Molecular markers obtained from draft genomic sequence data characterise an isolate of Oedogonium (Chlorophyceae) used for biomass applications

Abstract

ABSTRACT Local isolates of the species-rich, fast-growing chlorophyte genus Oedogonium have been employed in outdoor biomass cultivation for industrial applications such as wastewater remediation, but such isolates may not express structural traits needed for definitive species identification by microscopy alone. We used maximum likelihood and Bayesian phylogenetic methods to evaluate molecular marker gene sequences derived from genomic sequences to characterise an industrial isolate, Oedogonium sp. Lake Mendota strain, which could not be reliably classified at species level using only morphology. Molecular markers evaluated were rbcL, 23S rDNA, 28S rDNA, 18S rDNA, and a sequence that included ITS1+5.8S rDNA+ITS2. All five markers distinguished the Lake Mendota strain from other Oedogonium accessions in GenBank. Using full genome sequences allowed the efficient acquisition of multiple types of marker sequences whose sequencing depth was known. In the absence of a classical species determination, these markers provided a taxonomic reference background for future genomic, biochemical, and other investigations of the local isolate. Local isolates are advantageous for outdoor industrial biomass cultivation applications because such isolates are already adapted to climatic conditions prevailing at cultivation sites. The results should encourage industrial use of local isolates of Oedogonium because these can be characterised by molecular markers even if structural features needed for accurate species determinations are not expressed.