尿素通过提高Nitrosospira丰度促进酸性土壤中的氨氧化作用

Urea Promotes Ammonia Oxidation in Acidic Soils by Increasing the Abundance of Nitrosospira

本研究旨在通过探究酸性土壤中的氨氧化作用,提供制定合理施肥策略的科学依据。采用土壤微宇宙实验、液体培养和传代培养,研究尿素对酸性土壤氨氧化作用及其微生物群落的影响。结果表明,三种酸性土壤尿素组的平均硝化速率显著高于空白对照组和铵态氮肥组(P<0.05)。尿素的施用显著提高了氨氧化细菌(ammonia oxidizing bacteria,AOB)amoA基因丰度(P<0.05),而不是氨氧化古菌(ammonia oxidizing archaea,AOA)amoA基因丰度(P<0.05),表明尿素通过提高AOB的丰度促进氨氧化作用。液体培养结果表明,尿素促进了不同酸性土壤悬液的氨氧化活性,且这一促进作用与尿素水解过程中p H值的上升无关。传代培养结果表明,酸性条件下以尿素为初始底物的培养方式有利于AOB,特别是未培养的亚硝化螺菌(Uncultured Nitrosospira)的繁殖。本研究证实尿素通过提高Nitrosospira的丰度促进酸性土壤中的氨氧化作用,为制定合理的氮肥施用策略提供了科学依据。

The purpose of this study is to provide scientific basis for formulating rational fertilization strategy by exploring the ammonia oxidation in acidic soil.The effects of urea on ammonia oxidation and microbial community in acidic soil were studied by soil microcosmic experiment,liquid culture and subculture.The results showed that the average nitrification rate of three acid soil urea groups was significantly higher than that of blank control group and ammonium nitrogen fertilizer group(P<0.05).Urea application significantly increased amoA gene abundance of ammonia oxidizing bacteria(AOB)(P<0.05).However,amoA gene abundance of ammonia oxidizing archaea(AOA)was not found(P<0.05),indicating that urea promoted ammonia oxidation in acid soils by increasing AOB abundance.The results of liquid culture showed that urea promoted the ammonia oxidation activity of different acidic soil suspensions,and this promotion effect was not related to the rise of pH during urea hydrolysis.The passage culture showed that the culture method with urea as the initial substrate under acidic conditions was beneficial to the reproduction of AOB,especially uncultured Nitrosospira.This study confirmed that urea promoted ammonia oxidation in acidic soil by increasing the abundance of Nitrosospira,which provided a scientific basis for formulating a reasonable nitrogen fertilizer application strategy.