Investigation of the role of porin protein in biofilm formation in E. coli

Biofilms are the life forms of microorganisms against environmental stress conditions and are a great advantage for microorganisms. In this study, the roles of porin proteins (OmpA, OmpC, OmpF, OmpG, OmpT, LamB and PhoE) in the outer membrane of Escherichia coli were investigated. In addition, the presence of pH (5.5, 6.0, 6.5, 7, 7.5 and 8) and some metals (Copper, Nickel, Zinc) on relationship between the formation of biofilm and porin genetic regulation were investigated. According to the data obtained, it was observed that ompA, ompC and lamB mutant E. coli formed biofilm at different pH values although they were not seen in wild type E. coli W3110. In the case of pH 5.5, 6.0, 7, 7.5 and 8 the ompC mutant E. coli strain in the solid-liquid intermediate phase forms the biofilm. The ompA mutant E. coli strain forms mid-level biofilm in the air-liquid and solid-liquid intermediate phases of 6.5, 7, 7.5 and 8 environments. The lamB mutant E. coli strain was found to form biofilm in the solid-liquid intermediate phase only in pH 7 and 7.5 media. No biofilm formation was detected in E. coli W3110 and ompF, ompG, ompT and phoE porin mutants. Biofilm tests in the presence of different metals, in the presence of copper, nickel, the biofilm formation in the glass tube by the ompA and lamB mutant E. coli strains is the same as that of metal-free media. Therefore, it was found that there was no role in the formation of biofilm in the presence of copper and nickel. But in the ompC mutant E. coli strain, stronger biofilm formation was detected in the presence of copper and nickel. An interesting result was obtained in the ompA, ompC and lamB mutant E. coli strains in the presence of zinc, another metal used in the study. While biofilm formation was observed in these mutant strains when there was no zinc, but biofilm did not occur in the presence of zinc. Biofilm was not detected in all metals studied in wild type E. coli W3110, ompF, ompG, ompT and phoE mutant strains. The absence of the ompA, ompC and lamB genes thus produced a result that triggered the biofilm formation mechanism.