• 미생물학회지
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• 제29권6호
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• pp.402-407
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• 1991

As a baseline survey to clarify the structure and function of bacterial populations in the intertidal waters of the Yellow Sea near Kunsan in 1987/1988, annual variation of bacterial number and biovolume was estimated by AODC method. Rod-shaped bacteria were more than 74% of all cells during the investigation period. Average biovolume of sampled bacteria ranged from ${3.19}\pm0.59*10^{-2}$ to $6.19\pm0.76*10^{-2}$ .$\mu$$m^{3}$ for coccoid bacteria, and from 4.57.+-.0. $17*10^{-2}$ to $12.94\pm0.21*10^{-2}$ .$\mu$$m^{3}$ for rod-shaped ones. It showed that larger biovolume occurred at surface in case of coccoid bacteria, while at bottom in case of rod-shaped ones. There was little correlation between population density and biovolume. Diameters of edlls were below 0.5$\mu$m among 77-89% of all measured coccoid bacteria, and lengthes of cells more than 70% of all measured rod-shaped ones were below $1\mu$m. It explains the high percentage of "mini-bacteria" was distributed in the investigation area.tion area.

• Journal of Microbiology and Biotechnology
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• 제33권6호
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• pp.745-752
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• 2023

Gut symbionts play crucial roles in host development by producing nutrients and defending against pathogens. Phloem-feeding insects in particular lack essential nutrients in their diets, and thus, gut symbionts are required for their development. Gram-negative Pantoea spp. are known to be symbiotic to the western flower thrips (Frankliniella occidentalis). However, their bacterial characteristics have not been thoroughly investigated. In this study, we isolated three different bacteria (BFoK1, BFiK1, and BTtK1) from F. occidentalis, F. intonsa, and T. tabaci. The bacterial isolates of all three species contained Pantoea spp. Their 16S rRNA sequences indicated that BFoK1 and BTtK1 were similar to P. agglomerans, while BFiK1 was similar to P. dispersa. These predictions were supported by the biochemical characteristics assessed by fatty acid composition and organic carbon utilization. In the bacterial morphological analysis, BFoK1 and BTtK1 were distinct from BFiK1. All these bacteria were relatively resistant to tetracycline compared to ampicillin and kanamycin, in which BFoK1 and BTtK1 were different from BFiK1. Feeding ampicillin (100,000 ppm) reduced the bacterial density in thrips and retarded the development of F. occidentalis. The addition of BFoK1 bacteria, however, rescued the retarded development. These findings indicate that Pantoea bacteria are symbionts to different species of thrips.

• 한국토양비료학회지
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• 제47권1호
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• pp.28-35
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• 2014

Due to recent interest of the consumers on safe farm products and the government's political support for eco-friendly agriculture, organic fruit production has been growing continuously. This research was conducted in order to study the effect of cover plants on soil microbial community on cover plants and establish an organic fruit cultivation method through choosing optimal cover plant. As a result of investigating soil microbial population density, the bacterial density in soil showed an increasing trend in June compared to April, and there was a decreasing trend in bacterial density of the soil in August compared to June. The density of actinomycetes in soil increased around 1.6 times in June compared to April when the soil was covered with hairy vetch. The increase of filamentous fungus in crimson clover group was 6.1 times higher in June compared to April and in hairy vetch group, the increase was 4.9 times higher in June compared to April. As a result of analyzing DNA extracted from the soil categorized by different types of cover plants using DGGE method, soil collected from April had higher number of bands detected from different locations according to different types of cover plants. Diversity of the bands from the soil collected from August showed higher range of reduction. As a result of analyzing soil microbial community by different period and the types of cover plants using Pyrosequencing method, microbes were detected in the order of Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, and Firmicutes. Distribution rate of Firmicutes increased in the soil collected in August compared to June and this was shown in all types of cover plants by twice the amount.

• The Plant Pathology Journal
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• 제30권2호
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• pp.125-135
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• 2014

A population model of bacterial spot caused by Xanthomonas campestris pv. vesicatoria on hot pepper was developed to predict the primary disease infection date. The model estimated the pathogen population on the surface and within the leaf of the host based on the wetness period and temperature. For successful infection, at least 5,000 cells/ml of the bacterial population were required. Also, wind and rain were necessary according to regression analyses of the monitored data. Bacterial spot on the model is initiated when the pathogen population exceeds $10^{15}cells/g$ within the leaf. The developed model was validated using 94 assessed samples from 2000 to 2007 obtained from monitored fields. Based on the validation study, the predicted initial infection dates varied based on the year rather than the location. Differences in initial infection dates between the model predictions and the monitored data in the field were minimal. For example, predicted infection dates for 7 locations were within the same month as the actual infection dates, 11 locations were within 1 month of the actual infection, and only 3 locations were more than 2 months apart from the actual infection. The predicted infection dates were mapped from 2009 to 2012; 2011 was the most severe year. Although the model was not sensitive enough to predict disease severity of less than 0.1% in the field, our model predicted bacterial spot severity of 1% or more. Therefore, this model can be applied in the field to determine when bacterial spot control is required.

