Analysis of microbial diversity in sulfur oxidizing denitrification process with culture dependent and PCR, DGGE, cloning-based culture independent methods

Abstract

Sulfur oxidizing denitrification has many interesting physical, chemical and biological characteristics. Although Sulfur oxidizing denitrification process has been extensively studied since 1978, knowledge about microbial community is still very limited. Sulfur particles covered with thin biofilm are regarded as key area of sulfur oxidization. Also supplement of organic carbon sources into the sulfur oxidizing denitrification process may provide huge diversity to microorganism community. In this study, 16S rDNA-based PCR-DGGE and cloning were applied to analyze the microbial community in the sulfur oxidizing denitrification. The extent of microbial community diversity in two different types of sulfur oxidizing denitrification processes was analyzed with culture-dependent and culture-independent approaches. As the culture-dependent method in lab-scale sulfur oxidizing denitrification process, about 50 isolates were obtained and they were classified into 6 important sulfur oxidizing groups by comparing their partial 16S rDNA in Blastin database. Strains ST1, C1T3, C4T1, C4T2, C4T3 and C4T5 were most closely related to Paracoccus pantotrophus. Strains ST3, C1T4, C3T1, C3T2, C3T4, and C3T5 had high similarities to Paracoccus versutus. Strains ST4, C7T1, C7T2, C7T3, C7T4 and C7T5 had similarities to the genus Thiothrix. Strains ST2, C5T1, C5T2, C5T3, C5T4 and C5T5 had similarities to Sulfurimonas denitrificans. Strains SN2, SN3, SN4, SN5, C1N2, C1N3, C1N5, C2N3 and C2N4 are in the group of SN2 and it could be placed under the genus Pseudomonas. All isolates were 97.4 – 99.8 % similar to the type strains of the related species. Strain ST1 and ST3 were Paracoccus species which were α Proteobacteria. Strain SN2 was Pseudomonas species which were γ Proteobacteria. While ST4 and C7T1 were Thiothrix species which were also γ Proteobacteria. Strain ST2 was Sulfurimonas species which was ε Proteobacteria. ß and δ Proteobacteria were not isolated from culture depen...