Renewable monomers for bio-styrene formation using phenolic acid decarboxylase

Lignocellulose is an abundant natural polymer on earth that contains renewable resource of aromatic compound, the lignin. Many industrially valuable chemicals can be developed from lignin and this can reduce the dependency on petrochemicals. Wheat straw contains ferulic acid as one of its building blocks, which can be accumulated as a major metabolite from growth with Rhodococcus jostii RHA1, a known lignin degrading bacteria in minimal media. Using the enzyme phenolic acid decarboxylase (PAD) in engineered E.coli, ferulic acid was converted into 4-vinylguaiacol (3-methoxy-4-hydroxystyrene). The substituted monostyrene was then enzymatically polymerised by laccase to form a polymer that showed an adhesive property. This enzymatically generated polymer can potentially provide an alternative to synthetic process, besides providing renewable option to generate environmental friendly material in ambient condition

Production of substituted styrene bioproducts from lignin and lignocellulose using engineered pseudomonas putida KT2440

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. [Abstract copyright: © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.