• Korean Journal of Microbiology
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• v.41 no.3
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• pp.208-215
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• 2005

This study was accomplished in order to collect fundamental data on microbial roles in recycling process of reed rhizosphere. Sunchon bay, which is considered as one of the marsh and mud environments severely affected by human activities such agriculture and fisheries, was selected as a model place. In our initial efforts, two bacterial consortia were obtained by enrichment culture using PAH mixtures containing anthracene, naphthalene, phenanthrene and pyrene as the sources of carbon and energy, and four pure bacteria capable of rapid degradation of PAH were isolated from them. Four strains designated as SCB1, SCB2, SCB6, and SCB7 revealed by morphological, physiological and molecular analyses were identified as Burkholderia anthina, Alcaligenes sp., Achromobacter xylosoxidans., and Pseudomonas putida, respectively with over $99{\%}$ confidence. Notably, Burkholderia anthina SCB1 and Alcaligenes sp. SCB2 were found to utilize anthracene and pyrene more quickly than naphthalene and phenanthrene, whereas Achromobacter xylosoxidans SCB6 and Pseudomonas putida SCB7 exhibited similar growth and degradation patterns except for pyrene. These facts suggest that the rhizosphere microorganisms capable of PAH degradation might be used to clean up the contamination sites with polycyclic aromatic hydrocarbons.

• Advances in environmental research
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• v.2 no.3
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• pp.229-243
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• 2013

Coagulation-flocculation (CF) was tested coupled with an aerobic biofilter to reduce total petroleum hydrocarbon (TPHs) concentration and toxicity from petrochemical wastewater. The efficiency of the process was followed using turbidity and chemical oxygen demand (COD). The biofilter was packed with a basaltic waste (tezontle) and inoculated with a bacterial consortium. Toxicity test were carried out using Lactuca sativa var. capitata seeds. Best results for turbidity removal were obtained using alum. Considerable turbidity removal was obtained when using Opuntia spp. COD removal with alum was 25%, for Opuntia powder it was 36%. The application of the biofilter allowed the removal of 70% of the remaining TPHs after 30 days with a biodegradation rate (BDR) value 47 $mgL^{-1}d^{-1}$. COD removal was slightly higher with BDR value 63 $mgL^{-1}d^{-1}$. TPH kinetics allowed a degradation rate constant equal to $4.05{\times}10^{-2}d^{-1}$. COD removal showed similar trend with $k=4.23{\times}10^{-2}d^{-1}$. Toxicity reduction was also successfully achieved by the combined treatment process.

• Journal of Korean Society on Water Environment
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• v.36 no.3
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• pp.220-228
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• 2020

Anaerobic ammonium oxidation (AMX) is a cost-efficient biological nitrogen removal process. The coexistence of ammonia-oxidizing bacteria (AOB) in an AMX reactor is an interesting research topic as a nitrogen-related bacterial consortium. In this study, a sequencing batch reactor for AMX (AMX-SBR) was operated with a conventional activated sludge. The AOB in an AMX bioreactor were identified and quantified using terminal restriction fragment length polymorphism (T-RFLP) and real-time qPCR. A T-RFLP assay based on the ammonia monooxygenase subunit A (amoA) gene sequences showed the presence of Nitrosomonas europaea-like AOB in the AMX-SBR. A phylogenetic tree based on the sequenced amoA gene showed that AOB were affiliated with the Nitrosomonas europaea/mobilis cluster. Throughout the enrichment period, the AOB population was stable with predominant Nitrosomonas europaea-like AOB. Two OTUs of amoA_SBR_JJY_20 (FJ577843) and amoA_SBR_JJY_9 (FJ577849) are similar to the clones from AMX-related environments. Real-time qPCR was used to quantify AOB populations over time. Interestingly, the exponential growth of AOB populations was observed during the substrate inhibition of the AMX bacteria. The specific growth rate of AOB under anaerobic conditions was only 0.111 d^-1. The growth property of Nitrosomonas europaea-like AOB may provide fundamental information about the metabolic relationship between the AMX bacteria and AOB.

• Journal of Microbiology
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• v.42 no.3
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• pp.216-222
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• 2004

In a previous paper, the ogdH gene that encodes 2-oxoglutarat dehydrogenase was isolated from Salmonella typhimurium. The catalytic N-terminal region in the enzyme was found to be very specific for the Salmonella species. Therefore, the aim of the present study was to detect S. typhimurium in food sources using primers designed for OGDH-l and OGDH-2 which were based on the salmonella-specific region of the ogdH gene. A simple polymerase chain reaction (PCR) detection method was developed to detect low numbers of S. typhimurium in a chicken meat microbial consortium. Using the ogdH-specific primers under stringent amplification conditions and for gene probe analysis, fewer than 100 colony-forming units (CFUs) were detectable when pure cultures were employed. When the PCR assay was run on S. typhimurium-contaminated meat contents, only the positive meat samples containing as few as 200 CFUs reacted to the assay. The method employed for sample processing is simple and it was determined to provide a sensitive means of detecting trace amounts of S. typhimurium-specific sequences in the presence of mixed meat microbial populations. When compared with six representative intestinal gram-negative bacterial strains in foods, including Vibrio parahaemolyticus, V. vulnificus, Enterobacter cloacae, E. coli O157:H7, Pseudomonas aeruginosa, and Proteus sp., S. typhimurium had a unique and distinct PCR product (796 bp). In conclusion, the two OGDH primers were found to be rapid and sensitive detectors of Salmonella spp for the PCR method.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.144-149
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• 2006

