• Journal of Species Research
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• 제8권3호
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• pp.249-258
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• 2019

Owing to a distinct environmental regime and anthropogenic effects, freshwater bacterial communities of urban streams are considered to be different from those of large freshwater lakes and rivers. To obtain unrecorded, freshwater bacterial species in Korea, water and sediment samples were collected from various urban streams of the Han River watershed in 2018. After plating the freshwater samples on R2A agar, approximately 1000 bacterial strains were isolated from the samples as single colonies and identified using 16S rRNA gene sequence analyses. A total of 26 strains, with >98.7% 16S rRNA gene sequence similarity with validly published bacterial species but not reported in Korea, were determined to be unrecorded bacterial species in Korea. The unrecorded bacterial strains were phylogenetically diverse and belonged to four phyla, six classes, 12 orders, 16 families, and 21 genera. At the generic level, the unreported species were assigned to Nocardioides, Streptomyces, Microbacterium, Kitasatospora, Herbiconiux, Corynebacterium, and Microbacterium of the class Actinobacteria; Paenibacillus and Bacillus of the class Bacilli; Caulobacter, Methylobacterium, Novosphingobium, and Porphyrobacter of the class Alphaproteobacteria; Aquabacterium, Comamonas, Hydrogenophaga, Laribacter, Rivicola, Polynucleobacter, and Vogesella of the class Betaproteobacteria; Arcobacter of the class Epsilonproteobacteria; and Flavobacterium of the class Flavobacteriia. The details of the 26 unreported species, including Gram reaction, colony and cell morphology, biochemical properties, and phylogenetic position are also provided in the strain descriptions.

• Journal of Microbiology and Biotechnology
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• 제33권6호
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• pp.707-714
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• 2023

Plant-derived insecticide-neonicotinoid insecticides (NIs) played a crucial role in the development of agriculture and food industry in recent years. Nevertheless, synthesis of these nitrogen-containing heterocyclic compounds with an effective and greener routing remains challenging especially to the notion raise of "green chemistry" and "atom economy". While bio-catalyzed methods mediated by nicotinate dehydrogenase (NDHase) then provide an alternative. The current review mainly focuses on the introduction of sources, components, structure, catalytic mechanism and applications of NDHase. Specifically, NDHase is known as nicotinic acid hydroxylase and the sources principally derived from phylum Proteobacteria. In addition, NDHase requires the participation of the electron respiratory chain system on the cell membrane. And the most important components of the electron respiratory chain are hydrogen carrier, which is mainly composed of iron-sulfur proteins (Fe-S), flavin dehydrogenase (FAD), molybdenum binding protein and cytochromes. Heterologous expression studies were hampered by the plasmid and host with high efficiency and currently only Pseudomonas entomophila L48 as well as Comamonas testosterone was successfully utilized for the expression of NDHase. Furthermore, it is speculated that the conjugate and inductive effects of the substituent group at position 3 of the substrate pyridine ring exerts a critical role in the hydroxylation reactions at position 6 concerning about the substrate molecular recognition mechanism. Finally, applications of NDHase are addressed in terms of pesticide industry and wastewater treatment. On conclusion, this critical review would not only deepen our understanding of the theory about NDHase, but also provides the guideline for future investigation of NDHase.

• 한국미생물·생명공학회지
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• 제28권3호
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• pp.180-184
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• 2000

