Molecular and trace metal signatures of pristine and anthropogenically altered mangrove sediments.

Mangroves contribute to long-term carbon sequestration and are considered as blue carbon ecosystems; however, they are facing increasing anthropogenic pressures, with trace metals emerging as an environmental concern. Despite their toxicological impacts, the mechanisms governing trace metal retention in mangrove sediments require further investigation, particularly their association with natural organic compounds. Here, we employed Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) to analyze a wide range of lipids in mangrove sediments from two pristine sites and one anthropogenically disturbed site collected in the Leizhou Peninsula (South China).

Differentiating estuarine dissolved organic matter composition by unsupervised and supervised machine learning.

Differentiating the composition of Dissolved Organic Matter (DOM) in estuaries is a major environmental concern, as the DOM characteristics are closely linked to biogeochemical and ecological considerations (e.g. water properties and trophic cycling).

New insights into the mechanism of phosphate release during particulate organic matter photodegradation based on optical and molecular signatures.

Phosphate release from particulate organic matter (POM) dominates phosphorus (P) cycling in aquatic ecosystems. However, the mechanisms underlying P release from POM remain poorly understood because of complex fractionation and analytical challenges. In this study, the release of dissolved inorganic phosphate (DIP) during POM photodegradation was assessed using excitation-emission matrix (EEM) fluorescence spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS).

Membrane lipid adaptation of soil isolates to temperature and pH.

3-hydroxy fatty acids (3-OH FAs) are characteristic components of the Gram-negative bacterial membrane, recently proposed as promising temperature and pH (paleo) proxies in soil. Nevertheless, to date, the relationships between the 3-OH FA distribution and temperature/pH are only based on empirical studies, with no ground truthing work at the microbial level. This work investigated the influence of growth temperature and pH on the lipid composition of three strains of soil Gram-negative bacteria belonging to the phylum.

Molecular acclimation of to halite brine inclusions.

Halophilic microorganisms have long been known to survive within the brine inclusions of salt crystals, as evidenced by the change in color for salt crystals containing pigmented halophiles. However, the molecular mechanisms allowing this survival has remained an open question for decades. While protocols for the surface sterilization of halite (NaCl) have enabled isolation of cells and DNA from within halite brine inclusions, "-omics" based approaches have faced two main technical challenges: (1) removal of all contaminating organic biomolecules (including proteins) from halite surfaces, and (2) performing selective biomolecule extractions directly from cells contained within halite brine inclusions with sufficient speed to avoid modifications in gene expression during extraction.

Improving the design and implementation of sediment fingerprinting studies: summary and outcomes of the TRACING 2021 Scientific School.

Purpose: Identifying best practices for sediment fingerprinting or tracing is important to allow the quantification of sediment contributions from catchment sources. Although sediment fingerprinting has been applied with reasonable success, the deployment of this method remains associated with many issues and limitations.

Methods: Seminars and debates were organised during a 4-day Thematic School in October 2021 to come up with concrete suggestions to improve the design and implementation of tracing methods.

Characterization of Functional Groups in Estuarine Dissolved Organic Matter by DNP-enhanced N and C Solid-State NMR.

Estuaries are key ecosystems with unique biodiversity and are of high economic importance. Along the estuaries, variations in environmental parameters, such as salinity and light penetration, can modify the characteristics of dissolved organic matter (DOM). Nevertheless, there is still limited information about the atomic-level transformations of DOM in this ecosystem.

Multiple stages of plant root calcification deciphered by chemical and micromorphological analyses.

Rhizoliths, that is, roots fossilized by secondary carbonates, have been known for ages and are increasingly used for paleoenvironmental reconstructions. However, knowledge about their formation mechanisms remains limited. This study reports the mineralogical and chemical characterization of rhizoliths at different stages of mineralization and fossilization in the Late Pleistocene loess-paleosol sequence of Nussloch (SW Germany).

Improved Isolation of SlaA and SlaB S-layer proteins in Sulfolobus acidocaldarius.

The Sulfolobus acidocaldarius S-layer is composed of two main proteins: SlaA, which forms the ordered structure of the S-layer matrix, and SlaB, which supports and anchors the S-layer into the tetraether lipid membrane. While SlaA has previously been purified by exploiting its thermotolerance and high resistance to detergents, SlaB has resisted isolation, particularly from the cell membrane. Removal of proteins other than those of the S-layer is especially difficult if large batch-scale culture volumes are unavailable.

Photochemical studies on bis-sulfide and -sulfone tethered polyenic derivatives.

This study focusses on the [2 + 2]-photocycloaddition of a symmetric polyenic system tethered by an aryl bis-sulfide or sulfone platform. Using direct irradiation or photosensitization, no expected ladderane product was isolated. In most cases, only tricyclic products including a single cyclobutane moiety were formed.

Disentangling interactions between microbial communities and roots in deep subsoil.

Soils, paleosols and terrestrial sediments serve as archives for studying climate change, and represent important terrestrial carbon pools. Archive functioning relies on the chronological integrity of the respective units. Incorporation of younger organic matter (OM) e.