scholarly journals Mechanisms Causing Rapid and Parallel Losses of Ribose Catabolism in Evolving Populations of Escherichia coli B

2001 ◽  
Vol 183 (9) ◽  
pp. 2834-2841 ◽  
Author(s):  
Vaughn S. Cooper ◽  
Dominique Schneider ◽  
Michel Blot ◽  
Richard E. Lenski
Keyword(s):  
Escherichia Coli ◽  
Minimal Medium ◽  
Molecular Genetic ◽  
Selective Advantage ◽  
Gene Replacement ◽  
High Rate ◽  
Glucose Minimal Medium ◽  
Fluctuation Test ◽  
The One ◽  
Escherichia Coli B

ABSTRACT Twelve populations of Escherichia coli B all lostd-ribose catabolic function during 2,000 generations of evolution in glucose minimal medium. We sought to identify the population genetic processes and molecular genetic events that caused these rapid and parallel losses. Seven independent Rbs−mutants were isolated, and their competitive fitnesses were measured relative to that of their Rbs+ progenitor. These Rbs− mutants were all about 1 to 2% more fit than the progenitor. A fluctuation test revealed an unusually high rate, about 5 × 10−5 per cell generation, of mutation from Rbs+ to Rbs−, which contributed to rapid fixation. At the molecular level, the loss of ribose catabolic function involved the deletion of part or all of the ribose operon (rbs genes). The physical extent of the deletion varied between mutants, but each deletion was associated with an IS150 element located immediately upstream of therbs operon. The deletions apparently involved transposition into various locations within the rbs operon; recombination between the new IS150 copy and the one upstream of therbs operon then led to the deletion of the intervening sequence. To confirm that the beneficial fitness effect was caused by deletion of the rbs operon (and not some undetected mutation elsewhere), we used P1 transduction to restore the functionalrbs operon to two Rbs− mutants, and we constructed another Rbs− strain by gene replacement with a deletion not involving IS150. All three of these new constructs confirmed that Rbs− mutants have a competitive advantage relative to their Rbs+ counterparts in glucose minimal medium. The rapid and parallel evolutionary losses of ribose catabolic function thus involved both (i) an unusually high mutation rate, such that Rbs− mutants appeared repeatedly in all populations, and (ii) a selective advantage in glucose minimal medium that drove these mutants to fixation.

scholarly journals Modification by an R determinant for streptomycin of hissd phenotype in a mutant strain of Escherichia coli B

1968 ◽  
Vol 12 (2) ◽  
pp. 109-116 ◽  
Author(s):  
A. M. Molina ◽  
L. Calegari ◽  
G. Conte
Keyword(s):  
Escherichia Coli ◽  
Cell Membrane ◽  
Mutant Strain ◽  
Minimal Medium ◽  
Specific Requirement ◽  
Resistance Level ◽  
E Coli ◽  
Level Characteristic ◽  
Escherichia Coli B

When an R determinant for streptomycin is transferred into a conditionally streptomycin-dependent E. coli B mutant—which requires in minimal medium either histidine or streptomycin—the latter behaves like a histidineless strain. This phenotype modification shows that the repairing action of streptomycin is prevented. The specific requirement of the strain is not now replaced even by streptomycin concentrations up to 10000 µg/ml at which the conditionally streptomycin-dependent mutant could originally grow, and which are well beyond the resistance level characteristic of the R determinant itself. These data seem to suggest that a reduction in permeability of the cell membrane cannot be held responsible for the phenomenon observed.

Effect of ascorbate on oxygen uptake and growth of Escherichia coli B

1988 ◽  
Vol 34 (6) ◽  
pp. 822-824 ◽  
Author(s):  
Holly E. Richter ◽  
Jacek Switala ◽  
Peter C. Loewen
Keyword(s):  
Escherichia Coli ◽  
Oxygen Uptake ◽  
Electron Acceptor ◽  
Minimal Medium ◽  
Anaerobic Growth ◽  
Rich Medium ◽  
Terminal Electron Acceptor ◽  
Subsequent Change ◽  
Escherichia Coli B

The addition of ascorbate to aerobically growing cultures of Escherichia coli B caused only a short pause in growth and no subsequent change in the rate or extent of growth. The effect of ascorbate on oxygen uptake varied from inhibition in minimal medium to stimulation in rich medium. Cyanide-resistant growth and oxygen uptake were stimulated by ascorbate. Both the rate and extent of anaerobic growth were stimulated in proportion to the amount of ascorbate added when fumarate was the terminal electron acceptor. Ascorbate had no effect on any aspect of anaerobic growth in the absence of a terminal electron acceptor or in the presence of nitrate.

