Environment Conditions Interfere With Microbial Aggregation Behavior In Aqueous System

Microbial cluster functions as a key unit in biological waste water treatment. In response to the often violent and dynamic changes in the immediate environments, microbes self-adjust extracellular polymeric substances (EPS) excretion and form aggregates, a stabilizing substantial life form, for survive and ecological functioning. Notwithstanding the importance of microbial EPS on practical functioning of activated sludge systems, mechanistic understanding of the role of EPS on microbial clusters formation remains elusive. Mechanistic understanding of early-stage microbial clustering, including kinetics of microbial cluster formation and the driving forces, still remains largely unclear.We investigated EPS production at resources allocation, reporting an experimental observation of resource availability, in terms of dissolved oxygen, carbon, and nitrogen sources, mediating early-stage formation of microbial clusters.Results showed that reflected that limited resource availability promotes early-stage microbial cluster formation through enhanced microbial motility essential for sufficient foraging. Interestingly, we found a negative correlation between EPS contents and yielded microbial cluster size. Quantitative estimations of clusters surface charges revealed that lowing EPS contents were perfectly correlated to decayed surface negative charges, which yielded lower energy barrier that facilitates cell-cell and cell-clusters collisions essential for efficient microbial aggregation and thereby, favors larger sizes formation.These results offer new insights into microbial clustering dynamics of activated sludge system, and are of important practical guiding for efficient functioning of biological waste water treatment processes. It may improve future design and operations in biological waste water treatment.