Geoderma (Aug 2024)
Multi-kingdom characterization of living organisms by 13C CPMAS NMR spectroscopy reveals unique traits in bacteria, fungi, algae, and higher plants
Abstract
Determining the chemical quality of soil organic matter and decomposing organisms is critical for predicting carbon fluxes in ecosystems. However, the classical C/N and lignin/N ratios have been criticized for their capability in predicting ecosystem function including litter decay rate, nitrogen mineralization and soil aggregation. Therefore, with our work we aim to complement information on the chemical properties of primary producers and decomposers based on 13C NMR. Overall, 108 unique 13C NMR spectra were collected from higher plant tissues including leaf litter, fine roots, woody debris, as well as a range of microbes i.e. bacteria, fungi, and marine algae. Results showed clear discrimination between organisms belonging to different kingdoms, but with limited variability within bacteria, fungi, and microalgae. In detail, bacteria were found to be distinct not only from plant tissues but also from fungi, characterized by a high proportion of alkyl and carbonyl C types and a rather low relative abundance of O Alkyl C and di-O Alkyl C types. Among the fungi, we found clear separation between yeasts, which are more similar to bacteria, and filamentous species, which are rich in O Alkyl and di-O Alkyl C types. Microalgae are characterized by a high content of aliphatic, carboxylic and methoxyl C fractions. In the spectra of terrestrial plants, the O Alkyl C region, associated with sugars and cellulose, is more abundant compared to algae and bacteria. In addition, the aromatic carbon signal, which is mainly associated with lignin, is much higher for higher plants than in microorganisms. As for plant tissues, woody tissues are clearly different from leaves and fine roots, with grasses, sedges, and ferns being well distinguished from forbs, coniferous and deciduous trees. In summary, our study contains the largest freely available 13C NMR spectral library of bacteria, fungi, algae, and higher plant tissues. However, the data from higher plants are sufficient to cover different functional types, which is not yet possible for bacteria and fungi.
