Authors: Fei Yuan Wei Ran Qirong Shen Dezhi Wang
Publish Date: 2004/11/13
Volume: 41, Issue: 1, Pages: 22-27
Abstract
Soil nitrification rate is very different among soil types as a result of differences in physical and chemical properties Little is known about the composition of the nitrifying bacteria community In this investigation three soils fluvoaquic soil permeable paddy soil and red earth from different geoecological regions in China were characterized for their nitrification activities and their nitrifying bacteria communities determined either by molecular approaches or by conventional culture methods A 28day longterm soil incubation showed that the maximum nitrification potential was found in the fluvoaquic soil with almost 100 of inorganic N present as NO 3 − N while the minimum nitrification potential was in red earth with only a 49 conversion rate from ammonium into nitrate There was no relationship between nitrification potential and numbers of nitrifiers in the soil The conventional most probable number MPN method could enumerate ammonia oxidizers but failed in enumerating nitrite oxidizers Therefore we used an MPNPCR procedure which gave a convincing nitrite oxidizer count result instead of MPNdiphylamine Soils were characterized by denaturing gradient gel electrophoresis DGGE of DNA extracted from soils and amplified using a primer specific for the 16S rRNA gene and/or for the amoA gene The DGGE columns of the three soils differed from each other There were two similar bands present in DGGE columns of the fluvoaquic and permeable paddy soils but no similar band was found in DGGE columns of the red earth The sequence of amoA indicated that all ammonia oxidizers in these soils were grouped into Nitrosospira clusters 1 and 3 and each soil had a common band similar to the other soils and a special band which differed from the other soils
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