Role of membrane components of Ensifer meliloti in the desiccation tolerance

KILMURRAY C; GALLARATO L; CESARI A; REGUERA Y.B.; YSLAS E; PAULUCCI N.S.; DARDANELLI M.S

Mar del Plata

Congreso; LI Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2015

SAIB

The low water availability impact mainly on biological membranes. To survive, bacteria must be able to senseenvironmental conditions and respond. The aim of this work was analyze the effect of drying on the viability, viable but not cultivable state, the membrane state and fatty acids (FA) composition in Ensifer meliloti 1021. Cells weregrown at 28°C to exponential phase and then 5 ml of culture were filtered on membranes S-Pak 0.45μm Type HA(Millipore Inc.). After filtration, the filters were placed on empty petri plates and placed in an oven at 28°C andhumidity 35%. The store time was 0, 1 and 7 days. The cultivable cells was determined by counting the UFC/ml andthe viable cells by LIVE/DEAD® BacLight? kit, the phase transition temperature (Tm) determined by DSCtechnique and the FA composition determined by GC. We observed a gradual decrease in the survival after 1 day ofdrying compared to the control (time 0 days), reaching a survival of only 1% after 7 days. Desiccation promotedviable non-culturable state after 1 day drying. Exposure to 1 day of drying caused an increase in saturated FA 16:0(65%) and 18:0 (500%) as well as a decrease the 18:1Δ11 (65%). The Tm of the cell membranes exposed to 1 daydesiccation resulted in 0.5ºC greater control. E. meliloti modifies its membrane FA by decreasing the degree ofunsaturation as an adaptation mechanism to tolerate desiccation.