Comparative biochemistry and short-term starvation effects on the earthworms Eisenia veneta and Lumbricus terrestris studied by 1H NMR spectroscopy and pattern recognition

The aim of this work was to determine the applicability of high resolution 1H nuclear magnetic resonance (NMR) spectroscopic methods to the analysis of earthworm extracts, as a prelude to toxicity testing. This has been applied to the characterisation and examination of starvation effects on the endogenous metabolites of extracts of Eisenia veneta and Lumbricus terrestris in Ringer solution. Identified metabolites include free amino acids, sugars and low molecular weight organic acids. In both E. veneta and L. terrestris NMR signals from: alanine, arginine, asparagine, glutamate, glycine, isoleucine, leucine, phenylalanine, threonine, tryptophan, tyrosine, valine, glucose, citrate, fumarate, inosine, lactate, propanone, succinate and uridine were detected. The E. veneta extracts contained N-methyl-nicotinic and urocanic acids that were not detected in L. terrestris. Higher concentrations of inosine, lysine and malonic acid were also observed for E. veneta. In L. terrestris a higher amount of glucose was observed. The effect of short-term starvation on E. veneta showed small metabolic changes for the first 5 days, with clear differences at 6 and 7 days. These included increases in glutamate, citrate, aspartate and isoleucine, and decreases in lysine, isoleucine and threonine. In contrast L. terrestris showed no consistent endogenous low molecular weight metabolite changes as detected by 1H NMR spectroscopy over this period, suggesting this species to be more suitable for soil toxicity testing and monitoring using this procedure.