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표고버섯의 추출물 첨가에 의한 Lactococcus lactis PK-8의 생리활성 증진에 대한 연구
석지원(Ji-Won Seok),박상국(Sang-Kook Park),오계헌(Kye-Heon Oh) 한국생물공학회 2018 KSBB Journal Vol.33 No.3
The purpose of this work was to investigate various physiological activities of Lactococcus lactis PK-8 isolated from shiitake mushrooms and to assess the efficacy of enhanced activities by the addition of mushroom extracts. Initially, we characterized the physiological and biochemical properties of this strain. Phylogenetic analysis using 16S rRNA sequencing was utilized for identification, and the strain was assigned and designated as L. lactis PK-8. Phylogenetic tree of the strain was plotted based on 16S rRNA sequence comparisons. Various physiological activities (e.g., tyrosinase inhibitory activity, ACE inhibitory activity, antioxidant activity, SOD-like activity, depletion of sodium nitrite, antibacterial acticity) of L. lactis PK-8 cultures with 10% mushroom extracts were evaluated and compared to the cultures without the extracts. According to the results, all of the physiological activities evaluated in this work were considerably higher in L. lactis PK-8 cultures with 10% mushroom extracts than in the cultures without the extracts. In consequence, this study demonstrated that shiitake mushroom extracts would be effective for enhancing the physiological activities of L. lactis PK-8.
Legionella pneumophila JK-3에 대한 녹차 카테킨 Epigallocatechin Gallate (EGCG)의 항세균 및 프로테옴 효과
석지원(Ji-Won Seok),이현호(Hyun-Ho Lee),오계헌(Kye-Heon Oh) 한국생물공학회 2019 KSBB Journal Vol.34 No.1
The objective of this study was to examine the antibacterial and proteomic effects of Legionella pneumophila exposed to a large green tea component, EGCG (epigallocatechin gallate). Initially, the isolate was identified and assigned to Legionella pneumonia JK-3 using the 16S rRNA sequencing. Phylogenetic tree of JK-3 was plotted on 16S rRNA sequencing comparison. EGCG showed a dose-dependent antibacterial effect on L. pneumophila JK-3, while JK-3 treated using 2,000 ug/mL EGCG completely inhibited growth within 3 h of incubation. SEM analysis demonstrated the presence of perforations and irregular rod forms with wrinkled surfaces in cells treated with sublethal concentrations of EGCG. SDSPAGE stained with silver revealed that the amount of lipopolysaccharide in JK-3 increased or decreased according to the concentrations and exposure times of EGCG. Both stress shock proteins (SSPs) (70-kDa DnaK and 60-kDa GroEL) increased in different concentrations of EGCG, whereas the SSPs increased during the early stage as EGCG exposure time of elapsed then gradually decreased. To identify proteins induced by EGCG exposure, 2-DE was applied to soluble protein fractions of JK-3 cultures. Notably, 19 protein spots were either increased or decreased after treatment with EGCG. Using MALDI-TOF mass spectrometry, twelve up-regulated proteins were identified as chaperones, cell envelope proteins, and cell lysis protein. Similarly, seven down-regulated proteins including proteins involved in some energy metabolism and DNA/RNA metabolism were identified. In conclusion, this study provides important clues in understanding of the cytotoxicity mechanisms that affect the antibacterial effect of EGCG exposure, and suggests its use as a phytochemical antibacterial.
IEEE 802.11ax UORA에서 우선순위 기반 추가 백오프 스테이지를 통한 처리량 향상
석지원(Jiwon Seok),김선명(Sunmyeng Kim) 한국정보기술학회 2021 Proceedings of KIIT Conference Vol.2021 No.11
IIEEE 802.11ax UORA는 랜덤 채널 접근 방법에 기반하여 동작하기 때문에 경쟁하는 단말 수가 증가하면, 충돌이 많이 발생하여 채널의 처리량이 저하되는 문제점을 갖고 있다. 본 논문에서는 채널 접근 전에 추가적인 백오프 스테이지를 통해 전송 간 충돌을 회피하여, 조밀한 네트워크 환경에서 처리량을 향상시킨다. In IEEE 802.11ax UORA, the more number of STAs participating in random access, the more rate of transmission in which collision occurs, and thus the throughput of the channel decreases. In this paper, Collision between transmissions is avoided through an additional backoff stage before random access. The proposed method improves throughput in dense networks.
