Microbial Decomposition of Synthetic 14 C-Labeled Lignins in Nature: Lignin Biodegradation in a Variety of Natural Materials

Abstract

Lignin biodegradation in a variety of natural materials was examined using specifically labeled synthetic 14 C-lignins. Natural materials included soils, sediments, silage, steer bedding, and rumen contents. Both aerobic and anaerobic incubations were used. No 14 C-labeled lignin biodegradation to labeled gaseous products under anaerobic conditions was observed. Aerobic 14 C-labeled lignin mineralization varied with respect to type of natural material used, site, soil type and horizon, and temperature. The greatest observed degradation occurred in a soil from Yellowstone National Park and amounted to over 42% conversion of total radioactivity to 14 CO 2 during 78 days of incubation. Amounts of 14 C-labeled lignin mineralization in Wisconsin soils and sediments were significantly correlated with organic carbon, organic nitrogen, nitrate nitrogen, exchangeable calcium, and exchangeable potassium.