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Formation of xylitol and xylitol-5-phosphate and its impact on growth of d-xylose-utilizing Corynebacterium glutamicum strains

Paper ID Volume ID Publish Year Pages File Format Full-Text
22676 43369 2016 7 PDF Available
Title
Formation of xylitol and xylitol-5-phosphate and its impact on growth of d-xylose-utilizing Corynebacterium glutamicum strains
Abstract

•Corynebacterium glutamicum accumulates extracellular xylitol during aerobic growth on d-xylose containing substrates.•Intracellular xylitol is partly converted to cytotoxic xylitol-5-phosphatein C. glutamicum pEKEx3-xylAXc-xylBCg (ISO).•Low amounts of supplemented xylitol strongly inhibit the growth of the ISO strain on d-xylose, d-glucose and d-arabitol.•Xylitol is a suitable substrate of the endogenous xylulokinase(encoded by xylB).•The Weimbergroute, operating independently from xylulokinase activity, could be an effective substitute towards efficient D-xylose utilization in C. glutamicum.

Wild-type Corynebacterium glutamicum has no endogenous metabolic activity for utilizing the lignocellulosic pentose d-xylose for cell growth. Therefore, two different engineering approaches have been pursued resulting in platform strains harbouring a functional version of either the Isomerase (ISO) or the Weimberg (WMB) pathway for d-xylose assimilation. In a previous study we found for C. glutamicum WMB by-product formation of xylitol during growth on d-xylose and speculated that the observed lower growth rates are due to the growth inhibiting effect of this compound. Based on a detailed phenotyping of the ISO, WMB and the wild-type strain of C. glutamicum, we here show that this organism has a natural capability to synthesize xylitol from d-xylose under aerobic cultivation conditions. We furthermore observed the intracellular accumulation of xylitol-5-phosphate as a result of the intracellular phosphorylation of xylitol, which was particularly pronounced in the C. glutamicum ISO strain. Interestingly, low amounts of supplemented xylitol strongly inhibit growth of this strain on d-xylose, d-glucose and d-arabitol. These findings demonstrate that xylitol is a suitable substrate of the endogenous xylulokinase (XK, encoded by xylB) and its overexpression in the ISO strain leads to a significant phosphorylation of xylitol in C. glutamicum. Therefore, in order to circumvent cytotoxicity by xylitol-5-phosphate, the WMB pathway represents an interesting alternative route for engineering C. glutamicum towards efficient d-xylose utilization.

Keywords
Corynebacterium glutamicum; Xylitol; Xylitol-5-phosphate; d-xylose; Isomerase pathway; Weimberg pathway
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Formation of xylitol and xylitol-5-phosphate and its impact on growth of d-xylose-utilizing Corynebacterium glutamicum strains
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 231, 10 August 2016, Pages 160–166
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us