Diversity and functionality of wood-tar degrading microbial consortia. Dinamics of wood-tar biodegradation

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.

木焦油是木材热解过程中产生的有害副产物，含有多种危险的多环芳烃（Polycyclic Aromatic Hydrocarbons, PAH）。迄今为止，由于其毒性与极为复杂的化学组成，焦油的生物降解难度极大。微生物资源管理（Microbial Resource Management）指利用具备潜在服务能力的环境微生物群落，我们将这一理念应用于焦油生物降解研究中。焦油取自某木材热解工厂，化学分析显示其含有高浓度的多种多环芳烃，包括萘（naphthalene）、菲（phenanthrene）与芘（pyrene）。本研究通过添加??%焦油的微宇宙培养体系（microcosms），接种从富含多环芳烃的土壤中采集的微生物群落开展降解实验。在20天的培养周期内，焦油浓度降至1%以下。研究通过自动化核糖体基因间区间隔分析（Automated Ribosomal Intergenic Spacer Analysis, ARISA）、真菌ITS区域与细菌16S rRNA的454焦磷酸测序（454 pyrosequencing），以及16S rRNA基因与儿茶酚2,3-双加氧酶（Catechol 2,3-dioxygenase）基因的实时定量PCR（quantitative Real Time PCR），对真菌与细菌群落的动态变化进行了分析。结果表明，在培养初期，降解焦油的真菌菌群发挥了关键作用；随后，以交叉营养行为调控的复杂细菌动态生长成为群落演替的主导因素。