Date of Award

Summer 2021

Document Type


Degree Name

Master of Science (MS)


Chemistry & Biochemistry



Committee Director

Lesley H. Greene

Committee Director

James W. Lee

Committee Member

Patrick G. Hatcher

Committee Member

Erin B. Purcell


As the world population is increasing and societies become more technology driven, there is an imperative to develop ‘green energy’ sources to protect our planet. Cyanobacteria that have been genetically engineered to produce organic compounds that may be burnt as fuels show great potential, as they are an environmentally friendly and self-renewable, net carbon-neutral option. However, there are potential risks in the development and use of genetically modified organisms (GMOs). We need to understand in advance the risks that GMOs may pose to our environment and to animal and human health. This will enable experimental procedures, containment strategies and policies to be developed to prevent accidents and eliminate potential harmful effects of GMOs in the environment such as sharing antibiotic genes to native microorganisms. My research seeks to assess the bio-risk posed by engineered cyanobacteria and their capability of transferring genes of antibiotic resistance to other bacteria, they may encounter in their environment outside of laboratory conditions. Here genetically engineered (GE) cyanobacteria that contain antibiotic resistance genes commonly used as selective markers, are being studied and their ability to horizontally transfer to wild-type bacterial strains. In aim one, the plasmid vector that carries the transgenes to confer antibiotic resistance and to theoretically produce biofuel was introduced into the cyanobacteria, Thermosynechococcus elongatus BP1 and select other gram-negative bacterial strains, Escherichia coli K12, Escherichia coli DH5α, and Pseudomonas putida KT2440, to assess their ability to carry the plasmid and obtain antibiotic resistance. In the second aim, the ability for the plasmid to undergo horizontal gene transfer (HGT), from GE cyanobacteria to two different strains of E. coli was determined. In the third aim, the ability of P. putida KT2440 to uptake the plasmid via HGT from GE cyanobacteria was studied. This research also examines the fundamental mechanisms of horizontal gene transfer, which is foundational to microbial life and not completely understood. The results reveal that HGT occurs between our model cyanobacteria and E. coli strains but not Pseudomonas. This research provides foundational knowledge to help develop policies and safeguards for the safe design and use of GMOs.


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