Pseudomonas taiwanensis biofilms for continuous conversion of cyclohexanone in drip flow and rotating bed reactors

Ingeborg Heuschkel, Selina Hanisch, Daniel C. Volke, Erik Löfgren, Anna Hoschek, Pablo I. Nikel, Rohan Karande*, Katja Bühler

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

In this study, the biocatalytic performance of a Baeyer-Villiger monooxygenase (BVMO) catalyzing the reaction of cyclohexanone to ε-caprolactone was investigated in Pseudomonas biofilms. Biofilm growth and development of two Pseudomonas taiwanensis VLB120 variants, Ps_BVMO and Ps_BVMO_DGC, were evaluated in drip flow reactors (DFRs) and rotating bed reactors (RBRs). Engineering a hyperactive diguanylate cyclase (DGC) from Caulobacter crescentus into Ps_BVMO resulted in faster biofilm growth compared to the control Ps_BVMO strain in the DFRs. The maximum product formation rates of 92 and 87 g m–2 d–1 were observed for mature Ps_BVMO and Ps_ BVMO_DGC biofilms, respectively. The application of the engineered variants in the RBR was challenged by low biofilm surface coverage (50–60%) of rotating bed cassettes, side-products formation, oxygen limitation, and a severe drop in production rates with time. By implementing an active oxygen supply mode and a twin capillary spray feed, the biofilm surface coverage was maximized to 70–80%. BVMO activity was severely inhibited by cyclohexanol formation, resulting in a decrease in product formation rates. By controlling the cyclohexanone feed concentration at 4 mM, a stable product formation rate of 14 g m–2 d–1 and a substrate conversion of 60% was achieved in the RBR.

Original languageEnglish
JournalEngineering in Life Sciences
Volume21
Issue number3-4
Pages (from-to)258-269
ISSN1618-0240
DOIs
Publication statusPublished - Mar 2021

Bibliographical note

Funding Information:
We acknowledge the use of the facilities of the Centre for Biocatalysis (MiKat) at the Helmholtz Centre for Environmental Research, which is supported by European Regional Development Funds (EFRE, Europe funds Saxony) and the Helmholtz Association. IH was funded from the ERA-IB- Project PolyBugs ID:16006 and the S?chsisches Ministerium f?r Wissenschaft und Kunst (SMWK) Project ID: 100318259. DCV and PIN acknowledge financial support by the Novo Nordisk Foundation (grants NNF10CC1016517 and NNF18OC0034818 to PIN). We thank Dr. Matthias Schmidt (UFZ-ProVis) for providing the SEM image. Open access funding enabled and organized by Projekt DEAL.

Funding Information:
We acknowledge the use of the facilities of the Centre for Biocatalysis (MiKat) at the Helmholtz Centre for Environmental Research, which is supported by European Regional Development Funds (EFRE, Europe funds Saxony) and the Helmholtz Association. IH was funded from the ERA‐IB‐ Project PolyBugs ID:16006 and the Sächsisches Ministerium für Wissenschaft und Kunst (SMWK) Project ID: 100318259. DCV and PIN acknowledge financial support by the Novo Nordisk Foundation (grants NNF10CC1016517 and NNF18OC0034818 to PIN). We thank Dr. Matthias Schmidt (UFZ‐ProVis) for providing the SEM image.

Publisher Copyright:
© 2021 The Authors. Engineering in Life Sciences published by Wiley-VCH GmbH

Keywords

  • Baeyer-Villiger oxidation
  • Biofilm reactors
  • Biotransformation
  • Continuous bioprocess
  • Cyclohexanone monooxygenase

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