Contemporary Alchemy: Turning Chemical Waste into Profit Under Extreme Conditions
EMBARGOED UNTIL: Sunday 5/19, 3 PM MDT
(Symposium Session 72, Paper )
Missouri University of Science and Technology
Rolla, MO, United States
Phone: 573 418 2803
1,3-propanediol is used to make many products, such as paint, adhesives, perfumes, and even personal care products. The compound is expensive, and up until very recently, has been synthesized from crude oil. We have discovered that the bacterium, Halanaerobium hydrogenoformans, can convert glycerol, a common waste product of biodiesel production, into 1,3-propanediol under extreme conditions, a pH of 11 and 7% salt. We can get a conversion of about 55% with our current process. We have also found that the organism can grow in media containing up to 1M glycerol and that it can thrive in a solution containing crude waste glycerol.
This research has been conducted at the Missouri University of Science and Technology by Daniel Roush, a master’s student, with assistance of Dylan Courtney, a Chemical Engineering undergraduate student, and under the advisement of Melanie Mormile (PI), Dwayne Elias, and Oliver Sitton. Funding was provided by the Department of Biological Sciences at the Missouri University of Science and Technology. This research will be presented at the American Society for Microbiology General Meeting at the Colorado Convention Center in Denver Colorado, on May 19 between 3:00 PM and 5:30 PM.
Our work has focused on using extremophiles to bypass steps found in common chemical processes. These steps involve making the processing streams more tolerable to bacteria for biological conversion. By adding large amounts of acids or bases, or using large amounts of energy to remove salts and impurities, industries make the conditions suitable for non-extremophilic life. What we have done is utilize extremophilic microorganisms can thrive in the presence of untreated chemical waste, and can skip these steps to synthesize chemicals in an inexpensive and environmentally friendly manner. Specifically our organism, Halanaerobium hydrogenoformans, grows in conditions with high pH (about pH 11 which is similar to laundry detergent) and high salt concentrations (7% salt, double that of the ocean). These conditions are found in treated biomass used to produce biofuels like ethanol and hydrogen, and crude glycerol generated during biodiesel production. We found that H. hydrogenoformans can ferment some of these waste chemicals into useful compounds. Our current target, 1,3-propanediol, is used frequently in the chemical industry as a building block for many common products, like adhesives, fragrances, and coatings like paint. Currently, processes use components of crude oil or glucose derived from corn to synthesize 1,3-propanediol. However, our process can utilize waste glycerol for a more economical and environmentally friendly process.
Our goal is to develop new technologies with extremophiles and build them up to full scale industrial processes. Our first step is to identify a pathway with a profitable return; we utilized the full genome sequence of our organism to identify the pathway with potential. We probed the metabolism of the organism to see how it reacts and tolerates various conditions and also optimize the production of 1,3-propanediol. We examined the growth of Halanaerobium hydrogenoformans to find out how much glycerol the organism could tolerate. Glycerol acts very much like salt, in the sense that it increases the pressure put onto the bacteria. We are currently examining how much 1,3-propanediol the organism can tolerate to better understand how the organism will behave in an industrial setting. We identified that supplementing the growth media with Vitamin B12 can increase 1,3-propanediol production significantly. We varied the amount of Vitamin B12 in the media and kept a constant concentration of glycerol. We used high pressure liquid chromatography analysis to measure the amount of glycerol that was used, and the amount of 1,3-propanediol that was produced. This process separates different compounds due to differences in their chemical properties. Our current data is giving us a conversion rate of about 60% at pH11 and a media containing 7% salt and 0.2% glycerol. Our final step involves examining how the bacteria behave in conditions more similar to a true industrial process. We have begun to look at how the organism grows and produces 1,3-propanediol while feeding on waste glycerol. We are also examining the organism’s tolerance to methanol, a common contaminant in waste glycerol, and to various types of salts, which can affect production costs.
As we begin to better understand extremophiles and how they interact with their environments, we can begin to wean ourselves off crude oil by finding biological processes that are both truly environmentally friendly and most importantly, economical to companies and taxpayers. Our processes, using Halanaerobium hydrogenoformens, are just small steps in developing haloalkaliphiles for use in industry. More famous applications of extremophiles have been cold water laundry detergents, and heat-stable enzymes used in food processing. We hope to take this further and provide avenues to replace our dependence on crude oil beyond energy, by producing components of paints, adhesives, and cosmetics; we can begin to move towards an oil independent economy.