• 미생물학회지
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• 제31권3호
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• pp.245-254
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• 1993

1991년 9월부터 1992년 9월까지 23회에 걸쳐 서울시 구의정수장의 상수도계통 즉 원수와 정수 및 이곳에서 공급되는 단일 배급수계통의 3개 수돗물에서 종속영양세균(heterotrophic plate count : HPC) 과 장내세균(Enterobacteriaceae : total coliforms) 의 분포를 조사하였다. $R_{2}A$ 한천배지에서의 종속영양세균수는 원수 $1.22{\times}10^{3}~3.05{\times}10^{5}$ 정수 $1.50{\times}10^{1}~4.29{\times}10^{3}$, 수돗물 $2~5.41{\times}10^{3}$ cfu/100ml, 수돗물 0-47.5 cfu/100 ml 의 범위였으며, m-T7 한천배지에서의 손상된장내세균을 포함하는 장내세균수는 전수 0-27, 수돗물 0-35 cfu/100 ml/의 범위였다. 이러한 결과로부터 정수장에서 공급된 물이 배급수관을 통하여 공급되면서 종속영양세균 및 장내세균의 개체수가 증가하는 세균재생장 현상이 발생한다는 것을 확인하였다. 종속영양세균의 동정결과 원수, 정수, 수돗물을 포함하는 상수도계통의 물에서는 Peudomonas 와 Acinetobacter 가 우점하였으나, 원수에서는 Pseudomonas 의 비율이, 그리고 정수와 수돗물에서는 Acinetobacter 의 비율이 상대적으로 높은 것으로 나타났다. 장내세균은 Enterobacter agglomerans 가 우점종이었으며, 수돗물에서는 정수에서 검출되지 않았던 Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, Shigella dysenteriae 등의 기회성 및 병원성 장내세균도 검출되었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.449-452
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• 2000

일반적으로 시중에서 유통되는 콩나물은 시루 채 출하되거나 200-300g 정도의 소포장으로 팔려지게 되며 상품으로써의 생명력도 3-4일 정도로 짧다. 본 실험은 콩나물의 저장 및 유통기간 연장방법의 일환으로 이온수 처리에 따른 저장기간 중의 변화를 조사하였다. $4^{\circ}C$와 $10^{\circ}C$에서의 이온수 처리 콩나물은 1/2 ${\sim}$ 1/3배 정도의 낮은 부패균 밀도를 나타내었으며, 실온과 가까운 $25^{\circ}C$에서도 1/2배의 낮은 부패균 밀도를 나타냄으로써 저온저장에서의 저장성 향상뿐만 아니라 콩나물의 실온유통에서도 하루정도의 저장기간 연장효과를 가져올 것으로 평가된다.

• 한국동물위생학회지
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• 제37권3호
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• pp.203-212
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• 2014

Frog culture industry is not yet familiar but has much potential. Generally, in farm, the population density is higher than that of in nature and frog farm is not the exception. But when population density is high, it can easily leads to stressful condition, poor sanitation. When a disease occur, it is a primary factor that makes the population more susceptible and the results more grave. Because of severe Rhabditoidea- helminth infection and subsequent bacterial septicemia, 50~70% of the total population had been died in a farm in Jeong-sun in Gangwon-do and Chungju in Chungcheongbuk-do from late June, 2012 to September, 2012. Diseased frogs showed ruptured lung, bloody ascites, liver discoloration, myocardium weakness, congested kidney, microcytic anemia and so on. Enterobacteriacea, Citrobacter.sp, Cupriavidus metallidurans, Acinetobacter.sp were isolated as major bacterium that had caused septicemia in frogs. Among isolated bacterium, Cupriavidus metallidurans, Ewingella americana, Shewanella aquimarina and Pseudoalteromonas sp. have not reported as potential pathogens in frogs before. It is a good example that severe helminth infection in frogs can lead to secondary infection of bacteria.

