By combination of FACS sorting based on lipid sensitive Nile Red staining and small cell number proteomics the occurrence of population heterogeneity was analyzed. First population heterogeneity was identified by Nile Red staining and FACS in N. oceanica cells grown in nitrogen replete and nitrogen deplete media. For each condition two subpopulations(+NP3,+NP4,-NP3,-NP4) were detected and three replicates were sorted. Using the gathered proteome data proteins were identified and quantified with the MaxQuant software. Based on these quantification results a two sample t-test was performed to show significant regulation between +NP3 vs. +NP4 or -NP3 vs. -NP4. Goal was to understand the biological reasons for differences in lipid production between subpopulations.