Diversity and functionality of wood-tar degrading microbial consortia

Wood-tar is an unwanted by-product produced during wood pyrolysis, and comprises several dangerous polycyclic aromatic hydrocarbons (PAH). Up to know the biodegradation of tar is very difficult due to its toxicity and to the very complex chemistry. Microbial Resource Management concerns the use of environmental microbial communities potentially able to provide us services. We applied this concept in tar biodegradation. Tar was obtained by a wood pyrolysis plant. Chemical analyses showed a high concentration of several PAH including naphthalene, phenantrene and pyrene. The biodegradation process was done in microcosms amended with ??% tar and of a microbial community collected from PAH-rich soils. In 20 days, tar concentration was reduced to less than 1%. The dynamics of fungal and bacterial communities had been studied through Automated Ribosomal Intergenic Spacer Analysis (ARISA), 454 pyrosequencing of the fungal ITS and of the bacterial 16S rRNA, and quantitative Real Time PCR of the 16S rRNA genes and of the Cathecol 2,3-dioxygenase genes. Results showed the importance of fungal tar-degrading population in the first day of incubation, followed by a complex bacterial dynamical growth ruled by a cross-feeding behavior.