Insights into the Metabolome of the Cyanobacterium Leibleinia gracilis from the Lagoon of Tahiti and First Inspection of Its Variability

Hiren Solanki,Olivier P Thomas,Mayalen Zubia,Manon Pierdet

doi:10.3390/metabo10050215

Hiren Solanki, Olivier P Thomas + Show 2 more

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https://doi.org/10.3390/metabo10050215

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Abstract

Cyanobacteria are known to produce a large diversity of specialized metabolites that can cause severe (eco)toxicological effects. In the lagoon of Tahiti, the benthic cyanobacterium Leibleinia gracilis is commonly found overgrowing the proliferative macroalga Turbinaria ornata or dead branching corals. The specialized metabolome of the cyanobacterium L. gracilis was therefore investigated together with its variability on both substrates and changes in environmental parameters. For the study of the metabolome variability, replicates of L. gracilis were collected in the same location of the lagoon of Tahiti before and after a raining event, both on dead corals and on T. ornata. The variability in the metabolome was inferred from a comparative non-targeted metabolomic using high resolution mass spectrometry (MS) data and a molecular network analysis built through MS/MS analyses. Oxidized fatty acid derivatives including the unusual 11-oxopalmitelaidic acid were found as major constituents of the specialized metabolome of this species. Significant variations in the metabolome of the cyanobacteria were observed, being more important with a change in environmental factors. Erucamide was found to be the main chemical marker highly present when the cyanobacterium grows on the macroalga. This study highlights the importance of combined approaches in metabolomics and molecular networks to inspect the variability in the metabolome of cyanobacteria with applications for ecological questions.

Highlights

Cyanobacteria represent old and essential constituents of aquatic ecosystems, where they play key ecological roles as primary producers [1], fixing carbon and nitrogen, and serve as a support for numerous planktonic and benthic heterotrophs [2]
The present study focuses on the less studied cyanobacterium Leibleinia gracilis (Rabenhorst ex Gomont) Anagnostidis and Komáerek, formerly known as Lyngbya gracilis Rabenhorst ex Gomont and Phormidium gracile (Rabenhorst ex Gomont) Anagnostidis, which are largely distributed in the lagoon of Tahiti
A desalting fractionation process was performed reversed phase vacuum liquid chromatography using a gradient elution of H2 O, MeOH, and by reversed phase vacuum liquid chromatography using a gradient elution of H2O, MeOH, and

Summary

Introduction

Cyanobacteria represent old and essential constituents of aquatic ecosystems, where they play key ecological roles as primary producers [1], fixing carbon (oxyphototrophy) and nitrogen (diazotrophy), and serve as a support for numerous planktonic and benthic heterotrophs [2]. In coral reefs of the Pacific Ocean, and under normal oligotrophic conditions, some cyanobacterial populations are observed on dispersed lifeless or living substrates, forming colonies and local benthic blooms. Larger blooms of benthic cyanobacteria have occurred with increasing frequency in coral reefs and tropical lagoons, probably in response to natural and man-made environmental disturbances [3,4]. Blooms of cyanobacteria have been shown to impair coral recruitment [5,6], and some cyanobacteria of the genera Geitlerinema, Leptolyngbya, Phormidium, and Pseudoscillatoria were identified as pathogens in coral “Black Band Disease” [7,8,9]. Some negative impacts of blooms of cyanobacteria have been related to the production of bioactive metabolites. Species of the genera Lyngbya or Moorea were for instance identified as outstanding

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