. The class includes many medicinally important molecules with antiviral, antimicrobial, antifungal and anticancer properties. Native bacterial, fungal and plant hosts are often difficult to cultivate and coax into producing the desired product. As a result, Escherichia coli has been used for the heterologous production of polyketides, with the production of 6-deoxyerythronolide B (6-dEB) being the first example. Current strategies for production in E. coli require feeding of exogenous propionate as a source for the precursors propionyl-CoA and S-methylmalonyl-CoA. Here, we show that heterologous polyketide production is possible from glucose as the sole carbon source. The heterologous expression of eight genes from the Wood-Werkman cycle found in Propionibacteria, in combination with expression of the 6-dEB synthases DEBS1, DEBS2 and DEBS3 resulted in 6-dEB formation from glucose as the sole carbon source. Our results show that the Wood-Werkman cycle provides the required propionyl-CoA and the extender unit S-methylmalonyl-CoA to produce up to 0.81 mg/L of 6-dEB in a chemically defined media.

scholarly journals  Faecal shedding of verotoxigenic Escherichia coli in cattle in the Czech Republic

2011 ◽  
Vol 56 (No. 4) ◽  
pp. 149-155 ◽  
Author(s):  
P. Alexa ◽  
L. Konstantinova ◽  
Z. Sramkova-Zajacova
Keyword(s):  
Escherichia Coli ◽  
Czech Republic ◽  
Dairy Cattle ◽  
Age Groups ◽  
Immunomagnetic Separation ◽  
The Other ◽  
Somatic Antigen ◽  
The Czech Republic ◽  
E Coli ◽  
One Year

A survey to estimate the prevalence of verotoxigenic E. coli (VTEC) or enterohaemorrhagic E. coli (EHEC) in rectal swabs from healthy dairy cattle aged three weeks, three months and one year was conducted in three herds from the Czech Republic. Screening for the presence of the stx1, stx2 and eaeA genes in faecal swab cultures was performed by PCR, and in positive samples, isolated colonies were examined. Immunomagnetic separation was used for the isolation of the VTEC serogroup O157 from samples. VTEC were detected in animals from all three herds under study. In the group of 3-week-old calves, VTEC were only detected in samples collected in the summer months. However, in the other age-groups, VTEC were detected in both the summer and winter months. EHEC shedding was observed in 30 to 100% of the total samples collected from cattle aged three months and one year in the summer months, and in 30 to 60% of samples taken in the winter months. EHEC strains of serogroup O157 were detected in two herds. The range of verotoxins shed by VTEC isolates of serogroup O157 differed between herds. Besides serogroup O157, additional EHEC belonging to the antigen groups O26, O103, O128 and O153 have been identified, and in some of them, no somatic antigen was detected.

scholarly journals Extraintestinal Pathogenic and Antimicrobial-Resistant Escherichia coli, Including Sequence Type 131 (ST131), from Retail Chicken Breasts in the United States in 2013

2017 ◽  
Vol 83 (6) ◽  
Author(s):  
James R. Johnson ◽  
Stephen B. Porter ◽  
Brian Johnston ◽  
Paul Thuras ◽  
Sarah Clock ◽  
...  
Keyword(s):  
United States ◽  
Escherichia Coli ◽  
Virulence Genes ◽  
Meat Products ◽  
The United States ◽  
Sequence Type ◽  
The Other ◽  
Antibiotic Resistant ◽  
Content Type ◽  
E Coli

