Metabolomic variability of four macroalgal species of the genus Lobophora using diverse approaches

Abstract

Among comparative metabolomic studies used in marine sciences, only few of them are dedicated to macroalgae despite their ecological importance in marine ecosystems. Therefore, experimental data are needed to assess the scopes and limitations of different metabolomic techniques applied to macroalgal models. Species of the genus Lobophora belong to marine brown algae (Family: Dictyotaceae) and are widely distributed, especially in tropical coral reefs. The species richness of this genus has only been unveiled recently and it includes species of diverse morphologies and habitats, with some species interacting with corals. This study aims to assess the potential of different metabolomic fingerprinting approaches in the discrimination of four well known Lobophora species (L. rosacea, L. sonderii, L. obscura and L. monticola). These species present distinct morphologies and are found in various habitats in the New Caledonian lagoon (South-Western Pacific).We compared and combined different untargeted metabolomic techniques: liquid chromatography-mass spectrometry (LC-MS), nuclear magnetic resonance (1 H-NMR) and gas chromatography (GC-MS). Metabolomic separations were observed between each Lobophora species, with significant differences according to the techniques used. LC-MS was the best approach for metabotype distinction but a combination of approaches was also useful and allowed identification of chemomarkers for some species. These comparisons provide important data on the use of metabolomic approaches in the Lobophora genus and will pave the way for further studies on the sources of metabolomic variations for this ecologically important macroalgae.

Impact of ocean acidification on the metabolome of the brown macroalgae Lobophora rosacea from New Caledonia

“…For marine organisms, and especially non-model organisms, metabolite annotation is often limited by a lack of standards (e.g. Gaubert et al, 2019b, 2019a, Greff et al, 2017b, 2017aSogin et al, 2016). This issue is one of the greatest challenges in untargeted metabolomic studies (Kumar et al, 2016).…”

“…The populations of L. rosacea growing at this site are assumed to have been exposed to acidified levels over the long-term (probably even for several generations). Because no L. rosacea was found in the other prospected mangrove areas presenting a normal pH, the site of Ricaudy (well studied for this species (Gaubert et al, 2019b(Gaubert et al, , 2019a was selected as our control site. It is a fringing coral reef flat where the seawater pH T is 7.99 ± 0.03 (pH T = pH in total scale), which is considered as within the normal pH range for shallow coastal reef flats in New Caledonia.…”

“…Samples collected from the natural analogue of Bouraké and the control site (16 samples hereafter referred to as "in situ samples") and during the ex situ experiment (53 samples, hereafter referred to as "ex situ samples") were freeze-dried and ground using liquid nitrogen. Metabolite extraction was done according to previous work on this alga (Gaubert et al, 2019b(Gaubert et al, , 2019a. For each sample, 250 mg of the powder was extracted three times using 5 mL of MeOH/CH 2 Cl 2 (1:1) during 5 min in an ultrasonic bath.…”

“…The algal metabolome referred then to the MeOH extracts through the text, which contain a majority of secondary metabolites, including allelopathic compounds (e.g. Gaubert et al, 2019a).…”

Macroalgal diversity for sustainable biotechnological development in French tropical overseas territories

“…The terpenoids isolated from the Dictyotaceae exhibit various types of bioactivity, such as feeding deterrence, anti-fungal, cytotoxic, antibiotic, anti-inflammatory, insecticidal or anti-viral activities (Vieira et al 2017). However, in the study by Gaubert et al (2019), no terpene derivatives were identified in the metabolome of the four species of Lobophora studied from New Caledonia. This observation could lead to interesting chemo-taxonomic considerations for this group and the search for terpene synthases in a larger set of Dictyotales.…”