Diversity of <i>Aspergillus oryzae</i> genotypes (RFLP) isolated from traditional soy sauce production within Malaysia and Southeast Asia

Abstract

DNA fi ngerprinting was performed on 64 strains of Aspergillus oryzae and 1 strain of Aspergillus sojae isolated from soy sauce factories within Malaysia and Southeast Asia that use traditional methods in producing "tamari-type" Cantonese soy sauce. PstI digests of total genomic DNA from each isolate were probed using the pAF28 repetitive sequence. Strains of A. oryzae were distributed among 32 genotypes (30 DNA fi ngerprint groups). Ten genotypes were recorded among 17 A. oryzae isolates from a single soy sauce factory. Genotypes Ao-46 and GTAo-47, represented by 8 and 5 strains, respectively, were isolated from a soy sauce factory in Kuala Lumpur and factories in two Malaysian states. Four strains of GTAo-49, isolated from three soy sauce factories in Malaysia; each produced sclerotia. Two strains were found to be naturally occurring color mutants of NRRL 32623 (GTAo-49) and NRRL 32668 (GTAo-52). Only two fi ngerprint matches were produced with the 43 DNA fi ngerprint groups in our database, representing A. oryzae genotypes from Japan, China, and Taiwan. Aspergillus sojae NRRL 32650 produced a fi ngerprint matching GTAo-9, the only known genotype representing koji strains of A. sojae. No afl atoxin was detected in broth cultures of these koji strains as determined by TLC.