The effect of nitrogen starvation on membrane lipids of Synechocystis sp. PCC 6803 investigated by using easy ambient sonic-spray ionization mass spectrometry.

Background: Glycerolipids are important components of membranes in cyanobacteria that possess vital roles in biological processes. The effect of nitrogen deprivation on membrane lipids of Synechocystis sp. PCC 6803 lipids has not been previously examined.

Methods: Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) was used for the analysis of Synechocystis 6803 cells with minimal sample preparation, providing rapid qualitative and relative quantitative information on the lipid content of their membranes.

Results: Changes in the degree of unsaturation of membrane lipids were observed for cells grown under normal conditions during different growth phases. This physiological remodeling was disrupted when nitrogen was withdrawn from the cultivation medium. However, this disruption was reversed when the cells were resuspended in normal N-containing medium. Mass spectrometric data were supported by examination of cells by electron microscopy.

Conclusions: EASI-MS was applied for the first time in the analysis of Synechocystis 6803 cells grown under nitrogen deprived conditions and was found to be a powerful technique operating in a high-throughput manner for the rapid lipid profiling of cells at different growth stages and under different growth conditions.

General Significance: The effect of nitrogen deprivation on membrane lipids of Synechocystis 6803 cells was revealed using an ambient ionization technique which enabled high-throughput cell analysis with minimal sample preparation. The results obtained have the potential to be used in future studies to decipher the involvement of enzymes in the observed lipid profile changes.