• 대한수의학회지
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• 제46권3호
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• pp.255-261
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• 2006

Experimental animals have been used to biological and medical purposes and the animals must be, for these purposes, healthy and clean to microbial infection. However, the animals can be easily exposed to pathogenic microorganism via several routes. Of the routes, environmental conditions are the most important factors to keep the animals healthy and clean, especially air condition. Monitoring of air-condition has been required to keep the animal healthy and clean. However, any guideline is not available for experimental conditions with pigs. Therefore, the sampling times and points were compared in different conditions to establish an optimal protocol for monitoring of air borne bacteria. Tryptic soy agar(TSA), blood agar containing 5% defibrinated sheep blood and Sabraud dextrose agar(SDA) were used as media to capture total bacteria, pathogenic bacteria and fungi, respectively. Two methods, compulsive capture using an air-sampler and capturing fall-down bacteria were used to capture the microorganisms in the air. The points and time of capturing were different at each experiment. Air borne microorganisms were captured at three and five points in the open and closed equipments, respectively. Air was collected using an air-sampler for 1 min and 5 min and the agar plates as open status were left from 30 min to 2hr. At first, we monitored an experimental laboratory which dealt with several pathogenic bacteria and then, a protocol obtained from the investigation was applied to open or close experimental conditions with pigs. Number of bacteria was high from 10:00 to 15:00, especially on 13:30-15:30 but sharply decreased after 17:00. The tendency of the number of bacteria was similar between two methods even though the absolute number was higher with air sampler. Critical difference in the number of cells was observed at 5 min with air sampler and 2 hr with fall-down capturing method. However, 1 min with air sampler and 1 hr with fall-down capturing were the best condition to identify bacterial species collected from the air. Number of bacteria were different depending on the sampling points in closed condition but not in opened condition. Based on our results, a guide-line was suggested for screening air-borne microorganism in the experimental conditions with pigs.

• 한국식품과학회지
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• 제36권6호
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• pp.1020-1025
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• 2004

생식제품 및 제조 공정 중 위해 미생물의 제어 및 저감화를 위하여 제조공정을 개선하고 전해수, 오존수 등 살균효과에 대하여 조사하였다. 7가지의 위해미생물 오염도가 높은 생식원료에 대한 전해수의 살균효과가 차아염소산소다수 또는 오존수에 비하여 전체적으로 강한 것으로 나타났으며 오존수의 살균효과는 차아염소산소다수와 비슷하거나 다소 강한 것으로 나타났다. 그러나 전해수나 오존수를 이용하여 생식원료를 세정, 살균하여도 원료의 종류에 따라 살균효과에 차이가 있으며, 비 가열가공이라는 생식의 특성상 원료에서 검출되는 위해미생물은 최종제품까지 생잔할 가능성이 높기 때문에, 각 원료에 따른 살균처리지침을 위한 database 축적이 요구된다. 한편 모델공장을 선택하여 공장위생, 종업원 개인위생 및 제조공정을 개선한 후 공정개선의 미생물학적 효과를 조사한 결과 공정개선 전에는 원료에서 보다 최종제품에서 위해미생물의 수가 증가하는 경향을 나타내었으나, 공정개선 후에는 원료의 균수를 그대로 유지하거나, 감소하였으며 외주 원료의 혼합으로 인하여 위해미생물의 균수가 증가하였다. 따라서 생식의 제조공정에서 위해미생물을 저감화를 위해서는 외주 원료의 철저한 위생관리가 요구되며, 전해수 오존수 등을 이용한 원료의 비가열 세정살균과 지속적이고 위생적인 공정관리가 이루어진다면 위해 미생물의 균수를 저감화할 수 있을 것으로 사료된다.

• 설비공학논문집
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• 제17권6호
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• pp.581-586
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• 2005

Recently, the use of UVGI system has been increasing in both medical and nonmedical buildings for the control of environmental microorganisms. In the present study, irradiance performance test of UVC lamp was carried out and indoor air sterilization effect of UV ray for preventing transimission of air borne contagion was investigated by using manufactured UVC air sterilizer. Experimental results show that the effective irradiance of UVC lamp is strongly dependent on air velocity and temperature in irradiance performance test. An individual microbiological killing effectiveness experiment also shows that the average kill rate of two microbiological samples such as bacteria and fungus is about $92\%$ by using manufactured UVC air sterilizer. Additionally irradiance performance experimental results also show that the ballast is very important factor to keep up irradiance performance of UVC lamp.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.429-435
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• 2006

In this study multi-zone modeling program CONTAM 2.4 which is developed by NIST is used for modeling the air disinfection system which is consist of dilution, filtration, ultra violet germicidal irradiation (UVGI) for removing the indoor microorganism such as bacteria and fungus. Developed models those protect occupants against indoor microorganism generated in our daily life are enable to use for immune building simulation tool. Also, results indicate that those models are enable to compute the real situation that is almost impossible of carrying out experiment and identify the disinfection rate with highly reliance. Results also suggest that engineers will use these models as a design tool for the immune building system.

