Enrichment of Uncultured Ammonium Oxidizing and Denitrifying Bacteria from Antarctic Soil

Abstract

Bacteria are contribution a large role in the nitrogen cycle of ecosystems, especially in limited habitat, such as Antarctica. For the cultivation of bacteria involved in the nitrogen cycle of the Antarctica, three soils of King George Island were enriched for nitrogen fixation (NF), ammonium oxidation (AO) and denitrification (DN). Changes in N2O gas, ammonium, nitrite and nitrate concentrations were measured every 14 days. Ammonium oxidation and denitrification were confirmed by measuring changes in nitrogen concentration, and 16S rRNA gene was amplified and analyzed for bacterial communities. Functional gene amoA, which is an ammonium oxidizing gene, and nirK, nirS and nosZ, denitrifying genes, were confirmed. As a result of the bacterial community analysis, it was found that the culture of ammonium oxidizing bacterium were cultivated with Micavibrio, Oxalobacteraceae and Pseudomonadaceae. Oxalobacteraceae, Pseudomonadaceae and Propionibacteriaceae were cultivated in denitrifying bacteria enriched culture. The denitrification pathway and the dissimilatory nitrite reductase pathway were found in the DN_1B and DN_3A denitrifying bacterium cultured in the SEED profile. The ammonia assimilation pathway was more abundant in AO_2C cultured with ammonium oxidizing bacteria. And environmental genetic analysis of the cultures obtained by enrichment will help to understand the ecological function and role of bacteria in the ecosystem. [Supported by the Korea polar Research Institute (Grant PE19090)]