Biodegradation of lignin monomers and dimers by bacteria

Abstract

In natural soil, many species of bacteria are actively involved in the degradation of lignin, a complex biomolecular matrix that makes up a portion of plant cell walls. This activity is of great interest to researchers in the biofuel industry who are attempting to unlock the secret to a biologically-derived biofuel, in which no costly chemical processes are necessary in order to produce biofuels like ethanol. However, the natural degradation of lignin is a complicated process that has not yet been efficiently executed in a controlled setting. In this study, I attempted to better understand the ability of three bacterial strains, Pseudomonas sp. strain YS-1p, Alcaligenes sp. strain -3K, and Arthrobacter sp. strain RT-1, to degrade lignin-derived monomers (ferulic acid and p-hydroxy-transcinnamic acid) and a dimer (benzyl-phenyl ether). Cultures were prepared with mineral salts medium and lignin-compounds as the sole carbon source and lignin degradation was monitored indirectly by measuring growth in CFU/mls. Experimental results indicated that both monomers inhibit growth of strain YS-1p and drastically reduce growth of strain 3K. On the other hand, strain RT-1 grew well with benzyl-phenyl ether as a carbon source. Further research with these bacteria on different lignin-derived aromatic compounds could shed more light on their possible roles in lignin degradation.