Brandt Franziska B, Martinson Guntars O, Pommerenke Bianca, Pump Judith, Conrad Ralf
Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg, Germany.
Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg, Germany
FEMS Microbiol Ecol. 2015 Feb;91(2):1-10. doi: 10.1093/femsec/fiu021. Epub 2014 Dec 10.
Tank bromeliads are highly abundant epiphytes in neotropical forests and form a unique canopy wetland ecosystem which is involved in the global methane cycle. Although the tropical climate is characterized by high annual precipitation, the plants can face periods of restricted water. Thus, we hypothesized that water is an important controller of the archaeal community composition and the pathway of methane formation in tank bromeliads. Greenhouse experiments were established to investigate the resident and active archaeal community targeting the 16S rDNA and 16S rRNA in the tank slurry of bromeliads at three different moisture levels. Archaeal community composition and abundance were determined using terminal restriction fragment length polymorphism and quantitative PCR. Release of methane and its stable carbon isotopic signature were determined in a further incubation experiment under two moisture levels. The relative abundance of aceticlastic Methanosaetaceae increased up to 34% and that of hydrogenotrophic Methanobacteriales decreased by more than half with decreasing moisture. Furthermore, at low moisture levels, methane production was up to 100-fold lower (≤0.1-1.1 nmol gdw(-1) d(-1)) than under high moisture levels (10-15 nmol gdw(-1) d(-1)). The rapid response of the archaeal community indicates that the pathway of methane formation in bromeliad tanks may indeed be strongly susceptible to periods of drought in neotropical forest canopies.
凤梨科贮水植物是新热带森林中极为丰富的附生植物，形成了一个独特的树冠湿地生态系统，该系统参与全球甲烷循环。尽管热带气候的特点是年降水量高，但这些植物仍可能面临水分受限的时期。因此，我们推测水分是凤梨科贮水植物中古菌群落组成和甲烷形成途径的重要调控因素。开展了温室实验，以研究三种不同水分水平下凤梨科贮水植物贮水池泥浆中以16S rDNA和16S rRNA为靶点的古菌群落（包括常驻群落和活跃群落）。使用末端限制性片段长度多态性和定量PCR来确定古菌群落组成和丰度。在另外一个培养实验中，测定了两种水分水平下甲烷的释放及其稳定碳同位素特征。随着水分减少，产乙酸的甲烷鬃毛菌科的相对丰度增加至34%，而嗜氢甲烷杆菌目的相对丰度下降超过一半。此外，在低水分水平下，甲烷产量比高水分水平下（10 - 15 nmol gdw(-1) d(-1)）低达100倍（≤0.1 - 1.1 nmol gdw(-1) d(-1)）。古菌群落的快速响应表明，凤梨科贮水植物池中甲烷形成途径可能确实极易受到新热带森林树冠干旱期的影响。
