Isolation of Dominant Lactic Acid Bacteria Strains in Pickled Wax Gourd from Eastern Zhejiang and Analysis of Its Enzyme-producing Characteristics
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Abstract:
By isolation and identification of microorganisms in traditional pickled wax gourd from eastern Zhejiang, four dominant lactic acid bacteria (LAB) strains were obtained which were Lactobacillus plantarum (Lz151), Lactobacillus fermentum (Lz152), Lactobacillus coryniformis (Lz153), and Lactobacillus pentosus (Lz154). The characteristics of all strains to produce lactate dehydrogenase, nitrite reductase, esterase, and aminotransferase were analyzed by enzymological methods. The results showed that the four strains presented the lactic dehydrogenase, nitrite reductase, esterase, and aminotransferase activities. Lactobacillus plantarum and Lactobacillus fermentum showed relatively high lactic dehydrogenase activity. The values reached 122.34 U/mL and 113.56 U/mL, respectively. Lactobacillus fermentum and Lactobacillus pentosus presented relatively high nitrite reductase activity. The values reached 17.62 U/mL and 13.42 U/mL, respectively. Lactobacillus coryniformis possessed the lowest nitrite reductase activity (4.74 U/mL). Compared with the other two strains, Lactobacillus plantarum and Lactobacillus coryniformis displayed higher esterase activity. The values reached 11.53 U/mL and 13.78 U/mL, respectively. Moreover, Lactobacillus plantarum and Lactobacillus pentosus exhibited higher aminotransferase activity, whose values were 25.37 U/mL and 23.19 U/mL, respectively. Inter-strain differences were presented in the optimal enzyme-producing temperature and pH among the four strains and the optimum conditions for the same strain to produce various enzymes were different. The optimum temperatures for the isolated LAB strains to produce various enzymes were 30?C, 35?C, and 40?C, respectively. The optimal enzyme-producing pH values of Lactobacillus fermentum and Lactobacillus plantarum were 6.0 and 7.0, respectively.
