A Multi-Bioassay Integrated Approach to Assess the Antifouling Potential of the Cyanobacterial Metabolites Portoamides

Abstract

The cyclic peptides portoamides produced by the cyanobacterium Phormidium sp. LEGE 05292 were previously isolated and their ability to condition microcommunities by allelopathic effect was described. These interesting bioactive properties are, however, still underexplored as their biotechnological applications may be vast. This study aims to investigate the antifouling potential of portoamides, given that a challenge in the search for new environmentally friendly antifouling products is to find non-toxic natural alternatives with the ability to prevent colonization of different biofouling species, from bacteria to macroinvertebrates. A multi-bioassay approach was applied to assess portoamides antifouling properties, marine ecotoxicity and molecular mode of action. Results showed high effectiveness in the prevention of mussel larvae settlement (EC50 = 3.16 µM), and also bioactivity towards growth and biofilm disruption of marine biofouling bacterial strains, while not showing toxicity towards both target and non-target species. Antifouling molecular targets in mussel larvae include energy metabolism modifications (failure in proton-transporting ATPases activity), structural alterations of the gills and protein and gene regulatory mechanisms. Overall, portoamides reveal a broad-spectrum bioactivity towards diverse biofouling species, including a non-toxic and reversible effect towards mussel larvae, showing potential to be incorporated as an active ingredient in antifouling coatings.

Environmentally Friendly Antifouling Metabolites from Red Sea Organisms

“…S. trocheliophorum (SH-13) was fractionated and led to isolation of trocheliane (7), sarcotrocheldiol A (8) and sarcotrocheldiol B (9), deoxosarcophine (10), sarcotrocheliol (11), and sarcotrocheliol acetate (12) (Figure 3). All isolated compounds (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) [30][31][32][33][34][35][36][37] have been evaluated for their antifouling activities, and the results are shown in Figure 4.…”

“…Biofouling occurs due to the adhesion of barnacles, microbial slimes, and macroalgae on wetted marine surfaces [1][2][3]. ese organisms produce adhesive organic materials which enhance the ability of microorganisms (microalgae, protozoa, and bacteria) to settle on the marine surfaces [4][5][6].…”

Cyanobacteria and Eukaryotic Microalgae as Emerging Sources of Antibacterial Peptides

“…All of them are cyclic peptides. Concerning the Nostocales order, the Nostoc genus stands out, with a variety of cyclic and linear antibacterial peptides; Anabaena and Scytonema genera produced depsipeptides and lipopeptides, respectively [ 88 , 94 , 125 , 128 , 129 , 130 , 131 , 132 ].…”

“…The cyclic peptides portoamides produced by Phormidium sp. display this activity against marine bacteria such as Cobetia marina , Halomonas aquamarina and Pseudoalteromonas atlantica , by inhibition of ATPase H + -transport activity [ 132 ]. This activity has a straightforward application as antifouling agents, and their test as antibiofilm compounds for relevant clinical bacteria is pending.…”

“…Portoamides are cyclic dodecapeptides from the cyanobacterium Phormidium sp. They were used for their antifouling activity with an EC 50 of 3.16 µM against the settlement of the larvae of the mussel Mytilus galloprovincialis [ 132 ]. Portoamides were nontoxic against the mussel larvae, therefore a deterrent effect towards surface colonization was instead proposed.…”