Enhanced butyric acid productivity by 2-deoxy-D-glucose-adapted Clostridium tyrobutyricum on glucose and xylose mixtures with non-diauxic growth

Title
Enhanced butyric acid productivity by 2-deoxy-D-glucose-adapted Clostridium tyrobutyricum on glucose and xylose mixtures with non-diauxic growth
Authors
우한민김기연이경민상병인엄영순
Keywords
Diauxie; Clostridium; butyric acid
Issue Date
2012-06
Publisher
Metabolic engineering conference
Citation
, 195-1958
Abstract
Lignocellulosic biomass is an attractive carbon source for bio-based chemical production and is mainly composed of glucose and xylose. However, most bacteria show diauxic growth when they are cultivated in mixed sugars and the diauxic growth must be resolved to ensure the consolidated bioprocessing. Clostridium tyrobutyricum is the most representative bio-producer for butyric acid, one of the most important building blocks. In this study, we develop an adaptive cultivation system to release the diauxic growth of C. tyrobutyricum strain for butyric acid production using the mixture of glucose and xylose. After the 13 commercially available strains were tested for butyric acid production on xylose as sole carbon source, the strain ATCC 25755 showed the most efficient butyric acid production with the highest xylose utilization rate. However, the xylose utilization rate was slowed when glucose was added because of carbon catabolite repression (CCR). To improve xylose utilization rate of this strain in the presence of glucose, the strain was adapted on xylose as sole carbon source with different concentrations of 2-deoxy-D-glucose (2DG), a glucose analogue. High level of 2DG-adapted strain showed the faster xylose utilization rate. In contrast, the slower glucose utilization rate was shown with the same 2DG concentrations. Optimally adapted strain with 2DG showed 1.44-fold higher productivity of butyric acid compared with the wild-type strain on the mixture of glucose and xylose. Acquired phenotype of the negative CCR was maintained when the cells were cultivated in xylose medium. In conclusion, we successfully developed an adaptive cultivation system that improves the productivity of butyric acid by C. tyrobutyricum grown on the mixture of glucose and xylose by releasing the diauxic growth.
URI
http://pubs.kist.re.kr/handle/201004/45669
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KIST Publication > Conference Paper
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