Gawande Bharat N, Sonawane Avinash M, Jogdand Vithal V, Patkar Anant Y
Biochemical Engineering Group, Chemical Engineering Division, National Chemical Laboratory, Pune 411 008, India.
Biotechnol Prog. 2003 Nov-Dec;19(6):1697-702. doi: 10.1021/bp034115t.
Production of a novel cyclodextrin glycosyltransferase (CGTase) from Klebsiella pneumoniae AS-22 strain, which converts starch predominantly to alpha-CD at high conversion yields, in batch, fed-batch, and continuous cultures, is presented. In batch fermentations, optimization of different operating parameters such as temperature, pH, agitation speed, and carbon-source concentration resulted in more than 6-fold increase in CGTase activity. The enzyme production was further improved by two fed-batch approaches. First, using glucose-based feed to increase cell density, followed by starch-based feed to induce enzyme production, resulted in high cell density of 76 g dry cell weight/L, although the CGTase production was low. Using the second approach of a single dextrin-based feed, 20-fold higher CGTase was produced compared to that in batch fermentations with media containing tapioca starch. In continuous operation, more than 8-fold increase in volumetric CGTase productivity was obtained using dextrin-based media compared to that in batch culture using starch-based media.
本文介绍了从肺炎克雷伯菌AS-22菌株生产一种新型环糊精糖基转移酶（CGTase）的方法，该酶在分批、补料分批和连续培养中能以高转化率将淀粉主要转化为α-环糊精。在分批发酵中，对温度、pH值、搅拌速度和碳源浓度等不同操作参数进行优化，使CGTase活性提高了6倍以上。通过两种补料分批方法进一步提高了酶产量。第一种方法是先使用基于葡萄糖的进料来增加细胞密度，然后使用基于淀粉的进料来诱导酶的产生，尽管CGTase产量较低，但细胞密度达到了76 g干细胞重量/L。使用第二种基于单一糊精的进料方法，与使用含木薯淀粉培养基的分批发酵相比，CGTase产量提高了20倍。在连续操作中，与使用基于淀粉培养基的分批培养相比，使用基于糊精的培养基使体积CGTase生产力提高了8倍以上。
