Pseudomonas nitroreducens p7によるp-menthaneからのtrans-p-menthane-1-olの生産とその他のマイナー代謝産物

Present work has been done with the aim of the direct production of worthy monoterpene alcohols as perfumes, such as l-menthol from p-menthane (1-methyl-4-isopropylcyclohexane), which is an unworthy perfume component, by microbial hydroxylation. We screened microbes able to utilize p-menthane as a sole carbon source and identified a soil bacterium able to produce trans-p-menthane-1-ol by stereoselective hydroxylation of the C-1 position of p-menthane , as well as cyclohexanebutanoic acid and seven other minor metabolites. Biochemical and molecular identification based on 16S ribosomal DNA sequence analysis confirmed that this bacterium was Pseudomonas nitroreducens. The trans-p-menthane-1-ol produced by strain p7 had a refreshing smell. Seven other minor metabolites were determined to be p-menthane-2-ol, p-menthane-7-ol, p-menthane-9-ol, methylcyclohexylacetate, p-menth-1(7)-en-9-ol, 6-octene-1-ol and 3-cyclohexene-1-acetaldehyde by gas chromatography-mass spectrometry. Additionally, the production yield and molar conversion efficiency of trans-p-menthane-1-ol from trans-p-menthane by strain p7 were estimated to be 13.7% and 12.3 %, respectively.
我々は香料としては殆ど価値の無いテルペン系炭化水素p-menthane (1-methyl-4-isopropyl cyclohexane)から微生物水酸化によりl-mentholのような香料として有用なモノテルペンアルコールの生産を目的として, 土壌よりp-menthaneを唯一の炭素源として生育する微生物をスクリーニングした結果、p-menthaneのC-1位が立体選択的に水酸化されたtrans-p-menthane-1-olとcyclohexanebutanoic acid及び7つのマイナー代謝物を生成する微生物を分離した。分離された菌は16S-rDNAの塩基配列解析の結果、Pseudomonas nitroreducensと100%の相同性を示したことからPseudomonas nitroreducensと同定された。当該菌が生成するtrans-p-menthane-1-olは清涼感のある芳香を有していた。加えて、7つのマイナー代謝物はそれぞれp-menthane-2-ol, p-menthane-7-ol, p-menthane-9-o, methylcyclohexylacetate, p-menth-1(7)-en-9-ol, 6-octene-1-ol, 3-cyclohexene-1-acetaldehydeと推定された。また, 当該菌によるtrans-p-menthaneからのtrans-p-menthane-1-olの生産収量とモル変換効率はそれぞれ13.7%と12.3%と算出された.