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Identification of Genes Required for Growth of Escherichia coli MG1655 at Moderately Low pH

The survival of some pathotypes of Escherichia coli in very low pH environments like highly acidic foods and the stomach has been well documented and contributes to their success as foodborne pathogens. In contrast, the ability of E. coli to grow at moderately low pH has received less attention, alt...

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Autores principales: Vivijs, Bram, Aertsen, Abram, Michiels, Chris W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5078493/
https://www.ncbi.nlm.nih.gov/pubmed/27826291
http://dx.doi.org/10.3389/fmicb.2016.01672
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author Vivijs, Bram
Aertsen, Abram
Michiels, Chris W.
author_facet Vivijs, Bram
Aertsen, Abram
Michiels, Chris W.
author_sort Vivijs, Bram
collection PubMed
description The survival of some pathotypes of Escherichia coli in very low pH environments like highly acidic foods and the stomach has been well documented and contributes to their success as foodborne pathogens. In contrast, the ability of E. coli to grow at moderately low pH has received less attention, although this property can be anticipated to be also very important for the safety of mildly acidic foods. Therefore, the objective of this study was to identify cellular functions required for growth of the non-pathogenic strain E. coli MG1655 at low pH. First, the role of the four E. coli amino acid decarboxylase systems, which are the major cellular mechanisms allowing extreme acid survival, was investigated using mutants defective in each of the systems. Only the lysine decarboxylase (CadA) was required for low pH growth. Secondly, a screening of 8544 random transposon insertion mutants resulted in the identification of six genes affecting growth in LB broth acidified to pH 4.50 with HCl. Two of the genes, encoding the transcriptional regulator LeuO and the elongation factor P-β-lysine ligase EpmA, can be linked to CadA production. Two other genes, encoding the diadenosine tetraphosphatase ApaH and the tRNA modification GTPase MnmE, have been previously implicated in the bacterial response to stresses other than low pH. A fifth gene encodes the LPS heptosyltransferase WaaC, and its mutant has a deep rough colony phenotype, which has been linked to reduced acid tolerance in earlier work. Finally, tatC encodes a secA-independent protein translocase that exports a few dozen proteins and thus is likely to have a pleiotropic phenotype. For mnmE, apaH, epmA, and waaC, de novo in frame deletion and genetic complementation confirmed their role in low pH growth, and these deletion mutants were also affected in growth in apple juice and tomato juice. However, the mutants were not affected in survival in gastric simulation medium at pH 2.5, indicating that growth at moderately low pH and survival of extremely low pH depend mostly on different cellular functions.
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spelling pubmed-50784932016-11-08 Identification of Genes Required for Growth of Escherichia coli MG1655 at Moderately Low pH Vivijs, Bram Aertsen, Abram Michiels, Chris W. Front Microbiol Microbiology The survival of some pathotypes of Escherichia coli in very low pH environments like highly acidic foods and the stomach has been well documented and contributes to their success as foodborne pathogens. In contrast, the ability of E. coli to grow at moderately low pH has received less attention, although this property can be anticipated to be also very important for the safety of mildly acidic foods. Therefore, the objective of this study was to identify cellular functions required for growth of the non-pathogenic strain E. coli MG1655 at low pH. First, the role of the four E. coli amino acid decarboxylase systems, which are the major cellular mechanisms allowing extreme acid survival, was investigated using mutants defective in each of the systems. Only the lysine decarboxylase (CadA) was required for low pH growth. Secondly, a screening of 8544 random transposon insertion mutants resulted in the identification of six genes affecting growth in LB broth acidified to pH 4.50 with HCl. Two of the genes, encoding the transcriptional regulator LeuO and the elongation factor P-β-lysine ligase EpmA, can be linked to CadA production. Two other genes, encoding the diadenosine tetraphosphatase ApaH and the tRNA modification GTPase MnmE, have been previously implicated in the bacterial response to stresses other than low pH. A fifth gene encodes the LPS heptosyltransferase WaaC, and its mutant has a deep rough colony phenotype, which has been linked to reduced acid tolerance in earlier work. Finally, tatC encodes a secA-independent protein translocase that exports a few dozen proteins and thus is likely to have a pleiotropic phenotype. For mnmE, apaH, epmA, and waaC, de novo in frame deletion and genetic complementation confirmed their role in low pH growth, and these deletion mutants were also affected in growth in apple juice and tomato juice. However, the mutants were not affected in survival in gastric simulation medium at pH 2.5, indicating that growth at moderately low pH and survival of extremely low pH depend mostly on different cellular functions. Frontiers Media S.A. 2016-10-25 /pmc/articles/PMC5078493/ /pubmed/27826291 http://dx.doi.org/10.3389/fmicb.2016.01672 Text en Copyright © 2016 Vivijs, Aertsen and Michiels. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Microbiology
Vivijs, Bram
Aertsen, Abram
Michiels, Chris W.
Identification of Genes Required for Growth of Escherichia coli MG1655 at Moderately Low pH
title Identification of Genes Required for Growth of Escherichia coli MG1655 at Moderately Low pH
title_full Identification of Genes Required for Growth of Escherichia coli MG1655 at Moderately Low pH
title_fullStr Identification of Genes Required for Growth of Escherichia coli MG1655 at Moderately Low pH
title_full_unstemmed Identification of Genes Required for Growth of Escherichia coli MG1655 at Moderately Low pH
title_short Identification of Genes Required for Growth of Escherichia coli MG1655 at Moderately Low pH
title_sort identification of genes required for growth of escherichia coli mg1655 at moderately low ph
topic Microbiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5078493/
https://www.ncbi.nlm.nih.gov/pubmed/27826291
http://dx.doi.org/10.3389/fmicb.2016.01672
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