title: Performance of a new thermostable mannanase in breaking guar-based fracturing fluids at high temperatures with little premature degradation.
abstract: A new thermostable β-1,4-mannanase (DtManB) cloned from Dictyoglomus thermophilum CGMCC 7283 showed the maximum activity towards hydroxypropyl guar gum at 80 °C, with a half-life of 46 h. DtManB exhibited good compatibility with various additives of fracturing fluid, retaining more than 50 % activity in all the cases tested. More importantly, premature degradation could be alleviated significantly when using DtManB as breaker, because at 27 and 50 °C it displayed merely 3.7 and 18.5 % activities compared to those at 80 °C. In a static test, 0.48 mg DtManB could break 200 mL borax cross-linked fracturing fluid dramatically at 80 °C, and merely 18 mPa s of the viscosity was detected even after the broken fluid was cooled down and only 161.4 mg L(-1) of the residue was left after the enzymatic reaction. All these positive features demonstrate the great potential of this mannanase as a new enzyme breaker for application in enhanced recovery of petroleum oil.
authors.affiliation: Laboratory of Biocatalysis and Synthetic Biotechnology, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Hu
authors.forename: Chun-Xiu
authors.initials: CX
authors.lastname: Li
authors.forename: Jiang
authors.initials: J
authors.lastname: Pan
authors.forename: Yan
authors.initials: Y
authors.lastname: Ni
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Zhang
authors.forename: Jian-He
authors.initials: JH
authors.lastname: Xu
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000201:enzymology*; D001881:Borates / Q000737:chemistry; D005685:Galactans / Q000737:chemistry; D006358:Hot Temperature; D007700:Kinetics; D008351:Mannans / Q000737:chemistry; D008361:Mannosidases / Q000737:chemistry* / Q000302:isolation & purification*; D008970:Molecular Weight; D053149:Plant Gums / Q000737:chemistry; D055550:Protein Stability; D059748:Proteolysis; D013379:Substrate Specificity
chemical_list: D001881:Borates; D005685:Galactans; D008351:Mannans; D053149:Plant Gums; C018851:borax; C007894:guar gum; D008361:Mannosidases; C041867:endo-1,4-beta-D-mannanase