Propagating an organism and related methods and compositions
The present invention is related to methods of propagating one or more organisms by using a carbon source that includes xylose (e.g., xylose syrup from pretreating lignocellulosic feedstock) and/or a nutrient source that includes a stillage component (e.g., thin stillage derived from a corn-to-ethanol process) in the propagation medium. The organisms include those that can convert one or more monosaccharides into an alcohol via fermentation, such as yeast. The present invention is also directed to related compositions.
1. A method of propagating an organism that can convert one or more monosaccharides into a biochemical, the method comprising:
providing a first cell mass of the organism;
providing a carbon source that can support growth of the first cell mass of the organism, wherein the carbon source comprises xylose;
providing a nutrient source that can support growth of the first cell mass of the organism, wherein the nutrient source comprises a stillage component and, wherein the stillage component comprises thin stillage that is a by-product of fermenting a grain material;
combining at least the carbon source and the nutrient source to form a medium for propagating the organism, wherein the weight ratio of xylose to solids of thin stillage is in the range of from 0.5 to 2.5; and
combining the first cell mass of the organism with the carbon source and the nutrient source to propagate the first cell mass of the organism for a time period to form a second cell mass of the organism.
2. The method of claim 1 , wherein the organism comprises one or more ethanologens.
3. The method of claim 2 , wherein the first cell mass is present in an amount less than 1.0 gram of ethanologens per liter of medium.
4. The method of claim 2 , wherein the first cell mass is present in an amount less than 0.1 grams of ethanologens per liter of medium.
5. The method of claim 4 , wherein the second cell mass of the ethanologens is present in an amount in the range of from 1 to 20 grams of ethanologens per liter of medium within a time period in the range of from 12 to 48 hours, wherein the time period begins when the first cell mass of the ethanologens is combined with the carbon source and the nutrient source to propagate the first cell mass of the ethanologens.
6. The method of claim 2 , wherein the one or more ethanologens comprise yeast capable of metabolizing at least xylose to ethanol.
7. The method of claim 6 wherein the yeast comprises genetically modified yeast capable of metabolizing at least xylose to ethanol.
8. The method of claim 7 , wherein the genetically modified yeast comprises genetically modified Saccharomyces cerevisiae.
9. The method of claim 1 , wherein the grain material comprises at least a portion of whole corn kernel material.
10. The method of claim 1 , wherein the thin stillage is provided in an amount in the range of from 5 to 35 grams solids per liter of the medium.
11. The method of claim 1 , wherein the xylose is provided in an amount in the range of from 0.1 to 10 percent by weight of medium.
12. The method of claim 1 , wherein the first cell mass of the organism is combined with the carbon source and the nutrient source to propagate the first cell mass of the organism to form a second cell mass of the organism according to a batch process.
13. The method of claim 1 , wherein the carbon source comprises xylose liquor that is a by-product of pretreating lignocellulosic substrate with at least water.
14. The method of claim 13 , wherein the pretreated lignocellulosic substrate is derived from corn cobs, corn stover, or combinations thereof.
15. The method of claim 1 , wherein the organism is exposed to aerobic conditions during at least a portion of the time period.
16. A method of propagating an organism that can convert one or more monosaccharides into a biochemical, the method comprising:
providing a first cell mass of the organism;
providing a carbon source that can support growth of the first cell mass of the organism, wherein the carbon source comprises xylose;
providing a nutrient source that can support growth of the first cell mass of the organism, wherein the nutrient source comprises a stillage component and, wherein the stillage component comprises thin stillage that is a by-product of fermenting a grain material;
combining at least the carbon source and the nutrient source to form a medium for propagating the organism, wherein the first cell mass is present in an amount less than 1.0 gram of organisms per liter of medium and wherein the weight ratio of xylose to solids of thin stillage is in the range of from 0.5 to 2.5; and
combining the first cell mass of the organism with the carbon source and the nutrient source to propagate the first cell mass of the organism for a time period to form a second cell mass of the organism.
17. The method of claim 16 , wherein the organism comprises genetically modified Saccharomyces cerevisiae.
18. A system of propagating an organism that can convert one or more monosaccharides into a biochemical, the system comprising:
a propagation vessel, comprising a composition comprising:
a carbon source that can support growth of the first cell mass of the organism, wherein the carbon source comprises xylose;
a nutrient source that can support growth of the first cell mass of the organism, wherein the nutrient source comprises a stillage component and, wherein the stillage component comprises thin stillage that is a by-product of fermenting a grain material;
wherein the stillage component comprises thin stillage and the weight ratio of xylose to solids of thin stillage is in the range of from 0.5 to 2.5; and
a first cell mass of the organism, wherein the first cell mass of the organism can use the xylose and thin stillage to propagate the first cell mass of the organism for a time period to form a second cell mass of the organism; and an aerator coupled to the propagation vessel to aerate the composition.