Isolation and characterization of Aspergillus nomius from Japanese soil and silkworm excrement

Abstract

Aspergillus nomius, an aflatoxigenic species in Aspergillus section Flavi was first reported by Kurtzman et al. in 1987, but this fungus in Japan has never been reported. Several aflatoxigenic fungi were isolated from Japanese tea-field soil and silkworm excrements that display characteristics consistent with A. nomius. In order to identify these isolates we examined their colony color, micromorphological characters, mycotoxin production and DNA sequences. These fungi have light olive to moss green colony color, the conidia are spherical to subspherical having very rough surface ornamentation and their diameter is about 4.6μm. They produce aflatoxins B₁, B₂, G₁, and G₂ but do not produce detectable amounts of cyclopiazonic acid. The DNA sequences from the ITS and large subunit rDNA are identical with the sequence of an ex type strain of A. nomius. On the basis of these data we determined that two of these isolates are A. nomius.