title: Utilizing protein-lean coproducts from corn containing recombinant pharmaceutical proteins for ethanol production.
abstract: Protein-lean fractions of corn (maize) containing recombinant (r) pharmaceutical proteins were evaluated as a potential feedstock to produce fuel ethanol. The levels of residual r-proteins in the coproduct, distillers dry grains with solubles (DDGS), were determined. Transgenic corn lines containing recombinant green fluorescence protein (r-GFP) and a recombinant subunit vaccine of Escherichia coli enterotoxin (r-LTB), primarily expressed in endosperm, and another two corn lines containing recombinant human collagen (r-CIα1) and r-GFP, primarily expressed in germ, were used as model systems. The kernels were either ground and used for fermentation or dry fractionated to recover germ-rich fractions prior to grinding for fermentation. The finished beers of whole ground kernels and r-protein-spent endosperm solids contained 127-139 and 138-155 g/L ethanol concentrations, respectively. The ethanol levels did not differ among transgenic and normal corn feedstocks, indicating the residual r-proteins did not negatively affect ethanol production. r-Protein extraction and germ removal also did not negatively affect fermentation of the remaining mass. Most r-proteins were inactivated during the mashing process used to prepare corn for fermentation. No functionally active r-GFP or r-LTB proteins were found after fermentation of the r-protein-spent solids; however, a small quantity of residual r-CIα1 was detected in DDGS, indicating that the safety of DDGS produced from transgenic grain for r-protein production needs to be evaluated for each event. Protease treatment during fermentation completely hydrolyzed the residual r-CIα1, and no residual r-proteins were detectable in DDGS.
authors.affiliation: Department of Food Science and Human Nutrition, Center for Crops Utilization Research, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Ilankovan
authors.initials: I
authors.lastname: Paraman
authors.forename: Lorena
authors.initials: L
authors.lastname: Moeller
authors.forename: M Paul
authors.initials: MP
authors.lastname: Scott
authors.forename: Kan
authors.initials: K
authors.lastname: Wang
authors.forename: Charles E
authors.initials: CE
authors.lastname: Glatz
authors.forename: Lawrence A
authors.initials: LA
authors.lastname: Johnson
mesh_terms: D000821:Animal Feed; D056804:Biofuels; D003094:Collagen / Q000032:analysis; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006801:Humans; D030821:Plants, Genetically Modified / Q000737:chemistry*; D011994:Recombinant Proteins / Q000032:analysis* / Q000096:biosynthesis; D012639:Seeds / Q000737:chemistry / Q000378:metabolism; D003313:Zea mays / Q000737:chemistry* / Q000378:metabolism
chemical_list: D056804:Biofuels; D011994:Recombinant Proteins; D000431:Ethanol; D003094:Collagen