초록
<P><B>Abstract</B></P><P>The prokaryotic microalga <I>Limnothrix redekei</I> KNUA012 isolated from a freshwater bloom sample from Lake Hapcheon, Hapcheon-gun, South Korea, was investigated for its potential as a biofuel feedstock. Microalgae produce straight-chain alkanes/alkenes from acyl carrier protein-linked fatty acyls via aldehyde decarbonylase (AD; EC 1.2.1.3), which can convert aldehyde intermediates into various biofuel precursors, such as alkanes and free fatty acids. In <I>L. redekei</I> KNUA012, long-chain ADs can convert fatty aldehyde intermediates into alkanes. After heterologous AD expression in <I>Escherichia coli</I> (pET28-AD), we identified an AD in <I>L. redekei</I> KNUA012 that can synthesize various alkanes, such as pentadecane (C<SUB>15</SUB>H<SUB>32</SUB>), 8-heptadecene (C<SUB>17</SUB>H<SUB>34</SUB>), and heptadecane (C<SUB>17</SUB>H<SUB>36</SUB>). These alkanes can be directly used as fuels without transesterification. Biodiesel constituents including dodecanoic acid (C<SUB>13</SUB>H<SUB>26</SUB>O<SUB>2</SUB>), tetradecanoic acid (C<SUB>15</SUB>H<SUB>30</SUB>O<SUB>2</SUB>), 9-hexa decenoic acid (C<SUB>17</SUB>H<SUB>32</SUB>O<SUB>2</SUB>), palmitoleic acid (C<SUB>17</SUB>H<SUB>32</SUB>O<SUB>2</SUB>), hexadecanoic acid (C<SUB>17</SUB>H<SUB>34</SUB>O<SUB>2</SUB>), 9-octadecenoic acid (C<SUB>19</SUB>H<SUB>36</SUB>O<SUB>2</SUB>), and octadecanoic acid (C<SUB>19</SUB>H<SUB>38</SUB>O<SUB>2</SUB>) are produced by <I>L. redekei</I> KNUA012 as the major fatty acids. Our findings suggest that Korean domestic <I>L. redekei</I> KNUA012 is a promising resource for microalgae-based biofuels and biofuel feedstock.</P>