Insight into quorum sensing and microbial community of an anammox consortium in response to salt stress: From “Candaditus Brocadia” to “Candaditus Scalindua”

Abstract

The shift of microbial community and signaling molecules release were studied to explore the potential mechanism of anammox consortium under salt stress. Due to increased salinity, the abundance of “Candidatus Brocadia” decreased from 29.5% to 1.9%. “Candidatus Brocadia” was reduced by the salinity shock. Besides, “Candidatus Scalindua”, marine anammox bacteria, was detected at 18 g L−1 NaCl and dominated the reactor. Principle coordinates analysis further proved that salinity was the driving force on the distribution and diversity of anammox consortium. Also, quorum sensing feedback mechanism of anammox bacteria under salt stress was investigated for the first time. The concentration of N-(3-oxohexanoyl)-DL-homoserine lactone (3OC6-HSL) increased from 0.27 ± 0.02 to 1.24 ± 0.09 μM at 7 to 9 g L−1 NaCl. The concentration of 3OC6-HSL maintained at a high level at 9 to 12 g L−1 NaCl. Nacylated-l-homoserine lactones (AHLs)-mediated QS became more active and then improved the coordinated interaction in anammox consortium. High concentration of AHLs promoted the bacteria to produce more extracellular polymeric substances, which increased the bacterial tolerance to salt stress.