Antimicrobial Potential of Bacteria Associated with Marine Sea Slugs from North Sulawesi, Indonesia

Abstract

Nudibranchia, marine soft-bodied organisms, developed, due to the absence of a protective shell, different strategies to protect themselves against putative predators and fouling organisms. One strategy is to use chemical weapons to distract predators, as well as pathogenic microorganisms. Hence, these gastropods take advantage of the incorporation of chemical molecules. Thereby the original source of these natural products varies; it might be the food source, de novo synthesis from the sea slug, or biosynthesis by associated bacteria. These bioactive molecules applied by the slugs can become important drug leads for future medicinal drugs. To test the potential of the associated bacteria, the latter were isolated from their hosts, brought into culture and extracts were prepared and tested for antimicrobial activities. From 49 isolated bacterial strains 35 showed antibiotic activity. The most promising extracts were chosen for further testing against relevant pathogens. In that way three strains showing activity against methicillin resistant Staphylococcus aureus and one strain with activity against enterohemorrhagic Escherichia coli, respectively, were identified. The obtained results indicate that the sea slug associated microbiome is a promising source for bacterial strains, which hold the potential for the biotechnological production of antibiotics.

Antibacterial potential of nudibranch-associated bacteria from Saparua and Nusa Laut Islands, Indonesia

“…In this study, only seven (4.83%) bacterial crude extracts showed antibacterial activity against MDR bacteria. This number was lower than a previous study by Böhringer et al (2017). However, Riyanti et al (2009) specifically looked at the ability of nudibranch-associated bacteria to combat MDR bacteria as opposed to Böhringer et al (2017) who targeted non-MDR bacteria.…”

“…This number was lower than a previous study by Böhringer et al (2017). However, Riyanti et al (2009) specifically looked at the ability of nudibranch-associated bacteria to combat MDR bacteria as opposed to Böhringer et al (2017) who targeted non-MDR bacteria. Finally, Sibero et al (2019b) proved that both intra-and extracellular metabolites from marine microorganisms performed antibacterial activity against MDR bacteria.…”

“…As depicted in Table 2, 11 prospective isolates showed antibacterial activity. A previous study of Böhringer et al (2017) also proved that nudibranch-associated bacteria in Indonesia are active in the production of antibacterial compounds.…”

“…Meanwhile, the isolates that were active against one pathogen were SM-N-19-12, SM-S-17-9, SM-N-10-23, SM-N-14-13; SM-N-10-2, and SM-N-3-77 (see Table 3). The antibacterial property of nudibranch-associated bacterial crude extract has been investigated by Böhringer et al (2017). They reported that among 49 isolated bacterial strains, 35 isolates (71.42%) showed antibiotic activity.…”

“…and Chromodoris sp. Moreover, Böhringer et al (2017) studied the diversity of nudibranchassociated bacteria from North Sulawesi, Indonesia and the potential of the bacterial isolates as a source of antimicrobial substances which resulted in 35 of 49 isolates with antimicrobial activity dominated by the genus Pseudoalteromonas and Vibrio. Our report aims to isolate the nudibranch-associated bacteria with antibacterial potential against MDR bacteria.…”