• Journal of Microbiology
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• 제43권1호
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• pp.1-10
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• 2005

We isolated and cultured bacteria inhabiting solar saltern ponds in Taean-Gun, Chungnam Province, Korea. All of the isolated 64 strains were found to be moderately halophilic bacteria, growing in a salt range of 2-20 %, with an optimal concentration of 5% salt. Bacterial diversity among the isolated halophiles was evaluated via RFLP analyses of PCR-amplified 16S rDNAs, followed by phylogenetic analysis of the partial 16S rDNA sequences. The combination of restriction enzyme digestions with HaeIII, CfoI, MspI and RsaI generated 54 distinct patterns. A neighbor-joining tree of the partial 16S rDNA sequences resulted in the division of the 64 strains into 2 major groups, 45 strains of ${\gamma}-Proteobacteria$ (70.3%) and 19 strains of Firmicutes (29.7%). The ${\alpha}-Proteobacteria$ and Cytophaga-Flavobacterium-Bacterioides groups, which were repeatedly found to exist in thalassohaline environments, were not represented in our isolates. The ${\gamma}-Proteobacteria$ group consisted of several subgroups of the Vibrionaceae (37.5%), Pseudoalteromonadaceae (10.9%), Halomonadaceae (7.8%), Alteromonadaceae (7.8%), and Idiomarinaceae (6.3%). Members of Salinivibrio costicola (29.7%) were the most predominant species among all of the isolates, followed by Halobacillus treperi (12.5%). Additionally, three new species candidates were found, based on similarities of the 16S rDNA sequences to those of previously published species.

• Journal of Microbiology and Biotechnology
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• 제17권9호
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• pp.1558-1562
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• 2007

To elucidate the influence of pipe materials on the VBNC (viable but nonculturable) state and bacterial numbers in drinking water, biofilm and effluent from stainless steel, galvanized iron, and polyvinyl chloride pipe wafers were analyzed. Although no HPC (heterotrophic plate count) was detected in the chlorinated influent of the model system, a DVC (direct viable count) still existed in the range between 3- and 4-log cells/ml. Significantly high numbers of HPC and DVC were found both in biofilm and in the effluent of the model system. The pipe material, exposure time, and the season were all relevant to the concentrations of VBNC and HPC bacteria detected. These findings indicate the importance of determining the number of VBNC cells and the type of pipe materials to estimate the HPC concentration in water distribution systems and thus the need of determining a DVC in evaluating disinfection efficiency.

• 한국식품저장유통학회지
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• 제22권6호
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• pp.920-925
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• 2015

발효 온도를 달리한 전통방식으로 제조된 두 가지 형태(TN-A와 TN-B)의 누룩들로부터 발효 기간별 배양된 유산균 총균수, 유산균 종들의 변화 및 분리된 유산균들의 효소활성을 비교하였다. TN-A의 유산균 총균수는 $10^4{\sim}10^5$ log CFU/mL로 발효 3일차부터 발효 기간에 관계없이 유지되었고, TN-B에서는 발효 6일차까지 $10^2$ log CFU/mL로 유지되다가 6일차 이후 유산균이 검출되지 않는 특징을 보였다. 유산균 종들의 변화에 있어서, TN-A는 발효 3일차에 우점종 유산균으로 나타난P. pentosaceus 종이 발효 종료 시점이 30일차 까지 우점하고 있음을 확인할 수 있었고, TN-B는 발효 3일차와 6일차에 각각 P. pentosaceus와 E. hirea로 나타나 유산균이 검출된 발효 기간까지 TN-A 보다는 많은 변화를 보였다. TN-A와 TN-B으로부터 분리된 유산균들의 효소 활성은 단백질분해효소와 당화효소 활성을 분석하였다. 단백질분해효소평가는 티로신 생성량으로, 당화효소 활성은 아밀로스 분해에 따른 아밀로스 잔여 함량으로 평가한 결과, 분리된 유산균(9종)들은 0.49~0.89 mg/mL의 티로신 생성 범위의 단백질분해 활성과 0.64~0.79 mg/mL의 아밀로스 분해 활성 범위를 보였고, 유산균들 중 가장 높은 단백질분해효소와 당화효소 활성을 보이는 균주는 각각 P. acidilactici와 L. sakei로 확인되었다. 이상의 결과들은 온도를 달리하여 전통적인 방법으로 누룩을 제조하였을 시 누룩 내에 유산균들을 조절할 수 있음을 시사한다. 이를 토대로 향후 많은 연구들이 진행된다면, 누룩관련 제품에 유산균들에 의해 만들어지는 산미와 풍미를 향상 시킬 수 있는 전통적인 누룩제조가 가능할 것으로 판단된다.

