title: Diversity of Ammonia Oxidation (amoA) and Nitrogen Fixation (nifH) Genes in Lava Caves of Terceira, Azores, Portugal.
abstract: Lava caves are an understudied ecosystem in the subterranean world, particularly in regard to nitrogen cycling. The diversity of ammonia oxidation (amoA) and nitrogen fixation (nifH) genes in bacterial mats collected from lava cave walls on the island of Terceira (Azores, Portugal) was investigated using denaturing gradient gel electrophoresis (DGGE). A total of 55 samples were collected from 11 lava caves that were selected with regard to surface land use. Land use types above the lava caves were categorized into pasture, forested, and sea/urban, and used to determine if land use influenced the ammonia oxidizing and nitrogen fixing bacterial communities within the lava caves. The soil and water samples from each lava cave were analyzed for total organic carbon, inorganic carbon, total nitrogen, ammonium, nitrate, phosphate and sulfate, to determine if land use influences either the nutrient content entering the lava cave or the nitrogen cycling bacteria present within the cave.Nitrosospira-like sequences dominated the ammonia-oxidizing bacteria (AOB) community, and the majority of the diversity was found in lava caves under forested land. The nitrogen fixation community was dominated byKlebsiella pneumoniae-like sequences, and diversity was evenly distributed between pasture and forested land, but very little overlap in diversity was observed. The results suggest that land use is impacting both the AOB and the nitrogen fixing bacterial communities.
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, New Mexico, USA.
authors.forename: Jennifer J Marshall
authors.initials: JJ
authors.lastname: Hathaway
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, New Mexico, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sinsabaugh
authors.affiliation: CITA-A, Departamento de Ciências Agrárias, Universidade dos Açores, Angra do Heroísmo, Portugal.
authors.forename: Maria De Lurdes N E
authors.initials: ML
authors.lastname: Dapkevicius
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, New Mexico, USA.
authors.forename: Diana E
authors.initials: DE
authors.lastname: Northup
keywords: amoA; bacteria; lava caves; nifH; nitrogen cycling