Date of Award
Doctor of Philosophy (PhD)
Chemistry & Biochemistry
Cyanobacteria are one of the oldest known lifeforms on Earth and found in environments ranging from aquatic to terrestrial ones. They are contributors to a several key biochemical processes and their presence in ecosystems can be critical in helping other lifeforms thrive. However, these organisms have the potential to grow into immense algal blooms which can be detrimental. With their advantages of being highly adaptable, and having the ability to produce useful products, they are also used for biotechnology purposes. This research seeks to investigate how the impact of humans whether through synthetic biology or climate change could influence natural selection and adaption in these organisms. The first aim seeks to address whether genetically engineered cyanobacteria’s usage in biotechnology poses a biosafety risk to humans and animals. Experimental studies showed that genetically engineered Thermosynechococcus elongatus BP-1 was able to horizontally transfer antibiotic resistance to both Gram-negative and Gram-positive bacteria that are naturally found in the environment: Bacillus licheniformis, Staphylococcus epidermis and Serratia marcescens. This finding has ramifications for global concerns over the rise of antibiotic resistance in microorganisms. The second aim focused on investigating genomic adaption to climate change conditions predicted for the year 2100. Genomic sequencing, assembly and phylogenomic characterization for two model cyanobacteria, a marine, non-toxin producing Synechococcus sp. and a freshwater, toxin producing Microcystis aeruginosa provided a deeper understanding of these organisms and laid the foundation for evolutionary studies. A genomic analysis to identify genetic signatures of climate change following exposure to high CO2 conditions revealed a small number of mutations, mainly in RNA informational genes and transposases, although most mutations appear to be ecological lab adaptions. Surprisingly, the Microcystis aeruginosa was found to be co-existing in culture with a novel species of Lacibacter. In aim 3 the genome of this bacteria was sequenced, assembled, and characterized providing deeper insight into this less well-known genus. An analysis of mutations following exposure to high CO2 conditions also revealed that the dominant locations were RNA informational genes and had more mutations than the cyanobacteria. Physiological characterization was conducted, and this organism was named Lacibacter prasino.
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Hept, Megan A..
"Human Impact on Cyanobacteria and Their Genetics: Potential Implications on Health, Evolution, and the Environment"
(2023). Doctor of Philosophy (PhD), Dissertation, Chemistry & Biochemistry, Old Dominion University, DOI: 10.25777/qfyk-xn26
Available for download on Wednesday, September 27, 2028