• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.532-535
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• 2003

Indigenous bacterial mediation of As in contaminated sediment after biostimulation with a variety of carbon sources was investigated under aerobic and anaerobic conditions. Under the aerobic condition with lactate supply, indigenous bacteria increased the amount of total As extracted from the sediment and most dissolved As existed as As(V). Under the anaerobic, glucose-supplied condition, dissolved As diminished with time likely due to production of As sulfide(s) and subsequent precipitation, which resulted from bacterial reduction of ${SO_4}^{2-}$. The results implied that bacterial natural attenuation of As in subsurface has a potential to be practically applied.

• 한국가정과학회지
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• 제5권2호
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• pp.45-54
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• 2002

Packaged Backsulgi cooked by steam/convection oven and then rapidly chilled was examined by research of microbiological test and sensory evaluation while storing them at the temperatures of 3$^{\circ}C$ and 3$0^{\circ}C$ for 0, 2, 4, 6, 10 days . The pH and reducing sugar content were seemed to change little at 3$^{\circ}C$. However the pH was rapidly reduced until 4 days and then decreased a little at 3$0^{\circ}C$, the reducing sugar content was inclosed little by little. In the microbiological test, any microbial growth in total aerobic, psychrophilic, anaerobic, spore forming bacteria, yeast and molds was not observed until 10 days at 3$^{\circ}C$, but microbial changes of aerobic, psychrophilic and anaerobic bacteria increased to 6 logCFU/g until 10 days at 3$0^{\circ}C$. However microbial changes of them decreased from 6 logCFU/g to 5 logCFU/g. As a result of the sensory evaluation, appearance, taste, color, softness, chewiness and overall Quality were significantly decreased during storage times(p<0.05), but scores of taste and overall quality on 6th days were 7.38${\pm}$1.06, 7.00${\pm}$0.93. Therefore we concluded that there was no problem about stability of storage 6 days at 3$^{\circ}C$.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.89-91
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• 2000

Polynuclear aromatic hydrocarbon (PAH) compounds are highly carcinogenic chemicals and common groundwater contaminants that are observed to persist in soils. The adherence and slow release of PAHs in soil is an obstacle to remediation and complicates the assessment of cleanup standards and risks. Biological degradation of PAHs in soil has been an area of active research because biological treatment may be less costly than conventional pumping technologies or excavation and thermal treatment. Biological degradation also offers the advantage to transform PAHs into non-toxic products such as biomass and carbon dioxide. Ample evidence exists for aerobic biodegradation of PAHs and many bacteria capable of degrading PAHs have been isolated and characterized. However, the microbial degradation of PAHs in sediments is impaired due to the anaerobic conditions that result from the typically high oxygen demand of the organic material present in the soil, the low solubility of oxygen in water, and the slow mass transfer of oxygen from overlying water to the soil environment. For these reasons, anaerobic microbial degradation technologies could help alleviate sediment PAH contamination and offer significant advantages for cost-efficient in-situ treatment. But very little is known about the potential for anaerobic degradation of PAHs in field soils. The objectives of this research were to assess: (1) the potential for biodegradation of PAH in field aged soils under denitrification conditions, (2) to assess the potential for biodegradation of naphthalene in soil microcosms under denitrifying conditions, and (3) to assess for the existence of microorganisms in field sediments capable of degrading naphthalene via denitrification. Two kinds of soils were used in this research: Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS). Results presented in this seminar indicate possible degradation of PAHs in soil under denitrifying conditions. During the two months of anaerobic degradation, total PAH removal was modest probably due to both the low availability of the PAHs and competition with other more easily degradable sources of carbon in the sediments. For both Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS), PAH reduction was confined to 3- and 4-ring PAHs. Comparing PAH reductions during two months of aerobic and anaerobic biotreatment of MHS, it was found that extent of PAHreduction for anaerobic treatment was compatible with that for aerobic treatment. Interestingly, removal of PAHs from sediment particle classes (by size and density) followed similar trends for aerobic and anaerobic treatment of MHS. The majority of the PAHs removed during biotreatment came from the clay/silt fraction. In an earlier study it was shown that PAHs associated with the clay/silt fraction in MHS were more available than PAHs associated with coal-derived fraction. Therefore, although total PAH reductions were small, the removal of PAHs from the more easily available sediment fraction (clay/silt) may result in a significant environmental benefit owing to a reduction in total PAH bioavailability. By using naphthalene as a model PAH compound, biodegradation of naphthalene under denitrifying condition was assessed in microcosms containing MHS. Naphthalene spiked into MHS was degraded below detection limit within 20 days with the accompanying reduction of nitrate. With repeated addition of naphthalene and nitrate, naphthalene degradation under nitrate reducing conditions was stable over one month. Nitrite, one of the intermediates of denitrification was detected during the incubation. Also the denitrification activity of the enrichment culture from MHS slurries was verified by monitoring the production of nitrogen gas in solid fluorescence denitrification medium. Microorganisms capable of degrading naphthalene via denitrification were isolated from this enrichment culture.

