Characterization of five fresh water microalgae with potential for biodiesel production

Microalgae biodiesel feedstocks have been investigated by numerous research groups to overcome dependence on fossil fuels. This study describes a detailed characterization of five freshwater microalgae strains of the family Scenedesmaceae, based on cell wall ultrastructure, ITS-2 sequence and secondary structure analysis, as well as the estimation of biodiesel properties from fatty acids produced before and after N-limitation. Characterization permitted the reclassification of SCRE-1 and SCRE-2 strains into the subgenus Scenedesmus; DSRE-1 and DSRE-2 strains into the subgenus Desmodesmus; and CORE-1 strain into the genus Coelastrum. Transesterification of fatty acids of the five strains was performed before and after N-limitation, and seven important biodiesel quality parameters were predicted by applying selected correlations. These parameters were then compared to the corresponding specifications in the American and European biodiesel standards. N-limitation promoted higher yields of biomass (up to 3.5 times) and lipids (up to 4.1 times) in all strains under study. Moreover, it was found that SCRE-2 was the only biodiesel that met all estimated parameters of the more stringent European standard before N-limitation. This was also true for DSRE-1 and DSRE-2 biodiesels after limitation, with the exception of their oxidative stability parameter, whose values met the limit of the American but not the European standard. (C) 2014 Elsevier B.V. All rights reserved.