Keywords: 
• Chlorella /
• element-deficient culture /
• molecular identification

Abstract: Energy crisis and environmental pollution have become increasingly prominent with the extensive use of fossil fuels, which is widely considered to be unsustainable. Biodiesel is a potential alternative to fossil fuels. Microalgae have been considered the most promising biodiesel sources. Microalgae were collected from tropical freshwater water sampled around Haikou, and 185 strains of pure algae were obtained by flat-panel separation. Of the strains four were preliminarily identified as chlorella strains, CE1, CE14, CE18 and CE31, and were cultured on 4 different high salt minimal （HSM） media, HSM, HSM-N （N-deficient）, HSM-S, and HSM-P. Their biomass and lipid content were determined. The cultural media deficient of N and S gave notable impact on biomass production of all the four chlorella strains, and significantly increased their lipid contents as compared with the control. The cultural medium deficient of P had less influence on biomass production of the four chlorella strains, but increased notably lipid contents of strains CE1 and CE18. The strain CE14 grew very fast and contained high liquid, and its lipid content was the highest when cultured under the medium HSM-S as against other three media and accounted for 86.55% of the cell dry weight. This strain was identified based on 18S rDNA sequencing and designated as the genus Chlorella, family Chlorellaceae, order Chlorocaccales, class Chlorophyceae, division Chlorophyta, and its gene shared 99% similarity with the 18S rDNA gene of Chlorella vulgaris. CE14 is a promising potential alga source for production of biodiesel fuel.