Study on the molecular basis of glucoamylase overproduction of a mutant strainAspergillus niger T21.
The molecular basis for increasing of the glucoamylase (GLA) production of anAspergillus niger mutant T21 was investigated. Northern blot analysis showed that the amount ofglaA specific mRNA ofA. niger T21 was about 20 times higher than that of its start strainA. niger AS 3.795. The twoglaA promoter fusions (PglaA)-uidAs were respectively introduced intoA. niger. Analysis of GUS activity of the transformants revealed that thePglaA activity of the strain T21 is about 3 times stronger than that of the strain AS 3.795. It is considered to be one of the reasons for the increase ofglaA transcriptional level in the strain T21. However, comparing with the 20 times increase in the amount of glaA mRNA the alteration oftrans regulation should be the most important reason for that. The results of deletion analysis of 5'-c/s region ofA. niger T21glaA gene indicated that the region from-408 to-513 bp upstream of ATG is responsible for the high level expression ofglaA.
Fan
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Institute of Microbiology, Chinese Academy of Sciences, 100080, Beijing, China.
Qiu
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Liu
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Tang
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