First published: 21 February 2020 at Journal of Chemical Technology and Biotechnology, Volume 95, Issue 7

Microbial adaptation to high ammonia concentrations during anaerobic digestion of manure-based feedstock: biomethanation and 16S rRNA gene sequencing

Sotirios D. Kalamaras
Department of Hydraulics, Soil Science and Agricultural Engineering,
School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece

Sotirios Vasiliadis
Department of Biochemistry and Biotechnology,
University of Thessaly, Larissa, Greece

Panagiotis Karas
Department of Biochemistry and Biotechnology,
University of Thessaly, Larissa, Greece

Irini Angelidaki
Department of Environmental Engineering,
Technical University of Denmark, Kgs. Lyngby, Denmark

Thomas A. Kotsopoulos [Corresponding Author] Department of Hydraulics, Soil Science and Agricultural Engineering,
School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece

Abstract

BACKGROUND

Microbial consortia resistant to high ammonia concentrations may facilitate biogas production from high ammonia-containing wastes and manures during anaerobic digestion. Microbial communities were gradually enriched via sequential batch cultivations (stepwise exposure) at increasing ammonia concentrations up to the extremely high concentration of 9 g total ammonia nitrogen (TAN) L−1. This study examined the adaptation of anaerobic microbial consortia to high ammonia concentrations by the use of a complex substrate based on manure in order to generate tailor-made inocula for bioaugmentation purposes. RNA analysis was performed to determine the microbial community composition and activity of anaerobic bacteria and methanogens.

RESULTS

The enrichment series was successful in terms of methane production at ammonia concentrations as high as 5 g TAN L−1 in comparison with the control concentration of 2 g TAN L−1. Methanosarcina was the core active dominant methanogen genus in all enrichment cultures and its relative activity was sharply increased at 3 g and 9 g TAN L−1. Cellulolytic bacteria activity mostly decreased with ammonia increase. Moreover, syntrophic butyrate and long-chain fatty acid degraders along with hydrogenotrophic methanogens were activated at increased ammonia concentrations.

CONCLUSIONS

The results of the study demonstrated an efficient method to enrich ammonia-tolerant microbial consortia for bioaugmentation purposes in biogas reactors with concentrations ≤5 g TAN L−1. RNA analysis revealed high relative abundances of Methanosarcina and hydrogenotrophic methanogens at high concentrations of ammonia. © 2020 Society of Chemical Industry

Acknowledgment

This research was co-financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH – CREATE -INNOVATE (project code T1EDK-00406).