PRODUCTION OF HALOCARBONS FROM SEAWEEDS - AN OXIDATIVE STRESS REACTION

The production of various volatile halogenated compounds by marine alg ae was investigated during light and darkness. The amounts of halocarb on formed were measured with a GC-ECD. Production of the volatile halo carbons was also measured with addition of 1 mM of H2O2 or sodium azid e. Production of hydrogen peroxide by different red and green algae wa s also studied. Bromination reaction with the red alga Meristiella gel idium incubated in natural seawater was studied using phenol red as a substrate. The high production of H2O2 by Ulva rigida is suggested to be derived from the Mehler reaction or pseudocyclic photophosphorylati on. Formed H2O2 is suggested to be scavenge in this alga mainly by dif fusion. In other algae brominating reactions by peroxidases are sugges ted to be a way of scavenging H2O2 during oxidative stress. Halogenate d compounds in marine algae should then just be secondary waste compou nds formed with help of peroxidases in order to lower the high concent rations of hydrogen peroxide formed in the algal cells.