Cell-to-cell communication regulates microalgae production via signaling molecules (SMs), but few microalgal SM species are known. Here, we document two new microalgae SMs, benzoic acid (BA) and salicylic acid (SA). Initially, crude SMs were extracted from a microalgae culture in which microalgae grew on heterotrophic-enriched phosphorus nutrition. The extracted SMs enhanced Chlorella growth by ∼72%, promoted nutrient uptake, and up-regulated the mitogen-activated protein-kinase signaling cascade. Fourier transform infrared and nuclear magnetic resonance analyses identified the putative SMs was aromatic carboxylic acids. BA and SA were identified using high-resolution mass spectrometry. BA and SA addition increased cell growth by ∼75% and ∼25%; and improved ATP production by ∼35% and ∼20%. Transcriptomic analysis showed that BA and SA were biosynthesized via CoA-dependent, non-oxidative pathway. The SMs upregulated TCA-cycle enzymes, which promoted carbon assimilation and activated DNA-replicating enzyme, so that accelerated cell division. This study identified two new SMs for microalgae cell communication and provides means to identify other SMs.

细胞之间的通信通过信号分子（SM）调节微藻的产生，但很少有微藻SM种类。在这里，我们记录了两种新的微藻SM，即苯甲酸（BA）和水杨酸（SA）。最初，从微藻培养物中提取粗制SM，在微藻培养中，微藻依靠富含异养菌的磷营养生长。提取的SM增强了小球藻生长约72％，促进养分吸收，并上调有丝分裂原激活的蛋白激酶信号传导级联。傅立叶变换红外和核磁共振分析确定推定的SM为芳族羧酸。BA和SA使用高分辨率质谱法鉴定。BA和SA的添加使细胞生长分别增加了约75％和约25％。并将ATP产量提高了约35％和约20％。转录组学分析表明，BA和SA是通过CoA依赖的非氧化途径生物合成的。SM上调TCA循环酶，从而促进碳同化并激活DNA复制酶，从而加速细胞分裂。这项研究确定了两个用于微藻细胞通讯的新SM，并提供了识别其他SM的方法。