Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
J Biosci Bioeng. 2012 Oct;114(4):418-23. doi: 10.1016/j.jbiosc.2012.05.012. Epub 2012 Jun 12.
The enzymatic synthesis of galacto-oligosaccharides (GOS) from lactose was studied using commercial grade β-galactosidase (Biolacta FN5) from Bacillus circulans. The reaction was carried out under free enzyme condition varying initial lactose concentration (ILC: 55-525 g/L), enzyme concentration (0.05-1.575 g/L), temperature (30-50°C) and pH (5.0-6.0). Reaction mixture compositions were analyzed utilizing high performance liquid chromatography (HPLC). A maximum GOS formation of 39% (dry basis) was achieved at an ILC of 525 g/L converting 60% of the lactose fed. Tri-saccharides were the major types of GOS formed, accounting approximately 24%; whereas, tetra-saccharides and penta-saccharides account approximately 12% and 3%, respectively. Design correlation was developed in order to observe the quantitative effect of operating parameters on GOS yield. Further, based on Michaelis-Menten model, four-step reaction pathways were considered for simplistic understanding of the kinetics. Apart from predicting the reaction mixture composition, the approach also provided kinetic parameters though simulation using COPASI 4.7®. Excellent agreements were observed between simulated and experimental results.
利用从环状芽孢杆菌中提取的商业化β-半乳糖苷酶（Biolacta FN5），研究了乳糖的酶法合成半乳糖低聚糖（GOS）。在游离酶条件下，通过改变初始乳糖浓度（ILC：55-525 g/L）、酶浓度（0.05-1.575 g/L）、温度（30-50°C）和 pH（5.0-6.0）来进行反应。利用高效液相色谱法（HPLC）分析反应混合物的组成。在 ILC 为 525 g/L 时，GOS 的最大生成量为 39%（干基），转化率为 60%。三糖是形成的主要 GOS 类型，约占 24%；而四糖和五糖分别约占 12%和 3%。为了观察操作参数对 GOS 产率的定量影响，开发了设计相关性。此外，基于米氏方程，考虑了四步反应途径，以便于简单理解动力学。该方法不仅可以预测反应混合物的组成，还可以通过使用 COPASI 4.7®进行模拟来提供动力学参数。模拟结果与实验结果吻合较好。
