The relatively new research discipline of Eco-Metabolomics is the application of metabolomics techniques to ecology with the aim to characterise biochemical interactions of organisms across different spatial and temporal scales. Metabolomics is an untargeted biochemical approach to measure many thousands of metabolites in different species, including plants and animals. Changes in metabolite concentrations can provide mechanistic evidence for biochemical processes that are relevant at ecological scales. These include physiological, phenotypic and morphological responses of plants and communities to environmental changes and also interactions with other organisms. Traditionally, research in biochemistry and ecology comes from two different directions and is performed at distinct spatiotemporal scales. Biochemical studies most often focus on intrinsic processes in individuals at physiological and cellular scales. Generally, they take a bottom-up approach scaling up cellular processes from spatiotemporally fine to coarser scales. Ecological studies usually focus on extrinsic processes acting upon organisms at population and community scales and typically study top-down and bottom-up processes in combination. Eco-Metabolomics is a transdisciplinary research discipline that links biochemistry and ecology and connects the distinct spatiotemporal scales. In this review, we focus on approaches to study chemical and biochemical interactions of plants at various ecological levels, mainly plant–organismal interactions, and discuss related examples from other domains. We present recent developments and highlight advancements in Eco-Metabolomics over the last decade from various angles. We further address the five key challenges: (1) complex experimental designs and large variation of metabolite profiles; (2) feature extraction; (3) metabolite identification; (4) statistical analyses; and (5) bioinformatics software tools and workflows. The presented solutions to these challenges will advance connecting the distinct spatiotemporal scales and bridging biochemistry and ecology.

The ring opening (co)polymerization of 3-ethyl-1,4-dioxane-2,5-dione (3-ethylglycolide, EtGly) and enantiopure lactide using benzyl alcohol as initiator and the organobase 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene as catalyst yielded polyesters with predictable lactide and EtGly content between 5 and 20 mol%, molar masses around 11 000 g mol⁻¹ and dispersities below 1.3. Due to the amorphous nature of the atactic poly(3-ethylglycolide) (PEtGly), dynamic scanning calorimetry revealed increasing glass transition and melting temperatures with an increasing lactide content of the statistical copolymers. Nanoparticles with a diameter of 160 nm and spherical shape were obtained from each polyester by applying the nanoprecipitation method, as confirmed by dynamic light scattering and scanning electron microscopy investigation. The constant hydrophilic to hydrophobic balance (HHB) of PLA and PEtGly was confirmed by fluorescence spectroscopy using pyrene loaded nanoparticles, confirming that a set of materials was obtained suitable to enlighten the effect of crystallinity on nanoparticle degradation.

Low-molecular-weight natural products from microbes are indispensable in the development of potent drugs. However, their biological roles within an ecological context often remain elusive. Here, we shed light on natural products from eukaryotic microorganisms that have the ability to transition from single cells to multicellular organisms: the social amoebae. These eukaryotes harbor a large number of polyketide biosynthetic genes in their genomes, yet virtually none of the corresponding products can be isolated or characterized. Using complementary molecular biology approaches, including CRISPR-Cas9, we generated polyketide synthase ( pks5 ) inactivation and overproduction strains of the social amoeba Dictyostelium discoideum . Differential, untargeted metabolomics of wild-type versus mutant fruiting bodies allowed us to pinpoint candidate metabolites derived from the amoebal PKS5. Extrachromosomal expression of the respective gene led to the identification of a yellow polyunsaturated fatty acid. Analysis of the temporospatial production pattern of this compound in conjunction with detailed bioactivity studies revealed the polyketide to be a spore germination suppressor.

N‐acyl homoserine lactones (AHLs) are molecules produced by many Gram‐negative bacteria as mediators of cell‐cell signaling in a mechanism known as quorum sensing (QS). QS is widespread in marine bacteria regulating diverse processes, such as virulence or excretion of polymers that mediate biofilm formation. Associated eukaryotes, such as microalgae, respond to these cues as well, leading to an intricate signaling network. To date, only very few studies attempted to measure AHL concentrations in phototrophic microbial communities, which are hot spots for bacteria‐bacteria as well as microalgae‐bacteria interactions. AHL quantification in environmental samples is challenging and requires a robust and reproducible sampling strategy. However, knowing about AHL concentrations opens up multiple perspectives from answering fundamental ecological questions to deriving guidelines for manipulation and control of biofilms. Here, we present a method for sampling and AHL identification and quantification from marine intertidal sediments. The use of contact cores for sediment sampling ensures reproducible sample surface area and volume at each location. Flash‐freezing of the samples with liquid nitrogen prevents enzymatic AHL degradation between sampling and extraction. After solvent extraction, samples were analyzed with an ultra‐high performance liquid chromatography‐high resolution mass spectrometry (UHPLC‐HRMS) method that allows to baseline‐separate 16 different AHLs in less than 10 min. The sensitivity of the method is sufficient for detection and quantification of AHLs in environmental samples of less than 16 cm³.

Itaconic acid and its derivatives can be obtained from renewable feedstocks. However, there are only very limited applications of polymers containing itaconic acid so far. One limitation of the application of this polymer is that commonly utilized polymerization techniques lead to very low conversions of the corresponding monomers. Consequently, itaconic acid and its derivatives are generally considered difficult or poorly polymerizable monomers. The current study presents the improvement of the polymerization by applying an emulsion polymerization of itaconic acid esters, leading to very high monomer conversions with a residual monomer content of less than 1%.

Three strains of the Aspergillus versicolor complex were isolated from a salty marsh at a former uranium mining site in Thuringia, Germany. The strains from a metal-rich environment were not only highly salt tolerant (up to 20% NaCl), but at the same time could sustain elevated Cs and Sr (both up to 100 mM) concentrations as well as other (heavy) metals present in the environment. During growth experiments when screening for differential cell morphology, the occurrence of guttation droplets was observed, specifically when elevated Sr concentrations of 25 mM were present in the media. To analyze the potential of metal tolerance being promoted by these excretions, proteomics and metabolomics of guttation droplets were performed. Indeed, proteins involved in up-regulated metabolic activities as well as in stress responses were identified. The metabolome verified the presence of amino sugars, glucose homeostasis-regulating substances, abscisic acid and bioactive alkaloids, flavones and quinones.