• 한국환경농학회지
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• 제37권2호
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• pp.146-149
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• 2018

아셀렌산염(selenite, ${SeO_3}^{2-}$)을 환원시키는 세균 SE4-1을 복합 산업단지 내 위치한 오염된 하천 퇴적토로부터 분리하였고, 계통분석결과 이 균주는 Citrobacter freundii와 가장 유사하였다. 이 균주는 혐기적 환경에서 아셀렌산염을 원소상 셀레늄(elemental selenium, $Se^0$)으로 환원시켰고, 그 형상은 구형으로 확인되었다. 이러한 고체상의 침전은 셀레늄 산소음이온의 이동성을 줄이고 생물가용성을 줄여, 생태계 독성을 줄이는 잠재성을 제시해 줄 수 있을 것이다.

• 동아시아식생활학회지
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• 제27권1호
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• pp.78-87
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• 2017

The objective of this study was to investigate the effects of various washing waters on the quality and safety characteristics of eggs during storage. Eggs were washed with tap water, 100 ppm of sodium hypochlorite, or 30 ppm of slightly acidic electrolyzed water and stored at $10^{\circ}C$ and $20^{\circ}C$. Effects of various washing waters on reduction of Salmonella Enteritidis and aerobic plate counts and survival of S. Enteritidis on egg shells were also analyzed at $10^{\circ}C$ and $20^{\circ}C$ for 25 days. As an index of quality, haugh unit, weight reduction, and pHs of egg white and egg yolk were measured. Reduction percentages of haugh unit and weight were higher at $20^{\circ}C$ than at $10^{\circ}C$. Egg qualities were less affected by tap water, slightly acidic electrolyzed water, and sodium hypochlorite, regardless of storage temperature. The greatest reductions in aerobic plate counts and S. Enteritidis were observed with slightly acidic electrolyzed water. The level of S. Enteritidis on egg shells gradually decreased during 20 days of storage at both $10^{\circ}C$ and $20^{\circ}C$, whereas S. Enteritidis survived longer at $20^{\circ}C$ than at $10^{\circ}C$. S. Enteritidis was not detected in eggs at $10^{\circ}C$, 2.13 log CFU/g of S. Enteritidis was detected in eggs washed with sodium hypochlorite after 20 days of storage at $20^{\circ}C$, indicating that S. Enteritidis penetrated into the egg shell during storage at $20^{\circ}C$. In conclusion, slightly acidic electrolyzed water increased microbial reduction and least affected quality of washed eggs. Thus, slightly acidic electrolyzed water can be recommended for washing of graded eggs, at retail markets.

• 한국축산식품학회지
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• 제39권4호
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• pp.677-685
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• 2019

Five Leuconostoc strains (CM17, CM19, PM30, PM32, and PM36) previously isolated from Indian meat showed promising antimicrobial activity against food pathogens in screening assay. This study evaluates the efficacy of these isolates against Escherichia coli Microbial Type Culture Collection and Gene Bank (MTCC) 443 and Listeria monocytogenes (MTCC 657) in spinach leaves. Challenge studies were conducted by inoculating E. coli and L. monocytogenes at 6 to 7 $Log_{10}CFU/g$ of the leaves respectively and treating them with cell free supernatant (CFS) of 48 h cultures of the isolates. The samples were stored at $4^{\circ}C$ and analyzed over a period of 5 d. The study was conducted in triplicates and statistical analysis was carried out using one-way Anova. The counts of the pathogens did not increase over the 5 d period in the control samples, without any treatment. Whereas in the case of CFS treatments, significant reduction (p<0.05) was observed in both E. coli and L. monocytogenes from 1 to 5 d with all the 5 strains as compared to the control. The counts of Listeria dropped by 0.5 to 1 log by 5 d, with PM 36 showing the highest reduction (1 log). In the case of E. coli, 1.1 to 1.5 log reduction was observed by 5 d, with again PM 36 showing the highest reduction (1.5). The overall results indicate that the isolates (specifically PM36) not only showed efficacy in in vitro studies but are also proved to be effective in food matrix making them potential clean label antimicrobial alternatives for food application.

• 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.

• Ocean and Polar Research
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• 제33권4호
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• pp.435-445
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• 2011

We investigated geochemical properties, and microbial sulfate- and iron(III) reduction in sediment influenced by the aquaculture of abalone in the Nohwa-do, southern coastal sea in Korea. Concentrations of ammonium, phosphate, and sulfide in the pore-water were higher at farm sites than at control sites. The differences between the 2 types of sites were most apparent in terms of the weights of abalone and the temperature increase during September. Accordingly, the rates of sulfate reduction at the farm sites during September (61 mmol S $m^{-2}d{-1}$) were 3-fold higher than the sulfate reduction during May (20 mmol S $m^{-2}d{-1}$). In contrast, Fe(III) reduction rates were highest at the control sites in May, but its significance was relatively decreased at farm sites during September when sulfate reduction rates were highest. During September, benthic ammonium flux was 3-fold greater at the farm sites (35 mmol N $m^{-2}d{-1}$) than at the control sites (12 mmol N $m^{-2}d{-1}$), and phosphate flux was 8-fold higher at the farm sites (0.018 mmol P $m^{-2}d{-1}$) than at control sites (0.003 mmol P $m^{-2}d{-1}$). Overall results indicated that the inappropriate operation of a large-scale aquaculture farm may result in excess input of biodeposits and high nutrient fluxes from the sediment, thereby decreasing diversity of the benthic ecosystem and deepening eutrophication in coastal waters.

