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Characterization of a cold‐adapted esterase and mutants from a psychotolerant Pseudomonas sp. strain
Author(s) -
Dong Juan,
Gasmalla Mohammed A. A.,
Zhao Wei,
Sun Jingtao,
Liu Wenyu,
Wang Mingming,
Han Liang,
Yang Ruijin
Publication year - 2017
Publication title -
biotechnology and applied biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.468
H-Index - 70
eISSN - 1470-8744
pISSN - 0885-4513
DOI - 10.1002/bab.1525
Subject(s) - esterase , hydrolysis , strain (injury) , glycerol , pseudomonas , mutant , biochemistry , lipase , chemistry , food science , enzyme , biology , bacteria , gene , genetics , anatomy
A cold‐adapted esterase‐producing strain named T1‐39 was isolated from Glacier No. 1, Tianshan, People's Republic of China and identified as Pseudomonas sp. from 16S rRNA sequence analysis. The esterase (EstT1‐39) secreted by this strain preferentially hydrolyzed esters of glycerol with short‐ and medium‐chain fatty acids. Mutants of T1‐39 were generated by the atmospheric and room temperature plasma method and screened for enhanced esterase activity. Among all the mutants, strain TB11 had 4.45‐fold higher esterase productivity than T1‐39, with high genetic stability over 10 generations of continuous cultivation. Maximum activity of EstT1‐39 and EstTB11 was observed at 30 ℃, pH 9.0 and 25 ℃, pH 8.5, respectively. EstTB11 was thermally more stable (50 ℃ for 1 H) and active over a broader pH range than EstT1‐39. EstTB11 also retained 38% of its maximal activity at 0 ℃ and was found to be able to hydrolyze milk fats into short‐ and medium‐chain fatty acids at 4 ℃. The characteristics of EstT1‐39 made it a cold‐adapted enzyme and the EstTB11 from the mutant, with its higher activity at lower temperatures, may be suitable for the production of aromas and flavors in the dairy industry.