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Effect of Sub-Stoichiometric Fe(III) Amounts on LCFA Degradation by Methanogenic Communities.

Authors :
Cavaleiro AJ
Guedes AP
Silva SA
Arantes AL
Sequeira JC
Salvador AF
Sousa DZ
Stams AJM
Alves MM
Source :
Microorganisms [Microorganisms] 2020 Sep 07; Vol. 8 (9). Date of Electronic Publication: 2020 Sep 07.
Publication Year :
2020

Abstract

Long-chain fatty acids (LCFA) are common contaminants in municipal and industrial wastewater that can be converted anaerobically to methane. A low hydrogen partial pressure is required for LCFA degradation by anaerobic bacteria, requiring the establishment of syntrophic relationships with hydrogenotrophic methanogens. However, high LCFA loads can inhibit methanogens, hindering biodegradation. Because it has been suggested that anaerobic degradation of these compounds may be enhanced by the presence of alternative electron acceptors, such as iron, we investigated the effect of sub-stoichiometric amounts of Fe(III) on oleate (C18:1 LCFA) degradation by suspended and granular methanogenic sludge. Fe(III) accelerated oleate biodegradation and hydrogenotrophic methanogenesis in the assays with suspended sludge, with H <subscript>2</subscript> -consuming methanogens coexisting with iron-reducing bacteria. On the other hand, acetoclastic methanogenesis was delayed by Fe(III). These effects were less evident with granular sludge, possibly due to its higher initial methanogenic activity relative to suspended sludge. Enrichments with close-to-stoichiometric amounts of Fe(III) resulted in a microbial community mainly composed of Geobacter , Syntrophomonas , and Methanobacterium genera, with relative abundances of 83-89%, 3-6%, and 0.2-10%, respectively. In these enrichments, oleate was biodegraded to acetate and coupled to iron-reduction and methane production, revealing novel microbial interactions between syntrophic LCFA-degrading bacteria, iron-reducing bacteria, and methanogens.

Details

Language :
English
ISSN :
2076-2607
Volume :
8
Issue :
9
Database :
MEDLINE
Journal :
Microorganisms
Publication Type :
Academic Journal
Accession number :
32906848
Full Text :
https://doi.org/10.3390/microorganisms8091375