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National Committee on Marine Sciences (NCMS)

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Author: search.filters.author.Malto, Zabrina Bernice L.Has files: Yes

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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.
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    Genomics and metabolomics-based assessment of the biosynthetic potential of the sponge-associated microorganism Streptomyces cacaoi strain R2A-843A from the Philippines
    Malto, Zabrina Bernice L.; Reyes, Joeriggo M.; Lo, Bernard Isaiah; Davis, Kevin Bossie S.; Concepcion, Gisela; Salvador-Reyes, Lilibeth A. (Philippine-American Academy of Science and Engineering, 2023-10-20)
    The biosynthetic machinery of the sponge-associated Streptomyces cacaoi strain R2A-843A was assessed using a combined genomics and metabolomics approach. Whole genome sequencing and molecular networking showed the high biosynthetic potential of this actinomycete. A significant proportion of the genome is dedicated to secondary metabolite production, with biosynthetic gene clusters for nonribosomal peptides, polyketides, and terpenes being the most represented. Seven cyclic pentapeptides, including a putative new analogue, and a glycosylated lanthipeptide were identified using HRMS and untargeted MS/MS analysis. To validate our genome and metabolome analysis, we undertook a mass spectrometry-guided purification and confirmed the production of the known peptides BE-18257A (1) and BE-18257B (2). The production of 1 and 2 and the growth of the microorganism were monitored for eight days. Compound 2 was produced at a higher concentration, starting at 48 h post-incubation. Both compounds were noncytotoxic against colorectal and breast cancer cell lines.
    The authors acknowledge funding support from the Department of Science and Technology - Philippine Council for Health Research and Development through the Discovery and Development of Health Products - Marine Component Program. Genome sequencing was made possible through the CHEDPCARI IHITM63 Project. We thank Ms. Shalice R. SusanaGuevarra for conducting the bioactivity assay. This work was done under the supervision of the Bureau of Fisheries and Aquatic Resources under Gratuitous Permit No. FBP-0035-10. This is MSI Contribution No. 501.