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首页> 外文期刊>Environmental microbiology >Effects of management regime and plant species on the enzyme activity and genetic structure of N-fixing, denitrifying and nitrifying bacterial communities in grassland soils
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Effects of management regime and plant species on the enzyme activity and genetic structure of N-fixing, denitrifying and nitrifying bacterial communities in grassland soils

机译：管理制度和植物种类对草地土壤固氮反硝化细菌群落酶活性和遗传结构的影响

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Management by combined grazing and mowing events is commonly used in grasslands, which influences the activity and composition of soil bacterial communities. Whether observed effects are mediated by management-induced disturbances, or indirectly by changes in the identity of major plant species, is still unknown. To address this issue, we quantified substrate-induced respiration (SIR), and the nitrification, denitrification and free-living N-2-fixation enzyme activities below grass tufts of three major plant species (Holcus lanatus, Arrhenatherum elatius and Dactylis glomerata) in extensively or intensively managed grasslands. The genetic structures of eubacterial, ammonia oxidizing, nitrate reducing, and free-living N-2-fixing communities were also characterized by ribosomal intergenic spacer analysis, and denaturing gradient gel electrophoresis (DGGE) or restriction fragment length polymorphism (RFLP) targeting group-specific genes. SIR was not influenced by management and plant species, whereas denitrification enzyme activity was influenced only by plant species, and management-plant species interactions were observed for fixation and nitrification enzyme activities. Changes in nitrification enzyme activity were likely largely explained by the observed changes in ammonium concentration, whereas N availability was not a major factor explaining changes in denitrification and fixation enzyme activities. The structures of eubacterial and free-living N2-fixing communities were essentially controlled by management, whereas the diversity of nitrate reducers and ammonia oxidizers depended on both management and plant species. For each functional group, changes in enzyme activity were not correlated or were weakly correlated to overall changes in genetic structure, but around 60% of activity variance was correlated to changes in five RFLP or DGGE bands. Although our conclusions should be tested for other ecosystems and seasons, these results show that predicting microbial changes induced by management in grasslands requires consideration of management-plant species interactions.
机译：在草原上通常采用放牧和割草相结合的管理方式，这会影响土壤细菌群落的活动和组成。尚不清楚观察到的效果是由管理诱导的干扰介导，还是间接地由主要植物种类的身份变化介导。为了解决这个问题，我们对三种主要植物（Holcus lanatus，Arrhenatherum elatius和Dactylis glomerata）草丛下的基质诱导呼吸（SIR）以及硝化，反硝化和自由生活的N-2固定酶活性进行了定量。广泛或集约化管理的草原。还通过核糖体基因间间隔区分析，变性梯度凝胶电泳（DGGE）或限制性片段长度多态性（RFLP）靶向组对真细菌，氨氧化，硝酸还原和自由活动的N-2-固定群落的遗传结构进行了表征特定基因。 SIR不受管理和植物物种的影响，而反硝化酶的活性仅受植物物种的影响，并且观察到管理植物与植物的相互作用对固着和硝化酶的活性产生了影响。硝化酶活性的变化很可能很大程度上是由观察到的铵浓度变化引起的，而氮的有效性不是解释反硝化和固定酶活性变化的主要因素。固氮和自由生活的固氮菌群落的结构基本上受管理控制，而硝酸盐还原剂和氨氧化剂的多样性取决于管理和植物种类。对于每个功能组，酶活性的变化与遗传结构的总体变化均不相关或微弱相关，但约60％的酶活性变化与五个RFLP或DGGE谱带的变化相关。尽管我们的结论应针对其他生态系统和季节进行检验，但这些结果表明，预测草原管理活动引起的微生物变化需要考虑管理植物物种之间的相互作用。

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