ABSTRACT Chicken meat products are hypothesized to be vehicles for transmitting antimicrobial-resistant and extraintestinal pathogenic Escherichia coli (ExPEC) to consumers. To reassess this hypothesis in the current era of heightened concerns about antimicrobial use in food animals, we analyzed 175 chicken-source E. coli isolates from a 2013 Consumer Reports national survey. Isolates were screened by PCR for ExPEC-defining virulence genes. The 25 ExPEC isolates (12% of 175) and a 2:1 randomly selected set of 50 non-ExPEC isolates were assessed for their phylogenetic/clonal backgrounds and virulence genotypes for comparison with their resistance profiles and the claims on the retail packaging label (“organic,” “no antibiotics,” and “natural”). Compared with the findings for non-ExPEC isolates, the group of ExPEC isolates had a higher prevalence of phylogroup B2 isolates (44% versus 4%; P < 0.001) and a lower prevalence of phylogroup A isolates (4% versus 30%; P = 0.001), a higher prevalence of multiple individual virulence genes, higher virulence scores (median, 11 [range, 4 to 16] versus 8 [range, 1 to 14]; P = 0.001), and higher resistance scores (median, 4 [range, 0 to 8] versus 3 [range, 0 to 10]; P < 0.001). All five isolates of sequence type 131 (ST131) were ExPEC (P = 0.003), were as extensively resistant as the other isolates tested, and had higher virulence scores than the other isolates tested (median, 12 [range, 11 to 13] versus 8 [range, 1 to 16]; P = 0.005). Organic labeling predicted lower resistance scores (median, 2 [range, 0 to 3] versus 4 [range, 0 to 10]; P = 0.008) but no difference in ExPEC status or virulence scores. These findings document a persisting reservoir of extensively antimicrobial-resistant ExPEC isolates, including isolates from ST131, in retail chicken products in the United States, suggesting a potential public health threat. IMPORTANCE We found that among Escherichia coli isolates from retail chicken meat products purchased across the United States in 2013 (many of these isolates being extensively antibiotic resistant), a minority had genetic profiles suggesting an ability to cause extraintestinal infections in humans, such as urinary tract infection, implying a risk of foodborne disease. Although isolates from products labeled “organic” were less extensively antibiotic resistant than other isolates, they did not appear to be less virulent. These findings suggest that retail chicken products in the United States, even if they are labeled “organic,” pose a potential health threat to consumers because they are contaminated with extensively antibiotic-resistant and, presumably, virulent E. coli isolates.

scholarly journals NikAB- or NikB-Dependent Intracellular Recombination between Tandemly Repeated oriT Sequences of Plasmid R64 in Plasmid or Single-Stranded Phage Vectors

2003 ◽  
Vol 185 (13) ◽  
pp. 3871-3877 ◽  
Author(s):  
Nobuhisa Furuya ◽  
Teruya Komano
Keyword(s):  
Escherichia Coli ◽  
Dna Transfer ◽  
The Other ◽  
E Coli ◽  
Core Sequence ◽  
Bacterial Plasmid ◽  
Plasmid R64 ◽  
Dna Processing ◽  
Origin Of Transfer

ABSTRACT The origin of transfer (oriT) of a bacterial plasmid plays a key role in both the initiation and termination of conjugative DNA transfer. We have previously shown that a conjugation-dependent recombination between the tandem R64 oriT sequences cloned into pHSG398 occurred, resulting in the deletion of the intervening sequence during DNA transfer. In this study, we tandemly cloned two oriT sequences of IncI1 plasmid R64 into pUC18. Specific recombination between the two oriT sequences in pUC18 was observed within Escherichia coli cells harboring mini-R64. This recombination was found to be independent of both the recA gene and conjugative DNA transfer. The R64 genes nikA and nikB, required for conjugal DNA processing, were essential for this recombination. Although a fully active 92-bp oriT sequence was required at one site for the recombination, the 44-bp oriT core sequence was sufficient at the other site. Furthermore, when two oriT sequences were tandemly cloned into the single-stranded phage vector M13 and propagated within E. coli cells, recombination between the two oriT sequences was observed, depending on the nikB gene. These results suggest that the R64 relaxase protein NikB can execute cleavage and rejoining of single-stranded oriT DNA within E. coli cells, whereas such a reaction in double-stranded oriT DNA requires collaboration of the two relaxosome proteins, NikA and NikB.

