Fatty Acids Profiling and Biomarker Identification in Snow AlgaChlamydomonas Nivalisby NaCl Stress Using GC/MS and Multivariate Statistical Analysis

Abstract The snow alga Chlamydomonas nivalis is a model species of microalgae for the investigation of cell response mechanism and adaptation ability in natural habitats in polar regions and similar extreme environments. The alteration of fatty acids in cellular lipids is known to play a vital role for cell survival and reproduction under various stress conditions. In the present work, an integrated approach of gas chromatography/mass spectrometry (GC/MS) coupled with multivariate statistical analysis was developed to investigate the fatty acid profiles and identify the biomarkers in response to NaCl stress. The data of fatty acid profiles between the control and NaCl-stress group was classified by orthogonal projection on latent structure discriminant analysis (OPLS-DA) and hierarchical cluster analysis (HCA); six of fatty acids (C16:0, C16:3, C18:0, C18:1, C18:2, and C18:3) were identified as biomarkers. These biomarkers showed a regulatory role by decreasing the degree of lipid unsaturation (DLU), providing an expected function in reducing membrane fluidity and permeability for enhancing the tolerance to higher salinity. This is the first report to demonstrate the fatty acid biomarkers in microalgae as the physiological regulators corresponding to the response and adaptation to NaCl stress based on an integrated approach at the lipidomic level. Keywords: Biomarker Chlamydomonas nivalis Fatty acidsGas chromatography/mass spectrometryMultivariate statistical analysisSalt stressAbbreviations: CIJFJK Jack-knifed confidence intervalDLUDegree of lipid unsaturationGC/MSGas chromatography/mass spectrometryHCAHierarchical cluster analysisOPLS-DAOrthogonal projection on latent structure discriminant analysisSFASaturated fatty acidsTDLUTotal degree of lipid unsaturationTSFATotal saturated fatty acidsTUFATotal unsaturated fatty acidsUFAUnsaturated fatty acidsVIPVery important in the projection. Acknowledgments This work was supported by NSFC Project (grant no. 20876058) and the Major State Basic Research Development Program of China (973 Project) (grant no. 2011CB200904, 2011CB200901). Notes *The identified fatty acids biomarkers. Data were means ±S.D. of three replicates.