• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.363-367
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• 2004

For comparative analysis of the eubacterial community structure at 8 sampling sites throughout the Nak-Dong River, FISH (fluorescence in situ hybridization) method was employed. The total ratio of each determined eubacterial group such as ${\alpha}\;{\cdot}\;{\beta}\;{\cdot}\;{\gamma}-subclasses$proteobacteria and Cytophaga-Flavobacterium(CF) group to total counts(DAPI) at each site varied 9.3-42.5% with the highest value at uppermost part. And each ratio of determined eubacterial groups reached mostly under 10% except that of CF group (23%) at uppermost part. Furthermore, compared to lower part, upper part represented unexpectedly higher proportions of ${\gamma}-subclass$ proteobacteria comprised almost fast growing bacteria on degradable organics. Also the variations of ammonia-oxidizing bacteria ranged from $2.7{\times}10^4$ to $18.0{\times}10^4$ cells $mL^{-1}$ with the lowest value in lower part and the highest value in mid part whereas those of nitrite-oxidizing bacteria varied 5.2-7.7{\times}10^4$ cells $mL^{-1}$ without noticeable differences throughout the sites. Additionally, the ratio of nitrifying bacteria to total counts ranged from 1.0% to 13.6% with no differences between ammonia-oxidizing bacteria and nitrite-oxidizing bacteria. In conclusion, FISH method introduced in this study for monitoring, normally used for the quantitative analysis of bacteria, provided also good information on their environmental status in the Nak-Dong River.

• Journal of Life Science
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• v.7 no.2
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• pp.107-111
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• 1997

To remove dissolved $NH_{4}$$^{+}$ in the aquaculture system, one ammonia oxidizing bacterium, Nitrsomonas sp. PK1, was isolated from samples collected in many aquacultural place and sludges of waste water. The stationary phase of this atrain was reached after 9 days, and the maximum $NO_{2}$ production was shown from 3 days to 9 days. In the selective medium, 0.1% of glucose was the good carbon source for growth. However, the $NO_{2}$productivity was repressed by the addition of glucose to the medium. When $Zn^{++}$ ion was supplemented to the medium, growth and the $NO_{2}$ productivity was increased, 10mM of $ZnCl_{2}$ was the optimal concentration for growth and 1 mM of $ZnCl_{2}$ was the optimal concentration for the production of $NO_{2}$, respectively.

• Korean Journal of Environmental Agriculture
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• v.39 no.1
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• pp.26-35
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• 2020

BACKGROUND: Microbes that govern a unique biochemical process of oxidizing ammonia into dinitrogen gas, such as anaerobic ammonium oxidation (anammox) have been reported to play a pivotal role in agricultural soils and in oceanic environments. However, limited information for anammox bacterial abundance and distribution in the terrestrial habitats has been known. METHODS AND RESULTS: Phylogenetic and next-generation sequencing analyses of bacterial 16S rRNA gene were performed to examine potential anammox bacteria in paddy soils. Through clone libraries constructed by using the anammox bacteria-specific primers, some clones showed sequence similarities with Planctomycetes (87% to 99%) and anammox bacteria (94% to 95%). Microbial community analysis for the paddy soils by using Illumina Miseq sequencing of 16S rRNA gene at phylum level was dominated by unclassified Bacteria at 33.2 ± 7.6%, followed by Chloroflexi at 20.4 ± 2.0% and Acidobacteria at 17.0 ± 6.5%. Planctomycetes that anammox bacteria are belonged to was 1.5% (± 0.3) on average from the two paddy soils. CONCLUSION: We suggest evidence of anammox bacteria in the paddy soil. In addition to the relatively well-known microbial processes for nitrogen-cycle, anammox can be a potential contributor on the cycle in terrestrial environments such as paddy soils.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.57-63
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• 2013

A combined process consisted of a biofilm reactor and a continuously stirred-tank reactor (CSTR) was investigated for highly loaded ammonium wastewater treatment via nitrite accumulation. To enhance ammonium oxidizing bacteria over nitrite oxidizing bacteria on the surface of carriers, the biofilm reactor was operated at temperature of $35^{\circ}C$ for more than three months but the influent ammonium (500 mg-N/L) was partially oxidized to nitrite (240 mg-N/L). As pH was increased from 7.5 to 8.0, nitrite accumulation was fully achieved due to the inhibition of nitrite oxidizing bacteria under high free ammonia concentration. The biofilm reactor performance was severely deteriorated at the hydraulic retention time of 12 hr, at which incomplete nitrification of ammonia was observed. Various solubilization methods were applied to sewage sludge for enhancing its biodegradability and the combined method, alkaline followed by ultrasonic, gave the highest solubilization efficiency (58%); the solubilized solution was used as the external carbon source for denitrification reaction in CSTR. FISH analysis showed that the dominant microorganisms on the carriers were ammonium oxidizing bacteria such as Nitrosomonas spp. and Nitrospirar spp. but low amounts of nitrite oxidizing bacteria as Nitrobacter spp. was also detected.

• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1193-1201
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• 2012

The analysis and quantification of ammonia-oxidizing bacteria (AOB) is crucial, as they initiate the biological removal of ammonia-nitrogen from sewage. Previous methods for analyzing the microbial community structure, which involve the plating of samples or culture media over agar plates, have been inadequate because many microorganisms found in a sewage plant are unculturable. In this study, to exclusively detect AOB, the analysis was carried out via denaturing gradient gel electrophoresis using a primer specific to the amoA gene, which is one of the functional genes known as ammonia monooxygenase. An AOB consortium (S1 sample) that could oxidize an unprecedented 100% of ammonia in 24 h was obtained from sewage sludge. In addition, real-time PCR was used to quantify the AOB. Results of the microbial community analysis in terms of carbon utilization ability of samples showed that the aeration tank water sample (S2), influent water sample (S3), and effluent water sample (S4) used all the 31 substrates considered, whereas the AOB consortium (S1) used only Tween 80, D-galacturonic acid, itaconic acid, D-malic acid, and $_L$-serine after 192 h. The largest concentration of AOB was detected in S1 ($7.6{\times}10^6copies/{\mu}l$), followed by S2 ($3.2{\times}10^6copies/{\mu}l$), S4 ($2.8{\times}10^6copies/{\mu}l$), and S3 ($2.4{\times}10^6copies/{\mu}l$).

• Journal of Korean Society of Water and Wastewater
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• v.27 no.1
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• pp.59-67
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• 2013

The odor occurring in the sewage system induces the displeasure, the disgust such as the headache, the vomit, etc. and increases the spiritual stress and disturbs the pleasant life of residents. These odors occur mainly in the area of combined sewage system treatment, being created in the personal sewage treatment plant such as septic tank and are incoming to sewage pipes and emitted to the outside through the manhole and the receiver, etc.; and this causes odors to the people. The Hydrogen Sulfide, the Methyl Mercaptan, the Ammonia, etc. are materials causing the odor, the more serious issue of odor is occurring since the septic tank of degradation process is being applied. The primary cause of odor is the decomposition of human feces in the septic tanks and sewage disposal facilities. The purpose of this study is reduction of hydrogen sulfide using air supplying and SOB(Sulfur-Oxidizing Bacteria). As a result of this study of the air supply system and the SOB media equipment by air supply, in case the air is injected to SOB media compared to the injection of air only, the removal efficiency the hydrogen sulfide was average 3.4 times higher.

• Journal of Microbiology and Biotechnology
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• v.19 no.12
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• pp.1656-1664
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• 2009

Bioaugmentation of bioreactors focuses on the removal of numerous organics, with little attention typically paid to the maintenance of high and stable nitrite accumulation in partial nitrification. In this study, a bioaugmented membrane bioreactor (MBR) inoculated with enriched ammonia-oxidizing bacteria (AOB) was developed, and the effects of dissolved oxygen (DO) and temperature on the stability of partial nitrification and microbial community structure, in particular on the nitrifying community, were evaluated. The results showed that DO and temperature played the most important roles in the stability of partial nitrification in the bioaugmented MBR. The optimal operation conditions were found at 2-3 mgDO/l and $30^{\circ}C$, achieving 95% ammonia oxidization efficiency and nitrite ratio ($NO_2^-/{NO_x}^-$) of 0.95. High DO (5-6 mg/l) and low temperature ($20^{\circ}C$) had negative impacts on nitrite accumulation, leading to nitrite ratio drop to 0.6. However, the nitrite ratio achieved in the bioaugmented MBR was higher than that in most previous literatures. Denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH) were used to provide an insight into the microbial community. It showed that Nitrosomonas-like species as the only detected AOB remained predominant in the bioaugmented MBR all the time, and coexisted with numerous heterotrophic bacteria. The heterotrophic bacteria responsible for mineralizing soluble microbial products (SMP) produced by nitrifiers belonged to the Cytophaga-Flavobacterium-Bacteroides (CFB) group, and $\alpha$-, $\beta$-, and $\gamma$- Proteobacteria. The fraction of AOB ranging from 77% to 54% was much higher than that of nitrite-oxidizing bacteria (0.4-0.9%), which might be the primary cause for the high and stable nitrite accumulation in the bioaugmented MBR.