Correlation of cefpodoxime susceptibility with cephalothin and cefuroxime for urinary tract isolates

2014 ◽  
Vol 63 (2) ◽  
pp. 218-221 ◽  
Author(s):  
David A. Bookstaver ◽  
Christopher M. Bland ◽  
Mitchell W. Woodberry ◽  
Karon B. Mansell
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Error Rate ◽  
Surrogate Marker ◽  
Error Rates ◽  
The Other ◽  
Colony Count ◽  
Major Error ◽  
E Coli ◽  
Microscan System

This study attempted to determine whether cefuroxime was superior to cephalothin as a surrogate marker for cefpodoxime among urinary tract isolates. The MicroScan system (Siemens) was used to determine susceptibility for cephalothin and cefuroxime on consecutive cultures with a colony count of ≥50 000 organisms. Simultaneously, an Etest (bioMérieux) for cefpodoxime was conducted. The cefpodoxime interpretation was compared to that of the other two agents, and the categorical agreement was calculated, defined as the percentage of identical susceptibility interpretations. Cefuroxime (83 %) had a significantly higher categorical agreement than cephalothin (63 %) among 300 isolates (P<0.01). The major error rate was 16 % for cephalothin and 3 % for cefuroxime. The very major error rate was 7 % for cephalothin and 14 % for cefuroxime among the 14 cefpodoxime-resistant isolates. For Escherichia coli, the major error rates were 15 % and 1 % for cephalothin and cefuroxime, respectively. Very major error rates were 9 % for both agents. Cefuroxime was a better predictor of cefpodoxime susceptibility than cephalothin, and appears to be the preferred surrogate agent for the MicroScan system, particularly for E. coli.

scholarly journals In Vitro Activity of Newer and Conventional Antimicrobial Agents, Including Fosfomycin and Colistin, against Selected Gram-Negative Bacilli in Kuwait

Pathogens ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 75 ◽  
Author(s):  
Wadha Alfouzan ◽  
Rita Dhar ◽  
David Nicolau
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agents ◽  
The Other ◽  
In Vitro Activity ◽  
Limited Data ◽  
Gram Negative ◽  
E Coli ◽  
Microbroth Dilution

Limited data are available on susceptibilities of these organisms to some of the recently made accessible antimicrobial agents. The in vitro activities of newer antibiotics, such as, ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (CZA) along with some “older” antibiotics, for example fosfomycin (FOS) and colistin (CL) were determined against selected strains (resistant to ≥ 3 antimicrobial agents) of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Minimum inhibitory concentrations (MIC) were determined by Clinical and Laboratory Standards Institute microbroth dilution. 133 isolates: 46 E. coli, 39 K. pneumoniae, and 48 P. aeruginosa were tested. Results showed that E. coli isolates with MIC50/90, 0.5/1 μ g / mL for CL; 4/32 μ g / mL for FOS; 0.25/32 μ g / mL for C/T; 0.25/8 μ g / mL for CZA, exhibited susceptibility rates of 95.7%, 97.8%, 76.1%, and 89.1%, respectively. On the other hand, K. pneumoniae strains with MIC50/90, 0.5/1 μ g / mL for CL; 256/512 μ g / mL for FOS; 2/128 μ g / mL for C/T; 0.5/128 μ g / mL for CZA showed susceptibility rates of 92.3%, 7.7%, 51.3%, and 64.1%, respectively. P. aeruginosa isolates with MIC50/90, 1/1 μ g / mL for CL; 128/128 μ g / mL for C/T; 32/64 μ g / mL for CZA presented susceptibility rates of 97.9%, 33.3%, and 39.6%, respectively. Higher MICs were demonstrated against most of the antibiotics. However, CL retained efficacy at low MICs against most of the isolates tested.

scholarly journals Dual Predation by Bacteriophage and Bdellovibrio bacteriovorus Can Eradicate Escherichia coli Prey in Situations where Single Predation Cannot

2020 ◽  
Vol 202 (6) ◽  
Author(s):  
Laura Hobley ◽  
J. Kimberley Summers ◽  
Rob Till ◽  
David S. Milner ◽  
Robert J. Atterbury ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Prey Availability ◽  
The United States ◽  
The Other ◽  
Bacteriophage Therapy ◽  
Bdellovibrio Bacteriovorus ◽  
Content Type ◽  
E Coli ◽  
Rapid Acquisition ◽  
Predatory Bacteria

