초록
<P><B>Abstract</B></P><P>Japanese cedar (<I>Cryptomeria japonica</I>) is a major species in artificial Japanese forests. The <I>Halomonas</I> sp. KM‐1 was recently isolated and found to grow effectively on saccharified Japanese cedar wood, resulting in the intracellular storage of poly‐(<I>R</I>)‐3‐hydroxybutyric acid (PHB) under aerobic conditions. Under microaerobic conditions, the extracellular secretion of (<I>R</I>)‐3‐hydroxybutyric acid ((<I>R</I>)‐3‐HB) led to the degradation of intracellular PHB. In this study, the production of PHB and the secretion of (<I>R</I>)‐3‐HB using saccharified Japanese cedar were much improved in cultures that were grown in the presence of urea. The level of intracellular PHB production after 36？h under aerobic cultivation was 23·6？g？l<SUP>−1</SUP>; after shifting to microaerobic conditions for 24？h, the (<I>R</I>)‐3‐HB concentration in the medium reached 21·1？g？l<SUP>−1</SUP>. Thus, KM‐1 efficiently utilizes saccharified Japanese cedar to produce PHB and secretes (<I>R</I>)‐3‐HB, making it a practical candidate for use in the industrial production of (<I>R</I>)‐3‐HB.</P><P><B>Significance and Impact of the Study</B></P><P>Japanese cedar is a major species grown in artificial Japanese forests, and its thinning is crucial for the health of artificial forests and the Japanese economy. <I>Halomonas</I> sp. KM‐1 grew effectively on saccharified Japanese cedar wood, resulting in intracellular storage of poly‐(<I>R</I>)‐3‐hydroxybutyric acid (PHB) under aerobic conditions. Under microaerobic conditions, extracellular secretion of (<I>R</I>)‐3‐hydroxybutyric acid ((<I>R</I>)‐3‐HB) caused intracellular PHB degradation. (<I>R</I>)‐3‐HB is a chiral compound that is useful in the chemical, health food and pharmaceutical industries. The production of PHB and secretion of (<I>R</I>)‐3‐HB using saccharified wood was dramatically improved, which may positively affect its future industrial production.</P>