Kowalchuk, George A., authorBruns, Mary Ann, authorStephen, John R., authorPaul, Eldor A., authorProsser, James I., authorAmerican Society for Microbiology, publisher2007-01-032007-01-031999-07Bruns, Mary Ann, John R. Stephen, George A. Kowalchuk, James I. Prosser and Eldor, A. Paul, Comparative Diversity of Ammonia Oxidizer 16S rRNA Gene Sequences in Native, Tilled, and Successional Soils. Applied and Environmental Microbiology 65, no. 7 (July 1999): 2994-3000. httpss://aem.asm.org/content/65/7/2994.full.http://hdl.handle.net/10217/81184Publisher version: https://aem.asm.org/content/65/7/2994.full.Autotrophic ammonia oxidizer (AAO) populations in soils from native, tilled, and successional treatments at the Kellogg Biological Station Long-Term Ecological Research site in southwestern Michigan were compared to assess effects of disturbance on these bacteria. N fertilization effects on AAO populations were also evaluated with soils from fertilized microplots within the successional treatments. Population structures were characterized by PCR amplification of microbial community DNA with group-specific 16S rRNA gene (rDNA) primers, cloning of PCR products and clone hybridizations with group-specific probes, phylogenetic analysis of partial 16S rDNA sequences, and denaturing gradient gel electrophoresis (DGGE) analysis. Population sizes were estimated by using most-probable-number (MPN) media containing varied concentrations of ammonium sulfate. Tilled soils contained higher numbers than did native soils of culturable AAOs that were less sensitive to different ammonium concentrations in MPN media. Compared to sequences from native soils, partial 16S rDNA sequences from tilled soils were less diverse and grouped exclusively within Nitrosospira cluster 3. Native soils yielded sequences representing three different AAO clusters. Probes for Nitrosospira cluster 3 hybridized with DGGE blots from tilled and fertilized successional soils but not with blots from native or unfertilized successional soils. Hybridization results thus suggested a positive association between the Nitrosospiracluster 3 subgroup and soils amended with inorganic N. DGGE patterns for soils sampled from replicated plots of each treatment were nearly identical for tilled and native soils in both sampling years, indicating spatial and temporal reproducibility based on treatment.born digitalarticleseng©1999 American Society for Microbiology.Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.AAO populationstillagenitrificationmicrobial oxidationN lossesN fertilizationecosystemsDGGE banding patternsText