Pyrolysis of Arundo donax L. to produce pyrolytic vinegar and its effect on the growth of dinoflagellate Karenia brevis

- Twenty-five kinds of chemicals were identified in PVs produced from giant reed at 300-600 °C.
- PV induced change in pH of the culture medium were not responsible for the inhibitory effect for K. brevis.
- Acetic acid in PVs were not the main reason for inhibition of K. brevis.
- The excess ROS from PV exposure resulted in lipid oxidation and organelle damage to K. brevis.
- Chloroplast and mitochondria were the main target sites of the PVs.

Harmful algal blooms (HABs) have become global environmental issues, and the demand for alternative algaecides is urgent. Pyrolytic vinegars (PVs) were pyrolyzed from giant reed at 300-600 °C to investigate the underlying mechanisms of their inhibitory effect on the red tide dinoflagellate Karenia brevis by sub-chronic toxicity experiments. The major components of PVs were acetic acid, phenols, aldehyde, ketone, and esters. The 96 h median effective concentration (96 h-EC50) values of PVs were 0.65-1.08 mL L−1, and PV300 showed the strongest inhibitory effect. The increased contents of reactive oxygen species (ROS) and malondialdehyde, antioxidant enzymes activities indicated that K. brevis cells were suffering from oxidative stress, leading to lipid oxidation and cell structure damage. The sites of ROS accumulation in the treated cells were chloroplasts and mitochondria. These results suggest the suitability of PVs as potential algaecides for HAB control, and also provide a new direction for biomass valorization.

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