cDNA cloning and expression of a Talaromyces emersonii beta-glucosidase determinant in Escherichia coli

Intact mRNA has been isolated from the thermophilic fungus Talaromyces emersonii following growth on lactose-containing media and this has been used as template to produce cDNA. This cDNA has been cloned into the Escherichia coli expression system, pUC18 and this DNA was used to transform E. coli. A 2.1 kb fragment was isolated and shown to encode functional beta-glucosidase activity in E. coli. When the fragment was sub-cloned into a leaky strain of E. coli K-12, beta-glucosidase activity was detected in culture supernatants. The fragment was characterised further using restriction enzyme analysis and was also used as a probe in Northern and Southern blotting analyses of T. emersonii mRNA and genomic DNA, respectively. Results obtained from these analyses verified that the cloned insert DNA was of T. emersonii origin.