title: Preparation of crosslinked enzyme aggregates (CLEAs) of acid urease with urethanase activity and their application.
abstract: An acid urease from Providencia rettgeri JN-B815 was purified via ultrasonication, ethanol precipitation, and DEAE ion-exchange column chromatography. It was found that the enzyme exhibits not only urease activity, but also urethanase activity, which made it possible to reduce EC already existed or would produce and its precursor urea at the same time. Then, crosslinked enzyme aggregates of P. rettgeri urease (PRU-CLEAs) were prepared using genipin as crosslinking agent. The purification process of acid urease, the effects of genipin concentration, and crosslinking time on PRU-CLEAs activity were investigated. The crosslinking was performed at pH 4.5 for 2.5 h, using 0.3% genipin as crosslinking agent, and 0.3 g · L(-1) bovine serum albumin as protein feeder. Using the obtained PRU-CLEAs, the removal rate of urea was up to 9.31 mg · L(-1) · h(-1). The removal rate of urea was still up to 7.56 mg · L(-1) · h(-1) after PRU-CLEAs was re-used for 6 times. When PRU-CLEAs were applied in a batch stirred and membrane reactor, the removal rate of urea in rice wine reached 5.16 mg · L(-1) · h(-1) and the removal rate of EC was 9.21 μg · L(-1) · h(-1). Furthermore, the treatment with PRU-CLEAs revealed no significant change of volatile flavor substances in Chinese rice wine. Thus PRU-CLEAs have great potential in the elimination of EC in Chinese rice wine.
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Zha
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
authors.forename: Nandi
authors.initials: N
authors.lastname: Zhou
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Tian
mesh_terms: D000581:Amidohydrolases / Q000737:chemistry / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000378:metabolism; D004755:Enterobacteriaceae / Q000201:enzymology / Q000378:metabolism; D004789:Enzyme Activation; D000431:Ethanol / Q000737:chemistry; D039823:Iridoids / Q000737:chemistry; D012275:Oryza / Q000378:metabolism / Q000382:microbiology; D014508:Urea / Q000737:chemistry / Q000378:metabolism; D014510:Urease / Q000737:chemistry / Q000378:metabolism*; D014920:Wine / Q000382:microbiology
chemical_list: D003432:Cross-Linking Reagents; D039823:Iridoids; D000431:Ethanol; D014508:Urea; C007834:genipin; D000581:Amidohydrolases; D014510:Urease; C074526:urethanase
keywords: Chinese rice wine; Crosslinked urease aggregates; Providencia rettgeri; Separation; Urethanse-urease