Methods for the Economical Production of Biofuel from Biomass

Abstract

Methods for producing a biofuel are provided. Also provided are biocatalysts that convert a feedstock to a biofuel.

What is claimed is: 
     
         1 . A method of making a biofuel, comprising:
 providing a biocatalyst selected to convert a feedstock into the biofuel at a yield of at least 80 percent of theoretical, a productivity of at least 0.75 grams biofuel per liter per hour, and a titer equivalent to a lower one of (i) a solubility limit of the biofuel in water under the process conditions and (ii) 2% (w/w) of the biofuel in water;   providing the biocatalyst selected to have at least two properties from a. to l. as follows:   a. the biocatalyst selected to convert at least two sugars, including each of (i) at least one of a six-carbon sugar and a six-carbon sugar oligomer, and (ii) at least one five-carbon sugar, derived from at least one of starch, cellulose, hemicellulose, and pectin into the biofuel;   b. the biocatalyst exhibiting a level of endotoxin toxicity or exotoxin toxicity, wherein the level of endotoxin or exotoxin toxicity in the biocatalyst has a median lethal dose (LD50) of at least 1000-fold more than the amount present in 1 kilogram of at least one of a DDG and a DDGS product;   c. the biocatalyst containing no DNA markers;   d. the biocatalyst operable to produce the biofuel free of byproducts that would require additional processing steps for removal from the biofuel;   e. the biocatalyst operable at a pH value between about 2 to 10 to produce the biofuel;   f. the biocatalyst selected to have a recoverable productivity from a sudden change of about 1 pH unit from the first pH;   g. the biocatalyst operable within a temperature range of about 20° C. to 60° C. to produce the biofuel;   h. the biocatalyst selected to have a recoverable productivity from a sudden change of about 5° C. from the first temperature;   i. the biocatalyst operable in a medium comprising feedstock;   j. the biocatalyst selected to have a growth rate of at least 0.2 per hour;   k. providing a facultative anaerobic biocatalyst operable at dissolved oxygen concentrations across a range of about 0% to about 0.01% air saturation to produce the biofuel; and   l. providing an anaerobic biocatalyst selected to have a productivity that recovers from an exposure to more than 1% air saturation that lasts for up to three hours;   and cultivating the biocatalyst in a culture medium until a recoverable quantity of the biofuel is produced;   and recovering the biofuel.