title: Production of halophilic proteins using Haloferax volcanii H1895 in a stirred-tank bioreactor.
abstract: The success of biotechnological processes is based on the availability of efficient and highly specific biocatalysts, which can satisfy industrial demands. Extreme and remote environments like the deep brine pools of the Red Sea represent highly interesting habitats for the discovery of novel halophilic and thermophilic enzymes. Haloferax volcanii constitutes a suitable expression system for halophilic enzymes obtained from such brine pools. We developed a batch process for the cultivation of H. volcanii H1895 in controlled stirred-tank bioreactors utilising knockouts of components of the flagella assembly system. The standard medium Hv-YPC was supplemented to reach a higher cell density. Without protein expression, cell dry weight reaches 10 g L(-1). Two halophilic alcohol dehydrogenases were expressed under the control of the tryptophanase promoter p.tna with 16.8 and 3.2 mg gCDW (-1), respectively, at a maximum cell dry weight of 6.5 g L(-1). Protein expression was induced by the addition of L-tryptophan. Investigation of various expression strategies leads to an optimised two-step induction protocol introducing 6 mM L-tryptophan at an OD650 of 0.4 followed by incubation for 16 h and a second induction step with 3 mM L-tryptophan followed by a final incubation time of 4 h. Compared with the uncontrolled shaker-flask cultivations used until date, dry cell mass concentrations were improved by a factor of more than 5 and cell-specific enzyme activities showed an up to 28-fold increased yield of the heterologous proteins.
authors.affiliation: Institute of Biochemical Engineering, Department of Mechanical Engineering, Technische Universität München, Munich, Germany.
authors.forename: Eva
authors.identifier: http://orcid.org/0000-0003-1159-6981
authors.initials: E
authors.lastname: Strillinger
authors.affiliation: Division of Physical Sciences and Engineering, Biological & Organometallic Catalysis Laboratory, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia.|Computer, Electrical and Mathematical Sciences and Engineering division, Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia.
authors.forename: Stefan Wolfgang
authors.initials: SW
authors.lastname: Grötzinger
authors.affiliation: Institute of Genetics, School of Biology, University of Nottingham, Queen's Medical Centre, Nottingham, UK.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Allers
authors.affiliation: Division of Physical Sciences and Engineering, Biological & Organometallic Catalysis Laboratory, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia. jorg.eppinger@kaust.edu.sa.
authors.forename: Jörg
authors.initials: J
authors.lastname: Eppinger
authors.affiliation: Institute of Biochemical Engineering, Department of Mechanical Engineering, Technische Universität München, Munich, Germany. d.weuster-botz@lrz.tum.de.
authors.forename: Dirk
authors.initials: D
authors.lastname: Weuster-Botz
mesh_terms: D000426:Alcohol Dehydrogenase / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D019843:Archaeal Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D019149:Bioreactors / Q000382:microbiology*; D004795:Enzyme Stability; D019622:Haloferax volcanii / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D007218:Industrial Microbiology / Q000295:instrumentation / Q000379:methods*; D014364:Tryptophan / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D014364:Tryptophan; D000426:Alcohol Dehydrogenase
keywords: Biocatalysis; Biotechnology; Gene expression; Haloferax volcanii; Halophile; Stirred-tank bioreactor