• 한국식품위생안전성학회지
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• 제34권4호
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• pp.361-366
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• 2019

본 연구에서는 다슬기 중의 자연균총의 정량적 오염도 분석과 해감 제거 공정(지하수, 상수)에 따른 저감화 효과를 조사하였다. 다슬기 중의 일반세균, 대장균군과 대장균, 진균 및 황색포도상구균의 정량적 검출을 위해 표준평판법을 사용하여 각각 plate count agar (PCA), potato dextrose agar (PDA), 대장균군/대장균용 3M Petrifilm 및 황색포도상구균용 3M Petrifilm에 도말하여 집락을 계수하였다. 지하수와 상수 처리에 따른 이들 균의 저감화 정도 역시 동일한 방법으로 수행되었다. 다슬기 원료 중의 미생물 오염도 분석시, 일반세균, 대장균군 및 진균은 각각 6.40, 2.70 및 $6.79{\log}_{10}CFU/g$로 조사되었다. 대장균과 황색포도상구균은 검출되지 않았다 (검출 한계: < $1{\log}_{10}CFU/g$). 그러나, 지하수로 해감 제거한 다슬기의 경우, 분석된 모든 미생물의 정량적 오염도가 원료 다슬기에 비해 높게 검출되었다. 특히 원료 다슬기에서 불검출이었던 대장균도 $2.46{\log}_{10}CFU/g$ 검출되었다. 상수로 해감 제거한 다슬기의 일반세균은 유의적으로 저감화 되지 않았으며(p<0.05), 대장균군은 유의적으로 증가하는 경향을 나타내었다(p>0.05). 진균만이 약간의 저감화(0.2 log 이하)를 유의적으로 보였다(p>0.05). 본 연구결과 지하수와 상수를 이용해서 해감 제거하는 공정만으로는 다슬기의 미생물학적 안전성을 확보하기 곤란한 것으로 판단된다.

• 대한치과보철학회지
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• 제36권1호
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• pp.64-80
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• 1998

The risk of cross-contamination in dental clinic is very high. Those who are engaged in dental clinic are exposed to various microorganisms in saliva and blood of patient. Potential possibility of cross-contamination of patient to patient, patient to dentist, dentist to laboratory technician always exist, which is important in the view of public health. It is well known that microorganisms may cause cross-contamination by suck-back of microorganisms into the water supply line or air supply line of dental unit and sprayed back into the next patient's oral cavity. The majority of microorganisms coming from dental unit are water microorganisms from the main water supply which have colonized the tube within the units and multiplied in the relatively warm and stagnant conditions. The purpose of this study is to measure the extent of microbial contamination of dental unit and ultrasonic scaler, to evaluate that dental unit water supply is suitable for drinking water, and to assess the effect of flushing on reduction of microbial contamination of dental unit and ultrasonic scaler. In the first experiment, water samples(50ml) from 20 dental units and 10 ultrasonic scalers in Seoul National Univ. Hosp. were tested for the presence of coliform. The samples were filtered by membrane filtration technique.(Microfil system, Millipore Co. U. S. A.) The filter was then placed onto MacConkey agar plate and the plates with filter on it were incubated aerobically at $37^{\circ}C$ for 5 days. The colors and shapes of colonies were examined if those were coliform. To verify the presence of coliform, the colonies were inoculated into phenol red lactose broth and incubated aerobically at $37^{\circ}C$ for 2 days. The fomation of gas was observed. In the second experiment, water samples from 20 handpieces, 10 ultrasonic scalers and 30 A/W syringes after 0, 2, 4, 6 min. flushing respectively were taken. $200{\mu}l$ water samples were spreaded on Brain Heart Infusion agar plate and the plates were incubated aerobically at $37^{\circ}C$ for 5 days. The number of colony was counted. The results obtained were summarized as follows 1. The water from dental unit and ultrasonic scaler was not suitable for drinking water. 2. No coliform was founded in dental unit and ultrasonic scaler water supply. 3. The number of colony of dental unit and ultrasonic scaler was highest in the group of o min. flushing(p<0.05). 4. There was no statistically significant difference in the extent of microbial contamination among handpiece, ultrasonic scaler and A/W syringe (p>0.05). 5. The number of colony was lowest in the group of 4 min. flushing, but there was no statistically significant difference among 2, 4, 6 min. flushing groups.(p>0.05) 6. It is recommended to flush dental unit water line for 4 min. after use on each patient.

