AccScience Publishing / MI / Online First / DOI: 10.36922/MI025510137
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Taxonomic characterization of bioactive hard coral-dwelling actinobacteria in Fiji

Galana Siro1* ,  Ketan Christi1 ,  Tamara Osborne1
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1 Department of Biological and Chemical Sciences, School of Agriculture, Geography, Environment, Ocean and Natural Sciences, The University of the South Pacific, Suva, Fiji
MI, 025510137 https://doi.org/10.36922/MI025510137
Received: 16 December 2025 | Revised: 27 January 2026 | Accepted: 28 January 2026 | Published online: 11 March 2026
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
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Abstract

Actinobacteria produce a plethora of bioactive molecules, yet research on these bacteria in the Pacific Island nations remains scarce. Previously, we isolated 16 actinomycete strains from Fijian hard corals, with varying degrees of antimicrobial activity against common pathogenic strains. The present study aims to identify these bioactive actinomycete isolates using 16S ribosomal RNA (16S rRNA) gene sequencing and phylogenetic analysis. The 16S rRNA gene characterization of the bioactive isolates predominantly revealed members of the genus Streptomyces, alongside three rare actinomycete genera: Micromonospora, Prauserella, and Kocuria. Additionally, antiSMASH analysis of the closest phylogenetic relatives of these cultured actinobacteria with notable antimicrobial activity revealed a strong potential for antibiotic biosynthesis. Overall, these findings suggest that Fijian hard corals represent a promising reservoir of bioactive actinobacteria for the discovery of antimicrobial compounds, particularly Streptomyces spp.

Graphical abstract
Keywords
Actinobacteria
Corals
Taxonomic identity
Phylogenetic analysis
16S rRNA
Fiji
Funding
The University of the South Pacific provided research funding (FD024 FST12 71502 001) to the lead author, GS, for DNA extraction kits and 16S rRNA gene sequencing.
Conflict of interest
The authors declare that they have no competing interests.
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Microbes & Immunity, Electronic ISSN: 3029-2883 Print ISSN: 3041-0886, Published by AccScience Publishing
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