Semenets A. Functioning of the quorum sensing system in Pseudomonas aeruginosa strains with different levels of cyclic diguanosine monophosphate

In present investigation P. aeruginosa strains with different levels of cyclo-diGMР were used: P. aeruginosa PA01 pJN2133 with low, P. aeruginosa PA01 ΔwspF1 with high and P. aeruginosa PA01 - parental strain with natural content of the secondary messenger. It was shown that the cells of the P. aeruginosa strain witha low level of c-di-GMP differ from other studied strains in diameter (by 36-38% larger) and in hydrophobicity (times 5 lower). P. aeruginosa cells PA01 pJN2133 are enriched with minor unsaturated fatty acids, and there are 2 times less lipids on their surface than in the parent strain and PA01 ΔwspF1. It is established that on the surface of planktonic cells amount of proteins was 60-80% of the total organic matter content. In biofilm cells, 80% of molecules are also represented by proteins and lipids. Biofilm cells are characterized by 1.5-3 times higher saturation index of fatty acids. Determining the nature of the three motility types in studied strains, showed that they are differ in swimming only in quantitative terms. Cells of P. aeruginosa strains PA01 and PA01 pJN2133 are actively moved by swarming, but their swarming zones differ significantly in morphological features. The concentration of autoinducers QS in the medium was found to be inversely related to the intracellular content of c-di-GMP: compared to the parent strain, it was increased in the strain with a low content of secondary messenger and decreased in the strain with its high level. Biosynthesis of quorumdependent secondary metabolites is activated against the background of a low level of secondary messenger. P. aeruginosa PA01 pJN2133 produced 2.2 times more pyocyanin and 3.5 times more rhamnolipids than P. aeruginosa PA01. P. aeruginosa PA01 ΔwspF1 synthesized these two metabolites only at the level of 10% and 15% of the parent strain. It is proved that the synthesis of biotechnologically attractive secondary metabolites (rhamnolipids and pyocyanin) in P. aeruginosa strains PA01 and PA01 pJN2133 is activated in the presence of exogenous signal quinolone. In presence of 80 μM PQS concentration, the yield of rhamnolipids increases 5.2 and 3 times, respectively. The biosynthesis of pyocyanin by these strains increases by 63% and 78%, respectively.