Exploring the chemodiversity of tropical microalgae for the discovery of natural antifouling compounds

Abstract

Marine microalgae and cyanobacteria have largely been studied for their biotechnological potential and proved their ability to produce a wide array of bioactive molecules. We investigated the antifouling potential of unexplored benthic tropical microalgae using anti-adhesion and toxicity bioassays against two major micro-and ma crobiofoulers, namely bacteria and barnacles. Fifty strains belonging to six phyla [Cyanobacteria, Miozoa (Dinoflagellata), Bacillariophyta, Cryptophyta, Rhodophyta and Haptophyta] were isolated from southwestern Islands of the Indian Ocean. They were chosen in order to represent as much as possible the huge biodiversity of such a rich tropical ecosystem. The associated chemodiversity was highlighted by both NMR-and LC-MS-based metabolomics. The screening of 84 algal fractions revealed that the anti-adhesion activity was concentrated in methanolic ones (i.e. 93% of all active fractions). Our results confirmed that microalgae constitute a promising source of natural antimicrofoulants as 17 out of the 30 active fractions showed high or very high capacity to inhibit the adhesion of three biofilm-forming marine bacteria. Dinoflagellate-derived fractions were the most active, both in terms of number and intensity. However, dinoflagellates were also more toxic and may not be suitable as a source of environmentally friendly antifouling compounds, in contrast to diatoms, e.g. Navicula mollis. The latter and two dinoflagellates of the genus Amphidinium also had interesting antisettlement activities while being moderately toxic to barnacle larvae. Our approach, combining the bioprospecting of a large number of tropical microalgae for their anti-settlement potential and metabolomics analyses, constituted a first step towards the discovery of alternative ecofriendly antifoulants.

Assessment of the Chemical Diversity and Potential Toxicity of Benthic Cyanobacterial Blooms in the Lagoon of Moorea Island (French Polynesia)

“…[3] in freshwater environments, produce toxins that can cause potential health issues. These previous findings thus encourage the implementation of an ad hoc surveillance of the toxicity of these three bloom-forming species in Moorea Island and more globally in French Polynesia, using, for instance, a non-targeted metabolomic approach [68,69] and/or other cytotoxicity-based functional assays [70].…”

Metabolic Analysis of Schizochytrium Mutants With High DHA Content Achieved With ARTP Mutagenesis Combined With Iodoacetic Acid and Dehydroepiandrosterone Screening

“…Among these technologies, the coupling of liquid chromatography to mass spectrometry (LC-MS) has gradually become an important tool to quantitative analysis of central carbon metabolites since its high throughput, good metabolites coverage and soft ionization ( Zhou et al, 2012 ). The LC-MS has been recently applied to many marine microorganisms, including explaining chemodiversity of a rich marine microorganism tropical ecosystem ( Reveillon et al, 2019 ), identifying hub metabolites relevant to resist Fe 2+ and high light stress condition in Haematococcus pluvialis ( Su et al, 2014 ), and exploring possible mechanisms of elevating fatty acid contents after overexpressing EL O3 gene in Schizochytrium sp . 31 ( Wang et al, 2019 ).…”

Anti-Bacterial Adhesion Activity of Tropical Microalgae Extracts

“…Four fractions were obtained and only the methanolic fraction was studied. Previous study has shown that methanolic fractions were the most active among the screening carried out [ 63 ]. The extraction yield was defined as the amount of methanolic fraction divided by the amount of dried algal biomass.…”