Comparison between Antimicrobial and Antibiofilm Activity of Exopolysaccharides (EPS) Extracted from and against Oral Bacteria.

Due to the increased resistance to antibiotics and chemical biocides, the use of bacterial exopolysaccharides has been considered. The objective of the current study was to investigate the strength of the antibacterial and antibiofilm activity of EPS extracted from and because previous studies showed there were structural differences between EPS, during this study, EPS extracted from and by ethanol precipitation method and estimated antibacterial and antibiofilm activity against several Oral Bacteria (, , , , in different concentration as (100,150,200,250,300 mg/ml ), the results showed carbohydrates rate in extracted EPS from and were recorded was 85, 80 % respectively.The concentration 100 and 150 mg/ml for EPS from and , there was no inhibitory effect, except in (1.1±0.10) and (1.0±0.10) at 100 mg/ml, 3.1±2.01, 2.1±0.54 mg/ml respectively at 150 mg/ml concentration but no significant differences (≤0.05). However, the antibacterial effect of that EPSs started at the concentration of 200 and upwards, where different results were recorded between the concentrations of both EPSs against all bacteria isolated (P≤0.05), On the other hand, the effect of EPS from and was clear against the formation of biofilm compared with the control, worth mentioning that EPS from was more effective compared with EPS from in all isolates (≤0.05) except for where it was noted that the EPS from is more effective than EPS from . Through the results obtained in this study, it was noted that the difference in the structural nature of EPS has an important role in its effectiveness as an antibacterial and anti-biofilm formation and, as it was found that the EPS from showed more effectiveness than EPS from and thus the mechanism of preventing and inhibiting bacteria depending of the structural nature of EPS.