Optimized Feeding Strategies for Biosurfactant Production from Acetate by Alcanivorax borkumensis SK2

Fermentation, vol. 10, pp. 257

Abstract

Biosurfactants are much-discussed alternatives to petro- and oleochemical surfactants. Alcanivorax borkumensis, a marine, Gram-negative γ-proteobacterium, produces a glycine-glucolipid biosurfactant from hydrocarbons, pyruvate, and acetate as carbon sources. Sustainable acetate production from lignocellulose or syngas adds to its relevance for the bioeconomy. This study investigated nitrogen sources and carbon-to-nitrogen ratios (C/N) to optimize fed-batch fermentation for biosurfactant production using A. borkumensis with acetate as the carbon source. Urea enabled high biosurfactant production, which was confirmed in DO-based fed-batch fermentation. Varying C/N ratios led to increased glycine-glucolipid production and decreased biomass production, with improvement plateauing at a C/N ratio of 26.7 Cmol Nmol−1. pH-stat fed-batch fermentation using glacial acetic acid as the carbon source and a pH-adjusting agent doubled the biosurfactant production. Finally, bubble-free membrane aeration was used to prevent extensive foam formation observed during conventional bubble aeration. The efficient production made it possible to investigate the bioactivity of glycine-glucolipid in combination with antibiotics against various microorganisms. Our findings allow for the leverage of glycine-glucolipid biosurfactant production using acetate as a carbon source.

Authors 8

1. Tobias Karmainski Aachen iAMB-Institute of Applied Microbiology

   RWTH Aachen University

   Affiliation as printed

   iAMB—Institute of Applied Microbiology, ABBt—Aachen Biology and Biotechnology, RWTH Aachen University, 52074 Aachen, Germany

2. Marie K. Lipa Aachen iAMB-Institute of Applied Microbiology

   RWTH Aachen University

   Affiliation as printed

   iAMB—Institute of Applied Microbiology, ABBt—Aachen Biology and Biotechnology, RWTH Aachen University, 52074 Aachen, Germany

3. Sonja Kubicki

   Heinrich Heine University Düsseldorf

   Affiliation as printed

   IMET—Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany

4. Amina Bouchenafa

   Heinrich Heine University Düsseldorf

   Affiliation as printed

   IMET—Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany

5. Stephan Thies

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany

6. Karl‐Erich Jaeger

   Forschungszentrum Jülich · Heinrich Heine University Düsseldorf

   Affiliation as printed

   IMET—Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany

   Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425 Jülich, Germany

7. Lars M. Blank Aachen iAMB-Institute of Applied Microbiology

   RWTH Aachen University

   Affiliation as printed

   iAMB—Institute of Applied Microbiology, ABBt—Aachen Biology and Biotechnology, RWTH Aachen University, 52074 Aachen, Germany

8. Till Tiso corresponding Aachen iAMB-Institute of Applied Microbiology

   RWTH Aachen University

   Affiliation as printed

   iAMB—Institute of Applied Microbiology, ABBt—Aachen Biology and Biotechnology, RWTH Aachen University, 52074 Aachen, Germany