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  1. Article ; Online: Periplasmic Acid Stress Increases Cell Division Asymmetry (Polar Aging) of Escherichia coli.

    Clark, Michelle W / Yie, Anna M / Eder, Elizabeth K / Dennis, Richard G / Basting, Preston J / Martinez, Keith A / Jones, Brian D / Slonczewski, Joan L

    PloS one

    2015  Volume 10, Issue 12, Page(s) e0144650

    Abstract: Under certain kinds of cytoplasmic stress, Escherichia coli selectively reproduce by distributing the newer cytoplasmic components to new-pole cells while sequestering older, damaged components in cells inheriting the old pole. This phenomenon is termed ... ...

    Abstract Under certain kinds of cytoplasmic stress, Escherichia coli selectively reproduce by distributing the newer cytoplasmic components to new-pole cells while sequestering older, damaged components in cells inheriting the old pole. This phenomenon is termed polar aging or cell division asymmetry. It is unknown whether cell division asymmetry can arise from a periplasmic stress, such as the stress of extracellular acid, which is mediated by the periplasm. We tested the effect of periplasmic acid stress on growth and division of adherent single cells. We tracked individual cell lineages over five or more generations, using fluorescence microscopy with ratiometric pHluorin to measure cytoplasmic pH. Adherent colonies were perfused continually with LBK medium buffered at pH 6.00 or at pH 7.50; the external pH determines periplasmic pH. In each experiment, cell lineages were mapped to correlate division time, pole age and cell generation number. In colonies perfused at pH 6.0, the cells inheriting the oldest pole divided significantly more slowly than the cells inheriting the newest pole. In colonies perfused at pH 7.50 (near or above cytoplasmic pH), no significant cell division asymmetry was observed. Under both conditions (periplasmic pH 6.0 or pH 7.5) the cells maintained cytoplasmic pH values at 7.2-7.3. No evidence of cytoplasmic protein aggregation was seen. Thus, periplasmic acid stress leads to cell division asymmetry with minimal cytoplasmic stress.
    MeSH term(s) Asymmetric Cell Division ; Escherichia coli/cytology ; Escherichia coli/metabolism ; Escherichia coli Proteins/metabolism ; Hydrogen-Ion Concentration ; Periplasm/metabolism ; Protein Aggregates ; Stress, Physiological
    Chemical Substances Escherichia coli Proteins ; Protein Aggregates
    Language English
    Publishing date 2015-12-29
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1932-6203
    ISSN (online) 1932-6203
    DOI 10.1371/journal.pone.0144650
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Acid Evolution of Escherichia coli K-12 Eliminates Amino Acid Decarboxylases and Reregulates Catabolism.

    He, Amanda / Penix, Stephanie R / Basting, Preston J / Griffith, Jessie M / Creamer, Kaitlin E / Camperchioli, Dominic / Clark, Michelle W / Gonzales, Alexandra S / Chávez Erazo, Jorge Sebastian / George, Nadja S / Bhagwat, Arvind A / Slonczewski, Joan L

    Applied and environmental microbiology

    2017  Volume 83, Issue 12

    Abstract: Acid-adapted strains ... ...

    Abstract Acid-adapted strains of
    Language English
    Publishing date 2017-06-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 223011-2
    ISSN 1098-5336 ; 0099-2240
    ISSN (online) 1098-5336
    ISSN 0099-2240
    DOI 10.1128/AEM.00442-17
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Acid-adapted strains of Escherichia coli K-12 obtained by experimental evolution.

    Harden, Mark M / He, Amanda / Creamer, Kaitlin / Clark, Michelle W / Hamdallah, Issam / Martinez, Keith A / Kresslein, Robert L / Bush, Sean P / Slonczewski, Joan L

    Applied and environmental microbiology

    2015  Volume 81, Issue 6, Page(s) 1932–1941

    Abstract: Enteric bacteria encounter a wide range of pHs throughout the human intestinal tract. We conducted experimental evolution of Escherichia coli K-12 to isolate clones with increased fitness during growth under acidic conditions (pH 4.5 to 4.8). Twenty-four ...

