title: Novel auto-inducing expression systems for the development of whole-cell biocatalysts.
abstract: Novel expression systems for the development of whole-cell biocatalysts were generated. Their novelty consists both in the host, Pseudomonas putida, and in the ability to auto-induce the expression of genes of interest at the exhaustion of the carbon source used for the biomass growth. The auto-induction relies on new expression vectors developed in this study and based on the activator TouR from Pseudomonas sp. OX1, which was shown to mediate the activation of target promoters in an effector-independent growth-phase-dependent manner when the carbon source is exhausted at the onset of the stationary phase. We validated the suitability of these expression systems through the production of (S)-styrene oxide by the styrene monooxygenase from Pseudomonas fluorescens ST. The yields of epoxides produced by these biocatalysts in flask experiments showed to be as efficient as those currently available based on inducible Escherichia coli systems. In addition, a larger scale of biomass production showed no reduction of biocatalysis efficiency. Therefore, the systems developed in this study constitute a valid alternative to current expression systems to use in bioconversion processes.
authors.affiliation: Department of Environmental Sciences, University of Milan-Bicocca, Milan, Italy. patrizia.digennaro@unimib.it
authors.forename: Patrizia
authors.initials: P
authors.lastname: Di Gennaro
authors.forename: Silvia
authors.initials: S
authors.lastname: Ferrara
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Bestetti
authors.forename: Guido
authors.initials: G
authors.lastname: Sello
authors.forename: Dafne
authors.initials: D
authors.lastname: Solera
authors.forename: Enrica
authors.initials: E
authors.lastname: Galli
authors.forename: Francesco
authors.initials: F
authors.lastname: Renzi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Bertoni
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018533:Biomass; D001711:Biotransformation; D002384:Catalysis; D004852:Epoxy Compounds / Q000378:metabolism; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D005818:Genetic Engineering / Q000379:methods*; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000201:enzymology; D016958:Pseudomonas putida / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004852:Epoxy Compounds; C013690:styrene oxide; D010105:Oxygenases; C026721:styrene monooxygenase