A strain of Fusarium kyushuense is able to produce aflatoxin B1 and G1

A strain of F. kyushuense is able to produce aflatoxin B1 and G1 under certain growth conditions. This was ultimately demonstrated by LC-MS analysis. By using a microarray covering oligonucleotides specific for the aflatoxin pathway genes of A. flavus, the expression of homologues of nearly the complete aflatoxin biosynthesis gene cluster was detected in F. kyushuense under producing conditions, e.g., after growth in liquid YES medium. In contrast, after growth of F. kyushuense on solid YES medium, only a very low transcription level of one of the homologues (nor-1) could be observed by microarray and Real Time PCR demonstrating differential gene expression. The cross-hybridization of the F. kyushuense mRNA to the A. flavus aflatoxin biosynthesis gene oligonucleotides of the array indicates homology between the sequences. PCR analyses with primers deduced from the nor-1 gene sequence of the aflatoxin biosynthesis gene cluster from A. flavus revealed the presence of a homologue of this gene in F. kyushuense. Sequencing of PCR fragments of the nor-1 homologue revealed a sequence similarity of >90% to the nor-1 gene of A. flavus.