The role of Cra in regulating acetate excretion and osmotic tolerance in <it>E. coli </it>K-12 and <it>E. coli </it>B at high density growth
<p>Abstract</p> <p>Background</p> <p><it>E. coli </it>B (BL21), unlike <it>E.coli </it>K-12 (JM109) is insensitive to glucose concentration and, therefore, grows faster and produces less acetate than <it>E. coli </it>K-12, especially...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2011-06-01
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| Series: | Microbial Cell Factories |
| Online Access: | http://www.microbialcellfactories.com/content/10/1/52 |
| _version_ | 1818037976747212800 |
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| author | Lee Sang Jun Trinh Loc B Phue Je-Nie Son Young-Jin Shiloach Joseph |
| author_facet | Lee Sang Jun Trinh Loc B Phue Je-Nie Son Young-Jin Shiloach Joseph |
| author_sort | Lee Sang Jun |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p><it>E. coli </it>B (BL21), unlike <it>E.coli </it>K-12 (JM109) is insensitive to glucose concentration and, therefore, grows faster and produces less acetate than <it>E. coli </it>K-12, especially when growing to high cell densities at high glucose concentration. By performing genomic analysis, it was demonstrated that the cause of this difference in sensitivity to the glucose concentration is the result of the differences in the central carbon metabolism activity. We hypothesized that the global transcription regulator Cra (FruR) is constitutively expressed in <it>E. coli </it>B and may be responsible for the different behaviour of the two strains. To investigate this possibility and better understand the function of Cra in the two strains, <it>cra </it>- negative <it>E. coli </it>B (BL21) and <it>E. coli </it>K-12 (JM109) were prepared and their growth behaviour and gene expression at high glucose were evaluated using microarray and real-time PCR.</p> <p>Results</p> <p>The deletion of the <it>cra </it>gene in <it>E. coli </it>B (BL21) minimally affected the growth and maximal acetate accumulation, while the deletion of the same gene in <it>E.coli </it>K-12 (JM109) caused the cells to stop growing as soon as acetate concentration reached 6.6 g/L and the media conductivity reached 21 mS/cm. <it>ppsA </it>(gluconeogenesis gene), <it>aceBA </it>(the glyoxylate shunt genes) and <it>poxB </it>(the acetate producing gene) were down-regulated in both strains, while <it>acs </it>(acetate uptake gene) was down-regulated only in <it>E.coli </it>B (BL21). These transcriptional differences had little effect on acetate and pyruvate production. Additionally, it was found that the lower growth of <it>E. coli </it>K-12 (JM109) strain was the result of transcription inhibition of the osmoprotectant producing <it>bet </it>operon (<it>betABT</it>).</p> <p>Conclusions</p> <p>The transcriptional changes caused by the deletion of <it>cra </it>gene did not affect the activity of the central carbon metabolism, suggesting that Cra does not act alone; rather it interacts with other pleiotropic regulators to create a network of metabolic effects. An unexpected outcome of this work is the finding that <it>cra </it>deletion caused transcription inhibition of the <it>bet </it>operon in <it>E. coli </it>K-12 (JM109) but did not affect this operon transcription in <it>E. coli </it>B (BL21). This property, together with the insensitivity to high glucose concentrations, makes this the <it>E. coli </it>B (BL21) strain more resistant to environmental changes.</p> |
| first_indexed | 2024-12-10T07:35:24Z |
| format | Article |
| id | doaj.art-9aa56b23c04a4687aefe49ea7eca2d92 |
| institution | Directory Open Access Journal |
| issn | 1475-2859 |
| language | English |
| last_indexed | 2024-12-10T07:35:24Z |
| publishDate | 2011-06-01 |
| publisher | BMC |
| record_format | Article |
| series | Microbial Cell Factories |
