Michiko Aoki

Antiviral substances with systemic effects produced by basidiomycetes such as Fomes fomentarius

Inhibitors of plant virus infection with systemic effects were found in the culture filtrates of Basidiomycetes such as Fomes fomentarius and Schizophyllum commune. These inhibitors were widely distributed in Agaricales and Polyporales. The inhibitors designated as BAS (Basidiomycete Antiviral Substance) were highly active against the mechanical transmission of tobacco mosaic virus (TMV). No toxic effect was observed on the host plants. BAS-F, a polysaccharide produced by F. fomentarius, almost completely inhibited infection, when BAS-F at 2 μg/ml was applied to the same surface of leaves of Xanthi-nc tobacco 24 h before TMV inoculation to the upper surface of the leaves, and 500/0 inhibition was shown when BAS-F at 10 μg/ml was applied to the under surface of leaves. BAS-F also induced systemic resistance to the non-treated leaves when it was applied to only one leaf of the plant. BAS-F also had similar effects against the infection of TMV on bell pepper and tomato plants.

Production of Thermophilic Protease (Aqualysin I) by Fed-Batch Cultures of Recombinant Escherichia coli

Aqualysin I (AQI) is a subtilisin-type serine protease which is secreted into the culture medium by Thermus aquaticus YT-1, an extreme thermophile. AQI is considerably heat-stable and resistant to denaturing treatments in comparison with other microbial serine proteases. Terada et al. previously reported the production of the enzymatically active AQI by expressing the AQI gene under the control of the tac promoter in Escherichia coli [1]. In this study, to achieve efficient production of AQI, batch and fed-batch cultures of E.coli TG1 transformed with plasmid pAQN containing the AQI gene were investigated.