Identification of diverse bacteria in decaying wood in nature

Bacteria have been shown to decompose lignin in vitro, but their lignin-decomposing activity in nature has not been demonstrated at the genera and species levels. The objectives of this study were to identify bacterial communities present in wood decayed by white-rot fungi, which play a potential role in lignin degradation, and to establish the functional profile of bacterial lignin degradation in wood using microbial community analyses. The bacterial flora of forest soil and decayed wood showed marked differences; in particular, Sphingomonas, Methylobacterium, and Acidibrevibacterium were more abundant in decayed wood than in forest soil. The abundance of sphingomonads, which have been shown to degrade the major skeleton of lignin in vitro, was higher in the decayed wood than in forest soil, suggesting that multiple bacteria may be involved in lignin degradation. Our study provides evidence that can help clarify the lignin degradation process of decayed wood in a natural forest.

已有研究证实细菌可在体外降解木质素，但目前尚未在属和物种水平上证明其在自然环境中的木质素降解活性。本研究旨在鉴定白腐真菌（white-rot fungi）腐朽木材中携带的细菌群落——此类群落可能在木质素降解过程中发挥潜在作用——并借助微生物群落分析手段，构建木材内细菌介导的木质素降解功能谱。森林土壤与腐朽木材中的细菌菌群存在显著差异；其中鞘氨醇单胞菌属（Sphingomonas）、甲基杆菌属（Methylobacterium）及酸短杆菌属（Acidibrevibacterium）在腐朽木材中的丰度显著高于森林土壤。此前已被证实可在体外降解木质素核心骨架的鞘氨醇单胞菌类群，在腐朽木材中的丰度仍显著高于森林土壤，这一结果暗示多种细菌或共同参与木质素降解过程。本研究提供的证据有助于阐明天然森林中腐朽木材的木质素降解过程。