Differentiation of Aspergillus parasiticus from Aspergillus sojae by random amplification of polymorphic DNA.

Aspergillus parasiticus and Aspergillus sojae are two morphologically similar species belonging to the Aspergillus section flavi. A new method to distinguish the two species, the aflatoxin producer A. parasiticus and the koji mold A. sojae, was developed. Single primers with arbitrary sequences were used to generate random amplified polymorphic DNA (RAPD) markers from strains of these two species. Three decamers, OPA-04, OPB-10, and OPR-01, allowed adequate discrimination between strains of A. parasiticus and A. sojae in RAPD analyses. A. sojae was further separated into group I and group II with the three primers. On the other hand, A. parasiticus was divided into group A and group B when amplified with OPA-04 and OPR-10 primers. The previously misidentified stain CCRC 32423 and the misclassified strain CCRC 30227 were identified as Aspergillus flavus and A. sojae, respectively, on the basis of RAPD patterns and morphological characteristics. We suggest that the RAPD technique is a rapid and reliable tool to distinguish A. parasiticus from A. sojae.