Numerical simulation of seasonality in the distribution and fate of pyrene in multimedia aquatic environments with Markov chains

Exogenous refractory protein enhances biofilm formation by altering the quorum sensing system: A potential hazard of soluble microbial proteins from WWTP effluent

Soluble microbial refractory proteins are major components of effluent from wastewater treatment plants that utilize a biological wastewater treatment process. The remaining proteins could negatively affect downstream treatment processes by altering the bacterial quorum sensing system. In this work, we elaborated the effects of exogenous refractory protein on biofilm formation. The results showed a linear relationship between biofilm formation and experimental protein concentrations at the range typically found in effluent, 0-8.0 mg/L. Micro-observation revealed that the exogenous refractory protein stimulated extracellular polysaccharide secretion to promote biofilm maturation. Extracellular polysaccharides increased by ~200% with the addition of only 2.0 mg/L protein. In addition, exogenous refractory proteins altered the quorum sensing system gene expression and polysaccharide gene expression. This work found that exogenous protein accelerated biofilm formation by influencing the quorum sensing system, thus providing new insight into the potential harm of soluble microbial refractory products.