Abstract (Expand)
Biomass-derived d-xylose represents an economically interesting substrate for the sustainable microbial production of value-added compounds. The industrially important platform organism Corynebacterium … glutamicum has already been engineered to grow on this pentose as sole carbon and energy source. However, all currently described C. glutamicum strains utilize d-xylose via the commonly known isomerase pathway that leads to a significant carbon loss in the form of CO2, in particular, when aiming for the synthesis of alpha-ketoglutarate and its derivatives (e.g. l-glutamate). Driven by the motivation to engineer a more carbon-efficient C. glutamicum strain, we functionally integrated the Weimberg pathway from Caulobacter crescentus in C. glutamicum. This five-step pathway, encoded by the xylXABCD-operon, enabled a recombinant C. glutamicum strain to utilize d-xylose in d-xylose/d-glucose mixtures. Interestingly, this strain exhibited a tri-phasic growth behavior and transiently accumulated d-xylonate during d-xylose utilization in the second growth phase. However, this intermediate of the implemented oxidative pathway was re-consumed in the third growth phase leading to more biomass formation. Furthermore, C. glutamicum pEKEx3-xylXABCDCc was also able to grow on d-xylose as sole carbon and energy source with a maximum growth rate of mumax=0.07+/-0.01h(-1). These results render C. glutamicum pEKEx3-xylXABCDCc a promising starting point for the engineering of efficient production strains, exhibiting only minimal carbon loss on d-xylose containing substrates.
Authors: A. Radek, K. Krumbach, J. Gatgens, V. F. Wendisch, W. Wiechert, M. Bott, S. Noack, J. Marienhagen
Date Published: 12th Oct 2014
Publication Type: Not specified
PubMed ID: 25304460
Citation: J Biotechnol. 2014 Dec 20;192 Pt A:156-60. doi: 10.1016/j.jbiotec.2014.09.026. Epub 2014 Oct 7.
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