• 한국물환경학회지
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• 제38권4호
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• pp.171-176
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• 2022

Recently, an autotrophic single-stage nitrogen removal (ASSNR) process based on the anaerobic ammonium oxidation (ANAMMOX) reaction has been proven as an economical ammonia treatment. It is highly evident that double-layered gel beads are a promising alternative to the natural biofilm for ASSNR because of the high mechanical strength of poly(vinyl alcohol) (PVA)/alginate structure and efficient protection of ANAMMOX bacteria from dissolved oxygen (DO) due to the thick outer layer. However, the thick outer layer results in severe mass transport limitation and consequent lowered bacterial activity. Therefore, the effects of the thickness of the outer layer on the overall reaction rate were tested in the biofilm model using AQUASIM for ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and ANAMMOX bacteria. A thickness of 0.5~1.0 mm is preferred for the maximum total nitrogen (TN) removal. In addition, a DO of 0.5 mg/L resulted in the best total nitrogen removal. A higher DO induces NOB activity and consequent lower TN removal efficiency. The optimal density of AO B and NO B density was 1~10% for a 10% ANAMMOX bacterial in the double-layered PVA/alginate gel beads. The real effects of operating parameters of the thickness of the outer layer, DO and concentrations of biomass balance should be intensively investigated in the controlled experiments in batch and continuous modes.

• 한국수산과학회지
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• 제8권4호
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• pp.217-221
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• 1975

1975년 5월부터 10월까지 자리돔의 식품위생학적인 안전성을 검토하기 위하여 자리돔의 서식해수, 어획직후의 자리돔, 시판자리돔, 자리물회 및 자리무침 회의 일반세포수, coliform group MPN 및 parahaemolyticus의 유무를 조사한 결과를 요약하면 다음과 같다, 1) 서식해수의 일반세균수는 평균 $1.7\times10^2/ml$ 정도였고 coliform group MPN은 4/ml이하였다. 2) 어획직후의 자리돔은 일반세균수가 평균 $3.2\times10^3/g$였고 coliform group MPN은 300g이하였다. 3) 시판되고 있는 자리돔의 일반세균수는 8월 중순경에는 평균 $1.1\times10^6/g$ 9월중순경에는 $2.2\times10^6/g$ 였다. 4) 자리무침회 및 자리물회의 일반세균수는 각각 $1.1\times10^7/g,\;4.9\times10^5/g\~1.7\times10^7/g$였다. 5) 자리무침회와 자리물회에서는 V.purahamolyticus 균이 검출 되지 않았으나 서식해수와 자리돔에서는 V. parahaemolyticus 균이 검출 되었는데 식중독을 일으킬수 있는 균량은 아니였다. 5) 자리돔 및 각종 자리돔회의 일반세균수, coliform group MPN 및 V. parahaemolyticus는 8월과 9월에 오염도가 가장 높았다. 본 연구의 지도와 많은 조언을 주신 부산수산대학 식품공학료 최위경, 이강호, 이응호, 박사들과 실험을 도와 준 제주대거 이창환, 박철우, 이진영 제군에게 감사를 드리는 바이다.

• 한국미생물·생명공학회지
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• 제50권2호
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• pp.245-254
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• 2022

Cellulases are a group of biocatalyst enzymes that are capable of degrading cellulosic biomass present in the natural environment and produced by a large number of microorganisms, including bacteria and fungi, etc. In the current study, we isolated, screened and characterized cellulase-producing bacteria from soil. Three cellulose-degrading species were isolated based on clear zone using Congo red stain on carboxymethyl cellulose (CMC) agar plates. These bacterial isolates, named as HB2, HS5 and HS9, were subsequently characterized by morphological and biochemical tests as well as 16S rRNA gene sequencing. Based on 16S rRNA analysis, the bacterial isolates were identified as Bacillus cerus, Bacillus subtilis and Bacillus stratosphericus. Moreover, for maximum cellulase production, different growth parameters were optimized. Maximum optical density for growth was also noted at pH 7.0 for 48 h for all three isolates. Optical density was high for all three isolates using meat extract as a nitrogen source for 48 h. The pH profile of all three strains was quite similar but the maximum enzyme activity was observed at pH 7.0. Maximum cellulase production by all three bacterial isolates was noted when using lactose as a carbon rather than nitrogen and peptone. Further studies are needed for identification of new isolates in this region having maximum cellulolytic activity. Our findings indicate that this enzyme has various potential industrial applications.