Sponges from Lembeh Strait: antimicrobial activity and prokaryotic diversity

This study aims to assess the antimicrobial activity of sponges from Lembeh Strait, explore their prokaryotic diversity, and investigate correlations between sponge antimicrobial activities and their associated prokaryotic communities.

Secondary metabolites were extracted from sixty two sponge tissues using MeOH: EtOAc as solvent (1:1). Antimicrobial activity of the sponge crude extracts was tested against Escherichia coli, Aeromonas salmonicida, Bacillus subtilis, Staphylococcus simulans, Saprolegnia parasitica, and Candida oleophila. The strongest antimicrobial activity was observed for sponge extracts from Theonella sp. against Sa. parasitica. Microbial community profiling was performed for sponges and environmental samples (seawater and sediment) using 16S rRNA gene amplicon sequencing. Distinct prokaryotic community compositions were observed in sponges compared to their environments, with a strong influence of host-identity. A significant positive correlation between the phylum Actinobacteriota and sponge antimicrobial activity suggests importance of Actinobacteriota for sponge's bioactive properties. In addition, six amplicon sequence variants (ASVs) belonging to the phyla Actinobacteriota, Chloroflexota, Rhodothermota, and candidate phylum PAUC34f showed significant positive correlations with particular sponge antimicrobial activities, indicating these taxa as interesting targets for future bioprospecting endeavours.

This study highlights sponges from the Lembeh Strait, Indonesia, as producers of antimicrobial compounds and the importance of host identity on sponge-prokaryotic community composition. Moreover, poorly studied taxa such as candidate phylum PAUC34f and Chloroflexota members might represent interesting targets for future bioprospecting endeavours.