High-level expression and characterization of recombinant acid urease for enzymatic degradation of urea in rice wine
Ethylcarbamate, a carcinogenic compound, is formed from urea and ethanol in rice wine, and enzymatic elimination of urea is always attractive. In the present work, we amplified the acid urease gene cluster ureABCEFGD from Lactobacillus reuteri CICC6124 and constructed robust Lactococcus lactis cell factories for the production of acid urease. The titer of the recombinant acid urease was increased from 1,550 to 11,560 U/L by optimization of the cultivation process. Meanwhile, the enzyme showed satisfied properties toward urea elimination in the rice wine model system. By incubating the enzyme (50 U/L) at 20 °C for 60 h, about 95.8 % of urea in rice wine was removed. Interestingly, this acid urease also exhibited activity toward ethylcarbamate. The results demonstrated that this recombinant acid urease has great potential in the elimination of urea in rice wine.
KeywordsAcid urease Lactococcus lactis Lactobacillus reuteri Nisin-induced system
- Kleerebezem M, Beerthuyzen MM, Vaughan EE, de Vos WM, Kuipers OP (1997) Controlled gene expression systems for lactic acid bacteria: transferable nisin-inducible expression cassettes for Lactococcus, Leuconostoc, and Lactobacillus spp. Appl Environ Microbiol 63:4581–4584PubMedCentralPubMedGoogle Scholar
- Mierau I, Leij P, van Swam I, Blommestein B, Floris E, Mond J, Smid EJ (2005) Industrial-scale production and purification of a heterologous protein in Lactococcus lactis using the nisin-controlled gene expression system NICE: The case of lysostaphin. Microb Cell Factories 4:15CrossRefGoogle Scholar
- Ough CS, Trioli G (1988) Urea removal from wine by an acid urease. Am J Enol Vitic 39:303–307Google Scholar