• Environmental Engineering Research
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• v.23 no.1
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• pp.28-35
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• 2018

$17{\alpha}-ethinylestradiol$ (EE2), a synthetic estrogen which interfere the endocrine and reproductive function in living organisms, has been found extensively to be deposited into municipal wastewater treatment plants and the environment via human excretion. EE2 has long been known to be efficiently cometabolized by ammonia-oxidizing bacteria (AOB) during ammonia ($NH_3$) oxidation. Current study aims to investigate the effect of culture history on the biotransformation of EE2 by nitrifying sludge which was enriched under different ammonia loading rates in continuous flow reactors. Result showed that past growth condition largely affected not only the metabolic rate of $NH_3$ oxidation but also EE2 cometabolism. Sludge previously acclimated with higher $NH_3$ loads as well as sludge dominated with AOB belong to high growth cluster (Nitrosomonas europaea-Nitrosococcus mobilis) showed higher rate of EE2 biotransformation than those one being acclimated with lower $NH_3$ loads because of its ability to provide more reducing power from $NH_3$ oxidation. Moreover, the correlation between the degradation rates of $NH_3$ and EE2 was higher in sludge being acclimated with higher load of $NH_3$ in comparison with other sludge. Implication of the findings emphasized the role of volumetric $NH_3$ loading rate in determining EE2 removal in wastewater treatment system.

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.541-547
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• 2023

The effect of temperature and influent alkalinity/ammonia (K/A) ratio on the start-up of the partial nitrification (PN) process for an activated sludge-based domestic wastewater treatment was studied. Two different sequence batch reactors (SBR) were operated at 26 ℃ and 32 ℃. The relationship between temperature and the concentration of free ammonia (FA) and free acid nitrite (FNA) was investigated. A stable PN process was achieved in the 32 ℃ reactor when the influent ammonium concentration was lower than 150 mg-N/L. In contrast, the PN process in the 26 ℃ reactor had a higher nitrite accumulation rate (NAR) and ammonium removal efficiency (ARE) when the influent ammonia concentration was increased to more than 150 mg-N/L. Then three different ranges of the K/A ratio were applied to an SBR reactor. In the K/A range of 2.48~1.65, the SBR reactor achieved the highest NAR ratio (75.78%). This ratio helps to achieve the appropriate level of alkalinity to maintain a stable pH and provide a sufficient amount of inorganic carbon source for the activity of microorganisms. At the same time, FA and FNA values also reached the threshold to inhibit nitrite-oxidizing bacteria (NOB) without a significant effect on ammonia-oxidizing bacteria (AOB). Results showed that the control of temperature and K/A ratio during the start-up period may be important in establishing a stable and steady PN process for the treatment of domestic wastewater.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.112-118
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• 2009

Ammonia-oxidizing bacteria (AOB) are chemolithoautotrophs that play a key role in nitrogen removal from advanced wastewater treatment processes. Various AOB species inhabit and their community compositions vary over time in the wastewater treatment bioreactors. In this study, a hypothesis that operational and environmental conditions affect both the community compositions and the diversity of AOB in the bioreactors was proposed. To verify the hypothesis, the clone libraries based on ammonia monooxygenase subunit A were constructed using activated sludge samples from aerobic bioreactors at the Pohang, the Palo Alto, the Nine Springs, and the Marshall wastewater treatment plants (WWTPs). In those bioreactors, AOB within the Nitrosomonas europaea, N. oligotropha, N.-like, and Nitrosospira lineages were commonly found, while AOB within the N. communis, N. marina, and N. cryotolerans lineages were rarely detected in the samples. The AOB community structures were different in the bioreactors: AOB within the N. oligotropha lineage were the major microorganisms in the Pohang, the Palo Alto, and the Marshall WWTPs, while AOB within the N. europaea lineage were dominant in the Nine Springs WWTP. The correlations between the AOB community compositions of the wastewater treatment bioreactors and their operational (HRT, SRT, and MLSS) and environmental conditions (temperature, pH, COD, $NH_3$, and $NO_3{^-}$) were evaluated using a multivariate statistical analysis called the Redundancy Analysis (RDA). As a result, COD and $NO_3{^-}$ concentrations in the bioreactors were the statistically significant variables influencing the AOB community structures in the wastewater treatment bioreactors.