Abstract: Background and Objectives: Physiological response in micro-algae triggered by nutrient stress to induce triacylglycerol accumulation is a promising solution to produce micro-algae based biofuel. The main objective of the study was to determine the response of micro-algae to nutrient stress by means of lipid accumulation. Materials and Methods: This study investigated the effect of nitrogen sufficient and nitrogen deficient conditions (N+ and N-) in micro-algal biomass and lipid productivity to determine the response to nutrient stress by micro-algae. A micro-alga was isolated from fresh water lake and amplification of 18S rDNA genes with the primers NS1 and NS4 resulted in 1300 bp fragments. The 18s rDNA sequences obtained were compared against sequences in the GenBank nucleotide collection through the Basic Local Alignment Search Tool (BLAST). Results: The micro-algae were identified as Chlorococcopsis minuta based on sequence similarities. In the case of micro-algae grown in nutrient limited conditions (N- media), the biomass content was lower with the yield of 8.4 g L–1, however, there was a 62.5% increase in the total lipid content (11.7%) compared to nutrient sufficient conditions. Confocal imaging of lipid droplets stained by Nile red showed that lipid droplets was increased in N deficient (N-) conditions when compared to N sufficient (N+) conditions. Conclusion: Increase in lipid content of C. minuta was confirmed by accumulation of more lipid droplets under nutrient stress conditions.