THE INFLUENCE OF TIME AND MEDIA CHANGES ON THE INDUCTION AND SUPPRESSION OF β-GALACTOSIDASE SYNTHESIS IN ESCHERICHIA COLI B

1967 ◽  
Vol 13 (3) ◽  
pp. 257-269
Author(s):  
S. J. Webb ◽  
Janet L. Walker
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Minimal Medium ◽  
Sole Source ◽  
Enzyme Synthesis ◽  
Induction Medium ◽  
Nucleic Acid Bases ◽  
Apparent Effect ◽  
Lag Period ◽  
Escherichia Coli B

When cells of Escherichia coli B were grown in a glucose – amino acid medium and then transferred to a minimal medium containing lactose or isopropyl-β-D-thiogalactopyranoside as a sole source of carbon, no induction of β-galactosidase occurred unless one or several amino acids were supplied. Of the amino acids tested, aspartic acid was the most effective and its ability to initiate the synthesis of the enzyme was increased by the addition of arginine. In the presence of these two, or all of the amino acids, there was a lag period of 10 min before enzyme synthesis occurred. The duration of the lag period was unaffected by the addition of nucleic acid bases or succinate to the induction medium. Succinate or glutamate partially inhibited the synthesis of the enzyme, whereas glucose, inositol, or chloramphenicol completely suppressed it. With the exception of that produced by chloramphenicol, inhibition was dependent on the time at which the inhibitor was added. If inhibitors were added after the 10-min lag period, they had no apparent effect until 45 min had elapsed. Cells transferred after 15 min from one induction medium to another displayed for 30 min the induction characteristics of the first medium. It appears that a process occurring during the early 15-min period determines the rate at which enzymes will be synthesized for the next 30 min and that the action of inhibitors is to prevent this process. The process seems to require intact DNA and amino acids and it is suggested that it determines the specificity and quantity of mRNA manufactured.

scholarly journals Global transcriptional response of Escherichia coli O157:H7 to growth transitions in glucose minimal medium

2007 ◽  
Vol 7 (1) ◽  
pp. 97 ◽  
Author(s):  
Teresa M Bergholz ◽  
Lukas M Wick ◽  
Weihong Qi ◽  
James T Riordan ◽  
Lindsey M Ouellette ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Minimal Medium ◽  
Transcriptional Response ◽  
Escherichia Coli O157 ◽  
Glucose Minimal Medium ◽  
Growth Transitions

scholarly journals The Small RNA GcvB Regulates sstT mRNA Expression in Escherichia coli

2008 ◽  
Vol 191 (1) ◽  
pp. 238-248 ◽  
Author(s):  
Sarah C. Pulvermacher ◽  
Lorraine T. Stauffer ◽  
George V. Stauffer
Keyword(s):  
Escherichia Coli ◽  
Minimal Medium ◽  
Small Region ◽  
Luria Bertani ◽  
Negative Regulation ◽  
Transport Systems ◽  
Mrna Levels ◽  
Glucose Minimal Medium ◽  
Reverse Transcription Pcr ◽  
Luria Bertani Broth

ABSTRACT In Escherichia coli, the gcvB gene encodes a nontranslated RNA (referred to as GcvB) that regulates OppA and DppA, two periplasmic binding proteins for the oligopeptide and dipeptide transport systems. An additional regulatory target of GcvB, sstT, was found by microarray analysis of RNA isolated from a wild-type strain and a gcvB deletion strain grown to mid-log phase in Luria-Bertani broth. The SstT protein functions to transport l-serine and l-threonine by sodium transport into the cell. Reverse transcription-PCR and translational fusions confirmed that GcvB negatively regulates sstT mRNA levels in cells grown in Luria-Bertani broth. A series of transcriptional fusions identified a region of sstT mRNA upstream of the ribosome binding site needed for negative regulation by GcvB. Analysis of the GcvB RNA identified a sequence complementary to this region of the sstT mRNA. The region of GcvB complementary to sstT mRNA is the same region of GcvB identified to regulate the dppA and oppA mRNAs. Mutations predicted to disrupt base pairing between sstT mRNA and GcvB were made in gcvB, which resulted in the identification of a small region of GcvB necessary for negative regulation of sstT-lacZ. Additionally, the RNA chaperone protein Hfq was found to be necessary for GcvB to negatively regulate sstT-lacZ in Luria-Bertani broth and glucose minimal medium supplemented with glycine. The sstT mRNA is the first target found to be regulated by GcvB in glucose minimal medium supplemented with glycine.

