OVEREXPRESSION OF THE ASPERGILLUS-NIGER PH-2.5 ACID-PHOSPHATASE GENE IN A HETEROLOGOUS HOST TRICHODERMA-REESEI

An Aspergillus gene coding for a pH 2.5 acid phosphatase enzyme was su ccessfully overexpressed in Trichoderma reesei under the strong main c ellobiohydrolase I (cbh1) promoter. The best transformants produced up to 240 times more of the acid phosphatase than the Aspergillus strain from which the phosphatase gene was originally isolated. The recombin ant enzyme was effectively secreted into the culture medium both by it s own and the cbh 1 secretion signal. The heterologous pH 2.5 acid pho sphatase enzyme produced by the Trichoderma transformants was seen as four protein bands of about 55-66 kD resulting from variable glycosyla tion in Trichoderma. The activity of the recombinant enzyme was not af fected. Enzyme preparations rich in both cellulose and phytate hydroly sing enzymes are of interest in the animal feed industry. (C) 1997 Els evier Science B.V.