ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Microbiotechnology
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1650167
Comparative transcription profiles of Candidatus Accumulibacter and Propionivibrio under phosphate limitation in sequencing batch reactors
Provisionally accepted
- Ecole Polytechnique fédérale de Lausanne, Lausanne, Switzerland
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Polyphosphate-accumulating organisms (PAOs) are key in enhanced biological phosphorus removal (EBPR) processes. In addition to biosynthesis, they rely on phosphate for energy generation. However, Candidatus Accumulibacter, a model PAO, have been shown to adapt to low phosphate conditions by switching to a glycogen-accumulating metabolism (GAM), with variable success across genus members and experiments. This study explored the metabolic shift of several Accumulibacter species subjected to low-phosphate concentration in different operating conditions using metatranscriptomics analysis. In addition, the study allowed the comparison of the transcriptomics profiles of Accumulibacter to Propionivibrio, a glycogen-accumulating organism typically found in EBPR plants. Two sequencing batch reactors were operated with different carbon sources to enrich for different populations of Accumulibacter. After decreasing the influent phosphate concentration, carbon removal performances were maintained while anaerobic phosphate release dropped dramatically, suggesting a shift from a phosphate-accumulating to a glycogen-accumulating metabolism. Analysis of metatranscriptomics data showed that Accumulibacter regalis (type I) and Propionivibrio aalborgensis remained the most abundant species after the phosphate decrease in the reactor with acetate-propionate and allylthiourea, while Accumulibacter delftensis (type I) and Accumulibacter phosphatis (type II) remained active in the reactor with acetate-glucose and no allylthiourea. Transcription of the genes from the ethylmalonyl-CoA pathway involved in the production of propionyl-CoA and regulation of the anaerobic redox balance, was enhanced under low-phosphate condition especially for type I Accumulibacter. In contrast, the transcription of the methylmalonyl-CoA pathway was enhanced under low-phosphate condition in Propionivibrio and type II Accumulibacter.
Keywords: Genome-resolved metatranscriptomics, Phosphate-accumulating organism, glycogen-accumulating metabolism, Ethylmalonyl-CoA pathway, Methylmalonyl-CoA pathway, aerobic granular sludge
Received: 19 Jun 2025; Accepted: 06 Oct 2025.
Copyright: © 2025 Cardona, Rodilla Ramírez, Adler and Holliger. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Laëtitia Cardona, laetitia.cardona64@gmail.com
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