植物乳杆菌RS2-2发酵法生产乳酸脱氢酶

Fermentative production of lactate dehydrogenase by Lactobacillus plantarum RS2-2

筛选到一株产乳酸脱氢酶的植物乳杆菌RS2-2(Lactobacillus plantarumRS2-2)。产酶条件研究表明,以蔗糖为碳源,酵母膏为氮源,起始pH 6.5左右,30℃发酵,接种量为10%,产酶量最高。在25 L发酵罐放大实验,并通过流加NaOH控制发酵过程中的pH,所产乳酸脱氢酶比活力为18.73 U/mg,菌重量为1 g/L以上。粗酶液经分离纯化得到成品酶液,比酶活提高了51.7倍,达到1210.7 U/mg,总收率为30.2%。用凝胶过滤检测其分子量分布,分子量约为85,000 Da,酶纯度为88%。

A strain of Lactobacillus plantarum RS2-2 producing lactate dehydrogenase was isolated and identified. Using sucrose as carbon source and yeast extract as nitrogen source, the maximum enzyme activity was obtained at 30℃ with initial pH 6.5. Fermentation was scaled up to 25 L, and the pH of medium was maintained at 6.5. The LDH activity and dry weight of cells of RS2-2 were increased to 18.73 U/mg and 1 g/L, respectively. After purification, the specific activity of LDH was enhanced to 1210.7 U/mg with 30.2 % total recovery. Its purity was 88 % measured, and MW of the enzyme was about 85000 Da.