Wei Likun, Huang Xuxiong
Key Laboratory of Genetic Resources for Freshwater Aquaculture and Fisheries, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China.
Shanghai Engineering Research Centre of Aquaculture, Shanghai, China.
PLoS One. 2017 Mar 27;12(3):e0174646. doi: 10.1371/journal.pone.0174646. eCollection 2017.
Microalga Nannochloropsis oculata is a promising alternative feedstock for biodiesel. Elevating its oil-yielding capacity is conducive to cost-saving biodiesel production. However, the regulatory processes of multi-factor collaborative stresses (MFCS) on the oil-yielding performance of N. oculata are unclear. The duration effects of MFCS (high irradiation, nitrogen deficiency and elevated iron supplementation) on N. oculata were investigated in an 18-d batch culture. Despite the reduction in cell division, the biomass concentration increased, resulting from the large accumulation of the carbon/energy-reservoir. However, different storage forms were found in different cellular storage compounds, and both the protein content and pigment composition swiftly and drastically changed. The analysis of four biodiesel properties using pertinent empirical equations indicated their progressive effective improvement in lipid classes and fatty acid composition. The variation curve of neutral lipid productivity was monitored with fluorescent Nile red and was closely correlated to the results from conventional methods. In addition, a series of changes in the organelles (e.g., chloroplast, lipid body and vacuole) and cell shape, dependent on the stress duration, were observed by TEM and LSCM. These changes presumably played an important role in the acclimation of N. oculata to MFCS and accordingly improved its oil-yielding performance.
微藻眼点拟微绿球藻是一种很有前景的生物柴油替代原料。提高其产油能力有利于降低生物柴油生产成本。然而，多因素协同胁迫（MFCS）对眼点拟微绿球藻产油性能的调控过程尚不清楚。在18天的分批培养中研究了MFCS（高辐照、缺氮和增加铁补充）对眼点拟微绿球藻的持续时间效应。尽管细胞分裂减少，但由于碳/能量储存库的大量积累，生物量浓度增加。然而，在不同的细胞储存化合物中发现了不同的储存形式，蛋白质含量和色素组成都迅速且剧烈地发生了变化。使用相关经验方程对四种生物柴油性质进行分析表明，它们在脂质类别和脂肪酸组成方面有逐步有效的改善。用荧光尼罗红监测中性脂质生产率的变化曲线，并与传统方法的结果密切相关。此外，通过透射电子显微镜（TEM）和激光扫描共聚焦显微镜（LSCM）观察到，细胞器（如叶绿体、脂质体和液泡）和细胞形状会随着胁迫持续时间发生一系列变化。这些变化可能在眼点拟微绿球藻对MFCS的适应过程中发挥了重要作用，从而提高了其产油性能。
