<論文・報告>Microbial Synthesis of Oxo Cyclic Amino Acids

Abstract

In order to obtain microorganisms that can synthesize of oxo cyclic amino acids from hydroxy cyclic amino acids, we performed screening of microorganisms that are able to do so from 10 microbial samples collected from the Kyoto University Botanical Garden. Isolated microorganism colonies were shake-incubated in a liquid nutrient medium containing hydroxy cyclic amino acids as the only source of carbon, and the resulting suspension was subjected to TLC analysis with ninhydrin detection. According to the analysis, hydroxy cyclic amino acids in the liquid medium were decomposed by the microorganisms; however, oxo cyclic amino acids could not be detected. The resting microbial reaction of the isolated colonies was also performed, but the same results were obtained. Therefore, we isolated microorganisms that utilize hydroxy cyclic amino acids from the environment during single carbon source?medium cultivation, but were unable to isolate any microorganisms able to produce oxo cyclic amino acids from hydroxy cyclic amino acids. 医薬品の出発素材であるオキソ環状アミノ酸の化学合成にはコストがかかり，環境負荷も大きい．そこで，水酸化環状アミノ酸を基質とする温和かつ安価なオキソ環状アミノ酸の微生物変換を目指し，環境中の有用微生物の探索を行った．まず，水酸化環状アミノ酸資化性菌の入手を目的として，京大理学部植物園から10 個の微生物分離源を採取，水酸化環状アミノ酸を単一炭素源とする液体培地で20℃，2 週間の振とう培養を行った．黄濁が認められた培養液をTLC 分析に供したところ，基質となる水酸化環状アミノ酸の消失が観察された．そこで，培養液中の微生物を同一組成の寒天培地上で分離し，得られた各水酸化環状アミノ酸資化性菌を水酸化環状アミノ酸を基質とする最小栄養液体培地での振とう培養と休止菌体反応に供した．TLC 分析の結果，両溶液中で水酸化環状アミノ酸の消費が認められたものの，目的物であるオキソ環状アミノ酸は検出されなかった