• 한국환경보건학회지
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• 제38권6호
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• pp.510-519
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• 2012

Objectives: This study was conducted in order to evaluate the microbiological contamination of the indoor air of the lunchrooms at child care centers and investigate the toxin genes and toxin production ability of food-borne pathogens. Methods: A total of 64 child care centers were sampled to test total aerobic bacteria, coliform bacteria, fungi, Staphylococcus aureus, Bacillus cereus and Salmonella spp. according to the Korea Food Code. All toxin genes of pathogens were detected using the Polymerase Chain Reaction method. The Sthaph. aureus enterotoxin was detected by a Staphylococcus aureus enterotoxin-reversed passive latex agglutination kit. The heamolysin BL (HBL) and non-heamolytic enterotoxin (NHE) produced by B. cereus were detected using a B. cereus enterotoxin-reversed passive latex agglutination kit and Bacillus diarrheal enterotoxin visual immunoassay kit, respectively. Results: The means of total aerobic bacteria and coliform bacteria were $1.91{\pm}1.84$ log CFU/plate and $0.47{\pm}0.62$ log CFU/plate, respectively. The mean of fungi also showed $0.59{\pm}0.71$ log CFU/plate. Among the pathogenic bacteria tested in this study, Staphy. aureus and B. cereus were detected in four (6.3%) and 21 (32.8%) out of 64 indoor air samples from lunchrooms in child care centers, respectively. All Staphy. aureus tested in this study possessed no toxin genes and did not produce enterotoxin. The detection rate of nheABC, hblCDA, entFM and ces toxin gene in B. cereus was 100, 57.1, 76.2 and 0%, respectively. B. cereus isolates were classified into four groups according to the presence or absence of toxin genes. The nheABC gene was the major toxin gene among B. cereus tested in this study. The HBL was detected in 11 out of 21 B. cereus isolates (52.4%) and three B. cereus isolates produced NHE (14.3%). Conclusion: The results indicated that the contamination by microorganisms in the indoor air of lunchrooms was unqualified to supply safe catering in child care centers. The ongoing control of indoor air quality is required.

• 한국식품과학회지
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• 제36권3호
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• pp.501-506
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• 2004

생식제품의 미생물학적 안전성을 확보를 위한 기초 자료로 활용하고자 생식제품 및 제조 공정 중에 있어서 Bacillus cereus, Clostridium perfringens, Staphylococus aureus 등 식중독세균을 중심으로 한 자연 환경 유래 위해미생물의 분포 및 주 오염공정을 조사하였다. 생식 원료 중 위해미생물의 검출율이 높은 원료는 주로 곡류이었으며, 원료를 일반수도수로 세척하고 동결건조 하여도 위해미생물은 완전히 제거되지 않아 원료에 대한 비가열살균 대책이 필요할 것으로 사료된다. 한편 최종제품의 위해미생물의 검출율이 원료보다 높게 나타나 제조공정 중 미생물 오염이 증가하는 것을 알 수 있었으며 위해미생물은 원료의 1차 분쇄 후 공정이 진행됨에 따라 증가하였고, 특히 외주분말(하청공장에서 원료를 세척, 건조, 분쇄한 것)을 혼합한 후 균수가 급속히 증가하였다. 공중부유균은 분쇄실과 혼합실에서 많이 검출되었으며, 생식 제조 공정에 사용되는 기계 및 기구에서도 위해미생물이 검출되어 공중부유균과 기계 및 기구의 오염, 그리고 기계에 끼여 있는 분말 찌꺼기가 제조공정 중 생식의 미생물 오염 원인이라는 것을 알 수 있었으며, 따라서 공중부유균의 살균대책 및 하청공장의 철저한 위생관리가 요구되며, 분쇄기 및 혼합기의 정기저인 소독 및 살균이 필요 할 것으로 사료된다.

