Evaluation of biofilm-producing ability in Escherichia coli and Staphylococcus aureus and its structural analysis

The predominant mode of growth of bacteria in the environment is, matrix-enclosed communities known as biofilms. This bacterial structure often complicate chronic and difficult-to-treat infections by protecting bacteria from the immune system, decreasing antibiotic efficacy, and dispersing planktonic cells to distant body sites. The purpose of the present study was to evaluate the biofilm producing ability of three standard strains of Escherichia coli and one standard strain of Staphylococcus aureus in different enrichment media and compared its structures.
For this study, Escherichia coli and staphylococcus aureus strains were cultured in four enrichment media (Brain-heart infusion broth contain 1% sucrose, Luria-Bertani, Tripti soy broth contain 3.5% glucose and Pepton Water) for phenotypic evaluation of biofilm production based on micro titer plate crystal violet method presented by stepanovic et al. (2007). Then, two Escherichia coli strains (1, 3) with strong and moderate biofilm producing ability, were selected for carbohydrate and protein extraction and compared with SDSPAGE by periodic acid shiff and methylene blue staining, respectively.
Based on results, BHI contain 1% sucrose, was selected for two strains. Protein profile of two studied strains were differences in protein components higher than 68 Kd, but, had a same carbohydrate and glycoprotein profiles. Finally, by observing the difference in protein structure of studied strains, identification and structural survey on different protein components can be useful in order to applying effective strategies to eradication of chronic infections.