Metabolomics Uncovers the Regulatory Pathway of Acyl-homoserine Lactones Based Quorum Sensing in Anammox Consortia

Acyl-homoserine lactones (AHLs)-mediated
quorum sensing in bacterial
communities have been extensively observed. However, the metabolic
pathways regulated by AHLs in bacteria remain elusive. Here, we combined
long-term reactor operation with microbiological and metabolomics
analyses to explore the regulatory pathways for different AHLs in
anammox consortia, which perform promising nitrogen removal for wastewater
treatment. The results showed that no obvious shifts induced by exogenous
AHLs occurred in the microbial community and, mainly, dosing AHLs
induced changes in the metabolites. 3OC6-HSL, C6-HSL, and C8-HSL controlled
the electron transport carriers that influence the bacterial activity.
In contrast, only 3OC6-HSL regulated LysoPC(20:0) metabolism, which
affected bacterial growth. AHLs mainly regulated the synthesis of
the amino acids Ala, Val, and Glu and selectively regulated Asp and
Leu to affect extracellular proteins. Simultaneously, all the AHLs
regulated the ManNAc biosynthetic pathways, while OC6-HSL, OC8-HSL,
and C6-HSL particularly enriched the UDP-GlcNAc pathway to promote
exopolysaccharides, resulting in different aggregation levels of the
anammox consortia. Our results not only provide the first metabolic
insights into the means by which AHLs affect anammox consortia but
also hint at potential strategies for overcoming the limitations of
the long start-up period required for wastewater treatment by anammox
processing.