Twenty-one Aspergillus strains representing different A. awamori, A. phoenicis and A. foetidus isolates were studied in order to explore the potential of a fast RFLP analysis to identify fungal strains. The patterns were compared with those characteristic for A. niger, A. tubingensis, A. carbonarius, A. japonicus and A. aculeatus represented by A. niger CBS 120.49, A. tubingensis NW 756, A. carbonarius CBS 111.26, A japonicus CBS 114.51 and A. aculeatus CBS 101.43 and also with those of the type strains of A. heteromorphus CBS 117.55 and A. ellipticus CBS 707.79.

Sma I digested chromosomal DNA revealed characteristic rDNA patterns after ethidium bromide staining which were used in combination with hybridization patterns of Pst I/Sal I double digested chromosomal DNA with well-defined probes. This allowed clear distinction of eight separate species within the Aspergillus sect. Nigri group. The probes used were a 0·9 kb fragment of the 28S rDNA from Agaricus bisporus, an internal fragment of the pkiA gene from A. nidulans, and the pelA gene from A. niger. All the strains examined including those indicated as A. awamori and A. phoenicis were shown to belong either to A. niger, A. tubingensis or a group representing isolates of A. foetidus varieties, amongst which A. foetidus var. acidus CBS 564.65 and A. foetidus var. pallidus CBS 565.65.