박지훈,석지원,이상아,권오훈,이경숙,허용,윤충식,Park, Jihoon,Seok, Jiwon,Lee, Sangah,Kwon, Ohhun,Lee, Kyungsuk,Heo, Yong,Yoon, Chungsik 한국환경보건학회 2015 한국환경보건학회지 Vol.41 No.5
Objectives: There are many hazardous agents at livestock farms. In particular, gases can be detrimental to both workers and animals. This study evaluated ammonia and hydrogen sulfide concentrations in broiler hen barns and beef cattle barns according to sampling location and height. Methods: Three broiler hen barns and three beef cattle barns were selected for gas monitoring in this study. Ammonia and hydrogen sulfide concentrations were measured using a direct-reading instrument which could measure the target gases simultaneously. Gas monitoring was conducted at human breathing height and animal breathing height at three points in each livestock farm. Results: Ammonia concentrations at the broiler hen barns ranged from 3.3 to 12.5 ppm by sampling location and height, but hydrogen sulfide was not detected. In the beef cattle barns, ammonia ranged from 3.1 to 16.3 ppm and low concentrations of hydrogen sulfide were detected at some animal breathing heights. The gas concentrations detected at each livestock farm were significantly higher in the animal breathing zones than in human breathing zones (p<0.0001). Conclusions: We found a difference in gas concentrations between human breathing zones and animal breathing zones. Gas monitoring should be conducted to improve the related environment considering both workers' and animals' health and safety.
이병욱,최문섭,석지원,오계헌,Lee, Bheong-Uk,Choi, Moon-Seop,Seok, Ji-Won,Oh, Kye-Heon The Microbiological Society of Korea 2018 미생물학회지 Vol.54 No.4
이전 연구에서 우리는 RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) 분해세균 Pseudomonas sp. HK-6에서 xenobiotic reductase B를 암호화하는 xenB 유전자의 돌연변이 균주를 이용하여 RDX 스트레스에 대한 xenB 유전자의 역할에 관하여 연구를 보고하였다[Lee et al. (2015) Curr. Microbiol. 70(1): 119-127]. 본 연구에서는 Pseudomonas sp. HK-6 xenA 돌연변이 균주로 연구 범위를 확대하여 RDX 스트레스 조건에서 세포반응과 프로테옴 프로필의 변화를 분석하였다. RDX 첨가 배지에서 xenA 돌연변이 균주는 야생균주와 비교하여 RDX를 약 2배 정도 느리게 분해하였으며, RDX 스트레스 하에서 xenA 돌연변이 균주의 생장률과 생존율은 야생균주와 비교하여 낮았다. RDX 스트레스에 의한 심한 형태적 손상이 xenA 돌연변이 균주의 세포 표면에 발생하는 것이 주사전자현미경을 통해서 확인되었다. RDX 스트레스 하에서 야생균주에서 발현된 충격단백질인 DnaK 및 GroEL의 양은 배양 초기 혹은 상대적으로 낮은 RDX 농도에서는 증가하였으나, 배양시간이 길어지거나 높은 RDX 농도에서는 다소 감소하였다. 그러나 xenA 돌연변이 균주에서는 DnaK와 GroEL의 발현양은 RDX 농도가 증가함에 따라 점차 감소되었다. RT-qPCR에 의해 측정된 야생균주에서 dnaA와 groEL의 전사 수준은 RDX 스트레스가 증가된 상태에서 잘 유지되었으나, xenA 돌연변이 균주에서는 점차 감소되어 결국에는 소멸되었다. RDX 스트레스에서 xenA의 돌연변이에 의한 프로테옴 프로필의 변화를 2-DE PAGE를 통해서 관찰한 결과에 따르면 27개 단백질이 감소하고 3개가 증가한 것으로 나타났다. 이들 결과로 보아, 정상적인 xenA 유전자는 RDX 스트레스 하에서 세포의 온전한 형태 유지와 효율적인 RDX 분해 과정을 수행하기 위해서 필요하다는 것을 의미하였다. Our previous research demonstrated the essential role of the xenB gene in stress response to RDX by using Pseudomonas sp. HK-6 xenB knockout. We have extended this work to examine the cellular responses and altered proteomic profiles of the HK-6 xenA knockout mutant under RDX stress. The xenA mutant degraded RDX about 2-fold more slowly and its growth and survival rates were several-fold lower than the wild-type HK-6 strain. SEM revealed more severe morphological damages on the surface of the xenA mutant cells under RDX stress. The wild-type cells expressed proportionally-increased two stress shock proteins, DnaK and GroEL from the initial incubation time point or the relatively low RDX concentrations, but slightly less expressed at prolonged incubation period or higher RDX. However the xenA mutant did not produced DnaK and GroEL as RDX concentrations were gradually increased. The wild-type cells well maintained transcription levels of dnaA and groEL under increased RDX stress while those in the xenA mutant were decreased and eventually disappeared. The altered proteome profiles of xenA mutant cells under RDX stress also observed so that the 27 down-regulated plus the 3 up-regulated expression proteins were detected in 2-DE PAGE. These all results indicated that the intact xenA gene is necessary for maintaining cell integrity under the xenobiotic stress as well as performing an efficient RDX degradation process.