ABSTRACT
Environmental metabolomics is a developing topic that provides global information about free-living organisms since it is reflecting the changes in phenotype and therefore accounts for the influence of external factors. This methodology has an especial interest in the marine environment where many variables affect the organisms, both extreme natural factors such as salinity, temperature, or food restriction and anthropogenic factors, mainly metal contamination, organic compounds, pesticides, drugs, and nanoparticles. Most conventional metabolomic methods are based on the use of 1 HNMR, but it slow sensitivity has triggered the development and implementation of procedures based on mass spectrometry, which allows fingerprinting or profiling of metabolites altered by the exogenous factors. Instrumental couplings based on HPLC- and GC-MS have been proposed in the metabolomics approach, although direct infusion of the sample in high resolution mass spectrometers also provides valuable feasibility and high throughput analysis. Other critical aspects in the metabolomics workflow are suitable extraction of metabolites to get a complete coverage of them and statistic treatment of a result. One important point is related to the overriding role of metals in the metabolism and wellbeing of living organisms whose fluxes and homeostasis have to be maintaining, which generates a host of metal-containing molecules and opens the door to possible interactions and competitions between metals, particularly toxic metals, whose characterization is fundamental to understanding the changes and evolution of metabolic cycles. Therefore, metabolomic techniques for metal-containing metabolites (Metallomics) are also included in most of the recent approaches in this field, incorporating atomic mass spectrometry to the work scheme. In addition, the complementary application of environmental metabolomics with other omics, such as transcriptomics and proteomics has also been proposed. Metabolomics has been applied to marine organisms, ranging from microbes to marine mammals, although most of the studies have been focused on bivalves and crustaceans, since application of metabolomics to big organisms such as Pinnipeds and cetaceans is still very limited.
