A Gluconobacter oxydans mutant converting glucose almost quantitatively to 5-keto-D-gluconic acid
A Gluconobacter oxydans mutant converting glucose almost quantitatively to 5-keto-D-gluconic acid
复制标题
DOI：
10.1007/s00253-004-1721-4
复制
发表时间：
2005-03-01
影响因子：
5
通讯作者：
Görisch, H
中科院分区：
文献类型：
--
作者：
Elfari, M;Ha, SW;Görisch, H
氧化葡萄糖杆菌通过膜结合的吡咯喹啉依赖和黄素依赖的脱氢酶将葡萄糖转化为葡萄糖酸，然后生成2-酮基-D-葡萄糖酸(2-KGA)和5-酮-D-葡萄糖酸(5-KGA)。几个菌株得到的产物图谱差异很大。为了提高5-KGA的产量，对发酵条件进行了优化。5-KGA可转化为工业上重要的L-(+)-酒石酸。而氧化棉ATCC 621H的静息细胞将约11%的有效葡萄糖转化为2-KGA和6%的有效葡萄糖为5-KGA，在确定的条件下(pH 5，10%Po(2)，0.05%PCO(2))进行细胞生长和促进生长，有效葡萄糖的转化率约为45%5-KGA。由于副产物2-KGA的积累非常不利于氧合葡萄糖的工业化应用，因此产生了一个膜结合葡萄糖酸-2-脱氢酶复合体失活的突变体。该突变体MF1的生长方式与野生型相似，但没有观察到不需要的2-KGA的形成。在改进的生长条件下，突变株MF1几乎完全将有效葡萄糖(84%)转化为5-KGA。因此，该重组菌株适合工业化生产5-KGA。
Gluconobacter oxydans converts glucose to gluconic acid and subsequently to 2-keto-D-gluconic acid (2-KGA) and 5-keto-D-gluconic acid (5-KGA) by membrane-bound periplasmic pyrroloquinoline quinone-dependent and flavin-dependent dehydrogenases. The product pattern obtained with several strains differed significantly. To increase the production of 5-KGA, which can be converted to industrially important L-(+)-tartaric acid, growth parameters were optimized. Whereas resting cells of G. oxydans ATCC 621H converted about 11% of the available glucose to 2-KGA and 6% to 5-KGA, with growing cells and improved growth under defined conditions (pH 5, 10% pO(2), 0.05% pCO(2)) a conversion yield of about 45% 5-KGA from the available glucose was achieved. As the accumulation of the by-product 2-KGA is highly disadvantageous for an industrial application of G. oxydans, a mutant was generated in which the membrane-bound gluconate-2-dehydrogenase complex was inactivated. This mutant, MF1, grew in a similar way to the wild type, but formation of the undesired 2-KGA was not observed. Under improved growth conditions, mutant MF1 converted the available glucose almost completely (84%) into 5-KGA. Therefore, this newly developed recombinant strain is suitable for the industrial production of 5- KGA.