Six pure strains of obligate anaerobes capable of degrading the toxin beta-N-oxalyl-L-alpha, beta-diaminopropionic acid (beta-ODAP) contained in grass pea (Lathyrus sativus) have been isolated from cow rumen. The new isolates were identified as Megasphaera elsdenii (five different genotypes) and Clostridium bifermentans using 16S rDNA analysis. The beta-ODAP degrading efficiency of the isolates was evaluated by measuring the amount of beta-ODAP in the growth medium, which contained beta-ODAP as the only carbon source, before and after incubation with the microbes. The method of analysis was liquid chromatography employing bioelectrochemical detection. The biosensor is based on coimmobilising two enzymes, glutamate oxidase (GlOx) and horseradish peroxidase (HRP), on the end of a spectrographic graphite electrode. beta-ODAP is oxidised by GlOx to form H2O2, which in turn is bioelectrocatalytically reduced by HRP through a mediated reaction using a polymeric mediator incorporating Os2+/3+ functionalities rapidly shuttling electrons with the electrode-giving rise to the analytical signal. On the basis of this analysis system, the new isolates are capable of utilising beta-ODAP as sole carbon source to a maximum of 90-95% within 5 days with concomitant increase in cell protein. (c) 2005 Society of Chemical Industry.