Abstract

Few studies expressed the β-galactosidase encoding gene from L. plantarum in E. coli so far. In the present study, the recombinant β-galactosidase from L. plantarum FMNP01 was used as a catalyst in transgalactosylation to form tri-GOS and lactosucrose. In the presence of lactose and sucrose, six transfer products were formed in the transgalactosylation reaction with recombinant β-galactosidase L.pFMNP01Gal as a catalyst. Three transfer products were tri-galacto-oligosaccharides (tri-GOS), lactosucrose, and lactulose; the other three transfer products needed to be identified further. Based on a single factor test and response surface methodological approach, the optimal transgalactosylation conditions of the production of tri-GOS and lactosucrose were determined as initial sugar concentration of 50%, lactose: sucrose ratio of 1:2, enzyme concentration of 3 U/mL, and reaction time of 6 h at 50 °C resulting in a maximum tri-GOS concentration of 47.69 ± 1.36 g/L and a maximum lactosucrose concentration of 8.18 ± 0.97 g/L.

摘要

迄今为止，很少有研究在大肠杆菌中表达植物乳杆菌的 β-半乳糖苷酶编码基因。在本研究中，来自植物乳杆菌的重组 β-半乳糖苷酶FMNP01 在转半乳糖基化反应中用作催化剂以形成三 GOS 和乳糖。在乳糖和蔗糖存在下，以重组β-半乳糖苷酶L.pFMNP01Gal为催化剂的转半乳糖基化反应形成了6种转移产物。三种转移产物是三低聚半乳糖（tri-GOS）、乳蔗糖和乳果糖；需要进一步确定其他三种转移产物。基于单因素试验和响应面法，确定了生产tri-GOS和乳蔗糖的最佳转半乳糖基化条件为初始糖浓度为50%，乳糖：蔗糖比例为1:2，酶浓度为3 U/ mL，在 50°C 下反应时间为 6 小时，导致最大 tri-GOS 浓度为 47.69 ± 1.36 g/L，最大乳蔗糖浓度为 8。