• 미생물학회지
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• 제37권1호
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• pp.85-91
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• 2001

생물학적 방법으로 토착 미생물에 의해 벤젠과 톨루엔을 효과적으로 분해할 수 있는 토양환경인자의 조건을 조사하기 위해 16가지의 서로 다른 환경의 미소환경(microcosm)을 제작하여 벤젠과 톨루엔 분해실험을 수행하였고, 아울러 분해과정에서 토착미생물의 분포변화를 조사하였다. 그 결과 실험 조건중 토양의 수분 포화도는 30%와 60%이면서 동시에 생물들이 흡착할 수 있는 미생물 흡착제로 활성탄을 1% 첨가한 미소환경(Case 6, Case 7)에서 벤젠과 톨루엔의 분해속도가 가장 빨랐다. 토착토양미생물의 분포변화를 조사한 결과 벤젠과 톨루엔의 분해가 가장 빨리 일어나는 Case 6 와 Case 7에서는 10일 배양 후 total culturable bacteria는 초기 세균 수에 비해 각각 488배와 308배가 증가하였다. 벤젠과 톨루엔 분해세균의 증가 역시 총 세균수가 증가하는 비율로 증가하여 초기 분포를 계속 유지하였고, 벤젠과 톨루엔을 첨가한 미소환경에서 분해 미생물 종의 변화는, 첨가 전 그람음성 세균이 반응 10일 후에는 그람양성 세균이 탈이 분리되었다.

• 미생물학회지
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• 제50권2호
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• pp.119-127
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• 2014

남극 로스해의 퇴적물로부터 배양을 통해 분리한 균주의 분류 및 생리학적 특성 분석을 수행하였다. 분리 세균 63균주의 16S rRNA 유전자 염기서열을 이용한 계통분류학적 분석 결과, 이들은 Actinobacteria, Bacteroidetes, Alphaproteobacteria 및 Gammaproteobacteria 내의 21개의 파일로타입(phylotypes)에 속하였다. 98.65% 염기서열 유사도를 기준으로, 약 49%의 균주가 잠재적으로 신종 또는 신속 후보인 것으로 나타났다. 분리된 균주 중, 각각 46%, 25% 및 32%의 균주가 세포외 단백질분해효소, 지질분해효소 및 외부다당체 생성에 대한 활성을 나타냈다. 43개의 균주는 최소 1개의 세포외 분비 물질을 생산하였고, 이들 중 21개 균주는 최소 2개의 세포외 단백질분해효소, 지질분해효소 또는/및 세포외다당체를 생성하였다. 이러한 결과는 남극 로스해 퇴적물 내의 배양된 세균 군집이 해당 환경에서 탄소와 질소와 관련된 유기물질의 가수분해에 영향을 미치고 있다는 것을 시사한다.

• Journal of Microbiology and Biotechnology
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• 제24권5호
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• pp.648-660
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• 2014

Doenjang, a traditional Korean fermented soybean paste, is made by mixing and ripening meju with high salt brine (approximately 18%). Meju is a naturally fermented soybean block prepared by soaking, steaming, and molding soybean. To understand living bacterial community migration and the roles of bacteria in the manufacturing process of doenjang, the diversity of culturable bacteria in meju and doenjang was examined using media supplemented with NaCl, and some physiological activities of predominant isolates were determined. Bacilli were the major bacteria involved throughout the entire manufacturing process from meju to doenjang; some of these bacteria might be present as spores during the doenjang ripening process. Bacillus siamensis was the most populous species of the genus, and Bacillus licheniformis exhibited sufficient salt tolerance to maintain its growth during doenjang ripening. Enterococcus faecalis and Enterococcus faecium, the major lactic acid bacteria (LAB) identified in this study, did not continue to grow under high NaCl conditions in doenjang. Enterococci and certain species of coagulase-negative staphylococci (CNS) were the predominant acid-producing bacteria in meju fermentation, whereas Tetragenococcus halophilus and CNS were the major acid-producing bacteria in doenjang fermentation. We conclude that bacilli, LAB, and CNS may be the major bacterial groups involved in meju fermentation and that these bacterial communities undergo a shift toward salt-tolerant bacilli, CNS, and T. halophilus during the doenjang fermentation process.

• Journal of Microbiology and Biotechnology
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• 제27권5호
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• pp.995-1004
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• 2017