• 설비공학논문집
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• 제18권11호
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• pp.933-940
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• 2006

In this study multi-zone modeling program CONTAM 2.4 developed by NIST is used for estimating the air disinfection rate of the interior of a room which is set up the indoor air disinfection system with filter and ultra violet germicidal irradiation (UVGI). Developed models those enable to predict the transmission of air home contagion such as bacteria and fungus generated in our daily life are useful model for designning air cleaning & ventilation system of building. Also, results indicate that these models are enable to compute the real situation that is almost impossible of carrying out experiment in an actual condition due to biohazard problems and suggest that engineers will use these models as a design tool for the future immune building system.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2018년도 춘계학술대회 및 임시총회
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• pp.33-33
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• 2018

Air-borne plant pathogenic fungus Fusarium graminearum and seed-borne plant pathogenic bacterium Burkholderia glumae are cause similar disease symptoms in rice heads. Here we showed that two pathogens frequently co-isolated in rice heads and F. graminearum is resistant to toxoflavin produced by B. glumae while other fungal genera are sensitive to the toxin. We have tried to clarify the resistant mechanism of F. graminearum against toxoflavin and the ecological reason of co-existence of the two pathogens in rice. We found that F. graminearum carries resistance to toxoflavin as accumulating lipid in fungal cells. Co-cultivation of two pathogens resulted in increased conidia and enhanced chemical attraction and attachment of the bacterial cells to the fungal conidia. Bacteria physically attached to fungal conidia, which protected bacterium cells from UV light and allowed disease dispersal. Chemotaxis analysis showed that bacterial cells moved toward the fungal exudation compared to a control. Even enhanced the production of phytotoxic trichothecene by the fungal under presence of toxoflavin and disease severity on rice heads was significantly increased by co-inoculation rather than single inoculation. This study suggested that the undisclosed potentiality of air-born infection of bacteria using the fungal spores for survival and dispersal.

• 설비공학논문집
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• 제21권1호
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• pp.63-70
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• 2009

The air sterilization systems are investigated experimentally in this paper. The goal is to reduce bacteria, mold and viruses in office air by using a UV sterilizer installed inside a partition panel and wall-mounted unit. These systems allow occupants to turn the system on/off and to control the incoming air speed and direction. The partition air sterilization system conditions and sterilizes the air, and then delivers the clean air into the personal task area through the partition panels, which are connected to the pressurized under-floor plenum. Room air exits through the return grills mounted on the ceiling. The wall-mounted air sterilization system sterilizes the air, and then delivers the clean air to the personal task area from the wall. In this study a full-size experimental environment is established to investigate the immunization performance of these air sterilization systems. A typical office space scale is used in this study in order to find an optimal system to achieve a sterilized healthy micro-environment. Multiple system parameters, including volume flow rate and velocity of supplied air, were regulated during the experiments. The more air contact these air sterilization systems had, the better disinfection performance. Over 90% of eradication ratios were obtained by these two air sterilization systems. The results indicate that these systems can efficiently disinfect office air contamination.

• 한국환경보건학회지
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• 제36권3호
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• pp.191-198
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• 2010

The aim of this study was to determine the concentrations of air-borne microorganisms (bacteria, fungi, gram negative bacteria (GNB), endotoxins, and respirable suspended particles (RSPs), and their correlation with environmental parameters (temperature, humidity, and carbon dioxide levels) in duck houses. The mean concentrations of bacteria, fungi, and GNB were very high (> $10^6\;CFU/m^3$), and endotoxin levels exceeded $10^3\;EU/m^3$. Among the various work stages, in the task of receiving ducks, bacteria were $6.2{\times}10^6;CFU/m^3$, and GNB were $5.4{\times}10^6\;CFU/m^3$, while RSPs levels were $397.6\;{\mu}g/m^3$ and endotoxin levels were $47.2{\times}10^3\;EU/m^3$ in the task of dividing the ducks, and fungi were $4.9{\times}10^6\;CFU/m^3$ in the task of shipping the ducks. The concentrations of RSPs and endotoxins were significantly higher in tasks involving greater movement of ducks in the house, relative to tasks involving little movement of ducks (p<0.05). Further, with progression in growth of the ducks, the concentrations of bacteria, GNB, endotoxins, and RSPs were significantly increased. There was significant correlation between levels of GNB with bacteria (r=0.75) and fungi (r=0.86), endotoxins with RSPs (r=0.75), bacteria with fungi (r=0.39), and carbon dioxide with RSPs (r=0.38), bacteria (r=0.33), and endotoxins (r=0.31). These results suggest considerable respiratory hazard for farmers in these environments.