Applied Microbiology and Biotechnology, Vol.104, No.8, 3305-3320, 2020
Functional genomic analysis of bacterial lignin degraders: diversity in mechanisms of lignin oxidation and metabolism
Although several bacterial lignin-oxidising enzymes have been discovered in recent years, it is not yet clear whether different lignin-degrading bacteria use similar mechanisms for lignin oxidation and degradation of lignin fragments. Genome sequences of 13 bacterial lignin-oxidising bacteria, including new genome sequences for Microbacterium phyllosphaerae and Agrobacterium sp., were analysed for the presence of lignin-oxidising enzymes and aromatic degradation gene clusters that could be used to metabolise the products of lignin degradation. Ten bacterial genomes contain DyP-type peroxidases, and ten bacterial strains contain putative multi-copper oxidases (MCOs), both known to have activity for lignin oxidation. Only one strain lacks both MCOs and DyP-type peroxidase genes. Eleven bacterial genomes contain aromatic degradation gene clusters, of which ten contain the central beta-ketoadipate pathway, with variable numbers and types of degradation clusters for other aromatic substrates. Hence, there appear to be diverse metabolic strategies used for lignin oxidation in bacteria, while the beta-ketoadipate pathway appears to be the most common route for aromatic metabolism in lignin-degrading bacteria.
Keywords:Bacterial lignin degradation;Genome sequences;Aromatic degradation pathways;DyP-type peroxidase;Multi-copper oxidase