Chlorella vulgaris is a form of microalgae commonly employed as a biological source of oil for biodiesel production. Major algal cultivation strategies are focused on stimulating growth rate and lipid content. In the present study, the algal growth media was supplemented with iron (III) chloride (FeCl3), as a stimulating factor for growth and lipid production, in three iron concentrations including 90, 200, and 500 µM. The turbidity of algal cells was measured on different days, to determine the growth rate. In optimum iron concentration, this measurement experienced a 2.1-fold increase. Next, the lipid content was extracted, and the amount of lipid produced in each treatment was calculated, which demonstrated a 4.57-fold increase in lipid productivity. The expression of genes corresponding to the metabolic enzymes (i.e. acetyl-CoA carboxylase (accD) and ribulose bisphosphate carboxylase large chain (rbcL)) was evaluated using real-time PCR under different initial iron feeds. As demonstrated in the results, the initial iron feed of 90 µM was an optimum concentration that obtained the highest growth rate, more cell density, and increased lipid production. In 90 µM initial iron concentration, the expression of accD and rbcL genes showed a 4.8- and 35-fold increase, respectively, compared to that of the control genes. Based on the results, this optimum iron concentration could satisfy the industrial interest in biodiesel production from C. vulgaris as a potential stimulating factor. However, higher levels of iron (e.g. 200 and 500 µM) failed to act as positive stress for increasing biodiesel production. Finally, in this paper, different mechanisms where iron affects acetyl-CoA carboxylase (ACCase) and 1,5-ribulose bisphosphate carboxylase/oxygenase (RuBisCo) are illustrated.

中文翻译：

---

使用优化的铁浓度增加 accD 和 rbcL 基因的表达，以在普通小球藻中获得更高的生物量和生物柴油

小球藻是一种微藻，通常用作生物柴油生产油的生物来源。主要的藻类栽培策略侧重于刺激生长速度和脂质含量。在本研究中，藻类生长培养基补充有氯化铁 (III) (FeCl3)，作为生长和脂质产生的刺激因子，三种铁浓度包括 90、200 和 500 µM。在不同天测量藻细胞的浊度，以确定生长速率。在最佳铁浓度下，该测量值增加了 2.1 倍。接下来，提取脂质含量，并计算每个处理中产生的脂质量，这表明脂质生产率增加了 4.57 倍。对应于代谢酶的基因的表达（即 在不同的初始铁饲料下使用实时 PCR 评估乙酰辅酶 A 羧化酶 (accD) 和核酮糖二磷酸羧化酶大链 (rbcL)。结果表明，90 µM 的初始铁进料是获得最高生长速率、更高细胞密度和增加脂质产量的最佳浓度。在 90 µM 初始铁浓度下，与对照基因相比，accD 和 rbcL 基因的表达分别增加了 4.8 倍和 35 倍。根据结果​​，该最佳铁浓度可以满足作为潜在刺激因素的普通 C. vulgaris 生物柴油生产的工业利益。然而，较高水平的铁（例如 200 和 500 µM）未能作为增加生物柴油产量的积极压力。最后，在本文中，