Biochemical characterization and genetic identity of an oil-rich Acutodesmus obliquus isolate

Microalgae provide one of the more promising strategies for the production of renewable biodiesel and liquid fuels. Coupling biodiesel production and wastewater treatment based on the use of microalgae can be an effective approach for achieving sustainable production. Several pilot programs aimed at lipid production are currently working with Acutodesmus obliquus, and companies offering algal inocula are increasing in number. A. obliquus strain RL01 was isolated from a pretreated leachate, and preliminary analyses indicated a high growth rate, a final biomass concentration of 1.9 g∙L-1 and a lipid content of 47% DW. With the aim of strictly differentiating and unequivocally identifying the new strain in comparison with other A. obliquus lipid producers available in culture collections, we employed a DNA barcoding approach, targeting conventional and non-conventional genome regions. Genomic analyses were performed using two internal transcribed spacers (nuclear ITS1 and ITS2 sequences) and three selected chloroplast regions (the trnL genic intron and the rpl20-psbA and psbM-psbZ intergenic spacers). Our findings raise some concerns about the discriminant power of the ITS2 nuclear target and place particular emphasis on the psbM-psbZ plastid DNA barcode, which is characterized by high polymorphism, for use in studies addressing intraspecific genetic diversity.