Abstract: In order to study the enzymatic properties of laccase derived from Lactobacillus and its potential application in biogenic amine degradation, the gene encoding laccase from Lactobacillus plantarum was heterologously expressed and the recombinant laccase was enzymatically characterized. The optimum reaction temperature and pH, the effects of metal ions and chelators on laccase activity, the tolerance of the recombinant laccase to different concentrations of ethanol and the degradation of biogenic amines by the recombinant laccase were determined. The results showed that the optimum reaction temperature and pH of the purified recombinant laccase was 40 ℃ and 4.0, respectively. Low concentrations of Mg2+, Zn2+ and Ca2+ could promote the activity of the recombinant laccase in different degrees, Zn2+ and Ca2+ being most effective. On the contrary, high concentrations of Mn2+, Fe2+ and ethylenediaminetetraacetic acid could inhibit the activity of recombinant laccase by 85% or more. Toward the substrate 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), the Michaelis constant and maximum reaction rate of the recombinant laccase were 2.49 mmol/L and 0.22 mmol/(L·min), respectively. In addition, the recombinant laccase had a good tolerance to ethanol at low concentration, and the residual activity was more than 75% after incubation in 20% (V/V) ethanol for 1 h. The degradation rates of tyramine and tryptamine by the recombinant laccase were both 100%, while the degradation rates of spermidine, phenethylamine and histamine were 49.60%, 25.27% and 21.80%, respectively. Based on the above results, the recombinant laccase from L. plantarum has great application potential in the degradation of biogenic amines in low-alcohol fermented beverages and fermented foods.

Key words: biogenic amines; laccase; heterologous expression; enzymatic properties; Lactobacillus plantarum