Bacterial Community and Biological Nitrate Removal: Comparisons of Autotrophic and Heterotrophic Reactors for Denitrification with Raw Sewage

• Published in: Journal of microbiology and biotechnology Vol. 18; no. 11; pp. 1826 - 1835
• Main Authors: Lee, H.W. (Louisiana State University, Baton Rouge, LA, U.S.A.), E-mail: proteole@lsu.edu, Park, Y.K. (Korea University, Seoul, Republic of Korea), Choi, E.S. (Korea University, Seoul, Republic of Korea), Lee, J.W. (Korea University, Seoul, Republic of Korea)
• Format: Journal Article
• Language: English
• Published: Seoul Korean Society for Applied Microbiology 01.11.2008; 한국미생물·생명공학회
• Subjects: Alphaproteobacteria - classification; Alphaproteobacteria - genetics; Alphaproteobacteria - growth & development; Alphaproteobacteria - metabolism; autotrophic denitrification; Autotrophic Processes; BACTERIA; Bacteria - growth & development; Bacteria - metabolism; Bacterial communities; Betaproteobacteria - classification; Betaproteobacteria - genetics; Betaproteobacteria - growth & development; Betaproteobacteria - metabolism; Biological and medical sciences; Bioreactors; Biotechnology; Biotechnology - methods; DNA, Bacterial - analysis; DNA, Bacterial - isolation & purification; Ecosystem; Fundamental and applied biological sciences. Psychology; heterotrophic denitrification; Heterotrophic Processes; In Situ Hybridization, Fluorescence; Nitrates - metabolism; Phylogeny; Polymorphism, Restriction Fragment Length; RNA, Ribosomal, 16S - genetics; Sequence Analysis, DNA; Sewage - microbiology; 생물학; heterotrophic denitrification; Heterotrophy; Denitrification; Bacteria; Autotrophy; Nitrates; Bacterial communities; Reactor; autotrophic denitrification; Microbial community; Comparative study
• ISSN: 1017-7825; 1738-8872
• DOI: 10.4014/jmb.0800.276

An autotrophic denitrification reactor (ADR-1) and a heterotrophic denitrification reactor (HDR-2) were operated to remove nitrate and nitrite in an anoxic environment in raw sewage. The NO₃-N removal rate of ADR-1 was shown to range from 52.8% to 78.7%, which was higher than the NO₃-N removal rate of HDR-2. Specific denitrification rates (SDNR) of ADR-1 and HDR-2 were 3.0 to 4.0 and 1.1 to 1.2 mgNO₃-N/gVSS/h, respectively. From results of restriction fragment length polymorphism (RFLP) of the 16S rRNA gene, Aquaspirillum metamorphum, Alcaligenes defragrans, and Azoarcus sp. were β-Proteobacteria that are affiliated with denitrifying bacteria in the ADR-1. Specifically, Thiobacillus denitrificans was detected as an autotrophic denitrification bacteria. In HDR-2, the β-Proteobacteria such as Denitrifying-Fe-oxidizing bacteria, Alcaligenes defragrans, Acidovorax sp., Azoarcus denitrificans, and Aquaspirillum metamorphum were the main bacteria related to denitrifying bacteria. The β-and α-Proteobacteria were the important bacterial groups in ADR-1, whereas the β-Proteobacteria were the main bacterial group in HDR-2 based on results of fluorescent in situ hybridization (FISH). The number of Thiobacillus denitrificans increased in ADR-1 during the operation period but not in HRD-2. Overall, the data presented here demonstrate that many heterotrophic denitrifying bacteria coexisted with autotrophic denitrifying bacteria such as Thiobacillus denitrificans for nitrate removal in ADR-1. On the other hand, only heterotrophic denitrifying bacteria were identified as dominant bacterial groups in HDR-2. Our research may provide a foundation for the complete nitrate removal in raw sewage of low-COD concentration under anoxic condition without any external organic carbon or the requirement of post-treatment.