Pseudomonas putida, isolated from decomposing plant materials, degraded several lignin-related aromatic compounds. After 30 days of incubation in media containing polymeric Kraft-lignin (PKL), the amount of Klason lignin had decreased by about 13%. When (14)C-labelled dehydropolymers of coniferyl alcohol (DHP) lignins and (14)C-lignin-lignocelluloses were used as substrates, mineralization to (14)CO2 by the P. putida strain ranged from 1.4% to 2.1%.