Anaerobic biodegradation of eleven aromatic compounds to methane.

A range of 11 simple aromatic lignin derivatives are biodegradable to methane and carbon dioxide under strict anaerobic conditions. A serum-bottle modification of the Hungate technique for growing anaerobes was used for methanogenic enrichments on vanillin, vanillic acid, ferulic acid, cinnamic acid, benzoic acid, catechol, protocatechuic acid, phenol, p-hydroxybenzoic acid, syringic acid, and syringaldehyde. Microbial populations acclimated to a particular aromatic substrate can be simultaneously acclimated to other selected aromatic substrates. Carbon balance measurements made on vanillic and ferulic acids indicate that the aromatic ring was cleaved and that the amount of methane produced from these substrates closely agrees with calculated stoichiometric values. These data suggest that more than half of the organic carbon of these aromatic compounds potentially can be converted to methane gas and that this type of methanogenic conversion of simple aromatics may not be uncommon.