Oliveira Vanessa, Gomes Newton C M, Almeida Adelaide, Silva Artur M S, Simões Mário M Q, Smalla Kornelia, Cunha Ângela
Department of Biology & Center for Environmental and Marine Studies (CESAM), University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal.
Department of Chemistry & QOPNA, University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal.
Mol Ecol. 2014 Mar;23(6):1392-1404. doi: 10.1111/mec.12559.
Salt marsh sediments are sinks for various anthropogenic contaminants, giving rise to significant environmental concern. The process of salt marsh plant survival in such environment is very intriguing and at the same time poorly understood. The plant–microbe interactions may play a key role in the process of environment and in planta detoxification.In this study, a combination of culture-dependent and culture-independent molecular approaches [enrichment cultures, polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), DNA sequencing] were used to investigate the effect of petroleum hydrocarbons (PH) contamination on the structure and function[polycyclic aromatic hydrocarbon (PAH) dioxygenase genes] of endophytic bacterial communities of salt marsh plant species (Halimione portulacoides and Sarcocornia perennis)in the estuarine system Ria de Aveiro (Portugal). Pseudomonads dominated the cultivable fraction of the endophytic communities in the enrichment cultures. In a set of fifty isolates tested, nine were positive for genes encoding for PAH dioxygenases (nahAc)and four were positive for plasmid carrying genes encoding PAH degradation enzymes(nahAc). Interestingly, these plasmids were only detected in isolates from most severely PH-polluted sites. The results revealed site-specific effects on endophytic communities,related to the level of PH contamination in the sediment, and plant-species-specific ‘imprints’ in community structure and in genes encoding for PAH dioxygenases. These results suggest a potential ecological role of bacterial plant symbiosis in the process of plant colonization in urban estuarine areas exposed to PH contamination.
盐沼沉积物是各种人为污染物的汇，引发了重大的环境问题。盐沼植物在这种环境中的生存过程非常有趣，但同时人们对此了解甚少。植物与微生物的相互作用可能在环境和植物体内解毒过程中发挥关键作用。在本研究中，采用了依赖培养和不依赖培养的分子方法相结合的方式[富集培养、聚合酶链反应（PCR）、变性梯度凝胶电泳（DGGE）、DNA测序]，来研究石油烃（PH）污染对葡萄牙阿威罗河口系统里亚德阿威罗盐沼植物物种（盐角草和海滨盐沼藜）内生细菌群落结构和功能[多环芳烃（PAH）双加氧酶基因]的影响。假单胞菌在富集培养的内生群落可培养部分中占主导地位。在一组测试的50个分离株中，9个编码PAH双加氧酶（nahAc）的基因呈阳性，4个携带编码PAH降解酶（nahAc）基因的质粒呈阳性。有趣的是，这些质粒仅在来自PH污染最严重地点的分离株中检测到。结果揭示了沉积物中PH污染水平对内生群落的位点特异性影响，以及群落结构和编码PAH双加氧酶基因中植物物种特异性的“印记”。这些结果表明，在受PH污染的城市河口地区，细菌与植物的共生关系在植物定殖过程中可能具有潜在的生态作用。
