Earth Day Series Day 11: Microbial World for Renewable Fuels and Chemicals Production

by Anahita Bharadwaj* (Advanced Biofuels USA) The versatile world of microorganisms is a perfect source for the production of a variety of biobased fuels, chemicals and materials. Microorganisms have the ability to break down biomass, components of these biomass or other materials (e.g., CO2, organic acids) through the process of fermentation and convert them into various value-added products.

The most popular among these is the conversion of biomass sugars into ethanol by yeasts… and this technology has been in use for thousands of years, first for human consumption and now, also for energy production.

The possibilities for production of bio-based chemicals and materials are endless – through the potential use of thousands of types of microbes, both natural and engineered, in pure cultures (solo) or mixed cultures (groups of microbes working together).

Typically, for biomass-based fermentation, the complex structure of plant material is first broken down using physical, chemical, biological and/or enzymatic strategies through the process of pretreatment. The biological and enzymatic breakdown uses specialized microorganisms with the ability to breakdown cellulose and hemicellulose in plant material.

Subsequently, the sugars released from this process are broken down by the same or a different group of microbes into various chemicals. Some examples of these products are organic acids (like acetic acid, butyric acid, lactic acid) and alcohols (like ethanol, butanol, 2,3-butanediol).

Further downstream, these chemicals could be used directly or converted into materials (e.g., lactic acid as a starting point for plastic; 2,3-butanediol as a starting point for synthetic rubber). Some mixed populations of microorganisms also work together to break down biomass into organic acids and methane as well!

Interestingly, some unique microorganisms have the ability to use non-traditional material as their energy source and produce biochemicals. For example, syngas (CO and H2) can be converted into various alcohols and acids through fermentation with these unique microorganisms.

Recently, there has been exciting research and discovery of microorganisms with the ability to degrade plastic into environmentally friendly end products. Could this be the breakthrough we need to convert an otherwise existential threat and problematic waste stream into a source of fuels and chemicals?

Fermentation technology is currently used in various technologies including production of medicines, antibiotics and enzymes. It is also used extensively in the bioenergy industry, primarily for the production of bioethanol and biomethane.

Current research shows that more interesting chemicals can be produced through this method with single or mixed populations of microbes. These technologies could directly replace the current source stream for these produced, which is fossil-based.

-Next time you go hiking or into the wilderness, observe the beautiful living world around you! The fallen tree trunk with interesting biofilms, mushrooms and bugs around is nature doing its wonders in breaking down this material into simpler molecules.

-Reflect on the idea that human beings, with our knowledge and effort, have developed technologies to use some of these biological miracles to produce valuable food, fuels and chemicals!

*Anahita Bharadwaj, Ph.D. graduated from Penn State University with a PhD in Agricultural and Biological Engineering and currently works as a postdoc at the National Renewable Energy Lab in Colorado, where she conducts research associated with the production of value-added biofuels and biochemicals. She hopes to contribute towards sustainable development and climate mitigation through her expertise in bioprocess and bioenergy systems engineering. She is also very interested and involved with sustainability research and science communication.