富里酸诱导对三角褐指藻EPA合成积累的影响

Effects of fulvic acid induction on eicosapentaenoic acid accumulation in Phaeodactylum tricornutum

探究不同富里酸质量浓度对三角褐指藻二十碳五烯酸(EPA)合成积累的影响。结果表明,在质量浓度20 mg/L富里酸诱导下,三角褐指藻EPA含量和产量均达到最大值,为19.81 g/100 g和738.91 mg/L,较无富里酸诱导EPA含量和产量分别提高1.12和1.50倍。外源富里酸作用提高了三角褐指藻胞内过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的酶活,使色素(叶绿素、类胡萝卜素)和总多酚抗氧化组分比例增加,活性氧(ROS)和丙二醛(MDA)水平降低,整体抗氧化能力获得显著提升,有效阻抑EPA的氧化分解;富里酸作用同时还上调了EPA合成通路去饱和酶(Δ^(5)-FADS、Δ^(6)-FADS、Δ^(12)-FADS、Δ^(15)-FADS、Δ^(17)-FADS)和延长酶(Δ^(6)-ELOVL)等系列关键酶,使其上调表达量较无富里酸作用分别增加0.33、0.94、0.33、0.58、1.15和0.70倍,为EPA高效合成积累提供前驱物和能量。

The effects of fulvic acid(FA)mass concentration on eicosapentaenoic acid(EPA)accumulation in Phaeodactylum tricornutum(P.tricornutum)were investigated.The results showed that induction by FA with a mass concentration of 20 mg/L achieved highest EPA content and productivity of 19.81 g/100 g and 738.91 mg/L,respectively,approximately 1.12-and 1.50-fold increase in comparison to the controls without FA treatment group.The exogenous FA treatment enhanced activities of peroxidase(POD),superoxide dismutase(SOD),and catalase(CAT)in P.tricornutum,which increased the proportions of pigments(chlorophyll and carotinoid)and total polyphenol while simultaneously decreased the levels of ROS and MDA,demonstrating significant improvement of the antioxidative capacities of P.tricornutum cells and consequent inhibition of EPA oxidative decomposition.Meanwhile,FA treatment also led to up-regulations of pathway desaturases(Δ^(5)-FADS,Δ^(6)-FADS,Δ^(12)-FADS,Δ^(15)-FADS,Δ^(17)-FADS)and elongase(Δ^(6)-ELOVL)involved in EPA synthesis,resulting in 0.33-,0.94-,0.33-,0.58-,1.15-and 0.70-fold increments compared with those without FA treatment group.The enhancement of these crucial enzymes in EPA pathway would provide precursors and energy for efficient EPA synthesis.