Production of halocarbons from seaweeds: an oxidative stress reaction?
M. Pedersén, J. Collén, K. Abrahamsson and A. Ekdahl
The production of various volatile halogenated compounds by marine algae was investigated during light and darkness.The amounts of halocarbon formed were measured with a GC-ECD. Production of the volatile halocarbons was also measured with addition of 1 mM of H2O2 or sodium azide. Production of hydrogen peroxide by different red and green algae was also studied. Bromination reaction-with the red alga Meristiella gelidium incubated in natural seawater was studied using phenol red as a substrate. The highproduction of H2O2 by Ulva rigida is suggested to be derived from the Mehler reaction or pseudocyclic photophosphorylation. Formed H2O2 is suggested to be scavenge in this alga mainly by diffusion. In other algae brominating reactions by peroxidases are suggested to be a way of scavenging H2O2 during oxidative stress. Halogenated compounds in marine algae should then just be secondary waste compounds formed with help of peroxidases in order to lower the high concentrations of hydrogenperoxide formed in the algal cells.