Contaminant control in
View Patent ↗Contamination was controlled in fermentations using Zymomonas mobilis as the biocatalyst, without negative impact on fermentation production, by the addition of virginiamycin. The effective concentration of virginiamycin was found to be dependent upon the type of fermentation medium used.
1. A method for controlling bacterial contamination in a fermentation using a Zymomonas cell biocatalyst comprising:
a) providing a fermentation medium;
b) adding virginiamycin to the fermentation medium to a concentration of at least about 10 ppm;
c) adding to the fermentation medium an inoculum of Zymomonas cells, thereby producing a fermentation broth; and
d) maintaining the fermentation broth under conditions suitable for growth of the Zymomonas cells;
wherein steps b) and c) may be performed in either order or concurrently and wherein bacterial contamination is controlled.
2. The method of claim 1 wherein the Zymomonas cells produce ethanol in the fermentation broth.
3. The method of claim 1 or 2 wherein the fermentation medium lacks cellulosic biomass hydrolysate.
4. The method of claim 1 or 2 wherein the fermentation medium comprises cellulosic biomass hydrolysate.
5. A method for producing ethanol comprising:
a) providing a fermentation medium;
b) adding to the fermentation medium an inoculum of Zymomonas cells grown in the presence of virginiamycin, producing a fermentation broth, wherein the concentration of virginiamycin is at least about 10 ppm; and
c) maintaining the fermentation broth under conditions suitable for growth of the Zymomonas cells and production of ethanol by the Zymomonas cells;
wherein no virginiamycin is added to the fermentation medium separately from the inoculum of (b) and wherein ethanol is produced.
6. The method of claim 5 wherein the fermentation medium comprises cellulosic biomass hydrolysate or lacks cellulosic biomass hydrolysate.
7. A method for improving growth of Zymomonas cells comprising growing Zymomonas cells in fermentation medium comprising virginiamycin wherein the concentration of virginiamycin is at least about 10 ppm.