A mutant algal strain showing upregulation of mRNA transcripts encoding urea carboxylase, Δ-15-ω3-desaturase and downregulation of mRNA transcripts of gene encoding triacylglycerol lipase is provided herein. The mutant algal strain of the present disclosure is tolerant to low temperature and thus can be grown over a wide temperature range. The strain shows enhanced biomass and fatty acid production and enhanced growth rate and nitrogen metabolism over a wide temperature range of about 10° C. to about 37° C., wherein the enhancement is in comparison to the wild type algal strain. A method of obtaining the mutant algal strain and a method of producing industrially relevant products such as fatty acids from the mutant algal strain also are provided herein.