Salt-tolerance aerobic granular sludge: Formation and microbial community characteristics

The salt-tolerance aerobic granular sludge (SAGS) dominated by moderately halophilic bacteria was successfully cultured in a 9% (w/v) salty, lab-scale sequence batch reactor (SBR) system. Influence of high salinity (0-9% w/v NaCl) on the formation, performance and microbial succession of the SAGS were explored. Crystal nucleus hypothesis, selection pressure hypothesis and compressed double electric layers hypothesis were used to discuss the formation mechanism of SAGS. Notably, salinity could be seen as a kind of selection pressure contributed to the formation of SAGS, while salinity also declined the performance of SAGS system. High throughput 16S rRNA gene analysis showed that the salinity had great influence on the species succession and community structure of SAGS. Moreover, Salinicola and Halomonas were dominant at 9% salt concentration, therefore moderate halophiles were identified as functional groups for the tolerance of hypersaline stress.