An extracellular cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) has been characterized for the first time in a strain of bacteria of the species Caldalkalibacillus mannanilyticus IB-OR17-B1. The enzyme was isolated from the culture supernatant using ultrafiltration and affinity adsorption on corn starch. The specific activity of the CGTase increased by 18 times as a result of purification with an enzyme yield of 56%. The molecular weight of the isolated enzyme was 70 kDa according to the denaturing electrophoresis in polyacrylamide gel. The CGTase of C. mannanilyticus IB-OR17-B1 demonstrated its maximum cyclizing activity at pH 8 and a temperature of 60°C, respectively, and it was stable in the pH range of 7–10 and temperatures of 70°C or less. The thermal stability of the enzyme under 70°C increased by 10–15% in the presence of 5–10 mM of calcium and magnesium salts. The cations of Ag⁺, Cu²⁺, Zn²⁺, Fe²⁺ and Fe³⁺ at a concentration of 5 mM inhibited CGTase activity by 90, 26, 23, 18, and 11%, respectively. Under the optimal conditions and enzyme-substrate ratio 1 U/g the isolated CGTase converted potato starch to mixture of α-, β-and γ-cyclodextrins with weight ratio 38.8 : 52.6 : 8.6 and a yield of 42% in 24 h.

首次在Caldalkalibacillus mannanilyticus IB-OR17-B1 细菌菌株中表征了细胞外环糊精葡聚糖转移酶（CGTase，EC 2.4.1.19）。使用超滤和玉米淀粉亲和吸附从培养物上清液中分离酶。纯化后CGTase的比活性提高了18倍，酶产率为56%。聚丙烯酰胺凝胶变性电泳显示分离酶的分子量为70 kDa。C. 甘露聚糖酶的 CGTaseIB-OR17-B1分别在pH 8和60°C的温度下表现出最大环化活性，并且在pH 7-10和70°C或更低的温度范围内稳定。在 5-10 mM 钙盐和镁盐存在下，酶在 70°C 下的热稳定性提高了 10-15%。浓度为5 mM的Ag ⁺、Cu ²⁺、Zn ²⁺、Fe ²⁺和Fe ³⁺阳离子分别抑制CGTase活性90%、26%、23%、18%和11%。在最佳条件下，酶底物比为1 U/g，分离的CGTase将马铃薯淀粉转化为α-、β-和γ-环糊精的混合物，重量比为38.8：52.6：8.6，24 h内产率为42%。