This study investigated the effect of the surfactant cocamidopropyl betaine (CAB) on the growth of red tide microalgae Skeletonema costatum. It was found that CAB caused cell lysis in a time- and dose-dependent manner and significantly inhibited the growth of S. costatum. Additionally, the transcriptomic approach was coupled with physiological analysis to elucidate the inhibitory mechanism of CAB on S. costatum. Among the 30726 genes identified, 17720 and 20583 genes were differentially expressed after treatment for 3 h and 6 h, respectively, which revealed that CAB redirected metabolic pathways, of which the expressions of genes related to the proteasome, ABC transporters, and amino acid-related metabolism were significantly upregulated, while genes involved in photosynthesis, biofilm and cell wall synthesis, mitogen-activated protein kinase (MAPK) cascades and antioxidant system were downregulated. The results above corresponded to the decreasing antioxidant enzymes activities, protein and photosynthetic pigments contents, as well as the increasing malondialdehyde (MDA) content. Our study presented herein shed light on the algicidal mechanism of CAB at the transcriptome level and was useful to red tide control, and marine environmental protection.
