초록
<P><B>Background</B></P><P>The development of biorefinery systems that use lignocellulosic biomass as a renewable carbon source to produce fuels and chemicals is attracting increasing attention. The process cost of enzymatic saccharification of biomass is a major challenge for commercialization. To decrease this cost, researchers have proposed on-site solid-state fermentation (SSF). This study investigated the feasibility of using <I>Aspergillus oryzae</I> as a host microorganism for SSF recombinant enzyme production with ammonia-treated rice straw as model biomass. Eight <I>A. oryzae</I> strains were tested, all of which are used in the food industry. We evaluated the effects of acetic acid, a fermentation inhibitor. We also developed a platform strain for targeted recombinant enzyme production by gene engineering technologies.</P><P><B>Results</B></P><P>The SSF validation test showed variation in the visibility of mycelium growth and secreted protein in all eight <I>A. oryzae</I> strains. The strains used to produce <I>shoyu</I> and <I>miso</I> grew better under test conditions. The ammonia-treated rice straw contained noticeable amounts of acetic acid. This acetic acid enhanced the protein production by <I>A. oryzae</I> in a liquid-state fermentation test. The newly developed platform strain successfully secreted three foreign saccharifying enzymes.</P><P><B>Conclusions</B></P><P><I>A. oryzae</I> is a promising candidate as a host microorganism for on-site SSF recombinant enzyme production, which bodes well for the future development of a more cost-efficient saccharifying enzyme production system.</P>