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					                                       Adding Value
                                       to Biofuel Waste
by Stacy Kish, CSREES                  Biofuels represent the best sustain-         there are many potential uses for
                                       able, secure, and renewable alternative      the substance, it is difficult to break
                                       to fossil fuels. Unfortunately, biofuel      it down into products with greater
What do you get                        production is beset by the same              economic value.
when you cross E. coli                 problem as traditional petroleum                  With funding from USDA’s
with biofuel waste products?           refining – excess waste. In traditional      Cooperative State Research, Education,
A new process that may                 refining, only about 60 percent of the       and Extension Service (CSREES), Ramon
revolutionize the economic             crude oil becomes gasoline, the rest         Gonzalez at Rice University developed
                                       is used to make other products. Similarly,   a new fermentation process that uses
development of the growing
                                       as biofuel production increases, the         E. coli to convert glycerin into high-value
biofuel industry. >>
                                       market is being flooded with its waste       chemicals, like succinate.
                                       byproducts, specifically glycerin, also           Succinate and its derivatives
                                       known as glycerol.                           have an annual domestic market
                                            Glycerin is cheap and abundant          of more than $1.3 billion.
                                       in the current marketplace. Although                                   continued next page >>

                                                                                                                                       nri_impact_062_09_19_08_biofuel.pdf, pg. 1/2 | CSREES Communications Staff

Right: Ramon Gonzalez (center),
the William W. Akers Assistant
Professor in Chemical and
Biomolecular Engineering, joins
graduate students (from left)
James Clomburg, Clementina
Dellomonaco, Ashutosh Gupta
and Ruiqiang Sun in the lab.
Credit: Jeff Fitlow, Rice University
                                                      >> continued from previous page

                                                      Succinate is used in a variety of products
                                                      including flavoring agent in food and
                                                      beverages, an intermediate compound
                                                      for dyes and perfumes, and medical
                                                      applications. Another product, formate,
                                                      is principally used as a preservative and
                                                      antibacterial agent in livestock feed.
                                                            Most of the waste glycerin comes
                                                      from the production of biodiesel, one
                                                      of the two types of biofuels (the other
Above: Ramon Gonzalez, the William W. Akers           being ethanol). Biodiesel is converted
Assistant Professor in Chemical and Biomolecular
Engineering, and Syed Shams Yazdani,                  from a variety of oils, including rape-
postdoctoral research associate, have identified      seed and soybean oils, mustard, flax,
the metabolic processes and conditions that
allow a known strain of E. coli to convert glycerin
                                                      sunflower, and palm oil, waste vegetable
into ethanol.                                         oil, animal fat oil, and algae.
Credit: Jeff Fitlow, Rice University                        About one pound of glycerin
                                                      is produced for every 10 pounds              The research team is now working
                                                      of biodiesel. According to the National      to further understand the biochemical
                                                      Biodiesel Board, U.S. companies              pathways used by the organism to break
                                                      produced about 450 million gallons           down the glycerol so new organisms
                                                      of biodiesel in 2007. With 60 new plants     can be engineered for the production
References                                            capable of producing 1.2 billion gallons     of fuels and other chemicals from
Gonzalez, R. Murarka. A., Dharmadi, Y.,
                                                      of biofuel slated for operation by 2010,     glycerol.
and Yazdani, S. S. 2008. A New Model                  an answer to the glycerin question                 “Our goal goes beyond using this
for the Anaerobic Fermentation of Glycerol            cannot come soon enough.                     discovery for a single process,” Gonzalez
in Enteric Bacteria: Trunk and Auxiliary
                                                            “Biodiesel producers used to sell      said. “We want to use the technology
Pathways in Escherichia coli. Metab. Eng.
(In Press, doi:10.1016/j.ymben.2008.05.001).          their leftover glycerin, but the rapid       as a platform for the ‘green’ production
                                                      increase in biodiesel production has         of a whole range of high-value
Murarka. A., Dharmadi, Y., Yazdani, S. S.,
and Gonzalez, R. 2008. Fermentative                   left them paying to get rid of it,”          products.”
Utilization of Glycerol in Escherichia coli           Gonzalez said. “The new metabolic                  CSREES funded this research
and its Implications for the Production               pathways we have uncovered pave              project through the National
of Fuels and Chemicals. App. Environ.
Microbiol. 74 (4): 1124-1135.                         the way for the development of new           Research Initiative Biobased Products       nri_impact_062_09_19_08_biofuel.pdf, pg. 2/2 | CSREES Communications Staff

                                                      technologies to convert this waste           and Bioenergy Production Research
Yazdani. S. S. and Gonzalez, R. 2007. Anaerobic
Fermentation of Glycerol: A Path to Economic          product into high-value chemicals.”          program. Through federal funding
Viability for the Biofuels Industry. Curr. Opin.            Technologies based on Gonzalez’s       and leadership for research, education
Biotechnol. 18 (3): 213-219.                          work have been licensed to Glycos            and extension programs, CSREES
Dharmadi, Y., Murarka, A., and Gonzalez,              Biotechnologies Inc., a Houston-based        focuses on investing in science
R., (2006). Anaerobic Fermentation of
                                                      startup company that plans to open its       and solving critical issues that affect
Glycerol by Escherichia coli: A New Platform
for Metabolic Engineering. Biotechnol. Bioeng.        first demonstration facility within the      people’s daily lives and the nation’s
94 (5): 821-829 (Accelerated Publication).            next 12 months.                              future. For more information,

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