Karenia brevis: marine microbes to the rescue?

Colloquially referred to as “red tides”, Karenia brevis is a harmful dinoflagellate whose blooms contain brevetoxin. Brevetoxin disrupts sodium channels and affects neurotransmission, it is powerful enough to cause serious symptoms in humans.

Three fluorescently labelled conjugates of brevetoxin were used to study how the toxin was taken up by various microbial groups. Successful uptake of conjugates was demonstrated by intracellular fluorescence in a diverse array of microbes; diatoms, dinoflagellates, haptophytes, rotifers, cryptophytes and ciliates.

This study is unique in its attempt to ascertain whether specific microbial species’ could be utilised during Karenia brevis blooms to act as a biological sink for the algal toxin. As the work is the first of its kind it must serve as a building block for any future study, the conjugates they used were modified and results cannot be fully recognised to work for parent metabolites in the field until more research is completed. Future studies would do well to elucidate which microbes are best suited as biological sinks, as sequestration mechanisms had much variation. Whilst microbes are seemingly capable of taking up brevetoxin, questions remain about the long-term implications regarding the bioaccumulation of toxins as a result.

Kramer, B.J., Bourdelais, A.J., Kitchen, S.A., Taylor, A.R. (2019) Uptake and localization of fluorescently-labelled Karenia brevis metabolites in non-toxic marine microbial taxa. Phycological Society of America, 55, 47-59.
https://onlinelibrary.wiley.com/doi/full/10.1111/jpy.12787