ABSTRACT Bacteria are preyed upon by diverse microbial predators, including bacteriophage and predatory bacteria, such as Bdellovibrio bacteriovorus. While bacteriophage are used as antimicrobial therapies in Eastern Europe and are being applied for compassionate use in the United States, predatory bacteria are only just beginning to reveal their potential therapeutic uses. However, predation by either predator type can falter due to different adaptations arising in the prey bacteria. When testing poultry farm wastewater for novel Bdellovibrio isolates on Escherichia coli prey lawns, individual composite plaques were isolated containing both an RTP (rosette-tailed-phage)-like-phage and a B. bacteriovorus strain and showing central prey lysis and halos of extra lysis. Combining the purified phage with a lab strain of B. bacteriovorus HD100 recapitulated haloed plaques and increased killing of the E. coli prey in liquid culture, showing an effective side-by-side action of these predators compared to their actions alone. Using approximate Bayesian computation to select the best fitting from a variety of different mathematical models demonstrated that the experimental data could be explained only by assuming the existence of three prey phenotypes: (i) sensitive to both predators, (ii) genetically resistant to phage only, and (iii) plastic resistant to B. bacteriovorus only. Although each predator reduces prey availability for the other, high phage numbers did not abolish B. bacteriovorus predation, so both predators are competent to coexist and are causing different selective pressures on the bacterial surface while, in tandem, controlling prey bacterial numbers efficiently. This suggests that combinatorial predator therapy could overcome problems of phage resistance. IMPORTANCE With increasing levels of antibiotic resistance, the development of alternative antibacterial therapies is urgently needed. Two potential alternatives are bacteriophage and predatory bacteria. Bacteriophage therapy has been used, but prey/host specificity and the rapid acquisition of bacterial resistance to bacteriophage are practical considerations. Predatory bacteria are of interest due to their broad Gram-negative bacterial prey range and the lack of simple resistance mechanisms. Here, a bacteriophage and a strain of Bdellovibrio bacteriovorus, preyed side by side on a population of E. coli, causing a significantly greater decrease in prey numbers than either alone. Such combinatorial predator therapy may have greater potential than individual predators since prey surface changes selected for by each predator do not protect prey against the other predator.

scholarly journals Phospholipid distribution in the cytoplasmic membrane of Gram-negative bacteria is highly asymmetric, dynamic, and cell shape-dependent

2020 ◽  
Vol 6 (23) ◽  
pp. eaaz6333 ◽  
Author(s):  
Mikhail Bogdanov ◽  
Kyrylo Pyrshev ◽  
Semen Yesylevskyy ◽  
Sergey Ryabichko ◽  
Vitalii Boiko ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Physical Properties ◽  
Cell Shape ◽  
Yersinia Pseudotuberculosis ◽  
Cytoplasmic Membrane ◽  
The Other ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
Phospholipid Distribution

The distribution of phospholipids across the inner membrane (IM) of Gram-negative bacteria is unknown. We demonstrate that the IMs of Escherichia coli and Yersinia pseudotuberculosis are asymmetric, with a 75%/25% (cytoplasmic/periplasmic leaflet) distribution of phosphatidylethanolamine (PE) in rod-shaped cells and an opposite distribution in E. coli filamentous cells. In initially filamentous PE-lacking E. coli cells, nascent PE appears first in the periplasmic leaflet. As the total PE content increases from nearly zero to 75%, cells progressively adopt a rod shape and PE appears in the cytoplasmic leaflet of the IM. The redistribution of PE influences the distribution of the other lipids between the leaflets. This correlates with the tendency of PE and cardiolipin to regulate antagonistically lipid order of the bilayer. The results suggest that PE asymmetry is metabolically controlled to balance temporally the net rates of synthesis and translocation, satisfy envelope growth capacity, and adjust bilayer chemical and physical properties.

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