• KSBB Journal
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• 제18권4호
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• pp.272-276
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• 2003

혐기성 미생물에 저해가 되는 물질을 포함하는 고농도 폐수의 효모에 의한 처리에 관하여 연구하였다. 폐수는 furfural 부산물이 배출되는 식품가공 공정의 배출폐수를 대상으로 실험하였다. 본 연구에서는 호기성 효모의 일종인 Candida utilis가 실험에 적용되었다. 회분 실험을 통하여 본 폐수는 혐기성 미생물에 저해 영향을 주는 것으로 밝혀졌다. 본 공정의 최적 온도는 25에서 45$^{\circ}C$이었으며 효모의 성장에 적당한 pH는 4에서 8사이임을 알 수 있었다. 연속실험 결과, 체류시간 1일 이상에서 COD가 90% 이상 제거되었다. 그러나 유출수 중의 유기물 농도는 여전히 다소 높은 것으로 조사되었다. 따라서 동력학적으로 해석하여 추정한 결과 남은 유기물은 대부분은 용존 미생물 생성물 (SMP, Soluble Microbial Product)에서 기인하는 것으로 판단되었다.

• 한국축산식품학회지
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• 제34권4호
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• pp.525-532
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• 2014

This study was designed to elucidate the effect of ozone exposure on the bacteria counts and oxidative properties of ground Hanwoo beef contaminated with Escherichia coli O157:H7 at refrigeration temperature. Ground beef was inoculated with 7 Log CFU/g of E. coli O157:H7 isolated from domestic pigs and was then subjected to ozone exposure ($10{\times}10^{-6}kg\;O_3h^{-1}$) at $4^{\circ}C$ for 3 d. E. coli O157:H7, total aerobic and anaerobic bacterial growth and oxidative properties including instrumental color changes, TBARS, catalase (CAT) and glutathione peroxidase (GPx) activity were evaluated. Ozone exposure significantly prohibited (p<0.05) the growths of E. coli O157:H7, total aerobic and anaerobic bacteria in ground beef samples during storage. Ozone exposure reduced (p<0.05) the CIE $a^*$ value of samples over storage time. The CIE $L^*$ and CIE $b^*$ values of the samples fluctuated over storage time, and ozone had no clear effect. Ozone exposure increased the TBARS values during 1 to 3 d of storage (p<0.05). The CAT and GPx enzyme activities were not affected by ozone exposure until 2 and 3 d of storage, respectively. This study provides information about the use of ozone exposure as an antimicrobial agent for meat under refrigerated storage. The results of this study provide a foundation for the further application of ozone exposure by integrating an ozone generator inside a refrigerator. Further studies regarding the ozone concentrations and exposure times are needed.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.260-265
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• 2002

Microbiologically influenced Corrosion (MIC) is one of the most deleterious effects of metal microbe interactions. When a fresh metal surface comes in contact with a non-sterile fluid, biofilm formation is ensued. This might result in the initiation of corrosion. The sites and materials where MIC is implicated are versatile. Industries such as shipping, power generation, chemical etc are reported to be affected. The rapid and unexpected failure of AISI type 304 stainless steel was investigated in the laboratory by simulation studies for a period of 4 months. Slime and water samples from the failure site were screened for corrosion causing bacteria. Both aerobic and anaerobic nora were enumerated and identified using PCR techniques. Pseudomonas sp. and Bacillus sp. were the most common aerobic bacteria isolated from the water and slime samples, whilst sulfate reducing bacteria (SRB) were the major anaerobic bacteria. The aerobic bacteria were used for the corrosion experiments in the laboratory. Coupon exposure studies were conducted using a very dilute (0.1%V/V) nutrient broth medium. The coupons after retrieval were observed under a Scanning Electron Microscope (SEM) for the presence of MIC pits. Compared to sterile controls, metal coupons exposed to Pseudomonas sp and Bacillus sp. showed the initiation of severe pitting corrosion. However, amongst these two strains, Psudomonas sp. caused pits in a very short span of 14 days. Towards the end of the experiment, severe pitting was observed in both the cases. The detailed observation of pits showed they vary both in number and shapes. Whilst the coupons exposed to Bacillus sp. showed widely spread scales like pits, those exposed to Pseudomonas sp. showed smaller and circular pits, which had grown in number and size by the end of the experiment. From these results it is inferred that the rapid and unexpected failure of 304 SS might be due to MIC. Pseudonwnas sp. could be considered as the major responsible bacteria that could initiate pits in the metallic structures. As the appearance of pits was different in both the tested strains, it was thought that the mechanisms of pit formation are different. Experiments on these lines are being continued.

