<論文・報告>Bioconversion of Castor Oil by Microorganisms

Abstract

Sebacic acid, a monomer of nylon, is a promising carbon-neutral monomer because it is made from castor oil. Castor oil is an inedible vegetable oil that is rich in ricinoleic acid. However, the production of sebacic acid requires a large input of energy due to the need for high pressure and high temperature, as well as highly alkaline reaction conditions. Therefore, we applied microbial technology in an attempt to develop an eco-friendly sebacic acid production process. We collected microbial samples from the Kyoto University Botanical Gardens. These samples were inoculated into medium containing castor oil, following which, we performed subculturing. After isolating pure cultures of several kinds of microorganisms, we performed TLC and GC analysis. According to our TLC analysis, almost all the microbial isolates were able to degrade castor oil. Despite this, our GC analysis indicated that none of the isolated microorganisms were able to produce sebacic acid. ナイロン原料のセバシン酸は非可食性植物油であり，リシノール酸を豊富に含むヒマシ油から作られている．しかしそのプロセスは高アルカリ条件下で高温・高圧を必要とするため，環境負荷が高いという問題がある．そこで微生物のバイオテクノロジーを利用し，温和な条件でリシノール酸からセバシン酸を生産することを目的に研究を行った．京都大学理学部植物園でサンプリングを行い，ヒマシ油を基質とした最少栄養培地で植菌を行った．その後植え継ぎを行い，画線による分離，単離後，TLC とGC による脂質組成の分析を行った．単離した結果，16 種類のバクテリアやカビを得た．TLC 分析の結果，ほとんどのサンプルにおいてヒマシ油が分解されていることが分かった．GC 分析の結果，セバシン酸を生産している微生物は得られなかった．