Genetic analysis of D-xylose metabolism by endophytic yeast strains of Rhodotorula graminis and Rhodotorula mucilaginosa

Genetics and Molecular Biology

Ping Xu¹  Renata Bura¹  Sharon L. Doty¹ 

[1] ,University of Washington College of the Environment School of Forest ResourcesSeattle WA ,USA

关键词: Rhodotorula graminis;    Rhodotorula mucilaginosa;    D-xylose metabolism;    xylitol;    xylitol dehydrogenase;    xylose reductase;   

DOI  :  10.1590/S1415-47572011000300018

来源: SciELO

【 摘 要 】

Two novel endophytic yeast strains, WP1 and PTD3, isolated from within the stems of poplar (Populus) trees, were genetically characterized with respect to their xylose metabolism genes. These two strains, belonging to the species Rhodotorula graminis and R. mucilaginosa, respectively, utilize both hexose and pentose sugars, including the common plant pentose sugar, D-xylose. The xylose reductase (XYL1) and xylitol dehydrogenase (XYL2) genes were cloned and characterized. The derived amino acid sequences of xylose reductase (XR) and xylose dehydrogenase (XDH) were 32%~41% homologous to those of Pichia stipitis and Candida. spp., two species known to utilize xylose. The derived XR and XDH sequences of WP1 and PTD3 had higher homology (73% and 69% identity) with each other. WP1 and PTD3 were grown in single sugar and mixed sugar media to analyze the XYL1 and XYL2 gene regulation mechanisms. Our results revealed that for both strains, the gene expression is induced by D-xylose, and that in PTD3 the expression was not repressed by glucose in the presence of xylose.

【 授权许可】

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