Murase Jun, Takenouchi Yuriko, Iwasaki Kazufumi, Kimura Makoto
Graduate School of Bioagricultural Science, Nagoya University.
Microbes Environ. 2014;29(1):74-81. doi: 10.1264/jsme2.me13128. Epub 2014 Feb 7.
Irrigated rice field soil is subjected to frequent changes in oxygen status due to the water regime by agricultural management. In this study, the community response of microeukaryotes in rice field soil to the oxygen status was explored in a microcosm experiment under defined conditions. Water-saturated soil was incubated under a two-level factorial design of oxygen and organic enrichment with plant residue. The eukaryotic microbial community composition, which was either present or potentially active in the soils, was analyzed using denaturing gradient gel electrophoresis (DGGE) targeting the 18S rRNA gene or reverse-transcribed 18S rRNA. Oxygen availability was a primary factor shaping the microeukaryotic community in both DNA- and RNA-based analyses, revealing a shift within a week of incubation. Plant residue also affected the microeukaryotic community, which was more notable in the active community showing rRNA expression with time. Sequences of amplicons in DGGE bands indicated that protozoa (ciliates, flagellates, and amoebae) were the most prominent microeukaryotes in water-saturated rice field soil both in DNA- and RNA-based analyses. The use of a modified primer for soil protozoa suggested the functional importance of Heterolobosea amoeba in rice field soil, particularly in anoxic soil with organic enrichment.
由于农业管理中的水分状况，灌溉稻田土壤的氧气状态会频繁变化。在本研究中，通过在特定条件下的微观实验，探索了稻田土壤中微型真核生物群落对氧气状态的响应。将水饱和土壤在氧气和添加植物残体的有机富集的二级析因设计下进行培养。使用针对18S rRNA基因或逆转录18S rRNA的变性梯度凝胶电泳（DGGE）分析土壤中现存或潜在活跃的真核微生物群落组成。在基于DNA和RNA的分析中，氧气可利用性都是塑造微型真核生物群落的主要因素，这表明在培养一周内群落发生了转变。植物残体也影响微型真核生物群落，在显示rRNA随时间表达的活跃群落中这种影响更为显著。DGGE条带中扩增子的序列表明，在基于DNA和RNA的分析中，原生动物（纤毛虫、鞭毛虫和变形虫）是水饱和稻田土壤中最主要的微型真核生物。使用针对土壤原生动物的改良引物表明，异叶足虫变形虫在稻田土壤中具有重要功能，特别是在富含有机物的缺氧土壤中。
