Role of Pseudomonas aeruginosa lipopolysaccharide in controlling bacterial biofilm formation

Biofilm is a virulence factor used by pathogenic bacteria to facilitate their attachment to the host, thereby facilitating infection. Lipopolysaccharide(LPS) is a large amphipathic molecule found in the outer membrane of Gram-negative bacteria, was extracted from Pseudomonas aeruginosa by chloroform-methanol method, lyophilized, and analyzed by gas chromatography-mass spectrometry (GC-MS) and found many chemical compounds like, (11,14-eicosadienoic acid methyl ester, cis-13-Octadecenoic acid, n-Hexadecanoic acid, Octadecanoic acid, and 9,12-octadecadienoyl chloride, (Z, Z), to determine their inhibitory effect at four concentrations (25, 50, 100 and 200 mg/cm3) on biofilm formation in four species of bacteria Agrobacterium tumefaciens, Mesorhizobium cicero, Staphylococcus aureus, and Escherichia coli. It was found that the concentration of 100 mg/cm³ was effective in inhibiting the formation of biofilms in the three pathological species.Nevertheless, it had no inhibitory effect on the formation of biofilms by M.cicero. Some genes encoding proteins specific to the adhesion of bacteria to their host were also identified as part of the biofilm mechanism.The results showed that the studied bacteria retained some of these genes and lost others, as evidenced by the appearance of bundles on the agarose gel or not.In A. tumefaciens, the celA and celR genes were found to encode cellulose fibres that allow it to adhere to its plant host, M. cicero. M. cicero and S.aureus were found to possess both the NodC and eno genes, but they lost the Nod and ebps genes, respectively. Meanwhile, E. coli exhibited a loss of the FimH gene, which is responsible for its association with the pathogenicity.