• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.757-762
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• 2016

The group of Fe(III) oxide-reducing bacteria includes exoelectrogenic bacteria, and they possess similar properties of transferring electrons to extracellular insoluble-electron acceptors. The exoelectrogenic bacteria can use the anode in microbial fuel cells (MFCs) as the terminal electron acceptor in anaerobic acetate oxidation. In the present study, the anodic community was compared with the community using Fe(III) oxide (ferrihydrite) as the electron acceptor coupled with acetate oxidation. To precisely analyze the structures, the community was established by enrichment cultures using the same inoculum used for the MFCs. High-throughput sequencing of the 16S rRNA gene revealed considerable differences between the structure of the anodic communities and that of the Fe(III) oxide-reducing community. Geobacter species were predominantly detected (>46%) in the anodic communities. In contrast, Pseudomonas (70%) and Desulfosporosinus (16%) were predominant in the Fe(III) oxide-reducing community. These results demonstrated that Geobacter species are the most specialized among Fe(III)-reducing bacteria for electron transfer to the anode in MFCs. In addition, the present study indicates the presence of a novel lineage of bacteria in the genus Pseudomonas that highly prefers ferrihydrite as the terminal electron acceptor in acetate oxidation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.210-224
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• 2003

Sulfate reduction is a microbiological process which occurs ubiquitously in anaerobic marine environment. Sulfate reducing bacteria play a significant role in anaerobic decomposition of organic matter and regeneration of inorganic nutrients which supports the primary production in the water column (i.e., benthic-pelagic coupling) and, in special case, could be responsible for the harmful algal bloom in the coastal marine environment. Summary of the sulfate reduction rates reported in various marine sedimentary environments revealed that supply of organic substrates and presence of various electron acceptors (i.e., $O_2$, NO$_{3}$$^{[-10]}$ , Fe(III) and Mn(IV), etc.) for other aerobic and anaerobic respiration directly affect the sulfate reduction rate and relative significance of sulfate reduction in organic matter mineralization. Significance of temperature, macrophytes and bioturbation is discussed as factors controlling supply of organic substrates and distribution of electron acceptors. Finally, we suggest studies on the anaerobic microbiological processes associated with biogeochemical element cycles in the coastal environments of Korea where massive operation of organic enriched fish cage farm, frequent occurrence of toxic algal bloom and hypoxia and conservation of tidal flat are of major environmental issues.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.575-585
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• 2007

Microbial control of the geochemical behavior of heavy metals (Cd, Cu, Pb, and Zn) and As in contaminated subsurface soil and sediment was investigated through activation of indigenous bacteria with lactate under anaerobic condition for 25 days. The results indicated that dissolved Cd, Pb and Zn were microbially removed from solutions, which was likely due to the formation of metal sulfides after reduction of sulfate by indigenous sulfate-reducing bacteria. Soils from the Dukeum mine containing a large amount of sulfate resulted in complete removal of dissolved As after 25 days by microbial activities, while there were gradual increases in dissolved As concentration in soils from the Hwabuk mine and sediments from the Dongducheon industrial area which showed low $SO_4{^2-}$ concentrations. Addition of appropriate carbon sources and sulfate to contaminated geological media may lead to activation of indigenous bacteria and thus in situ stabilization of the heavy metals; however, potential of As release into solution after the amendment should be preferentially investigated.

• Journal of the Mineralogical Society of Korea
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• v.24 no.4
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• pp.279-287
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• 2011

In order to identify if bacteria surviving in soils and groundwater can change the oxidation/reduction potential of groundwater, Eh values of solution that contained bacteria were measured for 2 weeks. The Eh values of the solution reacted with sulfate-reducing bacteria decreased from -120 mV to -500 mV in 5 days, and $Desulfuricans$ was superior to $Vulgaris$ in reducing the solution. The Eh value was relatively higher for the solution containing $Shewanella$, iron-reducing bacteria, showing -400 mV. During the Eh decrease by the metal-reducing bacteria, a sulfide mineral such as mackinawite (FeS) started precipitating through the microbial reducing process for sulfate and ferric iron. These results show that the ORP of natrual groundwater may be sensitive to the geomicrobial respiration. In addition, a subsurface environment where groundwater is highly reduced and sulfide minerals are largely biogenerated may be a good place to retard the migration of oxidized radionu-clides by making them precipitated as reduced forms.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.55 no.6
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• pp.527-537
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• 2018

Column tests of a sulfate reducing bacteria (SRB) bioreactor were conducted to determine the design factors for sulfate-rich mine drainage. Various substrates were applied to the bioreactor, including cow manure and its mixture with a mushroom compost, with rice straw and limestone as subsidiary materials. This procedure provided a removal efficiency of up to 82% of the total sulfur with the mixture of cow manure (70%), mushroom compost (10%) and rice straw (20%), and higher efficiencies were observed after 2 days of retention time. In the downflow condition of the flow direction, oxygen supply and re-oxidation of the sulfates occurred, causing a decrease in sulfate removal efficiency. The addition of an inorganic sludge containing heavy metals, which was intended for production of metal-sulfides in the bioreactor, had a negative effect on the long-term operation owing to arsenic release and toxicity to the SRB. The results thus show that a bioreactor using a mixed substrate with cow manure and operating in the downflow direction could reduce sulfates and total dissolved sulfur content; this process confirms the applicability of the SRB bioreactor to sulfate-rich saline drainage.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.1
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• pp.13-21
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• 1996

