Effects of quorum quenching on temporal succession of activated sludge microbial community in a membrane bioreactor

Abstract

Aims Quorum quenching (QQ) is an attractive strategy for mitigating biofouling in membrane bioreactors (MBRs). However, the effects of QQ on the activated sludge (AS) process have not been adequately evaluated. This study investigated the long‐term effects of QQ on a laboratory‐scale anoxic–oxic MBR, focusing on AS performance and microbial community. Methods and Results Anoxic–oxic MBRs with and without QQ were operated for 91 days. QQ did not affect COD and TN removal efficiencies over the experimental period, during which its activity remained >90%. QQ reduced floc size by approximately 8% but had no effect on biomass concentration. AS microbial communities were regularly analysed using massively parallel sequencing. AS bacterial communities were temporally dynamic irrespective of QQ presence, for example, a temporal increase in bacterial diversity and a temporal decay of community similarity. QQ counteracted the temporal change in diversity and the temporal distance–community decay. Community comparison revealed that QQ changed the successional trajectory of the AS community at a late period, because it decelerated temporal changes of specific members, such as Thiothrix and Sphingomonadaceae*. Correlation networks revealed that QQ increased network clustering, complexity and density. The combined results suggest that the tighter microbial association by QQ increased the community resistance. Conclusions QQ can enhance the diversity and stability of the AS community in MBR by counteracting the innate temporal change in community structure. Significance and Impact of the Study Our findings are useful for the further advancement of QQ‐based strategies in engineered microbial environments.

History of the Study of the Genus Thiothrix: From the First Enrichment Cultures to Pangenomic Analysis

“…Later, 16S rRNA gene sequences assigned to Thiothrix were found by molecular profiling of microbial communities from organic-rich habitats, including the rhizosphere of the aquatic plant Eichhornia crassipes [ 21 ], the larvae of an aquatic insect Chironomus ramosus [ 22 ], and in activated sludge from wastewater treatment plants and laboratory bioreactors simulating wastewater treatment systems [ 23 , 24 , 25 , 26 , 27 ]. In all of the above works, the taxonomic composition of the microbiome of a plant, animal, or bioreactor was studied.…”

Two New Species of Filamentous Sulfur Bacteria of the Genus Thiothrix, Thiothrix winogradskyi sp. nov. and ‘Candidatus Thiothrix sulfatifontis’ sp. nov.

“…Additionally, in Yellowstone Lake [ 10 ], in sediments in the North and Baltic Seas [ 11 ], in communities from abandoned gold and uranium mines in Poland [ 12 ], in underground sulfide sources in a cave in the USA [ 13 ], in the system of shallow hydrothermal vents off Kueishantao Islet, Taiwan [ 14 ], representatives of the genus Thiothrix were found during metagenomic sequencing. Metagenome analyses led to the discovery of members of the genus Thiothrix in microbial communities in wastewater treatment plants [ 15 ], in sewers [ 16 ] and in fermenters simulating wastewater treatment systems [ 17 , 18 , 19 , 20 , 21 , 22 ].…”