• Journal of Microbiology and Biotechnology
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• 제27권12호
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• pp.2199-2210
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• 2017

Soil burial is the most widely used disposal method for infected pig carcasses, but composting has gained attention as an alternative disposal method because pig carcasses can be decomposed rapidly and safely by composting. To understand the pig carcass decomposition process in soil burial and by composting, pilot-scale test systems that simulated soil burial and composting were designed and constructed in the field. The envelope material samples were collected using special sampling devices without disturbance, and bacterial community dynamics were analyzed by high-throughput pyrosequencing for 340 days. Based on the odor gas intensity profiles, it was estimated that the active and advanced decay stages were reached earlier by composting than by soil burial. The dominant bacterial communities in the soil were aerobic and/or facultatively anaerobic gram-negative bacteria such as Pseudomonas, Gelidibacter, Mucilaginibacter, and Brevundimonas. However, the dominant bacteria in the composting system were anaerobic, thermophilic, endospore-forming, and/or halophilic gram-positive bacteria such as Pelotomaculum, Lentibacillus, Clostridium, and Caldicoprobacter. Different dominant bacteria played important roles in the decomposition of pig carcasses in the soil and compost. This study provides useful comparative date for the degradation of pig carcasses in the soil burial and composting systems.

• 상하수도학회지
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• 제26권3호
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• pp.399-408
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• 2012

The overall goal of this study was to characterize and quantify ammonia-oxidizing bacteria (AOB) in four different full-scale sequence batch reactor (SBR) wastewater treatment plants. Also, this study focused on assessing the occurrence of the alternative ammonia-oxidizing microbes such as anammox (anaerobic ammonia oxidation) bacteria (AMX) and ammonia-oxidizing archaea (AOA) in these systems. Based on total AOB numbers and the estimated cell density in the mixed liquor samples, AOB constituted 0.3 - 1.8% of the total bacterial population in the four WWTPs. Based on clone library, Nitrosomonas ureae-like AOB were dominant in plant A and B, while plant C and D had Nitrosomonas nitrosa-like AOB as major AOB group. The four different AMX primer sets targeting AMX 16S rRNA gene produced PCR amplicons distantly related to Chlamydia and Planctomycetales group bacteria. However, it was not clear these groups of bacteria perform anammox reaction in the SBR plants. Also, molecular evidence of AOA was found in one of the SBR plants, with a sequence located in the deep branch of the sediment creanarchaeota group.

• Journal of Microbiology
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• 제44권4호
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• pp.417-422
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• 2006

This study investigated the antibacterial effect of electrolyzed water on oral bacteria both in vitro and in vivo. Tap water was electrolyzed in a water vessel using platinum cell technology. The electrolyzed tap water (called Puri-water) was put in contact with five major periodontopathogens or toothbrushes contaminated with these bacteria for 30 sec. In addition, Puri-water was used as a mouthwash for 30 sec in 16 subjects and the antibacterial effect on salivary bacteria was evaluated. Puri-water significantly reduced the growth of all periodontopathogens in culture and on toothbrushes, and that of aerobic and anaerobic bacteria in saliva, when compared to the effect of tap water. It also significantly reduced mutans streptococci growing on mitis salivarius-bacitracin agar. Our results demonstrate that the electrolyzed tap water is effective as a mouthwash and for toothbrush disinfection.

• 미생물학회지
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• 제15권3호
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• pp.103-112
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• 1977

Several strains of spore-forming lacticacid bacteria were isolated from natural sources such as soils, cereals, and foods. The general morphological and physiological characteristics of the strain 6-4 were investigated nad compared with some other industrial strains. The effects of fructose-1,6-diphoshpate (FDP), adenosine triphosphate (ATP), and pH on the lactate dehydrogenase(LDH) activity of the strain were studied, and the changes in LDH activity and spore formation under various cultural conditions were researched. The results were as follows. 1. This strain was identified to Bacillus coagulans Hammer and distributed widely in natural sources. 2. The strain strongly converted various fermentation substrates in to L(+)-lacticacid in anaerobic conditioins, and many spores that were of great advantages to the industrial application were formed easily in the aerobic condition. 3. The LDH activity of this strain was activated by FDP and inhibited by ATP. The optimal pH for the enzyme activity was 6.0-6.5. 4. In the anaerobic culture condifion, the large amount of glucose added in the medium increased the LDH activity, but the cells were not committed to sporulate. 5. When none or a very small amount of glucose (less than 0.5%) was added to culture medium in the aerobic condition, the LDH activity was decreased and many spore were produced with final pH higher than 8.5. 6. The additioin of large amount of glucose (more than 2.0%) in aerobic culture increased the LDH activity and inhibited strongly the spore formation with final pH lower than 6.0.