根瘤菌BK-20固定化细胞生产L(+)-酒石酸

Production of L(+)-tartaric acid by immobilized Rhizobium strain BK-20

摘要:

顺式环氧琥珀酸水解酶(CESH)是根瘤菌BK-20生产L(+)-酒石酸的关键酶。为提高其生产效率和生产稳定性，首先优化根瘤菌BK-20的产酶条件，然后利用固定化细胞连续生产L(+)-酒石酸。结果显示，优化后游离细胞酶活达(3 498.0±142. 6) U/g，较优化前提高643%。固定化细胞酶活达(2 817.2±226.7) U/g，其最适包埋剂、菌体浓度和凝胶浓度分别为海藻酸钠，10% (W/V)和1.5% (W/V)。固定化细胞连续反应10批后，其形状和酶活均无明显改变，单批次转化率达98%以上，具有良好的生产稳定性。

Abstract:

The cis-epoxysuccinate hydrolase (CESH) from Rhizobium strain BK-20 is the key enzyme for L(+)-tartaric acid production. To establish a highly efficient and stable production process, we first optimized the enzyme production from Rhizobium strain BK-20, and then developed an immobilized cell-culture process for sustained production of L(+)-tartaric acid. The enzyme activity of free cells reached (3 498.0±142.6) U/g, and increased by 643% after optimization. The enzyme activity of immobilized cells reached (2 817.2±226.7) U/g, under the optimal condition with sodium alginate as carrier, cell concentration at 10% (W/V) and gel concentration at 1.5% (W/V). The immobilized cells preserved high enzyme activity and normal structure after 10 repeated batches. The conversion rate of the substrate was more than 98%, indicating its excellent production stability.