Ferulic acid is a renewable chemical found in lignocellulose from grasses such as wheat straw and sugarcane. Pseudomonas putida is able to liberate and metabolize ferulic acid from plant biomass. Deletion of the hydroxycinnamoyl-CoA hydratase-lyase gene (ech) produced a strain of P. putida unable to utilize ferulic and p-coumaric acid, which is able to accumulate ferulic acid and p-coumaric acid from wheat straw or sugar cane bagasse. Further engineering of this strain saw the replacement of ech with the phenolic acid decarboxylase padC, which converts p-coumaric and ferulic acid into 4-vinylphenol and the flavor agent 4-vinylguaiacol, respectively. The engineered strain containing padC is able to generate 4-vinylguaiacol and 4-vinylphenol from media containing lignocellulose or Green Value Protobind lignin as feedstock, and does not require the addition of an exogenous inducer molecule. Biopolymerization of 4-vinylguaiacol and 4-vinylcatechol styrene products is also carried out, using Trametes versicolor laccase, to generate "biopolystyrene" materials on small scale.
Keywords: 4-vinyl guaiacol; Pseudomonas putida KT2440; biopolystyrene; ferulic acid; metabolic engineering.
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