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KMID : 0545119980080010014
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Journal of Microbiology and Biotechnology
1998 Volume.8 No. 1 p.14 ~ p.20
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Regulation of β-Xylosidase(XylA) Synthesis in Bacillus stearothermophilus
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Cho Ssang-Goo
Choi Yong-Jin
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Abstract
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Syntheses of the B. stearothermophilus xylanolytic enzymes such as xylanases, β-xylosidases, α-arabinofuranosidases, and esterases, were observed to be regulated by the carbon source present in the culture media. Xylan induced synthesis of β-xylosidase at the highest level while xylose gave about 30% of the β-xylosidase activity induced by xylan. The lowest syntheses of the xylanolytic enzymes above mentioned were detected in the basal medium containing glucose as a sole carbon source. When a mixture of xylan and glucose was used as a carbon source, we could observe glucose repression of xylanase (about 70-fold) and 3-xylosidase (about 40-fold) syntheses. Whereas, the level of the glucose repression of the expression of the xylA gene encoding the major β-xylosidase of B. stearothermophilus was assessed to be about 10-fold when the relative amounts of the xylA transcript were determined. From the sequence of the xylA gene, we could find two CRElike sequences (CRE-1: nucleotides +124 to +136 and CRE-2: +247 to +259) within the reading frame of the xylA gene, either or both of which were suspected to be involved in catabolite repression of the xylA gene.
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