Heterologous xylAB expression enables d-xylose utilization in a naturally l-arabinose-utilizing Corynebacterium glutamicum strain
Year: 2026
Type: article
Abstract: Corynebacterium glutamicum CS176 is a naturally l -arabinose-utilizing strain that lacks the ability to metabolize d -xylose, limiting its capacity to utilize lignocellulosic pentose sugars. To expand its substrate range, a synthetic xylAB cassette encoding xylose isomerase ( xylA ) and xylulokinase ( xylB ) from Xanthomonas campestris was introduced into CS176, generating the recombinant strain CSX7. CSX7 exhibited IPTG-dependent growth on d -xylose as the sole carbon source, whereas the parental strain showed no detectable xylose utilization. HPLC analysis confirmed co-consumption of d -glucose and d -xylose in mixed-substrate cultures. Importantly, CSX7 retained the native ability of CS176 to co-utilize d -glucose and l -arabinose, indicating that heterologous xylAB expression expanded substrate utilization without disrupting the endogenous arabinose catabolic pathway. Oxygen availability influenced biomass formation and extracellular glutamate secretion, with reduced aeration generally promoting glutamate accumulation. In bioreactor cultivation with 2% (w/v) d -xylose, CSX7 achieved a maximum specific growth rate of 0.201–0.212 h⁻¹, consumed 98.2% of the supplied xylose within 48 h, and produced 264.6 ± 5.5 mg L⁻¹ extracellular glutamate. In mixed l -arabinose/ d -xylose cultivation, CSX7 concurrently consumed both pentose sugars, with l -arabinose consumed preferentially, to completion without a discernible diauxic lag in growth, and produced approximately twice the extracellular glutamate of the parental strain, directly confirming expanded pentose co-utilization. These findings demonstrate that xylose pathway engineering enables efficient utilization of both major lignocellulosic pentose sugars in the naturally arabinose-positive strain CS176, supporting its potential application in mixed-sugar bioconversion processes.
Source: Scientific Reports
Institution: Kasetsart University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,690
Funder: Kasetsart University
OpenAlex ID: W7221120185