국내의 대표적 섬이나 생태환경이 잘 보존된 토양으로부터 저영양세균 3,471주를 분리하였고 이로부터 질소발생 분석법에 의해 탈질균 135주를 최종 선발하였다. 이들 균주의 16S rDNA를 염기서열 분석한 결과 이들의 90% 가량이 Proteobacterium문에 속하였으며 다른 44속에 대부분 포함되었다. 대표적인 44속에 대해 분자생물학적 동정을 한 후 다양한 외부환경(온도, pH, 염, 무기질소염) 조건에 대한 이들의 생존성 범위를 조사한 결과, 넓은 온도($4^{circ}C{sim}42^{circ}C$)와 pH(4~10)범위에서 자랄 수 있는 탈질균 12종을 최종 선발하였다.
In an effort to isolate novel bacteria for the bioremediation of over-fertilized soils, we identified 135 denitrifying cells out of 3,471 oligotrophic bacteria pools (3.9%) using a denitrification medium supplemented with potassium nitrate as the sole nitrogen source. Soil samples were taken from ecologically well-conserved areas, including a mountain swamp around the demilitarized zone (Yongneup), two ecoparks (Upo and the Mujechi bog), and ten representative islands around the Korean peninsula (Jejudo, Daecheongdo, Socheongdo, Baekryeongdo, Ulrungdo, Dokdo, Geomundo, Hongdo, Huksando and Yeonpyeongdo). All of the 135 bacteria produced nitrogen gas from the denitrification medium, and were proved to be nitrate reductase positive by API-BioLog tests. Phylogenetic analysis using 16S rDNA sequences revealed that the 135 bacteria consisted of 44 different genera. Along with the most prominent, Proteobacteria (87.4%), we identified denitrifying bacteria from Firmicutes (9.4%), Actinobacteria (2.4%), and Bacteroidetes (0.8%). Physiological analyses of the 44 representative denitrifying bacteria, under various pH levels, growth temperatures and salt stresses, revealed 12 favorable denitrifying strains for soil bioremediation.
