By harnessing the principles of evolution, researchers have effectively created hybrids of bacteria and yeast capable of performing photosynthetic carbon assimilation, generating cellular energy, and facilitating yeast growth without relying on conventional carbon sources like glucose or glycerol. Through the engineering of photosynthetic cyanobacteria to coexist within yeast cells, these bacteria-yeast hybrids can synthesize crucial hydrocarbons, opening up new biotechnological avenues for energy sources that do not rely on petroleum, as well as further applications in synthetic biology and the study of evolution.
“All nucleated cells contain various organelles, including mitochondria and chloroplasts, which serve distinct purposes and possess their own DNA,” explained Angad Mehta, a chemistry professor at the University of Illinois Urbana-Champaign, who led the Illinois research team. “For years, scientists have speculated that complex life began when these types of cells merged through a process known as endosymbiosis.”
In a prior investigation, Mehta’s group demonstrated that lab-created cyanobacteria-yeast hybrids, or endosymbionts, could provide the yeast with photosynthetically produced ATP but not sugars. In their latest research, the team engineered cyanobacteria to decompose sugars and release glucose, subsequently combining them with yeast cells to form hybrids capable of thriving in CO2 environments, utilizing the sugars and energy generated by the bacteria.
The study’s results are published in the journal Nature Communications.
With the capability to transform a non-photosynthetic organism into a photosynthetic hybrid, the team concentrated on exploring how these chimeras could be utilized to bioengineer new metabolic routes to produce valuable substances like limonene, a simple hydrocarbon found in citrus.
“Limonene is a fairly straightforward yet significant molecule within a substantial market,” noted Mehta, who is also associated with the Carl R. Woese Institute for Genomic Biology. “This proof-of-concept study demonstrates that we can engineer pathways in our hybrids to photosynthetically generate limonene, which belongs to a category of molecules called terpenoids, serving as precursors for numerous high-value products, including fuels and drugs that combat cancer and malaria.”
Mehta expressed that their ambitions for this research are to explore whether their technique can yield more intricate compounds, such as fuels and pharmaceuticals, and if so, to scale the process for commercial viability.
“I think it would be fantastic to reach a point where we can guarantee that each bit of carbon in a valuable product comes from CO2,” said Mehta. “This might represent one method of recycling CO2 waste in the future.”
The researchers added that as they strive to better understand and refine endosymbiotic systems to boost biotechnology, they will inevitably address numerous fundamental questions of evolution. “This will occur regardless of our intent,” said Mehta. “We consistently monitor how our efforts can potentially clarify some of the mysteries surrounding the evolution of life. I believe the best way to develop endosymbiotic systems is by simulating the evolutionary process in the lab. Discovering answers to some of biology’s most significant questions will happen organically.”
Illinois researchers Yang-le Gao, Jason Cournoyer, Bidhan De, Catherine Wallace, Alexander Ulanov, and Michael La Frano were also co-authors on this study. The research received support from the National Institutes of Health.
