Methods for the cost-effective saccharification of lignocellulosic biomass

• US 20030109011A1
• Filed: 12/06/2002
• Published: 06/12/2003
• Est. Priority Date: 12/06/2001
• Status: Abandoned Application

• Current Assignee: Applied Biotechnology Institute LLC
• Original Assignee: Applied Biotechnology Institute LLC
• Inventors: Hood, Elizabeth E., Howard, John A.
• Application Number:
  US10/310,292
• Publication Number:
  US 20030109011A1
• Time in Patent Office: Days
• US Class Current: 435/105
• CPC Class Codes: C12N 15/8242 with non-agronomic quality (output) traits, e.g. for industrial processing; Value added, non-agronomic traits
• CPC Class Codes: C12N 15/8246 Non-starch polysaccharides, e.g. cellulose, fructans, levans
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel

Abstract

The invention provides methods for the cost-effective saccharification of polysaccharides in lignocellulosic biomass, particularly in crop residues. In one embodiment of the invention polysaccharide-degrading enzymes are expressed in the seeds of plants, preferably in germ (embryo) tissue of seed. Corn crop plants are used in one embodiment of the invention. The corn seeds and the corn stover are harvested concurrently in a single pass harvesting operation to lower costs. The corn seeds are fractioned which allows for additional uses for separated tissue. The endosperm can be used as a source of starch for existing industries to produce by-product credits. In an embodiment, the starch is used to produce ethanol in currently existing facilities and the tissue, preferably germ, containing the polysaccharide-degrading enzymes can be used as the enzyme source. The appropriate tissues that express polysaccharide-degrading enzymes, or extracts thereof, are combined with the corn stover and the combination is exposed to conditions favorable for the conversion of the cell wall polysaccharides in the corn stover into fermentable sugars. The fermentable sugars can then be utilized by microorganisms to produce ethanol or other desired fermentative products.

Claims

1. A method for the cost-effective saccharification of polysaccharides in crop residues comprising the steps of:

a) transforming tissue of a crop plant which can produce seed with a nucleotide sequence encoding at least one polysaccharide-degrading enzyme such that the expression of the polysaccharide-degrading enzyme is preferentially expressed to the seed of the plant;

b) culturing and growing a plant from the plant tissue;

c) producing seed from the plant or descendants of the plant, such that the enzyme is expressed in the seed of the plant or descendant;

d) harvesting the plant or descendant to obtain the seeds of the plant or descendant and crop residues;

e) fractionating the seeds into separate tissues such that at least one of said tissues contains said enzyme;

f) contacting the crop residues with at least one of the enzymes contained in at least one of the separated tissues containing the enzyme; and

g) exposing the crop residues and at least one of the enzymes to conditions favorable for the degradation of polysaccharides in the crop residues so as to produce fermentable sugars.

2. The method of claim 1 comprising extracting the at least one enzyme prior to contacting the crop residues with the at least one enzyme.

3. The method of claim 1 comprising contacting the crop residues with at least one of the separated tissues containing the at least one enzyme.

4. The method of claim 1 comprising harvesting the seeds of the plant or descendant in a first operation and the crop residues in a second operation such that the first operation and the second operation are carried out concurrently in a single step.

5. The method of claim 1 comprising preferentially expressing the enzyme in the germ tissue of the seed, fractionating the germ tissue from the seed in a commercial milling process and contacting the crop residues with at least the germ tissue of the seed.

6. The method of claim 5 comprising preferentially expressing the enzyme in the germ tissue of the seed at levels of at least about 0.1% of total dry weight of the seed.

7. The method of claim 1 further comprising fermenting the fermentable sugars under conditions favorable for ethanol production so as to produce ethanol.

8. The method of claim 1 further comprising pretreating the crop residues prior to contacting the crop residues with the enzyme.

9. The method of claim 1 wherein the polysaccharide-degrading enzyme is selected from the group consisting essentially of:

endo-β

-1,4-glucanase, exo-β

-1,4-glucanase, β

-D-glucosidase, hemicellulases and pectinases.

10. The method of claim 1 wherein the polysaccharide-degrading enzyme is cellulase.

11. The method of claim 1 wherein the plant is bred with at least one other plant and descendants grown having seeds containing at least one of the enzymes.

12. The method of claim 11 wherein at least one of the plants is transformed with a nucleotide sequence expressing protein which produces desired plant material.

13. The method of claim 1 wherein the crop plant is corn.

14. A method for the cost-effective saccharification of polysaccharides in corn stover comprising the steps of:

a) transforming corn tissue with a nucleotide sequence encoding at least one polysaccharide-degrading enzyme such that the expression of the polysaccharide-degrading enzyme is preferentially expressed in the germ of the seed;

b) culturing a plant from the corn tissue;

c) growing the plant and producing seeds from the plant or descendants of the plant such that the enzyme is expressed in the seed of the plant or descendant;

d) harvesting the seeds of the plant or descendants in a first operation and the plant stover in a second operation such that the first operation and the second operation are carried out concurrently in a single step;

e) fractionating the germ from the seed;

f) contacting the corn stover with at least one member from the group consisting essentially of the germ, an extract of the germ and cells of the germ tissue; and

g) exposing the corn stover and the member to conditions favorable for the degradation of polysaccharides in the corn stover so as to produce fermentable sugars.

15. The method of claim 14 wherein the polysaccharide-degrading enzyme is produced in the germ at a level of at least about 0.1% of total dry weight of the seed.

16. The method of claim 14 further comprising fermenting the fermentable sugars under conditions favorable for ethanol production so as to produce ethanol.

17. The method of claim 14 further comprising pretreating the crop residues prior to contacting the crop residues with the member.

18. The method of claim 14 wherein the polysaccharide-degrading enzyme is selected from the group consisting essentially of:

endo-β

-1,4-glucanase, exo-β

-1,4-glucanase, β

-D-glucosidase, hemicellulases and pectinases.

19. The method of claim 14 wherein the polysaccharide-degrading enzyme is cellulase.

20. A method for the cost-effective saccharification of polysaccharides in crop residues comprising the steps of:

a) transforming tissue of a crop plant which can produce seed with a nucleotide sequence encoding at least one polysaccharide-degrading enzyme such that the expression of the polysaccharide-degrading enzyme is preferentially expressed to the seed of the plant;

b) culturing and growing a plant from the plant tissue;

c) producing seed from the plant or descendants of the plant, such that the enzyme is expressed in the seed of the plant or descendant;

d) harvesting the plant or descendant to obtain the seeds of the plant or descendant and crop residues;

e) contacting the crop residues with at least one of the enzymes contained in at the seed; and

f) exposing the crop residues and at least one of the enzyme to conditions favorable for the degradation of polysaccharides