KINETICS OF DIRHAMNOLIPIDS BIOSYNTHESIS AND RHAMNOSYLTRANSFERASE 2 ACTIVITY IN THE PRESENCE OF PSEUDOMONAS AERUGINOSA SIGNAL QUINOLONE

Aim: Discovery of P. aeruginosa АТСС 15692 dirhamnolipids biosynthesis and rhamnosyltransferase 2 activity in the presence of Pseudomonas aeruginosa exogenous quorum sensing signal molecule 2-heptyl-3-hydroxy-4-quinolon (PQS). Methods. Pseudomonas aeruginosa АТСС 15692 were cultured in the Giss medium with 2% glucose at 37 оС for 24 h. All the discoveries were performed in «plancton-biofilm» system with using of the «Nunclon» 48-well plates. Dirhamnolipids separation conducted by TLC methods on Alugram Sil G/UV 254 TLC plates. Dirhamnolipids were eluted separately and its content was determined by the orcinol test. Rhamnosyltransferase 2 (RhlC) activity was analysed in P. aeruginosa cell extracts using a rhamnosyltransferase assay specific for the addition of L-rhamnose to monorhamnolipid. 2-heptyl-3-hydroxy-4-quinolon synthesized in ONU Biotechnological scientific-educational center. Results. The synthesis of dirhamnolipids in control culture is activated from the early stationary phase and the content of the biosurfactants is increased fivefold up 10 to 24 hour – up 0.83 to 4.3 mg/ml. Addition of increasing concentrations of PQS did not affect the growth of P. aeruginosa but increased dirhamnolipids content. After 10 h of growth, there were approximately 4.6 times more biosurfactant in the cultures supplemented with PQS compared with the control. After 24 hours its level in culture medium was 20.68 mg/ml in the presence of 80 μМ PQS and 4.3 mg/ml in the absence of PQS. The additions of PQS at the time of inoculation are sufficient to induce RhlC activity during the transition to stationary phase. So, after eight hours in the presence of 40, 60 or 80 μМ PQS rhamnosyltransferase 2 activity was higher at 40%, 75% and 93%, respectively. After 24 hours this enzymatic activity was 1.6, 1.8 and 2.1 times higher as compared with the control.