Metabolic Engineering of Pseudomonas Putida S12 for the Production of Styrene

Rational strain development of microorganisms can enable alternative production processes of styrene, an industrial relevant bulk chemical. However, styrene is toxic and many microorganisms cannot survive in its presence. Recent studies have shown that product toxicity is a major impairment of efficient microbial solvent production with traditional host organisms such as E. coli and S. cerevisiae.^1,2 Bacteria of the genus Pseudomonas are known for their extraordinary ability to adapt to challenging environments, making the organism an interesting candidate chassis for styrene production.³ The aim of this study is the production of styrene via the central metabolite phenylalanine with Pseudomonas putida S12. Through the application of targeted genome modifications, the phenylalanine overproducing strain P. putida S12 palM12⁴ was optimized as production host. Codon-optimized genes encoding a phenylalanine ammonia lyase from A. thaliana and ferulic acid decarboxylase from S. cerevisiae were co-expressed under the control of different expression systems, enabling the conversion of phenylalanine via cinnamic acid to styrene. The goal is the production of super-saturating amounts of styrene which would greatly facilitate product purification. This is only made possible by the high solvent-tolerance of the engineered P. putida S12 strains.

¹McKenna et al., Metab Eng (2011) 13: 544-554
²McKenna et al., Microb Cell Fact (2014) 13:123
³Ramos et al., FEMS Microbiol Rev (2015) 39(4):555 -566
⁴Nijkamp et al., Appl Microbiol Biotechnol (2005) 69: 170 -177