Culture-dependent methods, such as heterotrophic plate counting (HPC), are usually applied to evaluate the bacteriological quality of hemodialysis water. However, these methods cannot detect the uncultured or viable but non-culturable (VBNC) bacteria, both of which may be quantitatively predominant throughout the hemodialysis water treatment system. Therefore, propidium monoazide (PMA)-qPCR associated with HPC was used together to profile the distribution of the total viable bacteria in such a system. Moreover, high-throughput sequencing of 16S rRNA gene amplicons was utilized to analyze the microbial community structure and diversity. The HPC results indicated that the total bacterial counts conformed to the standards, yet the bacteria amounts were abruptly enhanced after carbon filter treatment. Nevertheless, the bacterial counts detected by PMA-qPCR, with the highest levels of $2.14{\times}10^7copies/100ml$ in softener water, were much higher than the corresponding HPC results, which demonstrated the occurrence of numerous uncultured or VBNC bacteria among the entire system before reverse osmosis (RO). In addition, the microbial community structure was very different and the diversity was enhanced after the carbon filter. Although the diversity was minimized after RO treatment, pathogens such as Escherichia could still be detected in the RO effluent. In general, both the amounts of bacteria and the complexity of microbial community in the hemodialysis water treatment system revealed by molecular approaches were much higher than by traditional method. These results suggested the higher health risk potential for hemodialysis patients from the up-to-standard water. The treatment process could also be optimized, based on the results of this study.

• Journal of Microbiology
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• 제43권3호
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• pp.219-227
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• 2005

Little is known about the bacterial communities associated with the plants inhabiting sand dune ecosystems. In this study, the bacterial populations associated with two major sand dune plant species, Calystegia soldanella (beach morning glory) and Elymus mollis (wild rye), growing along the costal areas in Tae-An, Chungnam Province, were analyzed using a culture-dependent approach. A total of 212 bacteria were isolated from the root and rhizosphere samples of the two plants, and subjected to further analysis. Based on the analysis of the 16S rDNA sequences, all the bacterial isolates were classified into six major phyla of the domain Bacteria. Significant differences were observed between the two plant species, and also between the rhizospheric and root endophytic communities. The isolates from the rhizosphere of the two plant species were assigned to 27 different established genera, and the root endophytic bacteria were assigned to 21. Members of the phylum Gammaproteobacteria, notably the Pseudomonas species, comprised the majority of both the rhizospheric and endophytic bacteria, followed by members of Bacteroidetes and Firmicutes in the rhizosphere and Alphaproteobacteria and Bacteroidetes in the root. A number of isolates were recognized as potentially novel bacterial taxa. Fifteen out of 27 bacterial genera were commonly found in the rhizosphere of both plants, which was comparable to 3 out of 21 common genera in the root, implying the host specificity for endophytic populations. This study of the diversity of culturable rhizospheric and endophytic bacteria has provided the basis for further investigation aimed at the selection of microbes for the facilitation of plant growth.

• 한국산업보건학회지
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• 제24권3호
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• pp.300-309
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• 2014

Objectives: The objective of this study is to evaluate microbial exposure hazards in the metal-working fluids(MWF) handling industry. Methods: Air quality parameters(airborne bacteria, fungi, endotoxin and oil mist) and bulk MWF in storage tanks were evaluated at 54 points at nine sites in South Korea. Results: The geometric means(GM) of culturable airborne bacteria, fungi, endotoxin and oil mist concentration were $133CFU/m^3$(n=376, range $7{\sim}6,510CFU/m^3$), $159CFU/m^3$(n=381, range $7{\sim}8,469CFU/m^3$), $8.06EU/m^3$(n=103, range $0.34{\sim}280.4EU/m^3$) and $0.20mg/m^3$(n=104, range $0.01{\sim}2.87mg/m^3$), respectively. The ratio of indoor to outdoor concentration was 2.7 for bacteria, 6.1 for endotoxin, and 4.8 for oil mist. Even though average airborne bacteria concentration did not exceed recommended exposure limits($1,000CFU/m^3$), MWF in the storage tanks was highly contaminated with bacteria(arithmetic mean $2.1{\times}10^6CFU/ml$) and exceeded recommended bacteria limits($10^5CFU/ml$). Conclusions: It is necessary for MWF handling workplaces to conduct periodical biohazard inspection of MWF storage tanks. Additionally, further research may be necessary to establish biological occupational exposure limits.

• 한국수산과학회지
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• 제51권4호
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• pp.450-455
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• 2018

We examined correlations of the density of fish farms with the distributions of indicator bacteria (Escherichia coli, fecal streptococci) and a bacterial fish pathogen (Streptococcus parauberis) off the coastline of Jeju Island. Seawater samples were collected at four coastal sites on the Island [Aewol (control), Gujwa, Pyoseon and Daejeong] in June, August and October 2016. The indicator bacteria were generally more frequently isolated from samples taken in August when water temperatures and human activities on nearby beaches were highest. Although fish farms were least common at Daejeong, the numbers of isolated fecal indicator bacteria were highest in the seawater and effluent water collected from this site. Hence, fish farms were not likely major contributors of indicator bacteria at Daejeong. We found discrepancies between the isolated bacterial counts and the predicted bacterial copy numbers deduced from our qPCR results, indicating that this pathogen may exist in a viable but non-culturable (VBNC) state in seawater. Thus, livestock wastewater and chemical fertilizer loading off Jeju Island may negatively impact seawater quality more than the effluent released from fish farms does.