Compositions and Methods for Fermentation of Biomass
In one aspect, this invention relates to production of useful fermentation end-products from biomass through simultaneous hydrolysis and fermentation by a microorganism, such as Clostridium phytofermentans . The invention also relates to the development of a process for efficient pretreatment and conversion of lignocellulosic biomass to end-products with high conversion efficiency (yield). In another aspect, methods for producing a fermentation end-product by fermenting hexose (C6) and pentose (C5) sugars with a microorganism, such as Clostridium phytofermentans are disclosed herein.
1 . A method for producing one or more fermentation end-products by fermenting a lignocellulosic biomass comprising hexose and pentose saccharides with a first microorganism, wherein said first microorganism simultaneously hydrolyses and ferments the lignocellulosic biomass to produce a fermentation end-product.
2 . The method of claim 1 , wherein at least one of the fermentation end-products is ethanol and wherein the ethanol is produced to a titer of at least about 45 g/L.
3 . The method of claim 1 , wherein said first microorganism is a Clostridium strain.
4 . The method of claim 3 , wherein said Clostridium strain is Clostridium phytofermentans.
5 . The method of claim 1 , wherein the method further comprises the fermentation of hexose and pentose saccharides using a second microorganism.
6 . The method of claim 5 , wherein the second microorganism is Saccharomyces cerevisiae, C. thermocellum, C. acetobutylicum, C. cellovorans , or Zymomonas mobilis.
7 . The method of claim 1 , wherein the hexose saccharides comprise carbohydrates selected from the group consisting of cellulose, hemicellulose, starch, mannan, fructose, glucose, galactose, rhamnose, and mannose.
8 . The method of claim 1 , wherein the pentose saccharides comprise carbohydrates selected from the group consisting of xylan, hemicellulose, xylose, and arabinose.
9 . The method of claim 4 , wherein the Clostridium phytofermentans is nonrecombinant or recombinant microorganism.
10 . The method of claim 4 , wherein the Clostridium phytofermentans comprises one or more heterologous polynucleotides.
11 . The method of claim 1 , further comprising adding one or more medium supplements comprising hexose or pentose saccharides to the medium during the growth of the first microorganism.
12 . The method of claim 11 , wherein the hexose or pentose saccharides are added in relation to the amount of sugar converted by the first microorganism to other compounds.
13 . The method of claim 1 , further comprising pretreatment of the biomass.
14 . The method of claim 1 , wherein said pretreatment comprises steam explosion or hot water extraction, exposure to acid or alkaline conditions.
15 . The method of claim 1 , further comprising adding a fermentation medium supplement, wherein said fermentation medium supplement is fatty acid, a surfactant, a chelating agent, vitamins, minerals, pH modifiers, yeast extract, and salts.
16 . The method of claim 1 , wherein said first microorganism simultaneously ferments said hexose and pentose saccharides.
17 . The method of claim 1 , further comprising adding one or more enzymes, wherein the one or more enzymes are not derived from first microorganism.
18 . The method of claim 17 , wherein said one or more enzymes is a cellulase, a hemicellulase, a galacturonase, a pectate lyase, a carbohydrase, a xylanase, a glucanase, and endoglucanase, an exoglucanase, a glucosidase, an amylase, a phytase, or a laccase.
19 . The method of claim 1 , wherein the hexose and pentose saccharides comprise malt syrup, corn steep liquor, distillers dried grains or corn steep solids.
20 . The method of claim 1 , wherein the method further comprises fed-batch fermentation of biomass with bolus addition of biomass solids.
21 . The method of claim 1 , wherein said biomass solids are recovered using a sieve.
22 . The method of claim 21 , wherein the sieve comprises a plurality of apertures between about 150-250 microns in diameter.
23 . A biofuel product produced by culturing a strain of Clostridium phytofermentans in a medium comprising a lignocellulosic biomass; wherein the Clostridium phytofermentans simultaneously hydrolyses and ferments the lignocellulosic biomass.
24 . A method of producing ethanol, the method comprising the steps of:
a) culturing a strain of Clostridium phytofermentans in a medium comprising a lignocellulosic biomass; wherein the Clostridium phytofermentans simultaneously hydrolyses and ferments the lignocellulosic biomass; and
b) producing ethanol at a yield greater than about 45 g/L.
25 . The method of claim 24 , further comprising adding one or more medium supplements to the medium during the growth of the Clostridium phytofermentans , wherein one or more of the medium supplements comprises one or more hexose and/or pentose sugar compounds, and the one or more sugar compounds are added in relation to the amount of sugar converted by the Clostridium phytofermentans to other compounds.
26 . A system for the production of a fermentation end product comprising:
(a) a fermentation vessel;
(b) a lignocellulosic biomass; and
(c) a first microorganism that simultaneously hydrolyses and ferments the lignocellulosic biomass; wherein the fermentation vessel is adapted to provide suitable conditions for the simultaneous hydrolysis and fermentation of the lignocellulosic biomass.
27 . The system of claim 26 , further comprising a medium supplement comprising with hexose and pentose saccharides.
28 . The system of claim 26 , wherein said first microorganism is a Clostridium strain.
29 . The system of claim 26 , wherein said Clostridium strain is Clostridium phytofermentans.
30 . The system of claim 29 , wherein the Clostridium phytofermentans comprises one or more heterologous polynucleotides.
31 . The system of claim 26 , wherein the biomass is pretreated by steam explosion or hot water extraction, exposure to acid or alkaline conditions before contact with the first microorganism.
32 . The system of claim 31 , wherein the pre-treated biomass is further treated with one or more enzymes not derived from the first microorganism.
33 . The system of claim 27 , wherein the hexose and pentose saccharides comprise one or more of corn steep solids, corn steep liquor, malt syrup, xylan, cellulose, hemicellulose, fructose, glucose, mannose, rhamnose, or xylose.
34 . The system of claim 26 , wherein the fermentation medium further comprises one or more enzymes not derived from the first microorganism.
35 . The system of claim 26 , wherein the fermentation medium further comprises a fermentation medium supplement selected from the group consisting of a fatty acid, a surfactant, a chelating agent, vitamins, minerals, pH modifiers, yeast extract, and salts.
36 . The system of claim 26 , further comprising a second microorganism.
37 . The system of claim 36 , wherein the second microorganism is Saccharomyces cerevisiae, C. thermocellum, C. acetobutylicum, C. cellovorans , or Zymomonas mobilis.