First insights into improvement of eicosapentaenoic acid content in Phaeodactylum tricornutum (Bacillariophyceae) by induced mutagenesis

A strain improvement program was initiated based on mutagenesis with the goal of commercial production of eicosapentaenoic acid (EPA)from EPA-overproducing microalgal strains. Two rounds of mutation. and selection were conducted using Phaeodactylum tricornutum Bohlin UTEX #640 as the parent strain. After the first round of mutagenesis, a putative mutant (provisionally labeled I14) was obtained. The EPA content (ro of dry weight) of this mutant strain was 37% higher than that of the wild type. I14 was further mutated and another putative mutant (provisionally cabled II242) was isolated, the EPA content of which was 44% higher than that of the wild type. When cultured with aeration in 1-L flasks, EPA content of the wild type and putative mutants I14 and II242 was 17.3 mg . g(-1), 31.5 mg . g(-1), and 38.6 mg . g(-1) dry biomass, respectively. EPA productivity was 3.48 mg . L(-1). d(-1), 4.01 mg . L(-1). d(-1), and 4.98 mg . L(-1). d(-1), respectively These figures compare favorably with many other promising EPA-producing microorganisms and suggest that the use of a single methodology such as mutation and selection is a way to improve the polyunsaturated fatty acid content of microalgae and other microorganisms.