Utilization of d-Lactate as an Energy Source Supports the Growth of Gluconobacter oxydans |
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| Authors: | Binbin Sheng Jing Xu Yingxin Zhang Tianyi Jiang Sisi Deng Jian Kong Chao Gao Cuiqing Ma Ping Xu |
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| Affiliation: | aState Key Laboratory of Microbial Technology, Shandong University, Jinan, People''s Republic of China;bState Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People''s Republic of China |
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| Abstract: | d-Lactate was identified as one of the few available organic acids that supported the growth of Gluconobacter oxydans 621H in this study. Interestingly, the strain used d-lactate as an energy source but not as a carbon source, unlike other lactate-utilizing bacteria. The enzymatic basis for the growth of G. oxydans 621H on d-lactate was therefore investigated. Although two putative NAD-independent d-lactate dehydrogenases, GOX1253 and GOX2071, were capable of oxidizing d-lactate, GOX1253 was the only enzyme able to support the d-lactate-driven growth of the strain. GOX1253 was characterized as a membrane-bound dehydrogenase with high activity toward d-lactate, while GOX2071 was characterized as a soluble oxidase with broad substrate specificity toward d-2-hydroxy acids. The latter used molecular oxygen as a direct electron acceptor, a feature that has not been reported previously in d-lactate-oxidizing enzymes. This study not only clarifies the mechanism for the growth of G. oxydans on d-lactate, but also provides new insights for applications of the important industrial microbe and the novel d-lactate oxidase. |
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