BIOFILM CHARACTERIZATION AND QUORUM QUENCHING IN PATHOGENIC STRAINS STAPHYLOCOCCUS AUREUS AND PSEUDOMONAS AERUGINOSA

A strategy for combating biofilm based bacterial infections different from antibiotic therapy is prevention of biofilm formation by quorum quenching and genetically modifying the pathogenic strains to reduce the pathogenic potential. Pathogenic strains of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia, Serratia marcescens were screened for biofilm production by qualitative (TM, CRA, GCR), quantitative method (TCP) as well by inverted microscopy. Staphylococcus aureus and Pseudomonas aeruginosa were found to be potent biofilm producers. The biofilms from these selected strains were then investigated for quorum quenching effects and natural genetic transformation. In the present study Bacillus. subtilis at 1:40 and 1:20 ratio in mixed culture with both Staphylococcus aureus and Pseudomonas aeruginosa; tannic acid at 100 mg/l and EDTA at 100 mM were determined to be effective quorum quenching agents. Natural genetic transformation in Staphylococcus aureus was investigated by using pBR322 plasmid DNA as donor. The transformation efficiency increased with increase in DNA concentration and was higher in case of young actively growing biofilms. We conclude that tannic acid a plant ingredient could be an effective nontoxic antibiofilm compound for strains Staphylococcus aureus and Pseudomonas aeruginosa.