Abstract
To investigate the biodegradation of lignin with high molecular weight (HMW) in sulfate reducing conditions, changes in the HMW lignin concentration and chemical structure were analyzed in the presence of a cellulose cosubstrate with a continuously-operated mesophilic reactor. Acid-precipitable polymeric lignin (APPL) and lignin monomers, which are known as degradation byproducts, were isolated and detected. The results showed that HMW lignin was degraded with a maximum degradation capacity of 3.49mg/L/day. APPL was confirmed to be a polymeric degradation byproduct and accumulated along with HMW lignin reduction. We also identified the nonlinear accumulation of aromatic lignin monomers such as hydrocinnamic acid. Through our experimental results, we observed that HMW lignin biodegrades into APPL and aromatic monomers in anaerobic sulfate reducing conditions with a cosubstrate of cellulose.
