Gördeşli Duatepe, Fatma Pınar2023-06-192023-06-1920232149-21232148-4171https://doi.org/10.17350/HJSE19030000295https://search.trdizin.gov.tr/yayin/detay/1177211https://hdl.handle.net/20.500.14365/4740FliA is an important regulatory component for the synthesis of surface macromolecules which are involved in motility and biofilm development of Escherichia coli. In this study, the roles of FliA-dependent surface macromolecules in E. coli surface tension, sur- face heterogeneity and surface roughness, and initial biofilm development consisting of re- versible and irreversible adhesion were investigated using E. coli MG1655 wild-type strain and fliA gene deleted mutant strain. Negative Gibbs free energy change values calculated using bacterial surface tensions obtained by a spectrophotometric method showed that both wild-type and mutant cells in water can reversibly adhere to the surface of the model solid, silicon nitride (Si3N4). The calculations further showed that bacterial reversible auto- adhesion and co-adhesion were also thermodynamically favorable. In comparison, the re- versible adhesion and auto-adhesion capacities of wild-type cells were higher than the mu- tant cells. Direct measurements by atomic force microscopy (AFM) and thorough analysis of the recorded adhesion data showed that the irreversible adhesion strength of wild-type cells to Si3N4 in water was at least 2.0-fold greater than that of the mutants due to signifi- cantly higher surface heterogeneity resulting in higher surface roughness for the wild-type cells compared to those obtained for the mutants. These results suggest that strategies aimed at preventing E. coli biofilm development should also consider a combined method, such as modifying the surface of interest with a bacterial repellent layer and targeting the FliA and FliA-dependent surface macromolecules to reduce both reversible and irreversible bacterial adhesion and hence the initial biofilm development of E. coli.eninfo:eu-repo/semantics/openAccessArticle10.17350/HJSE19030000295