• 한국산업보건학회지
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• 제34권1호
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• pp.48-56
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• 2024

Objectives: The coronavirus pandemic that began in 2019(COVID-19) has been one of the worst pandemics of the 21st century. Masks have been used to prevent COVID-19, but there are currently no standards for the long-term use of masks in the Republic of Korea. This study was conducted to assess the microbiological safety of KF94(Korea Filter 94) disposable face masks according to wearing duration by evaluating the bacterial filtration efficiencies of masks worn by research participants. Methods: A commercially available KF94 mask certified by the Ministry of Food and Drug Safety(MFDS) in the Republic of Korea was selected as the test mask. The research participants(n = 15) wore masks for the durations of one, three, and seven days. Participants also reported several parameters, including wearing time, makeup frequency, and storage. Bacterial filtration efficiencies of the worn masks were measured by a mask bioaerosol filtration tester. Staphylococcus aureus(S. aureus) was used as the test bacteria and quantitatively measured through the cultivation method. Then, bacterial filtration efficiency was calculated using the formula suggested by the MFDS. Results: All worn masks showed over 99.98% of mean bacterial filtration efficiency for S. aureus. There were no significant differences among bacterial filtration efficiencies of face masks according to wearing duration. There was also no significant difference among bacterial filtration efficiencies among participants. There was no correlation between the results of bacterial filtration efficiencies and reported parameters from participants. Conclusions: In the absence of significant external damage to the mask, the bacterial filtration efficiency of the mask can be maintained even after seven days of wearing. This result suggests that KF94 masks certified by the MFDS can be used repeatedly for about a week without loss of bacterial filtration efficiency.

• 한국환경보건학회지
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• 제48권2호
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• pp.116-122
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• 2022

Background: The recent COVID-19 pandemic is one of the worst disease outbreaks of the 21th century. Due to a lack of reliable antiviral therapeutics, wearing face masks is recommended to prevent airborne infection originating from virus-contaminated bioaerosols. Objectives: The aim of this study was to evaluate the filtration efficiencies of face masks that are commercially available in South Korea for a biological aerosol of Staphylococcus aureus (S. aureus) and murine coronavirus, a well-known surrogate for human coronaviruses. Methods: We collected six different kinds of commercial masks: two Korea Filter (KF)94 (KF94-1, KF94-2) masks, one surgical (Surgical-1) mask, one anti-droplet (KF-AD-1) mask, and two dust (Dust-1, Dust-2) face masks. S. aureus (ATCC 6538), a well-performing test bacteria and murine coronavirus (ATCC VR-764) were prepared under a suitable culture condition. Then, a mask biological filtration tester was used to examine the microbial filtration efficiencies of masks. Test microorganisms were quantitatively measured via cultivation methods and microbial filtration efficiencies were calculated appropriately. Results: All face masks showed over 99.6% filtration efficiency for S. aureus or murine coronavirus. There were no significant differences among the bacterial filtration efficiencies of the face masks. KF94-1 (99.97±0.08%) and Dust-1 mask (99.97±0.07%) showed the highest (over 99.9%) filtration efficiency for murine coronavirus. KF94-1 or Dust-1 masks showed a significant virus filtration efficiency compared to Surgical-1 mask (p<0.05; Mann-Whitney U test). Conclusions: All the commercially available face masks used in this study can filter S. aureus or murine coronavirus in bioaerosols efficiently, regardless of the mask type. Therefore, our results suggest that wearing a certified face mask is a reliable means to prevent the transmission of infectious airborne diseases via biological aerosols.

