利用Lactobacillus NCH26發酵進行單寧酶生產條件及其活性、特性探討

Abstract

In this study, 14 lactic acid bacteria were isolated from Mustard Pickle with tannase activity. Strain with the best enzyme activity was identified by API 50 CHL that indicated it may be Lactobacillus plantarum or Lactobacillus pentosus, with ID% of 53% or 46.9% respectively and the strain was named Lactobacillus NCH26 in this study. The better cultivation conditions for tannase production were as follows（g/L）: Tannic acid, 15; glucose, 3; NH4Cl, 3; MgSO4．7H2O, 2; KH2PO4, 0.5; K2HPO4, 0.5; CaCl2, 1., pH 3.6，inoculum size 2×109 cfu/mL, cultivation temperature 30℃ and agitation speed 140 rpm. Optimum tannase activity of 0.97 U/mL was obtained after 8 h of cultivation. The tannase activity was further increased to 1.14 U/mL after 8 h of cultivation in a 2-L fermentor, and 1.61 U/mL of activity was observed after 48 h of growth. The optimal pH and temperature of crude tannase from Lactobacillus NCH26 were pH 7.0 and 40℃, respectively. The crude enzyme exhibited good pH stability at range of pH 6.0 to 7.0. In respect to thermostability, the residual activity of tannase activity is 80% at 30-50℃ for 30 min. The results also showed that Fe3+、EDTA、Urea、Tween 80、DMSO were significantly decreased to tannase activity. The IC50 of the DPPH radical scavenging ability and the ABTS free radical scavenging capacity were 3.56 and 0.39 mg/mL, respectively. The highest reducing power was obtained at 7.5 mg/mL crude extract, whiche quivalent to 0.34 mg/mL ascorbic acid standard.The Trolox equivalent antioxidant capacity assay indicated that the best result was at 3.75 mg/mL crude extract that equivalent to 213.98 μg/mL Trolox standard. Test of antibacterial activities of crude extract of fermentation product to Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella enteric showed that at concentration of 100 mg/mL, clear zone of S. aureus and L. monocytogenes were 21.7 ± 0.15 and 21.3 ± 0.06 mm, respectively. The phenolic compounds of crude extract via HPLC analysis indicated that it contains gallic acid and p-Coumaric acid but other compounds need to be future investigated. Based on this study, Lactobacillus NCH26 fermentation product showed good antioxidant ability and antibacterial activity, and has the potential as food additive to drinks to increase functional capacity and clarification.