Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2001
Publication Date: N/A
Citation: Interpretive Summary: Aflatoxin is a naturally occurring toxin produced by certain molds. This toxin can kill livestock, and in humans it is believed to cause liver cancer. Maintaining pure, wholesome foods and keeping livestock healthy requires that we know which mold species make aflatoxin. This is a difficult matter because safe and dangerous mold species resemble each other in appearance. In this study, DNA sequences were determined for a large number of aflatoxin producing and non-producing isolates, and the DNA sequence was correlated with toxin production and appearance of the mold. On the basis of different appearance, different DNA sequences and some toxin formation differences, we have discovered and described a new aflatoxin producing species. We have found this new species only in the immediate vicinity of silk-worm rearing farms in eastern Asia. It appears to be associated only with silk-worms and has not been found on any edible commodities.
Technical Abstract: A new aflatoxigenic species of Aspergillus, A. bombycis, was discovered during isolation of fungi from insect frass collected in silkworm rearing houses in Japan. The new species resembles A. flavus, but produces B and G aflatoxins. It is distinguished from A. flavus and A. nomius by differences in growth rates at 37 and 42 C, by differences in the roughness of the stipe, and by differences in the nucleotide sequences in the beta-tubulin, calmodulin, norsolorinic acid reductase, ITS and lsu-rDNA genes. Aspergillus bombycis is known from nine isolates, eight collected in silkworm-rearing houses in Japan and one collected in a silk- worm rearing house in Indonesia. Phylogenetic analysis of the DNA sequences shows that A. bombycis is a phylogenetically distinct species most closely related to A. nomius and belongs in Aspergillus section Flavi. Analysis by partition homogeneity did not reveal evidence of meiotic recombination in A. bombycis, but in A. nomius the patterns of polymorphisms in different genes strongly suggest cryptic meiotic recombination.