Membrane fluidity of Pseudomonas putida and its relation with the tolerance to cationic surfactants.

HEREDIA R.M; LOPÉZ G.A; BOERIS P.S.; LUCCHESI G.I.

Congreso; 50th Annual Meeting Argentine Society for Biochemistry and Molecular Biology (SAIB); 2014

Adaptive response of P. putida to tetradecyltrimethylammonium (TTAB) involves changes in the content ofphospholipids (PL) and fatty acid (FA) of the membrane. Phosphatidylglycerol (PG) and phosphatidic acid increasedand cardiolipin (CL) decreased. The levels of unsaturated FA (UFA) decreased significantly while the amount ofsaturated FA (SFA) increased. Consequently, the SFA/UFA ratio increased 6 fold, indicating decreased the degree offluidity of the cell of membrane. CL, one of the major PL in P. putida, carries highest content of UFA (18%). In orderto assign a role to CL in the response to TTAB, a double mutant strain affected in the genes responsible for thesynthesis of CL was obtained and characterized. Compared with the wild-type, the fluorescence polarization showedthat the membrane of the mutant strain was more rigid (P=0.22), with high reduction in CL content (1.9% of total PL)and with UFA content similar to detected in the parental strain (9.8% and 11%, respectively), although distributedmainly in PG. When the mutant strain was exposed to TTAB, the P value was 0.14, the UFA content increased(16.5%) and the amount of viable cells decreased from 1012 ufc ml-1 to 106 ufc ml-1, demonstrating that the fluidizingeffect of surfactant cannot be counteracted. The set of results indicate that an adequate level of CL is indispensable inthe cell?s response to TTAB