Bacterial strategies to inhabit acidic environments.

Kobayashi, Hiroshi; Saito, Hiromi; Kakegawa, Tomohito

doi:10.2323/jgam.46.235

Cited by 41 publications

(22 citation statements)

References 68 publications

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“…2001), and these may work at neutral pH instead of OmpC and OmpF. Thus, our present results support the previous proposal that different systems are used under different pH conditions (Kobayashi et al. 1999, 2000).…”

Section: Discussionsupporting

confidence: 91%

OmpC and OmpF are required for growth under hyperosmotic stress above pH 8 in Escherichia coli

Kaeriyama

Machida

Kitakaze

et al. 2006

Lett Appl Microbiol

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Aims: To investigate the requirement of outer membrane porins for osmotic adaptation at alkaline pH in Escherichia coli. Methods and Results: Escherichia coli mutants deficient in ompC, ompF and both genes were constructed and the growth of these mutants was observed at alkaline pH. The growth rate of the mutant deficient in both ompC and ompF was slower than that of the wild type and mutants deficient in one of these genes under hyperosmotic stress at pHs above 8·0. The decreased rate was recovered when a cloned ompC was introduced to the mutant, but the growth recovery with a cloned ompF was partial. Such growth diminution was not observed at pHs below 8·0. Conclusion: OmpC and OmpF were shown to participate in hyperosmotic adaptation at alkaline pH in E. coli. Significance and Impact of the Study: This study is the first report to demonstrate that OmpC and OmpF are required for hyperosmotic adaptation at pHs above 8·0, but not below 8·0.

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Section: Discussionsupporting

confidence: 91%

OmpC and OmpF are required for growth under hyperosmotic stress above pH 8 in Escherichia coli

Kaeriyama

Machida

Kitakaze

et al. 2006

Lett Appl Microbiol

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“…E. coli K-12 is generally able to maintain an intracellular pH of 7.6±0.2 when grown in media with a pH between 6.0 and 7.5, as controlled by the addition of ionic buffering agents [59]. Outside of this range, growth is still observed at pH values between 4.5 and 9.0 [59], though growth is inhibited if intracellular pH falls below 7.1 [52]. It has been noted that E. coli does not grow if the intracellular pH falls below 6.0 [52].…”

Section: Resultsmentioning

confidence: 99%

Transcriptomic Analysis of Carboxylic Acid Challenge in Escherichia coli: Beyond Membrane Damage

Royce

Boggess

et al. 2014

PLoS ONE

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Carboxylic acids are an attractive biorenewable chemical. Enormous progress has been made in engineering microbes for production of these compounds though titers remain lower than desired. Here we used transcriptome analysis of Escherichia coli during exogenous challenge with octanoic acid (C8) at pH 7.0 to probe mechanisms of toxicity. This analysis highlights the intracellular acidification and membrane damage caused by C8 challenge. Network component analysis identified transcription factors with altered activity including GadE, the activator of the glutamate-dependent acid resistance system (AR2) and Lrp, the amino acid biosynthesis regulator. The intracellular acidification was quantified during exogenous challenge, but was not observed in a carboxylic acid producing strain, though this may be due to lower titers than those used in our exogenous challenge studies. We developed a framework for predicting the proton motive force during adaptation to strong inorganic acids and carboxylic acids. This model predicts that inorganic acid challenge is mitigated by cation accumulation, but that carboxylic acid challenge inverts the proton motive force and requires anion accumulation. Utilization of native acid resistance systems was not useful in terms of supporting growth or alleviating intracellular acidification. AR2 was found to be non-functional, possibly due to membrane damage. We proposed that interaction of Lrp and C8 resulted in repression of amino acid biosynthesis. However, this hypothesis was not supported by perturbation of lrp expression or amino acid supplementation. E. coli strains were also engineered for altered cyclopropane fatty acid content in the membrane, which had a dramatic effect on membrane properties, though C8 tolerance was not increased. We conclude that achieving higher production titers requires circumventing the membrane damage. As higher titers are achieved, acidification may become problematic.

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“…Microbial growth is impacted under acidic conditions as enzymatic activity is lowered (Langworthy, 1978;Baronofsky et al, 1984;Kobayashi et al, 2000). Decreased metabolic activity can lead to an accumulation of carbon intermediates in acidic sediments (Goodwin and Zeikus, 1987;Hines et al, 2001;Horn et al, 2003), and ORFRC groundwaters contain high concentrations of non metabolized short chain organic acids (0.49 mM acetate and 0.11 mM citrate; Shelobolina et al, 2003).…”

Section: Electron Donor Utilization In Acidic Subsurface Sedimentsmentioning

confidence: 97%

Electron flow in acidic subsurface sediments co-contaminated with nitrate and uranium

Edwards¹,

Küsel²,

Drake³

et al. 2007

Geochimica et Cosmochimica Acta

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Bacterial strategies to inhabit acidic environments.

Cited by 41 publications

References 68 publications

OmpC and OmpF are required for growth under hyperosmotic stress above pH 8 in Escherichia coli

OmpC and OmpF are required for growth under hyperosmotic stress above pH 8 in Escherichia coli

Transcriptomic Analysis of Carboxylic Acid Challenge in Escherichia coli: Beyond Membrane Damage

Electron flow in acidic subsurface sediments co-contaminated with nitrate and uranium

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