Proteomics and RNA sequencing analysis of Escherichia coli biofilm on reverse osmosis membrane for wastewater reclamation

As the molecular mechanisms of biofouling and biofilm formation are not fully understood, biofouling during the reverse osmosis (RO) process remains a challenging problem. In this study, the proteome from extracellular polymeric substances (EPS) of Escherichia coli biofilm as a model biofilm, was analyzed during the RO membrane process to understand the biofouling mechanism. Employing liquid chromatography combined with tandem mass spectrometry (LC-MS/MS), the intrinsically disordered peptide (IDP) INLLDDNQFTR located in outer membrane porin C (OmpC) was identified as one of the main fragments in the proteome. This peptide enhanced both the attachment of cells on the membrane surface and microbial swarming. A RNA sequencing analysis revealed that genes regulating cell division and flagellar movements were up-regulated for the formation of` biofilms. Nanomechanics based on atomic force microscopy (AFM) showed that the peptide strongly interacts with the lipopolysaccharides (LPS) of the cell wall. Overall, the OmpC IDP stimulates cell attachment through cell-to-cell communication or cell division, accelerating biofouling of the membrane surface. It is anticipated that an antagonist of the IDP of OmpC could be effective for regulating biofouling during the RO process.