As a strain EH741, having an excellent hexane degradability, was isolated from bacterial consortium using hexane as a sole carbon and energy source. EH741 was identified as a Rhodococcus sp. and the addition of a surfactant Pluronic F68(PF68), for increasing hexane solubility couldn't enhance the specific growth rate of the isolate EH741 n the mineral salt medium supplemented with hexane as a sole carbon source(hexane-BH medium). In the hexane-BH medium, the maximum specific growth rate(${\mu}_{max}$) of this strain was $0.04h^{-1}$, and the maximum hexane degradation rate($V_{max}$) and saturation constant($K_s$) were$161{\mu}mol{\cdot}g-DCW^{-1}{\cdot}h^{-1}$ and 10.5 mM, respectively. Rhodococcus sp. EH741 was one of excellent microorgamisms for hexane biodegradation processes.

• KSBB Journal
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• v.22 no.3
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• pp.157-161
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• 2007

This study is to investigate the biological degradation and the characteristics of MEA, a pH regulator to be put in the cooling water circulation system for power plants, loading to elevate concentrations of COD and N when eluted into the water environment. MEA, $NH_4^+$ and CODcr were monitored in flask cultures and in a batch aerator. MEA was found to be biologically degradable, producing substantial amount of ammonia (max. 78.1%) in a form of $NH_4^+$ and other carboneous intermediates. The degradation reaction rates were similar one another over all MEA concentrations tested as the activated sludge (microbial consortium) was acclimated to MEA with the gradual and stepwise increase in MEA input into the batch aerator. Also, MLVSS kept increasing with increasing MEA input. The COD-based degradation reaction order was determined to be 1.

• Journal of Microbiology and Biotechnology
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• v.23 no.12
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• pp.1765-1773
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• 2013

The cathode reaction is one of the most seriously limiting factors in a microbial fuel cell (MFC). The critical dissolved oxygen (DO) concentration of a platinum-loaded graphite electrode was reported as 2.2 mg/l, about 10-fold higher than an aerobic bacterium. A series of MFCs were run with the cathode compartment inoculated with activated sludge (biotic) or not (abiotic) on platinum-loaded or bare graphite electrodes. At the beginning of the operation, the current values from MFCs with a biocathode and abiotic cathode were $2.3{\pm}0.1$ and $2.6{\pm}0.2mA$, respectively, at the air-saturated water supply in the cathode. The current from MFCs with an abiotic cathode did not change, but that of MFCs with a biotic cathode increased to 3.0 mA after 8 weeks. The coulomb efficiency was 59.6% in the MFCs with a biotic cathode, much higher than the value of 15.6% of the abiotic cathode. When the DO supply was reduced, the current from MFCs with an abiotic cathode decreased more sharply than in those with a biotic cathode. When the respiratory inhibitor azide was added to the catholyte, the current decreased in MFCs with a biotic cathode but did not change in MFCs with an abiotic cathode. The power density was higher in MFCs with a biotic cathode ($430W/m^3$ cathode compartment) than the abiotic cathode MFC ($257W/m^3$ cathode compartment). Electron microscopic observation revealed nanowire structures in biofilms that developed on both the anode and on the biocathode. These results show that an electron-consuming bacterial consortium can be used as a cathode catalyst to improve the cathode reaction.

• Resources Recycling
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• v.24 no.6
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• pp.69-77
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• 2015

Heap bioleaching for detoxification of mine tailings is a promising technology; however, long-term studies that aim to understand the potential of this process are scarce. Therefore, this study assesses the feasibility of column bioleaching as an alternative technology for treatment of mine tailings with high concentrations of arsenic during a long-term experiment (436 days). To accomplish this objective, we designed a 350-mm plastic column that was packed with 750 g of mine tailings and inoculated with an acidophilic bacterial culture composed of A. thiooxidans and A. ferrooxidans. Redox potential, pH, ferric ion generation, and arsenic concentration of the off-solution were continuously monitored to determine the efficiency of the technology. After 436 days, we obtained up to 70% arsenic removal. However, several drops in removal rates were observed during the process; this was attributed to the harmful effect of arsenic on the bacteria consortium. We expect that this article will serve as a technical note for further studies on heap bioleaching of mine tailings.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.4
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• pp.179-185
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• 2005

Polycyclic aromatic hydrocarbons (PAHs) are a kind of toxic environmental pollutants and has been accumulated usually in marine sediments. Due to their potential hazardous to human, removal of PAHs from environments has been great concern. In the present study, the effect of microbial inoculation and the supplementation of mixed form cyclodextrin (M-CD) was assessed in the pre-sterilized or nonsterilized microcosms for optimizing operational conditions for ex situ bioremediation of sediments contaminated by PAHs. Activity of electron transport system (ETSA) was increased by the addition of M-CD regardless of inoculation of microorganisms in microcosms without sterilization. The degradation rate of PAHs in sterilized microcosms was app. 9-20% by the inoculation of single strain and 24-37% by the inoculation of microbial consortium supplemented with 1% M-CD, respectively. The degradation was not observed in microcosms without sterilization under the same conditions. The proportion of inoculated microorganisms also decreased in nonsterilized microcosms. Signals of inoculated bacteria were decreased to detection limit after 2 days in the microcosms without M-CD. In conclusion, microbial inoculation with appropriate carbon sources and removal of natural flora and grazers are required for the efficient ex situ bioremediation of sediments contaminated by PAHs in bioslurry reactor.