THE INVOLVEMENT OF HYDROGEN-PEROXIDE IN THE PRODUCTION OF VOLATILE HALOGENATED COMPOUNDS BY MERISTIELLA-GELIDIUM

The production of volatile halogenated compounds (VHCs) by the red alg a Meristiella gelidium has been studied in batch culture. Production o f CHBr3, CHBr2Cl, CHBrCl2, CHCl3, HCCl=CCl2, CH2Br2, CH2I2, CH2ClI, C4 H9I and MeI was found. The most common VHCs produced were CHBr3 and CH 2I2 with a formation rate of 100 and 12 pmol g(-1) fr. wt after 1 hr. Normally the production rate of VHCs slowed down after approximately 1 -2 hr. Addition of 1 mM H2O2 increased the production of HCCl=CCl2, CH Br3, CHBr2Cl, CHBrCl2 and CHCl3 by between 50 (CHBr3) and 500% (HCCl=C Cl2). The same compounds also showed a decreased production after the addition of 1 mM NaN3. This suggests the importance of peroxidases in the production of some of the VHCs by macroalgae. The iodine containin g VHCs did not increase with addition of H2O2. We propose that the bro mo-chloro VHCs are formed as a result of H2O2 production and subsequen t H2O2 scavenging activities by peroxidases.