The effect of DNA aptamers as antibiofilm agents on Salmonella biofilm formation

Five Salmonella enterica serovars were tested for their biofilm formation ability. Among which, S. Enteritidis 6(2014) and S. Enteritidis (86) demonstrated the highest biofilm formation ability. These two most potent biofilm formers were chosen for further experiments. Optimum production of SipA, cloned as a GST fusion protein into pGEX-4T-1 vector, was obtained when Rosetta cells were incubated over night at 28°C. Aptamers were developed against the purified protein by Systematic Evolution of Ligands by Exponential Enrichment. The characterized Apt17 was applied in inhibition studies. Maximum inhibition percentages, equivalent to (24.34%) and (26.81%), were recorded when Apt17 (2 µM) was co-incubated with S. Enteritidis 6(2014) and S. Enteritidis (68) respectively. SEM analysis revealed that treated S. Enteritidis 6(2014) biofilms didn't form the 3D structure and matrix wasn't evident. On the other hand, Apt17 reduced the surface coverage of Salmonella Enteritidis (68) cells on the attachment surface. A smaller diameter of cell aggregates was recorded in the treated specimens of both tested strains. Moreover, Apt 7 (2µM) inhibited the adhesion and invasion of Caco-2 cell line by 25 to 70 % and 18.03 to 39.5 % respectively