scholarly journals Extended-spectrum β-lactamase-producing Escherichia coli isolated from raw vegetables in South Korea

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jihyun Song ◽  
Sung-Suck Oh ◽  
Junghee Kim ◽  
Jinwook Shin
Keyword(s):  
Escherichia Coli ◽  
South Korea ◽  
Vegetable Intake ◽  
Molecular Genetic ◽  
Multidrug Resistant ◽  
E Coli ◽  
Extended Spectrum ◽  
Genetic Features ◽  
Global Concern ◽  
The One

AbstractThe increasing prevalence of oxyimino-cephalosporin-resistant Enterobacteriaceae has become a global concern because of their clinical impact on both human and veterinary medicine. The present study determined the prevalence, antimicrobial susceptibility, and molecular genetic features of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) isolates from raw vegetables. A total of 1324 samples were collected from two agricultural wholesale markets in Incheon, South Korea in 2018. The ESBL-EC strains were isolated from 0.83% (11/1324) samples, and all of them were resistant to ampicillin, piperacillin, cefazoline, cefotaxime, and nalidixic acid and yielded CTX-M-type ESBL, including CTX-M-14, CTX-M-15, CTX-M-55, CTX-M-27, and CTX-M-65. The isolates belonged to phylogenetic subgroups D (n = 5), A (n = 4), and B1 (n = 2). Multilocus sequence typing revealed nine known E. coli sequence types (STs), including ST10, ST38, ST69, ST101, ST224, ST349, ST354, ST2509, ST2847, and two new STs. Notably, ST69, ST10, ST38, and ST354 belong to the major human-associated extraintestinal pathogenic E. coli lineages. Our results demonstrate that ESBL-producing multidrug-resistant pathogens may be transmitted to humans through the vegetable intake, highlighting the importance of resistance monitoring and intervention in the One Health perspective.

Construction of an Escherichia coli strain which excretes abnormally large amounts of adenosine 3′,5′-cyclic monophosphate

1978 ◽  
Vol 24 (11) ◽  
pp. 1423-1425 ◽  
Author(s):  
Ann D. E. Fraser ◽  
Hiroshi Yamazaki
Keyword(s):  
Escherichia Coli ◽  
Minimal Medium ◽  
Coli Strain ◽  
Coli Cell ◽  
Wild Type ◽  
Camp Phosphodiesterase ◽  
E Coli ◽  
Cyclic Monophosphate ◽  
Glucose Minimal Medium ◽  
P1 Transduction

It has previously been shown that an Escherichia coli CRP− strain 5333 accumulates abnormally large amounts of adenosine 3′,5′-cyclic monophosphate (cAMP). Using P1 transduction, the CRP− character was transferred to E. coli Crookes strain which is deficient for cAMP phosphodiesterase (CPD−). The resulting strain HY22 (CRP−, CPD−) accumulates greater amounts of cAMP both intracellularly and extracellularly than does 5333. In glucose minimal medium, an HY22 cell accumulates 100 times more cAMP intracellularly and excretes cAMP 150 times faster than does a wild-type E. coli cell.

scholarly journals YjjG, a dUMP Phosphatase, Is Critical for Thymine Utilization by Escherichia coli K-12

2006 ◽  
Vol 189 (5) ◽  
pp. 2186-2189 ◽  
Author(s):  
Bernard Weiss
Keyword(s):  
Escherichia Coli ◽  
Thymidylate Synthase ◽  
Minimal Medium ◽  
Glucose Minimal Medium ◽  
K 12

ABSTRACT Exogenous thymine must be converted to thymidine to enable a thyA (thymidylate synthase) mutant to grow. The deoxyribose in the thymidine comes from dUMP, which must first be dephosphorylated. The nucleotidase YjjG is critical for this step. A yjjG thyA mutant cannot use thymine for growth on a glucose minimal medium.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

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