• Journal of Animal Science and Technology
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• 제65권2호
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• pp.387-400
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• 2023

Ruminal protozoa, especially entodiniomorphs, engulf other members of the rumen microbiome in large numbers; and they release oligopeptides and amino acids, which can be fermented to ammonia and volatile fatty acids (VFAs) by amino acid-fermenting bacteria (AAFB). Studies using defaunated (protozoa-free) sheep have demonstrated that ruminal protozoa considerably increase intraruminal nitrogen recycling but decrease nitrogen utilization efficiency in ruminants. However, direct interactions between ruminal protozoa and AAFB have not been demonstrated because of their inability to establish axenic cultures of any ruminal protozoan. Thus, this study was performed to evaluate the interaction between Entodinium caudatum, which is the most predominant rumen ciliate species, and an AAFB consortium in terms of feed degradation and ammonia production along with the microbial population shift of select bacterial species (Prevotella ruminicola, Clostridium aminophilum, and Peptostreptococcus anaerobius). From an Ent. caudatum culture that had been maintained by daily feeding and transfers every 3 or 4 days, the bacteria and methanogens loosely associated with Ent. caudatum cells were removed by filtration and washing. An AAFB consortium was established by repeated transfers and enrichment with casamino acids as the sole substrate. The cultures of Ent. caudatum alone (Ec) and AAFB alone (AAFB) and the co-culture of Ent. caudatum and AAFB (Ec + AAFB) were set up in three replicates and incubated at 39℃ for 72 h. The digestibility of dry matter (DM) and fiber (NDF), VFA profiles, ammonia concentrations, pH, and microscopic counts of Ent. caudatum were compared among the three cultures. The co-culture of AAFB and Ent. caudatum enhanced DM degradation, VFA production, and Ent. caudatum cell counts; conversely, it decreased acetate: propionate ratio although the total bacterial abundance was similar between Ec and the Ec + AAFB co-culture after 24 h incubation. The ammonia production and relative abundance of C. aminophilum and P. anaerobius did not differ between AAFB alone and the Ec + AAFB co-culture. Our results indicate that Ent. caudatum and AAFB could have a mutualistic interaction that benefited each other, but their interactions were complex and might not increase ammoniagenesis. Further research should examine how such interactions affect the population dynamics of AAFB.

• 한국산업보건학회지
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• 제31권4호
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• pp.427-439
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• 2021

Objectives: This study aims to investigate differences in microbial contamination according to the duration and environment of mask wearing. Methods: Forty-five participants were recruited from workers in an offices, multi-purpose facilities, and a schools. After wearing of KF94 mask for two. four, and six hours, the microorganisms adsorbed on the outer and inner layers of the mask were inoculated on BAP(Blood Agar Plate), Chocolate agar, and SDA plates. The bacterial count (CFUs: colony-forming units) cultured in each plate was measured and analyzed for changes in filtration efficiency. Results: The microbial contamination of masks worn in classrooms, offices, and multi-purpose facilities showed a significant difference depending on the environment (p<0.000). The measured CFUs increased significantly according to the time wearing the mask. The difference between the inner and outer layers of the mask was also significant (p<0.05). However, there was no statistical difference in the filtration efficiency of the masks by duration time (p=0.515). Conclusions: Masks worn by workers in the offices, multi-purpose facilities, and schools showed an increase of microbial contamination with the amount of time wearing the mask. The results indicate that the masks used in daily life may have adverse health effects if they are worn for a long time or reused over several days without the realizing that the masks can be contaminated with biological hazards. Guidelines on the safe threshold time for mask use should be established through further research.

• Journal of Microbiology
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• 제40권2호
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• pp.119-124
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• 2002

Experiments for the characterization of inactivation were performed in a series of batch processes with the total coliform used as a general indicator organism based on the chlorine residuals as a disinfectant. The water samples were taken from the outlet of a settling basin in a conventional surface water treat- ment system that is provided with the raw water drawn from the mid-stream of the Han River, The inactivation of total coliform was experimentally analysed for the dose of disinfectants contact time, filtration and mixing intensity. The curves obtained from a series of batch processes were shaped with a general tailing-off and biphasic mode of inactivation, i.e. a sharp loss of bacterial viability within 15 min followed by an extended phase. In order to observe the effect of carry-over suspended solids on chlorine consumption and disinfection efficiency, the water samples were filtered, prior to inoculation with coliforms, with membranes of both 2.5$\mu$m and 11.0 $\mu$m pore size, and with a sand tilter of 1.0 mm in effective size and of 1.4 in uniformity coefficient. As far as the disinfection efficiency is concerned, there were no significant differences. The parameters estimated by the models of Chick-Wat-son, Hom and Selleck from our experimental data obtained within 120 min are: log(N/N$\_$0/)=-0.16CT with n=1, leg(N/N$\_$0/)=-0.71C$\^$0.87/ with n 1 for the Chick-Watson model, log (N/N$\_$0/)=-1.87C$\^$0.47/ T$\^$0.36/ for the Hom model, log (MHo)=-2.13log (1+CT/0.11) for the Selleck model. It is notable that among the models reviewed with regard to the experimental data obtained, the Selleck model appeared to most closely resemble the total coliform survival curve.

