Systems and methods for co-culture of oxygen sensitive bacteria and yeast
Methods, compositions, and systems for propagation and fermentation of co-cultures of an oxygen sensitive bacteria and a yeast, particularly large scale operations for production of a bioproduct are provided. Methods of co-culture provide growth sufficient to minimize growth of contaminating bacteria.
1. A method of ethanol fermentation comprising:
(i) propagating yeast and an oxygen-sensitive bacteria selected from Zymomonas mobilis and Lactobacillus casei to form a propagated composition, the propagating comprising inoculating a culture medium with the yeast at least about 1 to 5 hours prior to inoculation with the oxygen-sensitive bacteria, and
(ii) fermenting a grain-based feedstock with the propagated composition to produce ethanol.
2. The method of claim 1 , wherein the yeast is Saccharomyces cerevisiae.
3. The method of claim 1 , wherein the oxygen sensitive bacteria is Z. mobilis.
4. The method of claim 1 , wherein the oxygen sensitive bacteria is L. casei.
5. The method of claim 1 , wherein during at least a portion of the at least about 1 to 5 hours prior to inoculation with the bacteria, aeration is performed with an aeration rate having a ratio of vapor volume to liquid volume per minute (vvm) of about 0.05.
6. A method of ethanol fermentation comprising:
(i) propagating an oxygen-sensitive bacteria selected from Z. mobilis and L. casei with yeast to form a propagated composition, the propagating comprising inoculating a culture medium with the oxygen-sensitive bacteria at least about 1 to 5 hours prior to inoculation with the yeast, and
(ii) fermenting a grain-based feedstock with propagated composition to produce ethanol.
7. The method of claim 6 , wherein the yeast is S. cerevisiae.
8. The method of claim 6 , wherein the oxygen sensitive bacteria is Z. mobilis.
9. The method of claim 6 , wherein the oxygen sensitive bacteria is L. casei.
10. A method of ethanol fermentation comprising:
(i) propagating an oxygen-sensitive bacteria selected from Z. mobilis and L. casei with yeast to form a propagated composition, the propagating comprising inoculating a culture medium with the oxygen-sensitive bacteria and yeast, allowing propagation to proceed in the absence of aeration, then aerating the propagation for several hours; and
(ii) fermenting a grain-based feedstock with the propagated composition to produce ethanol.
11. The method of claim 10 , wherein the yeast is S. cerevisiae.
12. The method of claim 10 , wherein the oxygen sensitive bacteria is Z. mobilis.
13. The method of claim 10 , wherein the oxygen sensitive bacteria is L. casei.
14. The method of claim 10 , wherein the step of aerating is performed for about 5 to about 20 hours.
15. The method of claim 10 , wherein the step of aerating is performed at a rate of about 0.85 vvm.
16. A method of ethanol fermentation comprising:
(i) propagating an oxygen-sensitive bacteria selected from Z. mobilis and L. casei with yeast to form a propagated composition, the propagating comprising inoculating a culture medium with the oxygen-sensitive bacteria and yeast, allowing propagation to proceed under aeration less than or equal to 0.85 vvm for 1 hour to 6 hours, then allowing the propagation to proceed in the absence of aeration for several hours; and
(ii) fermenting a grain-based feedstock with the propagated composition to produce ethanol.
17. The method of claim 16 , wherein the yeast is S. cerevisiae.
18. The method of claim 16 , wherein the oxygen sensitive bacteria is Z. mobilis.
19. The method of claim 16 , wherein the oxygen sensitive bacteria is L. casei.
20. The method of claim 16 , wherein the step of aerating is performed for about 2 to about 24 hours.
21. The method of claim 16 , wherein the step of aerating is performed at a rate of about 0.11 vvm.
22. The method of claim 1 , wherein the propagated composition is added to a fermenter to carry out (ii).
23. The method of claim 6 , wherein the propagated composition is added to a fermenter to carry out (ii).
24. The method of claim 10 , wherein the propagated composition is added to a fermenter to carry out (ii).
25. The method of claim 16 , wherein the propagated composition is added to a fermenter to carry out (ii).