title: Evaluation of Pyrolysis Oil as Carbon Source for Fungal Fermentation.
abstract: Pyrolysis oil, a complex mixture of several organic compounds, produced during flash pyrolysis of organic lignocellulosic material was evaluated for its suitability as alternative carbon source for fungal growth and fermentation processes. Therefore several fungi from all phyla were screened for their tolerance toward pyrolysis oil. AdditionallyAspergillus oryzaeandRhizopus delemar, both established organic acid producers, were chosen as model organisms to investigate the suitability of pyrolysis oil as carbon source in fungal production processes. It was observed thatA. oryzaetolerates pyrolysis oil concentrations between 1 and 2% depending on growth phase or stationary production phase, respectively. To investigate possible reasons for the low tolerance level, eleven substances from pyrolysis oil including aldehydes, organic acids, small organic compounds and phenolic substances were selected and maximum concentrations still allowing growth and organic acid production were determined. Furthermore, effects of substances to malic acid production were analyzed and compounds were categorized regarding their properties in three groups of toxicity. To validate the results, further tests were also performed withR. delemar. For the first time it could be shown that small amounts of phenolic substances are beneficial for organic acid production andA. oryzaemight be able to degrade isoeugenol. Regarding pyrolysis oil toxicity, 2-cyclopenten-1-on was identified as the most toxic compound for filamentous fungi; a substance never described for anti-fungal or any other toxic properties before and possibly responsible for the low fungal tolerance levels toward pyrolysis oil.
authors.affiliation: Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology (KIT) Karlsruhe, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Dörsam
authors.affiliation: Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology (KIT) Karlsruhe, Germany.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Kirchhoff
authors.affiliation: Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology (KIT) Karlsruhe, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bigalke
authors.affiliation: Thermochemical Conversation of Biomass, Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology (KIT) Karlsruhe, Germany.
authors.forename: Nicolaus
authors.initials: N
authors.lastname: Dahmen
authors.affiliation: Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology (KIT) Karlsruhe, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Syldatk
authors.affiliation: Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology (KIT) Karlsruhe, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Ochsenreither
keywords: Aspergillus oryzae; Rhizopus delemar organic acids; carbon source; fermentation; fungi; pyrolysis oil; tolerance mechanisms