Synthetic Biology for Autotrophic and Heterotrophic Production of Ethanol

<p>Growing energy demand and rising levels of greenhouse gases has put massive strain on the global environment. Alternatives to fossil fuels are being developed in an attempt to curb climate change. Biotechnology has made large strides in order to create a completely renewable energy source by genetically modifying microbes to produce biofuels and other “green” high value compounds. In this thesis project, (1) <em>E. coli</em> ATCC9637 <em>(E. coli W)</em> was genetically modified to produce bioethanol from beet juice which contains mainly sucrose. The ethanol productivity by engineered <em>E. coli</em> W was 18.8 mg/L/H/OD₆₀₀. <br />(2) Cyanobacterium <em>Anabaena</em> sp. PCC7120 was successfully engineered to produce and secrete biofuel ethanol using CO₂, water and sunlight.<br />(3) Another attempt in this study was made to increase production of bioethanol in ethanol-producing <em>Anabaena</em> strain by introducing a supplementary CO₂-fixing photorespiratory bypass pathway. Although Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) is responsible for the majority of carbon assimilation on Earth, RubisCO has poor specificity between CO₂ and O₂ which can lead to photorespiration and ultimately the loss of fixed carbon and nitrogen. The 3-hydroxypropionate (3-HPA) bypass was introduced into ethanol-producing Anabaena strain in an attempt to increase CO₂-fixation and then increase ethanol production. Introduction of the 3-HPA bypass into <em>Anabaena</em> showed only a marginal increase photosynthetic activity and a decrease in growth rate. Additional genetic manipulation would be required to alleviate bottlenecks and toxic intermediates in order to create a fully functioning supplementary CO₂-fixation pathway in <em>Anabaena</em> 7120.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis - Open Access

Discipline thesis:degree_discipline

Biology and Microbiology

Year dc:date.available

2016

Author dc:creator

• Braselton, Nathanael

Contributors dc:contributor

• Ruanbao Zhou

• biotechnology
• metabolic engineering
• microbiology
• synthetic biology
• Genomics

Licence

• http://rightsstatements.org/vocab/InC/1.0/

Repository record dc:identifier

https://openprairie.sdstate.edu/etd/1100

OAI identifier oai:identifier

oai:openprairie.sdstate.edu:etd-2101