AbstractThe heterologous protein production in Aspergillus niger is often limited by the activity of the host extracellular proteases. To improve heterologous production, a transcription factor controlling expression of several extracellular protease-encoding genes, prtT, was deleted in A. niger PY11 and the mutant (AnprtT) characterised.Extracellular proteolytic activity of AnprtT was reduced as compared to the wild type, a result that was confirmed by RT-PCR analyses that showed reduced expression levels of several protease gene transcripts. To compare the efficiency of the mutant and parental (PY11) strains as hosts for heterologous protein production, the cutinase gene from Glomerella cingulate, under control of the glucoamylase A promoter, was integrated into each genome. The cutinase activity of PY11 and AnprtT harbouring the G. cingulata cutinase gene was increased 20- and 36-fold higher, respectively, than the untransformed parental strains, suggesting that the ability of the mutant to.....