For treating tannery wastewater containing high sulfate and heavy metals, test was performed to assess their performance, competition between SRB (sulfate reducing bacteria) and MPB (methane producing bacteria), and the activity of MPB according to change of chromium concentrations. COD removal efficiency was above 70% at VLR (volumetric loading rate) of 2.0 gCOD/I.day and HRT (hydraulic retention time) of 18hrs at $35^{\circ}C$. In the competition between SRB and MPB, about 15% of the removed COD was utilized by SRB in the begining, but it became 43% at the end. It indicated that MPB was strongly suppressed by the occurrence of significant sulfate reduction since a large electron flow was uptaken by SRB. For the entire experiment, removal efficiencies of chromium concentration were more than 90%. Despite high removal efficiencies of chromium concentration, performance of reactor did not change significantly during the experimental periods. Expecially, chromium (III) is tannery wastewater is less toxic than chromium (VI).

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.843-853
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• 2009

The sediment samples were collected from Seonakdong River and were analyzed for sulfide species such Acid Volatile Sulfide(AVS) and Elemental Sulfur(ES) and Chromium Reducible Sulfide(CRS). Then characteristics of the formation of sulfide species were investigated for six selected samples. Finally the relationship between environmental factors and sulfate reducing rate(SRR) was investigated using two selected samples. Concentrations of AVS and CRS were relatively high, which suggests that organics input to the sediments has been continued until recently and that potential of heavy metals leaching from the sediments is low. SRR in the sediments was closely related to fraction of fine particles(silt+clay) and also to dissolved organic carbon content of the sediment(DOCsed). The dependences of environmental factors such as organic content, temperature, sulfate concentration on the SRR was relatively strong in the selected experiments conducted with the samples from Noksan gate and Daejeo gate samples. The environmental factor dependencies were stronger in the Noksan gate samples than in the Daejeo gate samples, which is probably due to higher surface area of the Noksan gate sediments.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.260-265
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• 2004

Acid mine drainage(AMD) is one of the most serious environmental concerns associated with the mining industry around the world. The objective of this study is to assess the potential of sewage sludge as a carbon source for sulfate reducing bacteria and waste lime and steel slag as a neutralize agent for acid mine drainage bioremediation for use in permeable reactive materials. The study was performed using synthetic AMD in six column experiments. The effluent solution was systematically analysed throughout the experiments. The results of the study indicated that sewage sludge, waste lime and steel slag were the most effective for the AMD treatment as a permeable reactive materials.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.5
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• pp.472-479
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• 2012

The formation of volatile fatty acids(VFAs) and changes in pH, oxidation and reduction potential(Eh) and acid volatile sulfide(AVS) with the addition of yellow clay were investigated using microcosm systems to examine the effects of yellow clay dispersion on the anaerobic decomposition of Cochlodinium polykrikoides in marine sediments. The acetate concentration reached a maximum by day 4 and was 1.2-1.8 fold less in the sample treated with yellow clay compared to the untreated sample (224-270 vs. 333 uM). The formate concentration reached a maximum by day 1 and was 1.3-2.8 fold less in the sample treated with yellow clay compared to the untreated sample (202-439 vs. 563 uM). The propionate concentration reached a maximum by day 2 and was 1.5-1.8 fold less in the sample treated with yellow clay compared to the untreated sample (32.6 vs. 57.2 uM). After the amounts of acetate, formate and propionate peaked the levels dropped dramatically due to the utilization by sulfate reducing bacteria. The Eh of the samples treated with yellow clay was similar to the untreated sample on day 0 but was higher in the sample treated with yellow clay(140-206 mV) from days 4 to 17. AVS started to form on day 3 and this was sustained until day 6, and 1.2-2.2 fold less was produced in the sample treated with yellow clay compared to the untreated sample (40.2-69.3 vs. 83.2-93.8 mg/L). Accordingly, during the anaerobic decomposition of C. polykrikoides in marine sediments, yellow clay dispersal seems to suppress the reduction state of Eh and the formation of volatile fatty acids(acetate, formate and propionate) used as an energy source by sulfate reducing bacteria, indicating that this process controls the production of hydrogen sulfide that negatively affects marine organisms and the marine sediment environment.

• Journal of Animal Environmental Science
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• v.4 no.2
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• pp.137-147
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• 1998

This study was carried out to find deodorization effect of swine-slurry by addition of phototrophic bacteria(PTB). The pilot-scale reactors operation conditions was designed by the inoculum amounts of PTB and light-conditions. Treatment conditions was divided into 3 types; 106 MPN/ml$.$Dark(T-1), 108 MPN/ml$.$Dark(T-2), 108 MPN/ml$.$Natural light(T-3). The changes of the concentration of volatile fatty acids(VFAs), hydrogen sulfide(H2S), ammonia (NH3) and odor intensity were analyzed during the treatment period(35 days). From results of this study, the maximum intensity of odor in the headspace of the reactor T-1 was 4.82 and T-2, T-3 was 2.63, respectively. In swine-slurry of reactors used, it almost took 10 days until to be stabilized with solid and liquid phase. Intensity of odor in headspace was mainly derived from the liquid phase. The PTB inoculum method to swine-slurry was very effective in reduction of VFAs, H2S and Sulfate-reducing bacteria(SRB) concentration. Expecially, It was interested in reverse growth behaviour of SRB and PTB in these conditions.