Development of high-frequency transformation methods in Aspergillus oryzae

High transformation efficiency was obtained by an improvement of transformation procedures in Aspergillus oryzae. When Yatalase was used as the protoplasting enzyme and the resultant protoplasts were stored at 5 degrees C for 1 d, the efficiency of transformation using integration vectors showed increases of 4.8-fold in A. oryzae argB(-) and 11-fold in A. oryzae niaD(-), compared to the usual method (Novozym 234 and CELLULASE R-10 were used as the protoplasting enzymes, and the resultant competent cells were transformed immediately). The efficiency of transformation using plasmid (AMA1) vectors showed increases of 5.6-fold in A. oryzae argB(-) and 4.2-fold in A. oryzae niaD(-), compared to the usual method.