Evidence for substantial acetate presence in cutaneous earthworm mucus

Purpose Earthworm mucus is a ubiquitous source of C and N for soil biochemical processes and likely fuels direct interactions with other soil organisms; however, its chemical composition is little known and was the research question addressed by this research. A method was developed for the collection of sufficient amounts of cutaneous mucus from highly isotopically labelled earthworms with the objective to analyse mucus chemically by state-of-the-art nuclear magnetic resonance (NMR) techniques. Materials and methods A clean sand method was developed to collect cutaneous mucus from highly 13 C, 15 N-labelled endogeic earthworms ( Allolobophora chlorotica ). Mucus was analysed by 1D and 2D NMR. Results and discussion NMR spectra showed a complex mixture dominated by carbohydrates with a high aliphatic/lipid content and relatively few resonances for protein/peptide material. A very large contribution from acetate was detected, likely in the form of acetylated carbohydrates. Conclusions The ample presence of acetate is noteworthy because acetate is an important component in soil carbon cycling and methanogenic pathways. Earthworm mucus may be involved in novel direct biochemical interactions with soil (and possibly also sediment) microorganisms and plant roots that have not been recognised before.