title: Purification and Characterization of a Lipase with High Thermostability and Polar Organic Solvent-Tolerance from Aspergillus niger AN0512.
abstract: An extracellular lipase (EC 3.1.1.3, AN0512Lip) from Aspergillus niger AN0512 was purified and its characteristics were investigated. After the process of ammonium sulfate precipitation followed by ion-exchange chromatography and gel filtration, the purified lipase was achieved with 203.6-fold purification and 22.1 % recovery. AN0512Lip exhibited the highest activity at 50 °C and pH 5.0. It was thermostable and pH-stable, as indicated by that more than 50 % activity retained at 60 °C for 20 h and more than 90 % activity retained at pH 3.0 for 20 h, respectively. AN0512Lip activity was stimulated by some divalent metal ions (especially Cu(2+), Ca(2+)), while greatly suppressed by EDTA, indicating that AN0512Lip was a metal-activated enzyme. Moreover, AN0512Lip exhibited high tolerance for various polar organic solvents with log P < 0.8, and the highest lipase activity (476 % of its original activity) was achieved after addition of 90 % (V/V) isopropanol to the reaction mixture. AN0512Lip also displayed 3-regiospecificity and great affinity for the long-chain fatty ester. The preliminary test showed that AN0512Lip was a candidate for enriching EPA and DHA in fish oil. All the unique properties, such as thermostability, Cu(2+)-dependent, 3-regiospecificity, and polar organic solvent-tolerance, indicated that AN0512Lip could have potential applications in the food industry, even in organic synthesis and the pharmaceutical industry.
authors.affiliation: School of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510641, Guangdong, China.
authors.forename: Guang
authors.initials: G
authors.lastname: Liu
authors.affiliation: School of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510641, Guangdong, China.|Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, 510641, Guangdong, China.
authors.forename: Songqing
authors.initials: S
authors.lastname: Hu
authors.affiliation: School of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510641, Guangdong, China.|Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, 510641, Guangdong, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: School of Light Industry and Food Sciences, South China University of Technology, Guangzhou, 510641, Guangdong, China. ceyhou@scut.edu.cn.|State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, 510641, Guangdong, China. ceyhou@scut.edu.cn.
authors.forename: Yi
authors.initials: Y
authors.lastname: Hou
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D012997:Solvents / Q000737:chemistry; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D012997:Solvents; D008049:Lipase
keywords: Aspergillus niger; Lipase; Polar organic solvent-tolerance; Purification; Thermostable