Gene inactivation allowing immediate growth on xylose medium by engineered zymomonas
AssigneeE. I. Du Pont de Nemours and Company
InventorsWILLIAM D. HITZ, Min Qi, Luan Tao, Paul V. Viitanen, Jianjun Yang
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Abstract
Zymomonas cells that are genetically engineered to have a disrupted aldose reductase gene such that aldose reductase activity for conversion of xylose to xylitol in the presence of NADPH is reduced by greater than 90%, and that are engineered to express a xylose utilization metabolic pathway, were found to have the ability to gro on medium containing xylose as the only sugar without adaptation in media containing xylose.
Claims19
A method of making a xylose-competent Zymomonas cell comprising:
- a) providing a Zymomonas host cell;
- b) creating a genetic modification in said cell in at least one endogenous gene encoding an aldose reductase enzyme of EC 1.1.1.21 having the ability to convert xylose to xylitol in the presence of NADPH;
- and
- c) introducing into said cell a xylose utilization metabolic pathway;
- wherein the order of steps (b) and (c) is not specified and wherein said xylose-competent Zymomonas cell has aldose reductase activity reduced by greater than 90% as compared with a Zymomonas cell lacking the genetic modification of step (b).
A xylose-competent and ethanol-producing Zymomonas cell having the following characteristics:
- a) the cell does not require a xylose-adaptation step for immediate growth on media containing xylose as the only sugar;
- b) the cell has aldose reductase activity for conversion of xylose to xylitol in the presence of NADPH reduced by greater than 90%;
- and
- c) the cell comprises a xylose utilization metabolic pathway comprising a series of polynucleotides encoding polypeptides, each having xylose isomerase, xylulokinase, transketolase, or transaldolase enzymatic activity.
Dependencies are inferred from the claim text.