[Expression of xylose-metabolic key genes of Trichoderma reesei on various carbon sources measured by a series of Northern hybridizations].

The expression of xylose reductase (XR), xylitol dehydrogenase (XDH) and transaldolase (TAL) genes from Trichoderma reesei, measured by Northern hybridization, were studied by adding different carbon sources (20 kinds, including single and mixed carbon sources) separately into the basal medium on which T. reesei QM9414 was grown. The experiment results indicated that the two disaccharides: sophrose and xylibiose act as a strong inducer for the expression of xr and xdh. The lactose and arabinose were identified as inducer also. The presence of glucose repressed the transcription of xr and xdh. When glucose depleted. xr and xdh were expressed at certain level, implying that expression of xr and xdh are controlled by the carbon catabolite repression mechanism and there existed a constitutive base level's expression of xr and xdh when the catabolite repression mechanism was derepressed. On the other hand, transaldolase gene strongly expressed on all the carbon sources used.