Investigations of the structure and function of bacterial communities associated with Sphagnum mosses
Investigations of the structure and function of bacterial communities associated with Sphagnum mosses
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DOI：
10.1111/j.1462-2920.2007.01391.x
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发表时间：
2007-11-01
影响因子：
5.1
通讯作者：
Berg, Gabriele
中科院分区：
文献类型：
--
作者：
Opelt, Katja;Chobot, Vladimir;Berg, Gabriele
高酸度、低温和极低浓度的营养物质使泥沼成为生物的极端栖息地。人们对与活的泥鳅苗相关的细菌知之甚少，尤其是它们对寄主的作用。因此，我们采用多相方法分析了与两个广泛分布的Sphagnum magellanicum和Sphagnum fallax相关的内生和外生细菌种群。对1222株菌株进行拮抗活性筛选，筛选出326株活性菌株。细菌群落中抗真菌菌株的比例较高（26%），而抗菌菌株的比例较低（0.4%）。伯克霍尔德菌属成员（38%）被发现是最占优势的拮抗菌群。大部分（89%）拮抗细菌产生抗真菌化合物的发现可能为某些Sphagnum物种众所周知的抗菌活性提供了解释。采用高效液相色谱- pda分析了藻属植物自身的次生代谢物。检测到的化合物的不同光谱不仅可以解释抗真菌活性，而且可以解释微生物群落的物种特异性。后者采用培养无关单链构象多态性（SSCP）分析。利用伯克霍尔德菌特异性引物，我们发现在Sphagnum的内生和外生生境中，伯克霍尔德菌分离株具有高度的多样性。此外，利用nifh特异性引物检测到固氮细菌的多样性，特别是在泥鳅苔藓中。综上所述，本研究提供的证据表明，两种Sphagnum物种都被特征细菌群体定殖，这似乎对病原体防御和固氮很重要。
High acidity, low temperature and extremely low concentration of nutrients form Sphagnum bogs into extreme habitats for organisms. Little is known about the bacteria associated with living Sphagnum plantlets, especially about their function for the host. Therefore, we analysed the endo- and ectophytic bacterial populations associated with two widely distributed Sphagnum species, Sphagnum magellanicum and Sphagnum fallax, by a multiphasic approach. The screening of 1222 isolates for antagonistic activity resulted in 326 active isolates. The bacterial communities harboured a high proportion of antifungal (26%) but a low proportion of antibacterial isolates (0.4%). Members of the genus Burkholderia (38%) were found to be the most dominant group of antagonistic bacteria. The finding that a large proportion (89%) of the antagonistic bacteria produced antifungal compounds may provide an explanation for the well-known antimicrobial activity of certain Sphagnum species. The secondary metabolites of the Sphagnum species themselves were analysed by HPLC-PDA. The different spectra of detected compounds may not only explain the antifungal activity but also the species specificity of the microbial communities. The latter was analysed using cultivation-independent single-stranded conformation polymorphism (SSCP) analysis. Using Burkholderia-specific primers we found a high diversity of Burkholderia isolates in the endophytic and ectophytic habitats of Sphagnum. Furthermore, a high diversity of nitrogen-fixing bacteria was detected by using nifH-specific primers, especially inside Sphagnum mosses. In conclusion, this study provides evidence that both Sphagnum species were colonized by characteristic bacterial populations, which appear to be important for pathogen defence and nitrogen fixation.