• 생명과학회지
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• 제28권7호
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• pp.864-873
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• 2018

나노 입자는 화장품, 식품, 기계, 화학 산업 등에 다양한 용도로 활용되고 있으며, 그 응용분야가 광범히 하여 나노 입자 사용에 대한 관심과 연구가 지속적으로 증가하고 있는 추세이다. 특히 금속나노 입자 중 하나인 은나노 입자는 항균 및 항진균 효과가 뛰어나 의류, 실내 공기필터, 증류필터 등 다양한 방면에 활용되고 있다. 하지만 은나노 입자의 지속적인 노출 시, 입자 크기와 노출방식에 따라 인체에 독성을 유발하는 것으로 알려져 있어 친환경적이고 생물학적으로 안전한 천연물 유래 소재를 활용한 은나노 입자의 기술개발이 필요하다. 천연물이 적용된 실내필터와 의류는 생산의 용이성, 제품 내구성 및 항균 활성에서 은나노 적용제품과 비교될 수 있는 것으로 나타고 있다. 본 연구에서는 은나노의 생체 내 미치는 독성 메커니즘에 대해 알아보고 은나노의 대안으로 항균 활성을 지닌 천연물의 항균 활성에 대해 기술하고자 한다.

• 대한수혈학회지
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• 제23권2호
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• pp.107-114
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• 2012

배경: 혈액제제 내에 혼입된 백혈구로 발생하는 부작용을 예방하기 위해서 백혈구필터를 이용한 백혈구의 제거가 널리 이용되고 있다. 그러나 상용 백혈구 필터로는 이식편대숙주병을 예방하기에는 충분한 백혈구제거가 되지 않아 고가의 기기를 이용한 방사선 조사를 시행하고 있는 실정이다. 한편 항체를 대체하는 압타머를 이용한 기술들이 활발히 개발되어 임상에 사용되기 시작하고 있다. 이에 백혈구에 결합하는 압타머를 이용한 압타머필터를 개발 하여 그 효율과 임상적용 가능성을 평가하고자 하였다. 방법: 포항공대 압타머사업단에 CD45항원에 결합하는 압타머 선별을 의뢰하여 제공받았으며 이를 비드에 부착시켜 백혈구와 결합하도록 한 후 자석을 이용해 제거하는 형식의 압타머필터를 개발하였다. 대한적십자사 혈액원에서 제공받은 백혈구제거적혈구 14단위에 압타머필터를 사용하여 잔여 백혈구를 제거한 후 백혈구 제거율과 적혈구 회수율, 세균배양을 시행하였다. 결과: 압타머필터 후 백혈구는 45.6%가 제거되었으며 92.8%의 적혈구회수율을 보였다. 세균배양에서는 아무것도 자라지 않았다. 결론: 압타머를 이용한 세포제거 기술을 혈액 필터에 적용하고자 CD45항원에 결합하는 압타머를 발굴하여 비드에 부착한 후 수혈 혈액을 필터링함으로써 해당 항원을 가진 세포 즉 백혈구를 제거하도록 하는 압타머필터를 개발하여 이를 평가하였다. 향후 압타머 부착 효율 및 필터과정 개선, 다른 항원에 대한 압타머 적용 등을 통해 혈액제제에서 백혈구 제거율을 높여 이식편대숙주병 예방을 위한 방사선조사를 대체하는 등 임상에 적용할 수 있을 것으로 생각된다.

