Utilization of alkaline phosphatase PhoA in the bioproduction of geraniol by metabolically engineered Escherichia coli.

Geraniol is a valuable acyclic monoterpene alcohol and has many applications in the perfume industries, pharmacy and others. It has been hypothesized that phosphatases can convert geranyl diphosphate (GPP) into geraniol. However, whether and which phosphatases can transform GPP to geraniol has remained unanswered up till now. In this paper, the catalysis abilities of 4 different types of phosphatases were studied with GPP as substrate in vitro. They are bifunctional diacylglycerol diphosphate phosphatase (DPP1) and lipid phosphate phosphatase (LPP1) from Saccharomyces cerevisiae, ADP-ribose pyrophosphatase (NudF) and alkaline phosphatase (PhoA) from Escherichia coli. The results show that just PhoA from E. coli can convert GPP into geraniol. Moreover, in order to confirm the ability of PhoA in vivo, the heterologous mevalonate pathway and geranyl diphosphate synthase gene from Abies grandis were co-overexpressed in E. coli with PhoA gene and 5.3 ± 0.2 mg/l geraniol was produced from glucose in flask-culture. Finally, we also evaluated the fed-batch fermentation of this engineered E. coli and a maximum concentration of 99.3 mg/l geraniol was produced while the conversion efficiency of glucose to geranoid (gram to gram) was 0.51%. Our results offer a new option for geraniol biosynthesis and promote the industrial bio-production of geraniol.