A filamentous fungus Aspergillus nidulans produces a mycotoxin sterigmatocystin (ST), in addition to other secondary metabolites (SMs). SM biosynthetic pathways share common precursor substances. However, how the loss of one SM affects the production of other SMs remains unclear. In this study, we deleted 8 biosynthetic gene clusters (BGCs) or a polyketide synthase gene wA, respectively, and analyzed ST production in those deletion strains. In aus1Δ lacking austinol (AUS) cluster A, ST production was increased compared to the control strain. However, in aus1Δ aus2Δ lacking both AUS cluster A and B, ST production was comparable to the control. In STΔ lacking ST cluster, AUS and dehydroaustinol (DAUS) production was comparable to the control.

  In a previous study, an in vitro cell-free assay of translation inhibition by H-2 toxin, HT-2 toxin, and deoxynivalenol using a commercially available kit was developed. They showed significant inhibition of the translation in the system. For further evaluation, I examined three additional modified deoxynivalenol compounds, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, and deoxynivalenol-3-glucoside, by the in vitro cell-free assay in this study. 15-acetyldeoxynivalenol inhibited translation as well as deoxynivalenol in the assay. On the other hand, 3-acetyldeoxynivalenol and deoxynivalenol-3-glucoside show around 100 times lower and no inhibitory activities, respectively, on the translation in the assay. These data are consistent with previous studies, suggesting that the assay is useful. It is hoped that it will be applied to other trichothecenes in the future.

  Aspergillus oryzae called as koji mold was designated as ‘National Microorganisms’ by Japanese Society for Brewing Science, had been widely utilized in traditional fermented foods in Japan and in the industrial enzyme production. The genome information was opened at 2005 along with the publication in Nature. After that, variety of research has been performed using genome information of koji mold. The author was employed by National Food Research Institute in 1986, then was continuously working on studies of koji mold. The author is currently managing donated laboratory of breeding engineering for koji mold in Osaka University. In this laboratory, the members are studying koji mold in the sight of microbial ecology in addition to brewing science. In this presentation, the author introduces my present study in addition to the past studies during these 37 years.

  The bean bug Riptortus pedestris is a notorious pest of leguminous crops widely distributed in East Asia, which harbors symbiotic bacteria of the genus Caballeronia in the gut symbiotic organ. We have revealed that the bean bug does not vertically transmit the symbiont but acquires it from the environmental soil after hatching. This paper outlines the multilayered mechanisms by which the host insect specifically selects the Caballeronia symbiont from the diverse microorganisms in the soil.