Merfort Marcel, Herrmann Ute, Ha Seung-Wook, Elfari Mustafa, Bringer-Meyer Stephanie, Görisch Helmut, Sahm Hermann
Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, Jülich, Germany.
Biotechnol J. 2006 May;1(5):556-63. doi: 10.1002/biot.200600032.
Gluconobacter oxydans DSM 2343 (ATCC 621H)catalyzes the oxidation of glucose to gluconic acid and subsequently to 5-keto-D-gluconic acid (5-KGA), a precursor of the industrially important L-(+)-tartaric acid. To further increase 5-KGA production in G. oxydans, the mutant strain MF1 was used. In this strain the membrane-bound gluconate-2-dehydrogenase activity, responsible for formation of the undesired by-product 2-keto-D-gluconic acid, is disrupted. Therefore, high amounts of 5-KGA accumulate in the culture medium. G. oxydans MF1 was equipped with plasmids allowing the overexpression of the membrane-bound enzymes involved in 5-KGA formation. Overexpression was confirmed on the transcript and enzymatic level. Furthermore, the resulting strains overproducing the membrane-bound glucose dehydrogenase showed an increased gluconic acid formation, whereas the overproduction of gluconate-5-dehydrogenase resulted in an increase in 5-KGA of up to 230 mM. Therefore, these newly developed recombinant strains provide a basis for further improving the biotransformation process for 5-KGA production.
氧化葡萄糖杆菌DSM 2343（ATCC 621H）可将葡萄糖催化氧化为葡萄糖酸，随后再氧化为5-酮基-D-葡萄糖酸（5-KGA），5-KGA是工业上重要的L-(+)-酒石酸的前体。为了进一步提高氧化葡萄糖杆菌中5-KGA的产量，使用了突变菌株MF1。在该菌株中，负责形成不想要的副产物2-酮基-D-葡萄糖酸的膜结合葡萄糖酸-2-脱氢酶活性被破坏。因此，大量的5-KGA积累在培养基中。氧化葡萄糖杆菌MF1携带了一些质粒，这些质粒可使参与5-KGA形成的膜结合酶过表达。过表达在转录水平和酶水平上均得到证实。此外，产生的过量表达膜结合葡萄糖脱氢酶酶的菌株显示葡萄糖酸形成增加，而过量表达葡萄糖酸-5-脱氢酶则导致5-KGA增加高达230 mM。因此，这些新开发的重组菌株为进一步改进5-KGA生产的生物转化过程提供了基础。
