高光限氮对莱茵衣藻响应环烷酸胁迫的影响

High light and nitrogen deprivation affect the response of Chlamydomonas reinhardtii to naphthenic acid stress

摘要:

目的 探究油脂积累型模式藻株莱茵衣藻(Chlamydomonas reinhardtii)响应环烷酸胁迫的生理生化适应机制。方法 通过研究高光富氮和高光限氮条件下，典型环烷酸——环己烷甲酸(cyclohexanecarboxylic acid, CHCA)暴露对高初始密度培养的莱茵衣藻生长、光合活性、培养液pH值、氮磷元素吸收及脂质、碳水化合物、蛋白质、色素等生理生化组分的影响，以全面评估莱茵衣藻对CHCA的耐受性。结果 在高光富氮条件下，CHCA暴露显著促进了莱茵衣藻对磷元素的吸收，同时显著增加了C16:0脂肪酸的相对丰度，而降低了C18:3n3脂肪酸的相对丰度；而在高光限氮条件下，CHCA暴露显著抑制了莱茵衣藻的光合活性以及对磷元素的吸收，但并未对其脂肪酸组成产生显著影响。此外，无论是高光富氮还是高光限氮条件下，CHCA暴露均未对莱茵衣藻的生长、培养液pH值以及脂质、碳水化合物、蛋白质和叶绿素含量产生明显影响。结论 微藻对环境胁迫的耐受性可通过生长曲线直观表征，并可通过藻细胞的生长、光合活性、氮磷吸收及关键生化组分综合考量进行评估。高光富氮条件通过促进磷元素吸收和改变脂肪酸组成，增强了莱茵衣藻对环烷酸的耐受性；而高光限氮条件则通过抑制光合活性和磷元素吸收，减弱了莱茵衣藻对环烷酸的耐受性。这些发现可为筛选与构建高度耐受环烷酸的藻株培养策略提供借鉴。

关键词:莱茵衣藻;环烷酸;高光限氮;生长;光合活性;氮磷元素吸收;脂肪酸标志物

Abstract:

Objective To explore the physiochemical response mechanism of a model algal strain Chlamydomonas reinhardtii that hyper-accumulates oils to exposure of naphthenic acids (NAs).Methods The impacts of a typical NA, cyclohexanecarboxylic acid (CHCA), on the physiochemical parameters, including growth, photosynthetic activity, pH value of the culture, uptake of nitrogen and phosphorus, and biochemical constituents (lipids, carbohydrates, proteins, and pigments), of C. reinhardtii with high initial cell density under high light-nitrogen repletion (HL+N) and high light-nitrogen deprivation (HL-N) conditions were studied.Results The exposure to CHCA prominently promoted the uptake of phosphorus by C. reinhardtii under HL+N, while significantly inceasing the relative abundance of saturated C16:0 and decreasing the relative abundance of polyunsaturated C18:3n3. In contrast, CHCA treatment significantly inhibited the photosynthetic activity and phosphorus uptake but did not affect the fatty acid profile of C. reinhardtii under HL-N stress. In addition, the growth, pH value of the culture, and content of lipids, carbohydrates, proteins, and pigments, in C. reinhardtii under both HL+N and HL-N conditions all remained relatively constant when subjected to CHCA exposure.Conclusion The tolerance of microalgae to environmental stress can be visualized by growth curves, photosythetic activity, uptake of nitrogen and phosphorus, and key biochemical constituents. HL+N improves the tolerance of C. reinhardtii to NAs by promoting the uptake of phosphorus and altering the fatty acid profile, while the case was contrary under HL-N. These findings are beneficial for establishing strategies on effective cultivation of microalgae that highly tolerate NAs.

Key words:Chlamydomonas reinhardtii;naphthenic acid;high light and nitrogen deprivation;growth;photosynthetic activity;uptake of nitrogen and phosphorus;fatty acid biomarker