Effects of hydrogen peroxide on the content of major volatile halogenated compounds in the red alga Asparagopsis taxiformis (Bonnemaisoniaceae)

Abstract

The genus Asparagopsis is a prolific source of halogenated metabolites. Due to its commercial applications, it has been intensively cultivated in southern Portugal. In the present study, we assess if the internal levels of the major halogenated metabolites (bromoform and dibromoacetic acid) in Asparagopsis taxiformis can be increased with hydrogen peroxide (H 2 O 2 ) addition. Previous studies with red algae showed that the production/release of bromoform can be enhanced by exogenously supplying H 2 O 2 . However, no study has assessed if H 2 O 2 supply enhances the content of secondary metabolites within the biomass. This detail is important as the objective of the proposed research is to enhance the content of these valuable metabolites in the produced biomass. Both the activity of the haloperoxidase enzyme and the metabolite content were assessed on shortterm and long-term incubation periods to H 2 O 2 . To determine the susceptibility of A. taxiformis photosynthetic performance to the imposed oxidative stress, the in vivo fluorescence of photosystem II was monitored. A. taxiformis was shown to be physiologically vulnerable to H 2 O 2 , given the observed decrease of the maximum quantum yield of photosynthesis (F v /F m ). Contrary to what was expected, the presence of H 2 O 2 inhibited the activity of the iodoperoxidase enzyme. Nevertheless, the extracted halogenated metabolites were higher over the first hours of exposure to H 2 O 2 , decreasing after 48 h. These results are probably related to the prosthetic group of the halogenated enzyme in A. taxiformis and the long-term oxidative stress damage of H 2 O 2 exposure. Considering the objective of the proposed research, addition of H 2 O 2 to the cultures, prior (3 h) to biomass harvesting, increases the metabolite content.

Different speciation for bromine in brown and red algae, revealed by in vivo X‐ray absorption spectroscopic studies

“…A (indicative of sp 3 C) and a Br shell at 3.15-3.20 A (i.e., one or more "geminal" bromine scatterers, attached to the same carbon as the absorber). This is in line with the observation that this alga is by orders of magnitude more active in evolving bromoform and analogs than the others (Carpenter et al 2000, Mata et al 2011). Asparagopsis species contain many different geminal dibromo and tribromo compounds (e.g., Woolard et al 1976).…”

“…, Mata et al. ). Asparagopsis species contain many different geminal dibromo and tribromo compounds (e.g., Woolard et al.…”

CARBON/NUTRIENT BALANCE IN RELATION TO BIOMASS PRODUCTION AND HALOGENATED COMPOUND CONTENT IN THE RED ALGA ASPARAGOPSIS TAXIFORMIS (BONNEMAISONIACEAE)1

“…2001). However, Mata et al. (2011) showed that this was not the case of bromoform content of A. taxiformis under long‐term exposure to H 2 O 2 enrichment.…”

“…The production of halogenated metabolites by seaweeds may be promoted by substrates and cofactors (e.g., bromide ions or hydrogen peroxide) involved in the activity of haloperoxidase, the enzyme responsible for the biogenesis of halogenated metabolites (Sundström et al 1996, Ohsawa et al 2001). However, Mata et al (2011) showed that this was not the case of bromoform content of A. taxiformis under long-term exposure to H 2 O 2 enrichment.…”

The role of vanadium haloperoxidases in the formation of volatile brominated compounds and their impact on the environment

“…Consequently volatile halogenated compounds will be formed as shown by several authors. [66][67][68][69][70][71][72] It is well known that plant cells during photosynthesis and photorespiration generate H 2 O 2 . 73 Also intra-and intercellular levels of H 2 O 2 increase during environmental stresses experienced by plant cells.…”