    Abstract Enteric bacteria encounter a wide range of pHs throughout the human intestinal tract. We conducted experimental evolution of Escherichia coli K-12 to isolate clones with increased fitness during growth under acidic conditions (pH 4.5 to 4.8). Twenty-four independent populations of E. coli K-12 W3110 were evolved in LBK medium (10 g/liter tryptone, 5 g/liter yeast extract, 7.45 g/liter KCl) buffered with homopiperazine-N,N'-bis-2-(ethanosulfonic acid) and malate at pH 4.8. At generation 730, the pH was decreased to 4.6 with HCl. By 2,000 generations, all populations had achieved higher endpoint growth than the ancestor at pH 4.6 but not at pH 7.0. All evolving populations showed a progressive loss of activity of lysine decarboxylase (CadA), a major acid stress enzyme. This finding suggests a surprising association between acid adaptation and moderation of an acid stress response. At generation 2,000, eight clones were isolated from four populations, and their genomes were sequenced. Each clone showed between three and eight missense mutations, including one in a subunit of the RNA polymerase holoenzyme (rpoB, rpoC, or rpoD). Missense mutations were found in adiY, the activator of the acid-inducible arginine decarboxylase (adiA), and in gcvP (glycine decarboxylase), a possible acid stress component. For tests of fitness relative to that of the ancestor, lacZ::kan was transduced into each strain. All acid-evolved clones showed a high fitness advantage at pH 4.6. With the cytoplasmic pH depressed by benzoate (at external pH 6.5), acid-evolved clones showed decreased fitness; thus, there was no adaptation to cytoplasmic pH depression. At pH 9.0, acid-evolved clones showed no fitness advantage. Thus, our acid-evolved clones showed a fitness increase specific to low external pH.
    MeSH term(s) Acids/toxicity ; Adaptation, Biological ; Culture Media/chemistry ; Drug Resistance, Bacterial ; Escherichia coli K12/drug effects ; Escherichia coli Proteins/genetics ; Escherichia coli Proteins/metabolism ; Hydrogen-Ion Concentration ; Mutation, Missense
    Chemical Substances Acids ; Culture Media ; Escherichia coli Proteins
    Language English
    Publishing date 2015-03
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 223011-2
    ISSN 1098-5336 ; 0099-2240
    ISSN (online) 1098-5336
    ISSN 0099-2240
    DOI 10.1128/AEM.03494-14
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Benzoate- and Salicylate-Tolerant Strains of Escherichia coli K-12 Lose Antibiotic Resistance during Laboratory Evolution.

    Creamer, Kaitlin E / Ditmars, Frederick S / Basting, Preston J / Kunka, Karina S / Hamdallah, Issam N / Bush, Sean P / Scott, Zachary / He, Amanda / Penix, Stephanie R / Gonzales, Alexandra S / Eder, Elizabeth K / Camperchioli, Dominic W / Berndt, Adama / Clark, Michelle W / Rouhier, Kerry A / Slonczewski, Joan L

    Applied and environmental microbiology

    2016  Volume 83, Issue 2

    Abstract: Escherichia coli K-12 W3110 grows in the presence of membrane-permeant organic acids that can depress cytoplasmic pH and accumulate in the cytoplasm. We conducted experimental evolution by daily diluting cultures in increasing concentrations of benzoic ... ...

    Abstract Escherichia coli K-12 W3110 grows in the presence of membrane-permeant organic acids that can depress cytoplasmic pH and accumulate in the cytoplasm. We conducted experimental evolution by daily diluting cultures in increasing concentrations of benzoic acid (up to 20 mM) buffered at external pH 6.5, a pH at which permeant acids concentrate in the cytoplasm. By 2,000 generations, clones isolated from evolving populations showed increasing tolerance to benzoate but were sensitive to chloramphenicol and tetracycline. Sixteen clones grew to stationary phase in 20 mM benzoate, whereas the ancestral strain W3110 peaked and declined. Similar growth occurred in 10 mM salicylate. Benzoate-evolved strains grew like W3110 in the absence of benzoate, in media buffered at pH 4.8, pH 7.0, or pH 9.0, or in 20 mM acetate or sorbate at pH 6.5. Genomes of 16 strains revealed over 100 mutations, including single-nucleotide polymorphisms (SNPs), large deletions, and insertion knockouts. Most strains acquired deletions in the benzoate-induced multiple antibiotic resistance (Mar) regulon or in associated regulators such as rob and cpxA, as well as the multidrug resistance (MDR) efflux pumps emrA, emrY, and mdtA Strains also lost or downregulated the Gad acid fitness regulon. In 5 mM benzoate or in 2 mM salicylate (2-hydroxybenzoate), most strains showed increased sensitivity to the antibiotics chloramphenicol and tetracycline; some strains were more sensitive than a marA knockout strain. Thus, our benzoate-evolved strains may reveal additional unknown drug resistance components. Benzoate or salicylate selection pressure may cause general loss of MDR genes and regulators.
    Importance: Benzoate is a common food preservative, and salicylate is the primary active metabolite of aspirin. In the gut microbiome, genetic adaptation to salicylate may involve loss or downregulation of inducible multidrug resistance systems. This discovery implies that aspirin therapy may modulate the human gut microbiome to favor salicylate tolerance at the expense of drug resistance. Similar aspirin-associated loss of drug resistance might occur in bacterial pathogens found in arterial plaques.
    MeSH term(s) Anti-Bacterial Agents/pharmacology ; Anti-Inflammatory Agents, Non-Steroidal/metabolism ; Benzoates/metabolism ; Biological Evolution ; Dose-Response Relationship, Drug ; Drug Resistance, Microbial/genetics ; Escherichia coli K12/drug effects ; Escherichia coli K12/genetics ; Escherichia coli K12/metabolism ; Food Preservatives/metabolism ; Gene Expression Regulation, Bacterial ; Salicylates/metabolism
    Chemical Substances Anti-Bacterial Agents ; Anti-Inflammatory Agents, Non-Steroidal ; Benzoates ; Food Preservatives ; Salicylates
    Language English
    Publishing date 2016-12-30
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, Non-U.S. Gov't
    ZDB-ID 223011-2
    ISSN 1098-5336 ; 0099-2240
    ISSN (online) 1098-5336
    ISSN 0099-2240
    DOI 10.1128/AEM.02736-16
    Database MEDical Literature Analysis and Retrieval System OnLINE

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