Quorum sensing molecules enhance cadmium detoxification and cellular removal in the marine diatom Phaeodactylum tricornutum.

Acyl-homoserine lactones (AHLs) are ubiquitous bacteria-derived quorum-sensing molecules in marine environments and play important roles in regulating microbial physiological processes. However, their influence on metal detoxification and handling in microalgae remains poorly understood. Here, we investigated the effects of exogenous AHLs on cell growth, metabolic responses, and cadmium (Cd) removal in the marine diatom Phaeodactylum tricornutum under both Cd-free and Cd-contaminated conditions. It was demonstrated that AHLs slightly inhibited the growth of P. tricornutum and increased extracellular polymeric substances (EPS) production under Cd-free conditions. Under Cd exposure, AHLs significantly suppressed growth and enhanced oxidative stress responses, as indicated by increased activities of superoxide dismutase (SOD) and elevated levels of malondialdehyde (MDA) and glutathione (GSH). Besides, AHLs increased the Cd removal per cell of P. tricornutum, reaching 1.15-2.12 times that of the control. These results demonstrate that quorum sensing molecules can regulate detoxification-related metabolic responses and enhance cellular Cd handling in microalgae, providing new insights into microbe-mediated metal detoxification and highlighting the potential relevance of quorum sensing in microalgae-based biotechnological applications.