Induction of gene expression using a high concentration sugar mixture
Described herein is a composition useful for inducing expression of genes whose expression is under control of an inducible promoter sequence and methods for the compositions preparation and use.
1. A method of producing an inducing feed composition capable of inducing the expression of a gene under the control of a sophorose-inducible promoter or a gentiobiose-inducible promoter, said method comprising the steps of:
a. Providing a whole cellulase preparation which is an end fermentation broth;
b. Mixing a concentrated glucose solution comprising from about 5% to about 75% glucose with the whole cellulase preparation of a. to give a first mixture; and
c. Incubating the first mixture at a temperature and for a sufficient time to produce the inducing feed composition.
2. The method of claim 1 wherein the whole cellulase preparation includes about 2 g/L to about 10 g/L protein.
3. The method of claim 2 wherein the whole cellulase preparation includes about 5 g/L protein.
4. The method of claim 1 wherein the temperature is from about 50° C. to about 75° C.
5. The method of claim 1 wherein the sufficient time to produce the inducing feed composition is between 8 hours and 500 hours.
6. The method of claim 5 , wherein the sufficient time to produce the inducing feed composition is between 48 hours and 72 hours.
7. The method of claim 1 wherein the whole cellulase preparation is immobilized.
8. The method of claim 1 , wherein the whole cellulase preparation comprises one or more beta-glucosidase, one or more endoglucanase, and one or more cellobiohydrolase.
9. The method of claim 1 , wherein the whole cellulase preparation is a naturally occurring composition.
10. The method of claim 1 , wherein the whole cellulase preparation is a non-naturally occurring composition.
11. The method of claim 1 , wherein the whole cellulase preparation is not a recovered cellulase from the fermentation broth.