GLYCOSYL HYDROLASE ENZYMES IN HIGH TEMPERATURE INDUSTRIAL PROCESSES

摘要

Novel hyperthermophilic Dictyoglomus beta-mannanases are provided for use in high temperature industrial applications requiring enzymatic hydrolysis of 1,4-β-D-mannosidic linkages in mannans, galactomannans, and glucomannans. Also provided are methods and compositions for fracturing a subterranean formation in which a gellable fracturing fluid is first formed by blending together a hydratable polymer and a Dictyoglomus beta-mannanase as an enzyme breaker. An optimized and stabilized recombinant Dictyoglomus beta-mannanase is provided that shows superior performance/effectiveness and properties in degrading guar and derivatized guars at pH ranges from 3.0 to 12 and temperatures ranging from 130° F. to in excess of 270° F.

主权项

1. A method of generating commercial quantities of an enzyme breaker for guar based polymer gels that comprise beta-(1,4) mannosidic linkages, the method comprising:
transforming a population of exogenous host cells with an expression cassette including a nucleic acid sequence encoding a hyperthermophilic Dictyoglomus beta-mannanase; culturing the transformed exogenous host cells in batch, fed batch or continuous fermentation; preparing a cell free supernatant containing the Dictyoglomus beta-mannanase from the fermentation; and partially purifying the Dictyoglomus beta-mannanase from the cell free supernatant by heat treatment at 70° C. or higher and removal of heat denatured proteins, wherein the partially purified Dictyoglomus beta-mannanase is provided as an enzyme breaker additive to a guar based polymer gel for downhole fracking in high temperature applications.