Phenotypic Heterogeneity in Biofilm Consortia of E. coli

In this study, a total of seventeen (17) waterborne, biofilm-producing isolates of Escherichia coli were used. The population analysis showed that biofilm consortia harbour three different phenotypes e.g. smooth surface phenotypes (SSP), rough surface phenotypes (RSP) and small colony variants (SCVs). The SSP was hydrophilic and the initiator of biofilm formation processes in response to environmental stress. The RSP exhibited hydrophobic properties and occupy the core of biofilm consortia. They were slow-growing and produced a high quantity of exopolysaccharides as compared to SSP and SCVs. The highly adhesive and hydrophobic SCVs appeared after 48 h of incubation and occupy the lower base of biofilm consortia. They were metabolically inactive and difficult to disperse after adhesion. Our experiments show that all the subject isolates of E. coli carry wcaF and flu gene. Besides, the comparative analysis showed that wcaF and flu gene expression was high in RSP. These phenotypes activate wcaF and flu genes to produce extracellular matrix material to persist in biofilm consortium. Comparative analysis showed the biofilm formation was initiated by SSP while the RSP and SCVs was a product of a cruel environment and has a major role in the stability and persistence of consortia.