Analysis of ammonia-oxidizing bacteria populations in acid forest soil during conditions of moisture limitation

Ammonia-oxidizer numbers decreased under conditions of moisture limitation in litter, fermentation and humus layers of forest soil in the field, but t he extent of regrowth after rehydration varied between layers. Nitrosospira 16S rRNA genes were amplified from all layers, regardless of moisture cont ent or soil pH which varied between 4.1 and 5.2. Nitrosomonas spp. were det ected less often, but appeared to exhibit mol-e rapid recovery than the Nit rosospira spp, when drought conditions were relieved by rainfall.