Full metadata
Title
Investigation of the Effects of Stress Related Genes on Escherichia coli Fermentation
Description
The current use of non-renewable fossil fuels for industry poses a threat for future generations. Thus, a pivot to renewable sources of energy must be made to secure a
sustainable future. One potential option is the utilization of metabolically engineered
bacteria to produce value-added chemicals during fermentation. Currently, numerous
strains of metabolically engineered Escherichia coli have shown great capacity to
specialize in the production of high titers of a desired chemical. These metabolic systems,
however, are constrained by the biological limits of E. coli itself. During fermentation, E.
coli grows to less than one twentieth of the density that aerobically growing cultures can
reach. I hypothesized that this decrease in growth during fermentation is due to cellular
stress associated with fermentative growth, likely caused by stress related genes. These
genes, including toxin-antitoxin (TA) systems and the rpoS mediated general stress
response, may have an impact on fermentative growth constraints. Through
transcriptional analysis, I identified that the genes pspC and relE are highly expressed in
fermenting strains of both wild type and metabolically engineered E. coli. Fermentation
of toxin gene knockouts of E. coli BW25113 revealed their potential impacts on E. coli
fermentation. The inactivation of ydcB, lar, relE, hipA, yjfE, chpA, ygiU, ygjN, ygfX,
yeeV, yjdO, yjgK and ydcX did not lead to significant changes in cell growth when tested
using sealed tubes under microaerobic conditions. In contrast, inactivation of pspC, yafQ,
yhaV, yfjG and yoeB increased cell growth after 12 hours while inactivation yncN
significantly arrested cell growth in both tube and fermentation tests, thus proving these
toxins’ roles in fermentative growth. Moreover, inactivation of rpoS also significantly hindered the ability of E. coli to ferment, suggesting its important role in E. coli
fermentation
Date Created
2022
Contributors
- Hernandez, Michaella (Author)
- Wang, Xuan (Thesis advisor)
- Nielsen, David (Committee member)
- Varman, Arul (Committee member)
- Arizona State University (Publisher)
Topical Subject
Resource Type
Extent
42 pages
Language
eng
Copyright Statement
In Copyright
Primary Member of
Peer-reviewed
No
Open Access
No
Handle
https://hdl.handle.net/2286/R.2.N.171698
Level of coding
minimal
Cataloging Standards
Note
Partial requirement for: M.S., Arizona State University, 2022
Field of study: Microbiology
System Created
- 2022-12-20 06:19:18
System Modified
- 2022-12-20 06:19:18
- 1 year 10 months ago
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