Metagenomic insights into the symbiotic relationship in anammox consortia at reduced temperature

•Anammox system could adapt to 5 °C and the NRR was maintained at 2.15 kg N/(m3·d).•25–15 °C promoted the cooperation between AnAOB and heterotrophic species.•Potential nitrite loop and ammonia loop were discovered in anammox consortia.•AnAOB together with Acidobacteriota species contributed to the secretion of EPS.•Patescibacteria could cross feed with AnAOB and heterotrophs about Glyceraldehyde-3P and lactate.