Temperature shifts induce intraspecific variation in microalgal production and biochemical composition

Three Isochrysis galbana strains, one I. galbana “substrain”, and one Nannochloropsis sp. strain were grown in nutrient replete conditions at 15, 20, 25, and 30°C. The interactive effect of temperature and isolate on growth rate, cell volume, production, dry weight, protein content, carbohydrate content, and total lipid content was examined. Nannochloropsis sp., growth rate had no relation with temperature; all I. galbana isolates increased linearly with temperature, with no significant differences. Cell volume and dry weight decreased linearly with temperature, with significant isolate and species differences. Biovolume-production did not vary significantly with temperature, but significant isolate and species differences occurred. Although significant temperature isolate interactions existed, no consistent trends in the change of protein, carbohydrate, and lipid with temperature occurred. We indicate a need to consider temperature induced affects in application using microalgae isolates, at various taxonomic levels, as some intraspecific differences were as great as interspecific differences.