|LOPEZ-NUNEZ, JUAN CARLOS - National Federation Of Columbia Coffee Growers|
|JONES, MARJORIE - Illinois State University|
|GALINDO-LEVA, LUZ ANGELA - Illinois State University|
|RODRIGUEZ-VALENCIA, NELSON - National Federation Of Columbia Coffee Growers|
|TASAKI, KEN - Mitsubishi Chemical Usa, Inc|
|BROWN, ROBERT - Iowa State University|
|DARZINS, AL - Gas Technology Institute (GTI)|
|BRUNNER, LANE - Gen2 Energy|
Submitted to: Applied Microbiology and Biotechnology
Publication Type: Review Article
Publication Acceptance Date: 7/25/2014
Publication Date: 9/16/2014
Publication URL: http://handle.nal.usda.gov/10113/60616
Citation: Hughes, S.R., Lopez-Nunez, J.C., Jones, M.A., Moser, B.R., Cox, E.J., Lindquist, M.R., Galindo-Leva, L., Rodriguez-Valencia, N., Tasaki, K., Brown, R.C., Darzins, A., Brunner, L., et al. 2014. Sustainable conversion of coffee and other crop wastes to biofuels and bioproducts using combined biochemical and thermochemical processes in a multi-stage biorefinery concept. Applied Microbiology and Biotechnology. 98(20):8413-8431.
Technical Abstract: The environmental impact of agricultural waste from processing of food and feed crops is an increasing concern worldwide. Concerted efforts are underway to develop sustainable practices for the disposal of residues from processing of such crops as coffee, sugarcane, or corn. Coffee is crucial to the economies of many countries because its cultivation, processing, trading, and marketing provide employment for millions of people. In coffee-producing countries, improved technology for treatment of the significant amounts of coffee waste is critical to prevent ecological damage. This mini-review discusses a multi-stage biorefinery concept with the potential to convert waste produced at crop processing operations, such as coffee pulping stations, to valuable biofuels and bioproducts using biochemical and thermochemical conversion technologies. The initial bioconversion stage uses a mutant Kluyveromyces marxianus yeast strain to produce bioethanol from sugars. The resulting sugar-depleted solids (mostly protein) can be used in a second stage by the oleaginous yeast Yarrowia lipolytica to produce biobased ammonia for fertilizer and are further degraded by Y. lipolytica proteases to peptides and free amino acids for animal feed. The lignocellulosic fraction can be ground and treated to release sugars for fermentation in a third stage by a recombinant cellulosic Saccharomyces cerevisiae, which can also be engineered to express valuable peptide products. The residual protein and lignin solids can be jet cooked and passed to a fourth-stage fermenter where Rhodotorula glutinis converts methane into isoprenoid intermediates. The residues can be combined and transferred into pyrocracking and hydroformylation reactions to convert ammonia, protein, isoprenes, lignins, and oils into renewable gas. Any remaining waste can be thermoconverted to biochar as a humus soil enhancer. The integration of multiple technologies for treatment of coffee waste has the potential to contribute to economic and environmental sustainability.