A1 Journal article (refereed)
Microbial communities in full-scale woodchip bioreactors treating aquaculture effluents (2022)

Aalto, S. L., Suurnäkki, S., von Ahnen, M., Tiirola, M., & Bovbjerg Pedersen, P. (2022). Microbial communities in full-scale woodchip bioreactors treating aquaculture effluents. Journal of Environmental Management, 301, Article 113852. https://doi.org/10.1016/j.jenvman.2021.113852

JYU authors or editors

Publication details

All authors or editors: Aalto, Sanni L.; Suurnäkki, Suvi; von Ahnen, Mathis; Tiirola, Marja; Bovbjerg Pedersen, Per

Journal or series: Journal of Environmental Management

ISSN: 0301-4797

eISSN: 1095-8630

Publication year: 2022

Volume: 301

Article number: 113852

Publisher: Elsevier Ltd.

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1016/j.jenvman.2021.113852

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/78357

Abstract

Woodchip bioreactors are being successfully applied to remove nitrate from commercial land-based recirculating aquaculture system (RAS) effluents. In order to understand and optimize the overall function of these bioreactors, knowledge on the microbial communities, especially on the microbes with potential for production or mitigation of harmful substances (e.g. hydrogen sulfide; H2S) is needed. In this study, we quantified and characterized bacterial and fungal communities, including potential H2S producers and consumers, using qPCR and high throughput sequencing of 16S rRNA gene. We took water samples from bioreactors and their inlet and outlet, and sampled biofilms growing on woodchips and on the outlet of the three full-scale woodchip bioreactors treating effluents of three individual RAS. We found that bioreactors hosted a high biomass of both bacteria and fungi. Although the composition of microbial communities of the inlet varied between the bioreactors, the conditions in the bioreactors selected for the same core microbial taxa. The H2S producing sulfate reducing bacteria (SRB) were mainly found in the nitrate-limited outlets of the bioreactors, the main groups being deltaproteobacterial Desulfobulbus and Desulfovibrio. The abundance of H2S consuming sulfate oxidizing bacteria (SOB) was 5–10 times higher than that of SRB, and SOB communities were dominated by Arcobacter and other genera from phylum Epsilonbacteraeota, which are also capable of autotrophic denitrification. Indeed, the relative abundance of potential autotrophic denitrifiers of all denitrifier sequences was even 54% in outlet water samples and 56% in the outlet biofilm samples. Altogether, our results show that the highly abundant bacterial and fungal communities in woodchip bioreactors are shaped through the conditions prevailing within the bioreactor, indicating that the bioreactors with similar design and operational settings should provide similar function even when conditions in the preceding RAS would differ. Furthermore, autotrophic denitrifiers can have a significant role in woodchip biofilters, consuming potentially produced H2S and removing nitrate, lengthening the operational age and thus further improving the overall environmental benefit of these bioreactors.

Keywords: aquaculture; waste water treatment; denitrification; bioreactors; wood chip; microbiome; fungi; sulphides

Free keywords: aquaculture; denitrification; fungi; microbiome; sulfate reduction

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Ministry reporting: Yes

Reporting Year: 2022

JUFO rating: 1