Found across oceans and in freshwater environments, including in lakes and streams throughout Tennessee, cyanobacteria is the oldest organism on the Earth to perform photosynthesis. Known commonly as blue-green algae, cyanobacteria grow well in warm, carbon-rich waters and contribute around 20% of oceanic primary production, or the process of removing carbon dioxide from water.
Scientists at the Oak Ridge National Laboratory, or ORNL, used the gene-editing technology CRISPR to change parts of the genetic code of Synechococcus cyanobacteria. In a study published in the Proceedings of the National Academy of Sciences, scientists highlighted the genes that were responsible for the bacteria thriving at different temperatures. They found that small changes in the DNA sequence could result in improvements in growth for cyanobacteria under environmental stressors, like colder temperatures or changes in sunlight.
“The main reason that we were interested in utilizing CRISPR as a tool for a genome wide library is because there’s still a lot of genes that we don’t know the function of,” said Carrie Eckert, synthetic biology group leader at ORNL and co-chief science officer of the Center for Bioenergy Innovation. “So this is a way to get, in a very global perspective of the genetics of an organism, to get at the genes that might be responsible for certain traits.”
This project is one of many that is working towards understanding the genetic makeup of microbes in general. If scientists know what genes change their ability to grow in warmer temperatures or which helps them to produce energy with very little sunlight, they can adapt plants and algae for a changing climate.
“Because it’s a little tiny chloroplast, it can give us some insight into how to potentially make plants more resilient,” Eckert said. “If we find that changing the expression of a particular gene can result in better growth under stress conditions, we can then potentially port that into other plants.”
One of the other reasons scientists are researching cyanobacteria is because of their potential to be a biofuel. Synechococcus cyanobacteria grow relatively quickly and only need water and carbon to grow, making it an easy resource.
“There’s a lot of carbon out in the environment that’s currently not used,” said Eckert. “The way we look at things is like, what carbon sources are out there that are available that we can utilize microbes and plants to use to make something useful.”
Synechococcus cyanobacteria may not be the perfect fix, however. While they currently contribute around 20% of global carbon cycling, or the process of removing carbon dioxide from water, they do have a downside. Synechococcus have the potential to produce large harmful algal blooms, or HABs, where algae produce toxins and all the oxygen in the water is eaten up. In 2024, Ijams Nature Center temporarily closed Meads Quarry Lake after a type of cyanobacteria bloomed, producing a toxin harmful to humans and pets in large concentrations.
Genetic modification has been around for a long time, however, from simple editing through selective breeding to now the more complex genetic editing of CRISPR. Eckert said understanding each gene like this will help scientists in future projects.
“We’ve been doing editing of organisms for a long time,” Eckert said. “So this is a way where we can precisely target a gene that we know will have a particular effect, and it’s actually just faster and safer in the long run.”