Botryococcus braunii, a green alga that can produce a variety of secondary metabolites such as lipids, protein, and carotenoid, is considered a potential biodiesel feedstock for industrial commercialization. This study investigated the effects of exogenous plant growth regulators (PGRs) (6-benzylaminopurine (6-BA), abscisic acid (ABA), 2,4-epibrassinolide (EBR), ethephon (ETH), gibberellic acid (GA₃), 1-naphthaleneacetic acid (NAA), salicylic acid (SA), and spermidine (SPD)) on the growth, protein, carotenoid and lipid biosynthesis, fatty acid composition, and expression of fatty acid biosynthetic genes in Botryococcus braunii B12 (B. braunii B12). NAA was the most effective inducer of microalgae biomass, which increased approximately 2-fold compared with that of the control. The maximum lipid accumulation and content were found under 15 mg/L GA₃ treatment; the lipid accumulation reached 0.27 g/L, and the lipid content reached 60.25%. Moreover, the soluble protein content reached 28.49 mg/g DCW under 0.05 mg/L 6-BA treatment. Similarly, the highest carotenoid content (108.70 mg/g DCW) was observed under 50 mg/L NAA treatment. Furthermore, all PGRs altered the fatty acid composition of B. braunii B12, particularly the C16-C18 content (%). Finally, the effects of eight PGRs on seven lipid-related genes (acyl-acyl carrier protein (ACP), biotin carboxylase (BC), ω-3 fatty acid desaturase (FAD), acyl carrier protein thioesterase (FATA), 3-ketoacyl carrier protein synthase gene (KAS), malonyl-CoA:ACP transacylase (MCTK), and stearoyl-ACP-desaturase (SAD)) were studied by qRT-PCR, and an apparent correlation was found between gene expression and lipid synthesis in the microalgae.

枯草芽孢杆菌（Botryococcus braunii）是一种绿色藻类，可以产生多种次级代谢产物，例如脂质，蛋白质和类胡萝卜素，被认为是工业化商业生产的潜在生物柴油原料。这项研究调查了外源植物生长调节剂（PGR）（6-苄基氨基嘌呤（6-BA），脱落酸（ABA），2,4-表油菜素内酯（EBR），乙烯利（ETH），赤霉素（GA ₃）， 1-萘乙酸（NAA），水杨酸（SA）和亚精胺（SPD））在Botryococcus braunii B12（B. braunii）中的生长，蛋白质，类胡萝卜素和脂质的生物合成，脂肪酸组成以及脂肪酸生物合成基因的表达B12）。NAA是最有效的微藻生物量诱导剂，与对照相比增加了约2倍。在15 mg / L GA ₃处理下，脂质的最大积累和含量最高。脂质积累达到0.27 g / L，脂质含量达到60.25％。此外，在0.05 mg / L的6-BA处理下，可溶性蛋白含量达到28.49 mg / g DCW。同样，在50 mg / L NAA处理下，类胡萝卜素含量最高（108.70 mg / g DCW）。此外，所有PGR均改变了布鲁氏菌B12的脂肪酸组成，特别是C16-C18的含量（％）。最后，八种植物遗传资源对七个脂质相关基因（酰基-酰基载体蛋白（ACP），生物素羧化酶（BC）），ω-3脂肪酸去饱和酶（FAD），酰基载体蛋白硫酯酶（FATA），3-酮酰基载体蛋白合酶基因（KAS），丙二酰辅酶A：ACP转酸酶（MCTK）和硬脂酰-ACP去饱和酶（SAD）通过qRT-PCR研究，并且在微藻中发现基因表达与脂质合成之间存在明显的相关性。