Processing biomass

Abstract

Provided herein are methods of increasing the efficiency of biomass saccharification. In particular, the methods include ways of avoiding feedback inhibition of enzymatic reactions during the production of useful products. The methods also include saccharifying recalcitrance-reduced lignocellulosic biomass and adding an isomerization agent to the saccharified biomass. The saccharified biomass can be further converted into products by a microorganism.

1 .- 21 . (canceled) 
     
     
         22 . A method of producing one or more products, the method comprising:
 saccharifying recalcitrance-reduced biomass to produce a saccharified mixture comprising glucose and xylose;   adding an isomerization agent to the saccharified mixture to produce an isomerized mixture comprising glucose, xylose and fructose; and   contacting the isomerized mixture with a microorganism capable of converting glucose, but not xylose, to a product.   
     
     
         23 . The method of  claim 22 , wherein the recalcitrance-reduced biomass is produced by treating biomass with accelerated electrons. 
     
     
         24 . The method of  claim 22 , wherein the recalcitrance-reduced biomass is wood, particle board, forestry wastes, sawdust, aspen wood, wood chips, grasses, switchgrass,  miscanthus , cord grass, reed canary grass, grain residues, rice hulls, oat hulls, wheat chaff, barley hulls, agricultural waste, silage, canola straw, wheat straw, barley straw, oat straw, rice straw, jute, hemp, flax, bamboo, sisal, abaca, corn cobs, corn stover, soybean stover, corn fiber, alfalfa, hay, coconut hair, sugar processing residues, bagasse, beet pulp, agave bagasse, algae, seaweed, manure, sewage, offal, agricultural or industrial waste, arracacha, buckwheat, banana, barley, cassava, kudzu, oca, sago, sorghum, potato, sweet potato, taro, yams, beans, favas, lentils, peas, or mixtures of any of these. 
     
     
         25 . The method of  claim 22 , wherein one or more cellulases saccharify the recalcitrance-reduced biomass. 
     
     
         26 . The method of  claim 25 , wherein the one or more cellulases is an endoglucanase, an exo-splitting glucanase, a cellobiase, or a combination thereof. 
     
     
         27 . The method of  claim 22 , wherein the isomerization agent comprises an enzyme. 
     
     
         28 . The method of  claim 27 , wherein the enzyme is immobilized on a support. 
     
     
         29 . The method of  claim 27 , wherein the enzyme is xylose isomerase. 
     
     
         30 . The method of  claim 29 , wherein the xylose isomerase is produced from  Pseudomonas hydrophila, Escherichia intermedia, Bacillus megaterium, Paracolobacterium aerogenoides , or a combination thereof. 
     
     
         31 . The method of  claim 22 , wherein the steps of saccharifying and adding are performed at a temperature of 60 degrees C. to 65 degrees C. 
     
     
         32 . The method of  claim 22 , wherein the steps of saccharifying and adding are performed at a pH of 7 or below. 
     
     
         33 . The method of  claim 22 , wherein the saccharifying is performed during the addition of the isomerization agent. 
     
     
         34 . The method of  claim 22 , wherein the saccharifying is performed before the addition of the isomerization agent. 
     
     
         35 . The method of  claim 22 , wherein the microorganism is from the genus  Saccharomyces  ssp. 
     
     
         36 . The method of  claim 22 , wherein the product comprises ethanol. 
     
     
         37 . The method of  claim 22 , further comprising isolating the product. 
     
     
         38 . The method of  claim 37 , wherein the product is isolated by distillation. 
     
     
         39 . The method of  claim 22 , further comprising isolating the xylose. 
     
     
         40 . The method of  claim 39 , wherein the xylose is isolated by crystallization. 
     
     
         41 . The method of  claim 22 , further comprising isolating the xylose and isolating the product.