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 alga Meristiella gelidium has been studied in batch culture. Production of CHBr3, CHBr2Cl, CHBrCl2, CHCl3, HCCl=CCl2, CH2Br2, CH2I2, CH2ClI, C4H9I and MeI was found. The most common VHCs produced were CHBr3 and CH2I2 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, CHBr3, CHBr2Cl, CHBrCl2 and CHCl3 by between 50 (CHBr3) and 500% (HCCl=CCl2). 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 containing VHCs did not increase with addition of H2O2. We propose that the bromo-chloro VHCs are formed as a result of H2O2 production and subsequent H2O2 scavenging activities by peroxidases.