Impact of the inoculum composition on the structure of the total and active community and its performance in identically operated anaerobic reactors
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Anaerobic digestion (AD) is a biological process that is acquiring increasing attention for both solid waste and wastewater treatment, as well as for the production of valuable chemicals. Despite the importance of the inoculum, the relationship between inoculum community composition, reactor performance, and reactor community composition remains vague. To understand the impact of the starting community on the composition and functioning of the AD microbiome, we studied three sets of biologically replicated AD reactors inoculated with different communities, but operated identically, targeting both total and active community compositions. All reactors performed highly similar regarding volatile fatty acid and methane production. The community analyses showed reproducible total and active community compositions in replicate reactors, indicating that particularly deterministic factors shaped the AD community. Moreover, strong variation in community composition between the differently seeded reactors was observed, indicating the role of inoculum composition in community shaping. In all three reactor sets, especially species that were low abundant or even not detected in the inoculum contributed to the reactor communities, supporting the importance of functional redundancy and high diversity in inocula used for AD seeding. The careful start-up of the AD process using initially low organic loading rates likely contributed to the successful assembly of initial low-abundance/rare species into a new cooperative AD community in the reactors.
KeywordsAnaerobic digestion Community composition Functional redundancy 16S rRNA gene/ transcript amplicon sequencing
We thank K. Simoens for VFA analysis and K. Moors and D. Grauwels for overall technical assistance.
This study was funded by the Anaerobic Membrane Bioreactor knowledge platform (KU Leuven project IOFKP/13/004 2012) and by the Inter-University Attraction Pole (IUAP) “μ-manager” of the Belgian Science Policy (BELSPO, P7/25).
Compliance with ethical standards
This article does not contain any studies with human participants or animals performed by any of the authors.
Conflict of interest
The authors declare that they have no conflict of interest.
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