Methods and systems for propagating microorganisms on stillage compositions
Provided are methods and systems of propagating a microorganism on a stillage composition. The methods involve growing microorganisms in a propagation medium formed from a polysaccharide-containing stillage composition with the majority of the of the polysaccharides in the propagation medium coming from the stillage composition. The propagation medium also includes cellulases and/or amylases to form monosaccharides from the polysaccharides. A first cell mass is grown in the propagation medium to form a second cell mass which is greater than the first cell mass.
1. A method of propagating a microorganism for use in a lignocellulosic fermentation process, the method comprising:
providing a propagation medium comprising:
a stillage composition obtained from a starch-based fermentation process, the stillage composition comprising polysaccharides, wherein the majority of the polysaccharides in the propagation medium are from the stillage composition;
an enzyme component comprising one or more enzymes selected from cellulases, amylases, and combinations thereof,;
converting the polysaccharides into one or more monosaccharides using the enzyme component;
growing a first cell mass of the microorganism on the one or more monosaccharides from the stillage composition to form a second cell mass of the microorganism, wherein the second cell mass of the microorganism is greater than the first cell mass of the microorganism; and
using the second cell mass in a lignocellulosic fermentation process.
2. The method of claim 1 wherein at least 99% (wt) of the polysaccharides in the propagation medium are from the stillage composition.
3. The method of claim 1 wherein the polysaccharides are present in an amount of about 2% (wt) or greater in the propagation medium.
4. The method of claim 3 wherein the polysaccharides are present in an amount in the range of about 2% (wt) to about 10% (wt) in the propagation medium.
5. The method of claim 1 , wherein the stillage composition is whole stillage, syrup, or a combination thereof.
6. The method of claim 1 , wherein the enzyme component ranges from 0.1 to about 10 units per gram of solids.
7. The method of claim 1 , wherein the enzyme component comprises cellulase.
8. The method of claim 1 , wherein the enzyme component comprises alpha-amylase, gluco-amylase or combinations thereof.
9. The method of claim 1 wherein the converting is at a pH in the range of 3 to 6 and at a temperature in the range of about 25° C. to 40° C. for a period of time in the range of 12 to 48 hours.
10. The method of claim 1 , wherein the converting and the growing steps are carried out partially or entirely simultaneously.
11. The method of claim 1 , wherein the monosaccharide concentration during the growing is in the range of about 0.5% (wt) to about 3% (wt) of the propagation medium.
12. The method of claim 1 , wherein the first cell mass of the microorganism is about 0.001 weight percent to 0.1 weight percent of the solids content of the propagation medium.
13. The method of claim 1 , wherein the second cell mass of the microorganism is 10 to 1000 times the first cell mass of microorganisms.
14. The method of claim 13 , wherein the second cell mass of the microorganism is 10-30 times the first cell mass.
15. The method of claim 1 , wherein the stillage composition is obtained following distillation of a bioproduct from a fermentation medium from a starch-based fermentation process.
16. The method of claim 1 , wherein the microorganism is yeast.
17. The method of claim 16 , wherein the yeast is a genetically modified yeast.
18. The method of claim 16 , wherein the yeast is Saccharomyces cerevisiae.
19. A method for obtaining a stillage composition, using the stillage composition to propagate a microorganism, and then performing lignocellulosic fermentation, the method comprising:
obtaining a stillage composition from a starch-based fermentation process that uses a plant material, wherein the stillage composition comprises polysaccharides;
forming a propagation medium for propagating a microorganism, the medium comprising the stillage composition from the starch-based fermentation process, wherein polysaccharides in the propagation medium consist essentially of the polysaccharides from the stillage composition, and (ii) an enzyme component comprising one or more enzymes selected from cellulases, amylases, and combinations thereof,
converting the polysaccharides into one or more monosaccharides using the enzyme component;
propagating the microorganism in the propagation medium to generate a cell mass; and
using the cell mass in a lignocellulosic fermentation process.
20. The method of claim 7 , wherein the enzyme component comprises a mixture of cellulase, hemicellulose, alpha-amylase, and gluco-amylase.