FIRST INSIGHTS INTO IMPROVEMENT OF EICOSAPENTAENOIC ACID CONTENT IN PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE) BY INDUCED MUTAGENESIS1

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Abstract
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 114) was obtained. The EPA content (% of dry weight) of this mutant strain was 37% higher than that of the wild type. 114 was further mutated and another putative mutant (provisionally called 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 114 and II242 was, 17.3 mg · g−1, 31.5mg · 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.