Cesari A B, Paulucci N S, Biasutti M A, Reguera Y B, Gallarato L A, Kilmurray C, Dardanelli M S
Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
J Appl Microbiol. 2016 Jan;120(1):185-94. doi: 10.1111/jam.12994.
We study the Azospirillum brasilense tolerance to water deficit and the dynamics of adaptive process at the level of the membrane.
Azospirillum brasilense was exposed to polyethylene glycol (PEG) growth and PEG shock. Tolerance, phospholipids and fatty acid (FA) composition and membrane fluidity were determined. Azospirillum brasilense was able to grow in the presence of PEG; however, its viability was reduced. Cells grown with PEG showed membrane fluidity similar to those grown without, the lipid composition was modified, increasing phosphatidylcholine and decreasing phosphatidylethanolamine amounts. The unsaturation FAs degree was reduced. The dynamics of the adaptive response revealed a decrease in fluidity 20 min after the addition of PEG, indicating that the PEG has a fluidizing effect on the hydrophobic region of the cell membrane. Fluidity returned to initial values after 60 min of PEG exposure.
Azospirillum brasilense is able to perceive osmotic changes by changing the membrane fluidity. This effect is offset by changes in the composition of membrane phospholipid and FA, contributing to the homeostasis of membrane fluidity under water deficit.
This knowledge can be used to develop new Azospirillum brasilense formulations showing an adapted membrane to water deficit.
我们研究了巴西固氮螺菌对水分亏缺的耐受性以及在膜水平上的适应性过程动态。
将巴西固氮螺菌暴露于聚乙二醇（PEG）生长和PEG冲击环境中。测定了耐受性、磷脂和脂肪酸（FA）组成以及膜流动性。巴西固氮螺菌能够在PEG存在的情况下生长；然而，其活力有所降低。用PEG培养的细胞显示出与未用PEG培养的细胞相似的膜流动性，脂质组成发生了改变，磷脂酰胆碱增加而磷脂酰乙醇胺减少。不饱和脂肪酸程度降低。适应性反应的动态变化显示，添加PEG后20分钟流动性降低，表明PEG对细胞膜疏水区域有流化作用。PEG暴露60分钟后流动性恢复到初始值。
巴西固氮螺菌能够通过改变膜流动性来感知渗透变化。这种效应被膜磷脂和脂肪酸组成的变化所抵消，有助于在水分亏缺条件下维持膜流动性的稳态。
这一知识可用于开发新的巴西固氮螺菌制剂，使其膜适应水分亏缺。