| spelling | doaj.art-9aa56b23c04a4687aefe49ea7eca2d922022-12-22T01:57:26ZengBMCMicrobial Cell Factories1475-28592011-06-011015210.1186/1475-2859-10-52The role of Cra in regulating acetate excretion and osmotic tolerance in <it>E. coli </it>K-12 and <it>E. coli </it>B at high density growthLee Sang JunTrinh Loc BPhue Je-NieSon Young-JinShiloach Joseph<p>Abstract</p> <p>Background</p> <p><it>E. coli </it>B (BL21), unlike <it>E.coli </it>K-12 (JM109) is insensitive to glucose concentration and, therefore, grows faster and produces less acetate than <it>E. coli </it>K-12, especially when growing to high cell densities at high glucose concentration. By performing genomic analysis, it was demonstrated that the cause of this difference in sensitivity to the glucose concentration is the result of the differences in the central carbon metabolism activity. We hypothesized that the global transcription regulator Cra (FruR) is constitutively expressed in <it>E. coli </it>B and may be responsible for the different behaviour of the two strains. To investigate this possibility and better understand the function of Cra in the two strains, <it>cra </it>- negative <it>E. coli </it>B (BL21) and <it>E. coli </it>K-12 (JM109) were prepared and their growth behaviour and gene expression at high glucose were evaluated using microarray and real-time PCR.</p> <p>Results</p> <p>The deletion of the <it>cra </it>gene in <it>E. coli </it>B (BL21) minimally affected the growth and maximal acetate accumulation, while the deletion of the same gene in <it>E.coli </it>K-12 (JM109) caused the cells to stop growing as soon as acetate concentration reached 6.6 g/L and the media conductivity reached 21 mS/cm. <it>ppsA </it>(gluconeogenesis gene), <it>aceBA </it>(the glyoxylate shunt genes) and <it>poxB </it>(the acetate producing gene) were down-regulated in both strains, while <it>acs </it>(acetate uptake gene) was down-regulated only in <it>E.coli </it>B (BL21). These transcriptional differences had little effect on acetate and pyruvate production. Additionally, it was found that the lower growth of <it>E. coli </it>K-12 (JM109) strain was the result of transcription inhibition of the osmoprotectant producing <it>bet </it>operon (<it>betABT</it>).</p> <p>Conclusions</p> <p>The transcriptional changes caused by the deletion of <it>cra </it>gene did not affect the activity of the central carbon metabolism, suggesting that Cra does not act alone; rather it interacts with other pleiotropic regulators to create a network of metabolic effects. An unexpected outcome of this work is the finding that <it>cra </it>deletion caused transcription inhibition of the <it>bet </it>operon in <it>E. coli </it>K-12 (JM109) but did not affect this operon transcription in <it>E. coli </it>B (BL21). This property, together with the insensitivity to high glucose concentrations, makes this the <it>E. coli </it>B (BL21) strain more resistant to environmental changes.</p>http://www.microbialcellfactories.com/content/10/1/52 |
| spellingShingle | Lee Sang Jun Trinh Loc B Phue Je-Nie Son Young-Jin Shiloach Joseph The role of Cra in regulating acetate excretion and osmotic tolerance in <it>E. coli </it>K-12 and <it>E. coli </it>B at high density growth Microbial Cell Factories |
| title | The role of Cra in regulating acetate excretion and osmotic tolerance in <it>E. coli </it>K-12 and <it>E. coli </it>B at high density growth |
| title_full | The role of Cra in regulating acetate excretion and osmotic tolerance in <it>E. coli </it>K-12 and <it>E. coli </it>B at high density growth |
| title_fullStr | The role of Cra in regulating acetate excretion and osmotic tolerance in <it>E. coli </it>K-12 and <it>E. coli </it>B at high density growth |
| title_full_unstemmed | The role of Cra in regulating acetate excretion and osmotic tolerance in <it>E. coli </it>K-12 and <it>E. coli </it>B at high density growth |
| title_short | The role of Cra in regulating acetate excretion and osmotic tolerance in <it>E. coli </it>K-12 and <it>E. coli </it>B at high density growth |
| title_sort | role of cra in regulating acetate excretion and osmotic tolerance in it e coli it k 12 and it e coli it b at high density growth |
| url | http://www.microbialcellfactories.com/content/10/1/52 |
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