Nicolaisen Mette Haubjerg, Risgaard-Petersen Nils, Revsbech Niels Peter, Reichardt Wolfgang, Ramsing Niels Birger
Department of Microbial Ecology, Institute of Biological Sciences, University of Aarhus, DK-8000 Aarhus C, Denmark.
FEMS Microbiol Ecol. 2004 Sep 1;49(3):359-69. doi: 10.1016/j.femsec.2004.04.015.
Nitrogen is the single most limiting factor for rice production. Detailed knowledge on nitrogen dynamics in rice fields is therefore of major importance for developing sustainable rice production. A combination of state-of-the-art microsensor, stable isotope tracer, and molecular techniques was used to evaluate coupled nitrification-denitrification potentials and community structure of ammonia-oxidizing bacteria in a high yield irrigated rice cropping system in the Philippines, without the use of microcosm incubations. The multiple approaches showed a high degree of concordance among methods and thereby clarified the investigated processes. Numbers and potential activity of ammonia-oxidizing bacteria in the system reflected the availability of substrate in three defined soil factions with a ranking of: surface soil > rhizosphere > bulk soil. No nitrification activity was measured between spit applications of N fertilizer. However, nitrification was induced upon nitrogen amendment in intact soil cores. Despite induction by nitrogen amendment, the loss of nitrogen through coupled nitrification-denitrification was less than 10% of the plant nitrogen uptake. Denaturant gradient gel electrophoresis of amoA fragments revealed no differences in diversity profiles between the soil fractions, and phylogenetic analysis, based on amoA genes retrieved from the rice paddy soil, identified a set of mutually very similar sequences related to Nitrosomonas nitrosa.
氮是水稻生产中最关键的单一限制因素。因此，详细了解稻田中的氮动态对于发展可持续水稻生产至关重要。在菲律宾的一个高产灌溉水稻种植系统中，结合了最先进的微传感器、稳定同位素示踪剂和分子技术，在不使用微观培养的情况下，评估了硝化-反硝化耦合潜力以及氨氧化细菌的群落结构。多种方法显示出方法之间的高度一致性，从而阐明了所研究的过程。系统中氨氧化细菌的数量和潜在活性反映了三个特定土壤部分中底物的可用性，其排序为：表层土壤>根际>土体。在两次施氮之间未检测到硝化活性。然而，在完整土壤芯中添加氮后诱导了硝化作用。尽管通过添加氮诱导，但通过硝化-反硝化耦合造成的氮损失不到植物氮吸收量的10%。amoA片段的变性梯度凝胶电泳显示土壤部分之间的多样性图谱没有差异，基于从稻田土壤中检索到的amoA基因进行的系统发育分析，确定了一组与亚硝化单胞菌密切相关的非常相似的序列。
