LABEM-Laboratory of Biotechnology and Microbial Ecology-Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, 21941-902, Brazil.
LEMM-Laboratory of Microbial Molecular Ecology-Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, 21941-902, Brazil.
Microb Ecol. 2018 Jan;75(1):183-191. doi: 10.1007/s00248-017-1014-y. Epub 2017 Jun 21.
Eucalyptus plantations offer a cost-effective and renewable source of raw material. There is substantial interest in improving forestry production, especially through sustainable strategies such as the use of plant growth-promoting bacteria. However, little is known about Eucalyptus microbiology. In this study, the endophytic bacterial community was assessed in Eucalyptus urograndis roots using culture-dependent and culture-independent techniques with plants grown under different conditions. Three phyla accounted for approximately 95% of the community, with Actinobacteria corresponding to approximately 59%. This contrasts with previous studies in which Actinobacteria accounted for only 5 to 10%. Our data also revealed a high diversity of bacteria, with 359 different genera but a high level of dominance. Six genera, Mycobacterium, Bradyrhizobium, Streptomyces, Bacillus, Actinospica, and Burkholderia, accounted for more than 50% of the classified sequences. We observed a significant influence of the treatments on some genera, causing changes in the bacterial community structure. The obtained data also suggest that Eucalyptus may benefit from biological nitrogen fixation, with many abundant genera being closely related to nitrogen-fixing bacteria. Using N-depleted media, we also cultured 95 bacterial isolates, of which 24 tested positive for the nifH gene and were able to maintain growth without any N source in the medium.
桉树种植园提供了一种具有成本效益和可再生的原材料来源。人们对提高林业生产力有着浓厚的兴趣，特别是通过使用植物生长促进细菌等可持续策略。然而，人们对桉树微生物学知之甚少。在这项研究中，使用依赖培养和非依赖培养的技术，评估了不同条件下生长的尾叶桉根内的内生细菌群落。三个门约占群落的 95%，其中放线菌约占 59%。这与以前的研究形成对比，以前的研究中放线菌仅占 5%至 10%。我们的数据还显示了细菌的高度多样性，有 359 个不同的属，但优势度很高。六个属，分枝杆菌属、慢生根瘤菌属、链霉菌属、芽孢杆菌属、放线螺旋菌属和伯克霍尔德氏菌属，占分类序列的 50%以上。我们观察到处理对一些属有显著影响，导致细菌群落结构发生变化。获得的数据还表明，桉树可能受益于生物固氮，许多丰富的属与固氮细菌密切相关。使用缺氮培养基，我们还培养了 95 个细菌分离株，其中 24 个分离株的 nifH 基因呈阳性，并且能够在培养基中没有任何氮源的情况下维持生长。
