Short Chain Fatty Acid Biosynthesis in Microalgae <i>Synechococcus</i> sp. PCC 7942

• Main Authors: Yi Gong, Xiaoling Miao
• Format: Article
• Language: English
• Published: MDPI AG 2019-04-01
• Series: Marine Drugs
• Subjects: microalgae; <i>Synechococcus</i> sp. PCC 7942; short chain fatty acids; β-ketoacyl ACP Synthase
• Online Access: https://www.mdpi.com/1660-3397/17/5/255

Short chain fatty acids (SCFAs) are valued as a functional material in cosmetics. Cyanobacteria can accumulate SCFAs under some conditions, the related mechanism is unclear. Two potential genes Synpcc7942_0537 (<i>fabB/F</i>) and Synpcc7942_1455 (<i>fabH</i>) in <i>Synechococcus</i> sp. PCC 7942 have homology with <i>fabB/F</i> and <i>fabH</i> encoding &#946;-ketoacyl ACP synthases (I/II/III) in plants. Therefore, effects of culture time and cerulenin on SCFAs accumulation, expression levels and functions of these two potential genes were studied. The results showed <i>Synechococcus</i> sp. PCC 7942 accumulated high SCFAs (C12 + C14) in early growth stage (day 4) and at 7.5g/L cerulenin concentration, reaching to 2.44% and 2.84% of the total fatty acids respectively, where <i>fabB/F</i> expression was down-regulated. Fatty acid composition analysis showed C14 increased by 65.19% and 130% respectively, when <i>fabB/F</i> and <i>fabH</i> were antisense expressed. C14 increased by 10.79% (<i>fab(B/F)</i>^&#8722;) and 6.47% (<i>fabH</i>^&#8722;) under mutation conditions, while C8 increased by six times in <i>fab(B/F)</i>^&#8722; mutant strain. These results suggested <i>fabB/F</i> is involved in fatty acid elongation (C &lt;18) and the elongation of <i>cis</i>-16:1 to <i>cis</i>-18:1 fatty acid in <i>Synechococcus</i> sp. PCC 7942, while <i>fabH</i> was involved in elongation of fatty acid synthesis, which were further confirmed in complementary experiments of <i>E. coli</i>. The research could provide the scientific basis for the breeding of SCFA-rich microalgae species.