Isolation and utilization of Dictyosphaerium ehrenbergianum Nageli for biodiesel production: lipid extraction and biodiesel property analysis

The present investigation evaluates the lipid production, fatty acid profile and biodiesel properties of Dictyosphaerium ehrenbergianum. The extracted lipids were estimated quantitatively using the gravimetric method and qualitatively using fluorescence microscopy and fluoro-spectrophotometric analysis. Among the 14 microalgal isolates, the highest lipid content was observed in isolate five, which was identified as D. ehrenbergianum using 18S rDNA sequence analysis and morphological study. A total of 10 fatty acids were identified from the transesterified lipid of D. ehrenbergianum using gas chromatography mass spectroscopy analysis, among which oleic acid, palmitic acid and linoleic acid were recorded as major fatty acids. The optimum lipid production from D. ehrenbergianum was observed at pH 8.0, a temperature of 28.0 +/- 2 degrees C, NaCl concentration of 0.2 mg l(-1), sucrose as carbon source and NH4NO3 as a nitrogen source. The transesterified lipid of D. ehrenbergianum showed kinematic viscosity 3.56 cSt at 40 degrees C, flash point was 103 degrees C, density at 15 degrees C was 0.86 kg m(-3), and ash content was 0.017% with no acid number. The percentage of biodiesel was found to be 54.05%. The obtained results confirm that the lipid extracted from D. ehrenbergianum could be used as an alternative source for biodiesel production.