Liquid chromatographic–mass spectrometric—analyses of anaerobe protein degradation products

A liquid chromatography–electrospray ionisation-mass spectrometry (LC–ESI-MS) method and a liquid chromatography–atmospheric pressure chemical ionisation-mass spectrometry (LC–APCI-MS) method was developed to identify metabolites from the anaerobe protein degradation to biogas. As consequence of a process failure the biogas production breaks down with increasing substrate loading, whereas different metabolites accumulate in the fermentation media. These compounds were identified as metabolites from the anaerobe degradation of the aromatic amino acids phenylalanine, tyrosine and tryptophan and accumulate in concentrations up to 300 mg/L when casein was used as model substrate.