Co-cultivation of Thermoanaerobacter strains with a methanogenic partner enhances glycerol conversion

Carla Pereira Magalhães, Joaquim A. Ribeiro, Ana P. Guedes, Ana L. Arantes, Diana Z. Sousa, Alfons J.M. Stams, Maria M. Alves, Ana Júlia Cavaleiro*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Glycerol-rich waste streams produced by the biodiesel, bioethanol and oleochemical industries can be treated and valorized by anaerobic microbial communities to produce methane. As current knowledge of the microorganisms involved in thermophilic glycerol conversion to methane is scarce, thermophilic glycerol-degrading methanogenic communities were enriched. A co-culture of Thermoanaerobacter and Methanothermobacter species was obtained, pointing to a non-obligately syntrophic glycerol degradation. This hypothesis was further studied by incubating Thermoanaerobacter brockii subsp. finnii and T. wiegelii with glycerol (10 mM) in pure culture and with different hydrogenotrophic methanogens. The presence of the methanogen accelerated glycerol fermentation by the two Thermoanaerobacter strains up to 3.3 mM day−1, corresponding to 12 times higher volumetric glycerol depletion rates in the methanogenic co-cultures than in the pure bacterial cultures. The catabolic pathways of glycerol conversion were identified by genome analysis of the two Thermoanaerobacter strains. NADH and reduced ferredoxin formed in the pathway are linked to proton reduction, which becomes thermodynamically favourable when the hydrogen partial pressure is kept low by the hydrogenotrophic methanogenic partner.

Original languageEnglish
Pages (from-to)962-973
Number of pages12
JournalMicrobial Biotechnology
Volume13
Issue number4
Early online date10 Mar 2020
DOIs
Publication statusPublished - Jul 2020

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