Microbial and biochemical characterization of a bacterial consortium isolated from decaying wood by growth on a β-O-4 lignin-related dimeric compound

As an approach to evaluate the contribution of bacteria to lignin degradation in wood, we have chosen to study these microorganisms in the natural wood decay ecosystem known as Palo Podrido. Initially, the characterization of bacteria able to metabolize lignin-related compounds present in samples of Palo Podrido was undertaken. For their isolation, minimal salt media containing lignin dimers of either the arylglycerol-β-aryl ether (β-O-4) or 1,2-diarylpropane (β-1) types as the only source of carbon and energy were inoculated with various wood samples exhibiting different degrees of decay. The β-1 dimers used failed to support bacterial growth. However, three bacterial consortia able to consume quantitatively the β-O-4 model 1-[3,4-dimethoxyphenyl]-2-[2-methoxyphenoxy]-3-hydroxypropanone (compound 1) were isolated. One of these was further characterized. It is composed of eight strains belonging to the families of Streptomycetaceae, Dermatophilaceae and Actinoplanaceae. HPLC and GC-MS analyses revealed that the consortium utilizes two pathways to degrade β-O-4 dimers, both involving direct cleavage of the ether linkage. The formation of a novel C6−C3 degradation intermediate is described. Some metabolic properties of each strain, as well as those of the intact consortium, are also reported.