초록
<P><B>Abstract</B></P><P>Microalgae offer a high potential for energetic lipid storage as well as high growth rates. They are therefore considered promising candidates for biofuel production, with the selection of high lipid‐producing strains a major objective in projects on the development of this technology. We developed a mutation‐selection method aimed at increasing microalgae neutral lipid productivity. A two step method, based on UVc irradiation followed by flow cytometry selection, was applied to a set of strains that had an initial high lipid content and improvement was assessed by means of Nile‐red fluorescence measurements. The method was first tested on <I>Isochrysis</I> affinis <I>galbana</I> (T‐Iso). Following a first round of mutation‐selection, the total fatty acid content had not increased significantly, being <TEX>$262\pm 21\,{\rm mgTFA}\,{\rm (gC)}^{- {\rm 1}} $</TEX><IMG src='/wiley-blackwell_img/equation/tex2gif-ueqn-1.gif' alt ='equation image'/> for the wild type (WT) and <TEX>$269\pm 49\,{\rm mgTFA}\,{\rm (gC)}^{- {\rm 1}} $</TEX><IMG src='/wiley-blackwell_img/equation/tex2gif-ueqn-2.gif' alt ='equation image'/> for the selected population (S1M1). Conversely, fatty acid distribution among the lipid classes was affected by the process, resulting in a 20% increase for the fatty acids in the neutral lipids and a 40% decrease in the phospholipids. After a second mutation‐selection step (S2M2), the total fatty acid content reached <TEX>$409\pm 64\,{\rm mgTFA}\,{\rm (gC)}^{- {\rm 1}} $</TEX><IMG src='/wiley-blackwell_img/equation/tex2gif-ueqn-3.gif' alt ='equation image'/> with a fatty acid distribution similar to the S1M1 population. Growth rate remained unaffected by the process, resulting in a 80% increase for neutral lipid productivity. Biotechnol. Bioeng. 2012; 109: 2737–2745. © 2012 Wiley Periodicals, Inc.</P>