From freshwater anammox bacteria (FAB) to marine anammox bacteria (MAB): A stepwise salinity acclimation process
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Science of the Total Environment
Abstract
An investigation into the effect of stepwise saline introduction (3–20 g·L−1 NaCl) on the anaerobic ammonium
oxidation (anammox) process in a lab-scale sequencing batch reactor was carried out for 252 days by evaluating
the changes in influent and effluent nitrogen concentrations, conductivity, microbial extracellular polymeric
substances' (EPS) ionic content, as well as stresses due to salinity, via microbial ATP analysis. It was observed
that, effluent nitrogen concentrations remained stable at low saline levels of 3 g·L−1 to 10 g·L−1. Nonetheless,
midway through 10 g·L−1 and the preliminary phase of 15 g·L−1 salinity presented a very unstable, highly fluctuating
aswell as deteriorating effluent nitrogen concentrations. A more satisfactory nitrogen removal efficiency
of 83.7±5.9%was obtained at higher saline concentrations implying that, the adaptation mechanismto tolerate
increasing salinitywas taking place. Saline induced stress,which measures the variation in viable anammox bacteria,
was correlative to the formation of EPS and changes in its cationic contents along the increasing salinity.
Although the specific anammox activity (SAA) dropped by approximately 15% fromthe beginning of the process
to themidpoint, the drop in SAA after the midpoint was not as drastic as the initial phase. A change in microbial
aggregation and dominance proved the existence of newsaline-dependent species that canwithstand high saline
stresses. Recovery from abrupt high saline shocks in batch experiment was seen to be almost impossible.
Description
Research Article
Keywords
Adaptation-mechanism, FAB, MAB, Saline induced stress (SIS)