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National Committee on Marine Sciences (NCMS)

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Ocean Decade Challenge: search.filters.odc.Challenge 1: Understand and beat marine pollutionUNESCO Keyword: search.filters.subject.Marine biology

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    Growth, nitrate uptake kinetics, and biofiltration potential of eucheumatoids with different thallus morphologies
    Narvarte, Bienson Ceasar V.; Genovia, Tom Gerald T.; Hinaloc, Lourie Ann R.; Roleda, Michael Y. (Wiley, 2021-12-30)
    The declining production of commercially important eucheumatoids related to serious problems like increasing susceptibility to ice‐ice disease and epiphytism may be ameliorated by nutrition. This ushered to an increasing interest in incorporating seaweeds into an integrated multi‐trophic aquaculture (IMTA) setup to take up excess inorganic nutrients produced by fish farms for their nourishment. In this regard, it is important to understand the nutrient uptake capacity of candidate seaweeds for incorporation in an IMTA system. Here, we examined the growth, nitrate (NO3‐) uptake kinetics and biofiltration potential of Eucheuma denticulatum and three strains of Kappaphycus alvarezii (G‐O2, TR‐C16 and SW‐13) with distinct thallus morphologies. The NO3‐ uptake rates of the samples were determined under a range of NO3‐ concentration (1‐ 48 µM) and uptake rates were fitted to the Michaelis‐Menten saturation equation. Among the examined eucheumatoids, only SW‐13 had a linear response to NO3‐ concentration while other strains had uptake rates that followed the Michaelis‐Menten saturation equation. Eucheuma denticulatum had the lowest Km (9.78 ± 1.48 µM) while G‐O2 had the highest Vmax (307 ± 79.3 µmol · g‐1 · min‐1). The efficiency in NO3‐ uptake (highest Vmax/Km and α) was translated into the highest growth rate (3.41± 0.58 % · d‐1) measured in E. denticulatum. Our study provided evidence that eucheumatoids could potentially take up large amount of NO3‐ and fix CO2 when cultivated proximate to a fish farm as one component of an IMTA system. During a 45‐d cultivation period of eucheumatoids, as much as 370 g NO3‐ can be sequestered by every 1 kg initial biomass E. denticulatum growing at 3% · d‐1. Furthermore, based on our unpublished photosynthetic measurements, the congeneric K. striatus can fix 27.5 g C · kg‐1 DW during a 12‐h daylight period.
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    Global mass spectrometric analysis reveals chemical diversity of secondary metabolites and 44-Methylgambierone production in Philippine Gambierdiscus strains
    Malto, Zabrina Bernice L.; Benico, Garry A.; Batucan, Jeremiah D.; Dela Cruz, James; Romero, Marc Lawrence J.; Azanza, Rhodora V.; Salvador-Reyes, Lilibeth A. (Frontiers Media SA, 2022-02-04)
    Surveillance and characterization of emerging marine toxins and toxigenic dinoflagellates are warranted to evaluate their associated health risks. Here, we report the occurrence of the ciguatera poisoning-causative dinoflagellate Gambierdiscus balechii in the Philippines. Toxin production and chemical diversity of secondary metabolites in G. balechii GtoxSAM092414, G. balechii Gtox112513, and the recently reported Gambierdiscus carpenteri Gam1BOL080513 were assessed using targeted and untargeted UPLC-MS/MS analysis and radioligand receptor-binding assay (RBA). 44-methylgambierone was produced by all three strains, albeitwith different levels based on RBA and UPLC-HRMS/MS analysis. The fatty acid composition was similar in all strains, while subtle differences in monosaccharide content were observed, related to the collection site rather than the species. Molecular networking using the GNPS database identified 45 clusters belonging to at least ten compound classes, with terpene glycosides, carbohydrate conjugates, polyketides, and macrolides as major convergence points. Species-specific peptides and polyhydroxylated compounds were identified in G. balechii GtoxSAM092414 and G. carpenteri Gam1BOL080513, respectively. These provide a glimpse of the uncharacterized biosynthetic potential of benthic dinoflagellates and highlight the intricate and prolific machinery for secondary metabolites production in these organisms.
    We would like to thank H. Junio and the Secondary Metabolites Profiling Laboratory of the Institute of Chemistry, University of the Philippines Diliman and K. B. Davis for assistance in the conduct of this study.