• 한국식품위생안전성학회지
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• 제33권5호
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• pp.325-329
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• 2018

본 연구에서는 신선편이 양배추 내 Bacillus cereus의 최적 증균 온도를 선정하고 증균배양액에 소수성필터를 적용하여 multiplex PCR의 검출률을 확인하였다. B. cereus 증균온도는 B. cereus 균주 5 개를 혼합하여 1 Log CFU/mL이 되도록 증균배지에 접종하고 $30^{\circ}C$, $37^{\circ}C$, $42^{\circ}C$에서 증균한 뒤 3시간 간격으로 MYP agar에 도말한 후 계수하여 선정하였다. 소수성필터 미적용 그룹은 B. cereus 균주 5 개를 혼합하여 신선편이 양배추에 접종한 뒤 최적 증균온도에서 증균하였으며, 증균배양액을 가열하여 DNA를 추출한 뒤 multiplex PCR을 진행하였다. 소수성필터 적용 그룹은 증균배양액을 소수성 필터에 적용하고 필터에 있는 균을 멸균증류수로 현탁한 뒤 가열하여 추출된 DNA로 multiplex PCR을 진행하였다. 증균온도 확인 결과, 6시간 증균 시 $42^{\circ}C$에서 증균된 샘플($5.4{\pm}0.3Log\;CFU/mL$)과 $30^{\circ}C$에서 증균된 샘플($4.6{\pm}0.6Log\;CFU/mL$) 간 유의차가 확인되었다(p < 0.05). 소수성필터 적용 유무에 따른 multiplex PCR 결과, 1 Log CFU/g 접종된 샘플의 검출률이 소수성 필터 적용 전 60%(3/5)에서 100%(5/5)로 향상되었다. 2 Log CFU/g 접종 샘플은 소수성필터 적용 전 80%(4/5)에서 소수성 필터 적용 후 100%(5/5)로 검출률이 증가하였으나, 3 Log CFU/g 접종 샘플은 소수성 필터 적용 전후 모두 100%(5/5)로 확인되었다. 이상의 결과를 통해 신선편이 양배추 내 B. cereus 검출 시 증균배양액에 소수성필터를 적용하고 multiplex PCR을 적용했을 때 신속하고 효율적인 검출이 가능할 것으로 판단된다.

• 공업화학
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• 제33권4호
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• pp.444-450
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• 2022

본 연구에서는 다중 코팅 폴리에스터(PET) 섬유 여재의 항바이러스 소재 응용 가능성을 고찰하기 위해 금속산화물, 키토산, 및 구리이온의 첨착 조건에 따른 PET의 항균 및 항바이러스 성능을 평가하였다. 항균 물질이 단독으로 코팅된 PET 대비 다중 코팅 PET의 경우 첨착량을 감소시킬 수 있을 뿐만 아니라 배양 후 박테리아가 육안상으로 검출되지 않는데(< 10 CFU/mL) 필요한 균 접촉시간을 단축할 수 있음을 확인하였다. 금속산화물은 촉매반응에 의해 라디칼 등의 산소 활성종을 생성하며, 구리이온은 접촉 살균 효과를 가지면서 산소 활성종에 의한 박테리아와 바이러스의 손상에 기여한다. 키토산은 구리이온의 배위결합을 통한 고정화뿐만 아니라 아민기에 의한 살균 효과로 코팅 PET의 항균 성능 향상 효과를 보였다. 다중 코팅 PET는 대장균과 황색포도상구균에 대한 항균 효과 외에 인플루엔자 A (H1N1)와 SARS-CoV-2에 대해 99.9% 이상의 항바이러스 효과가 있음을 확인하였다. 대면적 roll-to-roll 공정을 통해서도 다중 코팅 PET 섬유 여재의 제조가 가능하고 높은 항바이러스 성능이 유지됨을 보였으며, 이는 공기정화용 필터, 마스크, 및 개인 보호용구과 같은 항바이러스 직물 소재로서 관련 산업에 응용될 수 있음을 시사한다.