• 한국식품과학회지
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• 제52권5호
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• pp.529-537
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• 2020

본 연구에서는 재래누룩을 사용한 막걸리의 미생물 군집을 차세대 염기서열 분석기법(NGS)을 활용하여 조사하고, 미생물 군집이 막걸리의 품질에 미치는 영향을 구명하고자 효모 첨가에 따른 품질특성을 확인하였다. 발효 스타터로 효모의 첨가는 재래누룩 막걸리의 미생물 군집 분포에 영향을 주어 결과적으로 막걸리의 품질 차이를 나타냈다. 무첨가구의 경우 발효 초기의 진균류는 Saccharomycopsis fibuligera가 대부분이었고, 세균류는 Pediococcus pentosaceus, Weissella confusa, Pantoea vagans의 증식으로 인하여 총산 및 젖산 함량이 높게 나타났다. 첨가구는 발효 시작 전부터 Saccharomyces cerevisiae가 우점하여 알코올 생성 속도가 빠르고, 발효 초기의 높은 알코올 농도로 인해 재래누룩에서 기인한 젖산 생성 bacteria의 생육을 억제하는 것으로 나타났다. 따라서 재래누룩으로 막걸리를 제조할 때, 알코올 생성능이 우수한 효모의 첨가가 막걸리 시어짐의 원인이 되는 젖산균의 성장을 억제함으로써 산미를 낮추고 제품의 균일성을 확보할 수 있을 것으로 판단된다.

• 한국토양환경학회지
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• 제4권3호
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• pp.57-65
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• 1999

퇴비 제조장에서 발생하는 여러 가지 악취원 중 가장 문제가 되는 암모니아가스의 발생량을 감소시키기 위하여 (주)인바이오넷에서 유용미생물을 제제화 하여 개발한 미생물종균제, KMT-199(상품명: 콤포백)를 사용하여 현장시험을 수행하였다. KMT-199를 첨가한 경우 퇴비화 초기단계에서의 중온성, 고온성 미생물밀도가 무처리구에 비하여 10배 이상 증가되었으며, 발효 초기의 퇴비 내 온도와 pH의 증가 폭이 크게 나타났다. 온도는 KMT-199가 첨가된 처리구에서 발효 9일째, $75^{\circ}C$로 가장 높게 측정되어 무처리구에 비하여 퇴비의 최고 발열 시간을 3일 앞당겼으며, 최고 온도는 $4^{\circ}C$높았다. pH는 퇴비화가 진행되면서 지속적으로 증가되었는데, KMT-199가 첨가된 처리구에서는 발효 15일 째 이후에는 더 이상 증가하지 않고 감소되는 경향을 보였으나, 무처리구에서는 발효 38일째 까지 지속적으로 증가하는 경향을 나타내었다. 교반식 퇴비화 공정에 KMT-199를 투여한 결과 암모니아 가스의 발생량을 무처리구에 비하여 29%감소시킬 수 있었다. KMT-199를 사용하여 제조된 퇴비의 경우 대조구에 비하여 무 종자의 발아율이 증가하는 것으로 나타났다. 이것은 퇴비화 과정에서 미생물 생태를 변화시켜 줌으로서 퇴비화 과정에서 발생되는 유기물의 분해 촉진, 퇴비의 온도상승, 화학적변화의 촉진으로 퇴비의 부숙도 증가와 암모니아 가스 발생량이 감소된다는 것을 나타낸다.

• Applied Biological Chemistry
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• 제38권4호
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• pp.340-344
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• 1995

시중에서 구입한 출하 3일된 바나나를 5, 15, $25^{\circ}C$로 10일간 저장하면서 당과 유기산을 측정한 결과는 다음과 같다. 바나나 중의 유리당으로 glucose, fructose, sucrose가 확인되었다. 저장초(0일)의 각 유리당은 $0.30{\sim}0.36%$의 미량으로 sucrose가 다소 높았다. 저장기간의 경과에 따라 유리당 총량이 증가되었으나 저장온도에 따라 각 유리당 함량은 많은 차이를 보였다. $5^{\circ}C$ 저장구에서 각 유리당의 함량은 거의 변화가 없었고 유리당 중 sucrose가 다소 높았다. $15^{\circ}C$와 $25^{\circ}C$ 저장구에서 sucrose는 감소하고 glucose와 fructose는 현저히 증가하였으며 glucose는 fructose 보다 함량이 다소 높았다. $25^{\circ}C$ 저장구에서 총당, 환원당, glucose, fructose 및 유리당 총량이 시험구 중 가장 높았다. 유기산으로 citric acid, malic acid, lactic acid, acetic acid가 확인되었다. 저장 3일에 citric acid의 함량이 가장 높았으나 이후 현저히 감소되었고 acetic acid는 저장 초기보다 다소 증가되었다. 유기산 총량은 저장초 $305{\sim}373.3$ mg%였으나 9일에는 $45.9{\sim}67.9$ mg%로 현저히 감소하였고, $25^{\circ}C$ 저장구에서 감소가 컸다.