Department of Biotechnology and Chemical Technology, Aalto University, Finland.
Bioprocess Biosyst Eng. 2013 Apr;36(4):489-97. doi: 10.1007/s00449-012-0805-2. Epub 2012 Aug 18.
Bifidobacterium longum NRRL B-41409 L-arabinose isomerase (L-AI) was overexpressed in Lactococcus lactis using a phosphate depletion inducible expression system. The resting L. lactis cells harboring the B. longum L-AI were used for production of D-tagatose from D-galactose in the presence of borate buffer. Multivariable analysis suggested that high pH, temperature and borate concentration favoured the conversion of D-galactose to D-tagatose. Almost quantitative conversion (92 %) was achieved at 20 g L⁻¹ substrate and at 37.5 °C after 5 days. The D-tagatose production rate of 185 g L⁻¹ day ⁻¹ was obtained at 300 g L⁻¹ galactose, at 1.15 M borate, and at 41 °C during 10 days when the production medium was changed every 24 h. There was no significant loss in productivity during ten sequential 24 h batches. The initial D-tagatose production rate was 290 g L⁻¹ day⁻¹ under these conditions.
长双歧杆菌 NRRL B-41409 L-阿拉伯糖异构酶（L-AI）在乳球菌中通过磷酸盐耗尽诱导表达系统过表达。含有长双歧杆菌 L-AI 的静止乳球菌细胞在硼酸缓冲液存在下用于 D-半乳糖生产 D-塔格糖。多变量分析表明，高 pH 值、温度和硼酸浓度有利于 D-半乳糖转化为 D-塔格糖。在 20 g L ⁻¹ 底物和 37.5°C 下，经过 5 天，几乎实现了定量转化（92%）。在 10 天的时间里，当生产培养基每 24 小时更换一次时，在 300 g L ⁻¹ 半乳糖、1.15 M 硼酸和 41°C 的条件下，获得了 185 g L ⁻¹ 天 ⁻¹ 的 D-塔格糖生产速率，在十个连续的 24 小时批次中没有明显的生产力损失。在这些条件下，初始 D-塔格糖的生产速率为 290 g L ⁻¹ 天 ⁻¹。
