Isolation and characterization of an alkenone composition mutant in the haptophyte Tisochrysis lutea

Abstract

While long-chain alkenone (defined as alkenone) is known to have a potential for industrial application, its biosynthetic pathway is still largely unknown. In the present study, we obtained a novel mutant named C8–14 strain altering alkenone composition with heavy-ion beam irradiation to the haptophyte Tisochrysis lutea. This mutant showed higher levels of tri-unsaturated alkenones and significantly lower amounts of alkenones and alkenoates than the wild-type cells. In addition, the total amounts of fatty acids in the neural lipid fraction of the C8–14 strain were higher than those in the wild-type cells. The primary sequence of the genes related to alkenone desaturases in the C8–14 strain, including the paralogous genes found in this study, were identical to those in the wild-type cells. However, the expression level of the putative alkenone desaturase gene was altered. The expression of the TOD-2 gene was slightly higher in the C8–14 cells than in the wild-type cells. This is the first report, to the best of our knowledge, to create the mutant with the altered unsaturation of alkenones.