Microbial production of medium-chain-length α, ω-diols via two-stage process under mild conditions

Medium-chain-length alpha, omega-diols (mcl-diols) are versatile compounds widely used as building blocks of coating materials and polymers. Mcl-diols are currently synthesized through energy intensive chemical process. Recently, esterified diols have been produced from n-alkanes in E. coli by co-expression of the alkane monooxygenase module (AlkBGTL) and the esterification module (Atf1), thereby establishing the technical feasibility of the process. However, esterified diols need to be hydrolyzed for further applications. In this study, we developed bio-catalysts for mcl-diol production from n-alkanes under mild conditions. The engineered P. putida KT2440 with overexpression of Est12 can efficiently hydrolyze esterified diols (C6-C10). Later, the engineered strain was co-cultured with an E. coli strain (AlkBGTL-Atf1) to produce mcl-diols. In a two-stage approach, 5 mM 1,6-hexane-diol was produced, 61.5 times of one-stage test, from n-hexane by biocatalysts for the first time. In conclusion, the present work indicates that bio-catalysis offers a green biobased alternative for synthesis of mcl-diols.