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Selecting for lactic acid producing and utilising bacteria in anaerobic enrichment cultures
  • +3
  • Julius Rombouts,
  • Elsemiek Kranendonk,
  • Alberte Regueira,
  • David Weissbrodt,
  • Robbert Kleerebezem,
  • Mark van Loosdrecht
Julius Rombouts
Technische Universiteit Delft
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Elsemiek Kranendonk
Technische Universiteit Delft
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Alberte Regueira
Universidade de Santiago de Compostela
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David Weissbrodt
Delft University of Technology
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Robbert Kleerebezem
Delft University of Technology
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Mark van Loosdrecht
Delft University of Technology
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Peer review status:ACCEPTED

19 Nov 2019Submitted to Biotechnology and Bioengineering
20 Nov 2019Submission Checks Completed
20 Nov 2019Assigned to Editor
24 Nov 2019Reviewer(s) Assigned
07 Jan 2020Review(s) Completed, Editorial Evaluation Pending
07 Jan 2020Editorial Decision: Revise Major
27 Jan 20201st Revision Received
27 Jan 2020Submission Checks Completed
27 Jan 2020Assigned to Editor
28 Jan 2020Reviewer(s) Assigned
07 Feb 2020Review(s) Completed, Editorial Evaluation Pending
07 Feb 2020Editorial Decision: Accept

Abstract

Lactic acid producing bacteria are important in many fermentations, such as the production of biobased plastics. Insight in the competitive advantage of lactic acid bacteria over other fermentative bacteria in a mixed culture enables ecology-based process design and can aid the development of sustainable and energy-efficient bioprocesses. Here we demonstrate the enrichment of lactic acid bacteria in a controlled sequencing batch bioreactor environment using a glucose based medium supplemented with peptides and B vitamins. A mineral medium enrichment operated in parallel was dominated by Ethanoligenens species and fermented glucose to acetate, butyrate and hydrogen. The complex medium enrichment was populated by Lactococcus, Lactobacillus and Megasphaera species and showed a product spectrum of acetate, ethanol, propionate, butyrate and valerate. An intermediate peak of lactate was observed, showing the simultaneous production and consumption of lactate, which is of concern for lactic acid production purposes. This study underlines that the competitive advantage for lactic acid producing bacteria primarily lies in their ability to attain a high biomass specific uptake rate of glucose, which was two times higher for the complex medium enrichment when compared to the mineral medium enrichment. The competitive advantage of lactic acid production in rich media can be explained using a resource allocation theory for microbial growth processes.