Reorganization of Azospirillum brasilense cell membrane is mediated by lipid composition adjustment to maintain optimal fluidity during water deficit

CESARI ADRIANA; PAULUCCI NATALIA; BIASUTTI ALICIA; DARDANELLI M.S

JOURNAL OF APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 1 p. 185 - 194

1364-5072

Aims: We study the Azospirillum brasilense tolerance to water deficit and thedynamics of adaptive process at the level of the membrane.Methods and Results: Azospirillum brasilense was exposed to polyethyleneglycol (PEG) growth and PEG shock. Tolerance, phospholipids and fattyacid (FA) composition and membrane fluidity were determined. Azospirillumbrasilense was able to grow in the presence of PEG; however, its viabilitywas reduced. Cells grown with PEG showed membrane fluidity similar tothose grown without, the lipid composition was modified, increasingphosphatidylcholine and decreasing phosphatidylethanolamine amounts. Theunsaturation FAs degree was reduced. The dynamics of the adaptiveresponse revealed a decrease in fluidity 20 min after the addition of PEG,indicating that the PEG has a fluidizing effect on the hydrophobic region ofthe cell membrane. Fluidity returned to initial values after 60 min of PEGexposure.Conclusion: Azospirillum brasilense is able to perceive osmotic changes bychanging the membrane fluidity. This effect is offset by changes in thecomposition of membrane phospholipid and FA, contributing to thehomeostasis of membrane fluidity under water deficit.Significance and Impact of the Study: This knowledge can be used to developnew Azospirillum brasilense formulations showing an adapted membrane towater deficit.