Presentation by Professor Shota Atsumi (UC Davis) on using engineered cyanobacteria to recycle CO2 into useful chemicals. He frames the work in the context of US DOE priorities and climate targets, describes using Synechococcus elongatus engineered to produce 2,3-butanediol (a fuel/chemical precursor) from CO2, and reports laboratory results reaching 2.4 g/L after 20 days and a 1.8× improvement via translational tuning. The talk also motivates the need for reducing CO2 emissions (40–70% by 2050 to limit warming) and contrasts biofuel strategies that compete with food crops.
Questions this video answers
Synechococcus elongatus.
2,3-butanediol.
2.4 gram per liter after 20 days.
1.8-fold improvement.
Reduce carbon emissions by 40–70% by 2050.
Chapters
It's a pleasure hosting Professor Shota at Sumi to Emory Pharma's speaker series. Shota did his PhD at Kyoto University, Postdoctoral fellowship in Arizona and also additional postdoc at UCLA and he joined the faculty of UC Davis. He is also the recipient of Presidential Green Chemistry Challenge Award, UC Davis Hellman Fellowship and NSF Career Award and UC Davis Chancellor Fellow. It's an honor to have him. I think he's teaching at one of the most amazing universities in the United States, which happens to be my alma mater as well. It's an honor to have Professor Otsumi presenting on some of his carbon capture technology, which is of great interest to Emory Pharma, to me and to many of us who are really concerned about global warming and you know, the general condition of sustainability and really look forward to his presentation. Shota, please.
Okay, thank you Ron for invitation and kind introductions. I'm happy to share our research with MRE farmers. Okay, so we are trying to recycle CO2 and we want to produce useful chemical from CO2. Then this motivation fit to recent presidential report from President Biden and especially at DOE Park Department Energy they put several theme to focus next 10, 20 years especially stem 2 and 4 fit to our research. So theme 2 want to produce chemical renewable and theme 4 want to remove carbon dioxide from atmosphere. And especially theme 2 wanna reduce greenhouse gas emission from chemical industry. And also THM2 develop a new method to reduce carbon emission. As we know our daily life using out of energy, which means producing out of carbon dioxide. And last 50 years atmospheric CO2 concentration increased by 25%. It's a lot and it caused global warming. But if we want to keep good environment for next generation, we need to keep 2 degree increase by 2100. But if we maintain current daily life, we're going to get a 4.5 degree increase by 2500. But to achieve 2 degree increase, we need to reduce carbon emission by 40 to 70% by 2050, which is a lot. So zero carbon fuel is really important target for our environment. So to maintain clean environment for next generation, we need to reduce carbon emission from chemical and fuel industry. And to do so we are using biological system called photosynthesis plant use this system to convert solar energy to biological energy, then biology can fix CO2. So we even use this advantage to produce chemical and people use this strategy for a long time to produce biofuel. And the most popular biofuel is a corn ethanol. First step, plant pick CO2 and produce corn and convert corn to fermentable sugar and last step is a microbial fermentation. But this strategy competes with food production. We want to eat corn and not use for biofuel. Then current main focus is use non food part. But the non food part is really challenging to convert to a fermentable sugar. So we want to skip slow and challenging step. To produce biochemical from CO2 we use a photosynthetic bacteria called cyanobacteria so they can do photosynthesis and CO2 fixation. So they are bacteria. So genetical manipulation is much easier than plant. And also they can grow much faster than plant. So we want to use cyanobacteria to combat CO2 to biochemicals in nature. They don't need to produce chemicals at all. So we need to install new functions. This case biosynthetic pathway. To produce useful chemicals from CO2 we use a 2,3 butane diode as a model system. 2,3 butane diode is a great chemical feedstock. We can produce fuel molecule and also a rubber and plastic precursor. Also we can use as solvent. Currently these chemicals come from petroleum. So if we can produce 2,3 butanediol from CO2, we can reduce carbon emission and petroleum dependency. We are using model cyanobacterium Synecoccus elongatus and people use this strain for photosynthetic photosynthesis research and the circadian clock research. So we have all required genetic modification tool for dystron. So this strain can fix CO2 and produce pyruvate. Pyruvate is a central metabolite, but they cannot produce 2,3 butane diol. So we need to install at least three enzymes to convert a pyruvate to 2,3 butane diol. After some optimization we got 2.4 gram per liter of 2,3 butanediol after 20 days, which is a relatively high titer in cyanobacteria chemical production. But still we need out of improvement for commercialization. So we tune up expression level of our 2,3 butane diol pathway gene changing translational efficiency. Then we got a 1.8 fold improvement.
