低温域湿地植物根际硝化强度及氨氧化微生物研究

以低温域(0~15 ℃)下黄菖蒲(Iris pseudacorus)、菖蒲(Acorus calamus)和香蒲(Typha orientalis)3种湿地植物为研究对象,分别取其根际土壤测定硝化强度,并采用FISH(荧光原位杂交)技术,考察植物根际AOB(氨氧化细菌)、AOA(氨氧化古菌)的数量变化规律. 结果表明:低温条件下,香蒲根际土壤的硝化强度最高,平均值为1.40 mg/(kg·h),黄菖蒲和菖蒲的平均值均为0.96 mg/(kg·h). 湿地植物根际土壤中的细菌数量(数量级为1010)远高于古菌(数量级为108),其中AOB为优势菌种,3种湿地植物的AOA数量分别约占总古菌数量的46.0%、47.9%和49.7%. 3种湿地植物根际AOB的数量(以湿土计,下同)排序为香蒲(2.57×109 g-1)>黄菖蒲(1.23×109 g-1)≈菖蒲(1.14×109 g-1),AOA的数量(以湿土计)排序为黄菖蒲(2.78×108 g-1)>香蒲(2.57×108 g-1)>菖蒲(1.15×108 g-1). 微生物分布特性和硝化作用效果均表明,不同植物根际氨氧化过程的主要作用微生物具有一定差异,AOA和AOB对于湿地土壤氮转化均具有不可忽视的作用,并与植物本体、土壤硝化过程微环境之间有一定的耦合关系. 

Nitrification Intensity and Ammonia-Oxidizing Microorganisms in Wetland Plant Rhizosphere Soil at Low Temperature

In the present study, the growth of three species of wetland plants, Iris pseudacorus, Acorus calamus and Typha orientalis, were investigated at relatively low temperatures (0-15 ℃). Nitrification intensities were measured using rhizosphere soils. Fluorescence in situ hybridization (FISH) technique was utilized to examine the relative abundance shifts of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in different plant rhizosphere soils. The results indicated that T. orientalis achieved the highest nitrification intensity (1.40 mg/(kg·h) in average) at low temperature, while I. pseudacorus and A. calamus showed a similar average nitrification intensity (0.96 mg/(kg·h)). The estimated total bacteria were around 1010 cells g-1 wet, which were one to two orders of magnitude higher than that of archaea. AOB were the dominant bacteria species, while AOA dominated archaea, accounting for approximately 50% of the total archaea. The order of AOB in the rhizosphere soils for each plant was T. orientalis (2.57×109 g-1)>I. pseudacorus (1.23×109 g-1)≈A. calamus (1.14×109 g-1); the order of AOA was I. pseudacorus (2.78×108 g-1)>T. orientalis (2.57×108 g-1)>A. calamus (1.15×108 g-1). The characteristics of the microbial communities and their effects on nitrification indicated that the differences in dominant microorganisms linked their growth with the ammonia-oxidizing process in the soil. The results suggested that both AOA and AOB play important roles in nitrogen transformation in the soil of the wetland, and interact with plants and the microenvironments proceessing soil nitrification.