제지폐수 처리장에는 공정내에서 순환하는 분산성 미생물이 존재하는데 환경조건에 따라 이상중식 현상이 일어나 처리수질의 악화와 악취가 발생되는 현상이 발견되었다. 본 연구에서는 이러한 문제를 일으키는 분산성 미생물을 파악한후 우검종 분산성 미생물을 분리동정하고 각 폐수처리 공정중에서 호기 및 혐기적 미생물의 생태분석 및 그 생육특성을 조사하여 이를 토대로 안정적인 폐수처리를 위한 미생물관리 모델시스템 개발의 기초적인 연구를 수행하였다. 제지폐수내 1차 처리수중 주요 우점종 분산성균들의 분리동정 결과 호기성균으로 Pseudomonas carboxydohydrogena, Cardiobacterim hominis. Micrococcus lylae, Xantomonas cam-pestris pv juglandis, Micrococcus diversus, Comamaonas terrigena, 혐기성균으로는 Streptococcus bovis, Prevotella buccae등의 균이 동정되었다 3회의 분석때마다 서로 다른 buccae등의 균이 동정되었다. 호기적 균이 혐기성 균보다 더 많은 종류가 검출되었다 이중 주요 균의 생리특성을 관찰한 결과 온도는 $37^{\circ}C$에서 생육이 가장우수하였고 적정 pH는 균종에 따라 다르게 나타났으며 특히 1차 폐수처리시에 첨가되는 alumi-nium sulfate에 의한 sulfate의 요구 균주가 많았다 따라서 제지 폐수내의 분산성 미생물은 매우 다양한 균들로 이루어져 있으며 외부의 환경변화에 의하여 microflora 가 변하고 있음을 확인할 수가 있었다 그리고 이들 호기적처리 공정중에서도 많은 혐기성 미생물이 생육하들 호기적처리 공정중에서도 많은 혐기성 미생물이 생육하고 있으며 이들이 폐수처리에 많은 역할을 하고 있는 것으로 나타났다. 특히 1차 침전조에서의 긴 체류시간에 의하여 상등액에서 원폐수보다 호기성미생물보다 혐기성미생물의 생육이 3배나 많이 이루어졌고 1차침전조에서의 긴 체류시간에 의하여 상등액에서 원폐수보다 호기성미생물보다 혐기성미생물의 생육이 3배나 많이 이루어졌고 1차침전조 하부 슬러지액에서는 혐기성균이 10배나 많이 존재하였다 따라서 혐기성균이 침전된 유기물로부터 황화수소가스와 이산화탄소등의 가스를 발생시키고 이 가스가 하부에서 상부로 부상하면서 미생물의 침전성을 악화하여 분산성미생물을 증가시켜 폐수처리효율을 떨어뜨리며 아울러 심한 악취까지 발생시킬 것으로 사료된다.

• Fisheries and Aquatic Sciences
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• 제21권2호
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• pp.6.1-6.10
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• 2018

The intention of this study was to identify the bacterial pathogens infecting Oreochromis niloticus (Nile tilapia) and Clarias gariepinus (African catfish), and to establish the antibiotic susceptibility of fish bacteria in Uganda. A total of 288 fish samples from 40 fish farms (ponds, cages, and tanks) and 8 wild water sites were aseptically collected and bacteria isolated from the head kidney, liver, brain and spleen. The isolates were identified by their morphological characteristics, conventional biochemical tests and Analytical Profile Index test kits. Antibiotic susceptibility of selected bacteria was determined by the Kirby-Bauer disc diffusion method. The following well-known fish pathogens were identified at a farm prevalence of; Aeromonas hydrophila (43.8%), Aeromonas sobria (20.8%), Edwardsiella tarda (8.3%), Flavobacterium spp. (4.2%) and Streptococcus spp. (6.3%). Other bacteria with varying significance as fish pathogens were also identified including Plesiomonas shigelloides (25.0%), Chryseobacterium indoligenes (12.5%), Pseudomonas fluorescens (10.4%), Pseudomonas aeruginosa (4.2%), Pseudomonas stutzeri (2.1%), Vibrio cholerae (10.4%), Proteus spp. (6.3%), Citrobacter spp. (4.2%), Klebsiella spp. (4.2%) Serratia marcescens (4.2%), Burkholderia cepacia (2.1%), Comamonas testosteroni (8.3%) and Ralstonia picketti (2.1%). Aeromonas spp., Edwardsiella tarda and Streptococcus spp. were commonly isolated from diseased fish. Aeromonas spp. (n = 82) and Plesiomonas shigelloides (n = 73) were evaluated for antibiotic susceptibility. All isolates tested were susceptible to at-least ten (10) of the fourteen antibiotics evaluated. High levels of resistance were however expressed by all isolates to penicillin, oxacillin and ampicillin. This observed resistance is most probably intrinsic to those bacteria, suggesting minimal levels of acquired antibiotic resistance in fish bacteria from the study area. To our knowledge, this is the first study to establish the occurrence of several bacteria species infecting fish; and to determine antibiotic susceptibility of fish bacteria in Uganda. The current study provides baseline information for future reference and fish disease management in the country.

• Journal of Microbiology and Biotechnology
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• 제22권10호
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• pp.1330-1335
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• 2012

Foot and mouth disease (FMD) is one of the acute infectious diseases in hoofed and even-toed mammals, including pigs, and it occurs via acute infection by Aphthovirus. When FMD is suspected, animals around the location of origin are typically slaughtered and buried. Other methods such as rendering, composting, and incineration have not been verified in practice in Korea. After the FMD incident, the regular monitoring of the microbial community is required, as microorganisms greatly modify the characteristics of the ecosystem in which they live. This is the result of their metabolic activities causing chemical changes to take place in the surrounding environment. In this study, we investigated changes in the microbial community during a 24 week period with DNA extracts from leachate, formed by the decomposition of buried pigs at a laboratory test site, using denaturing gradient gel electrophoresis (DGGE) with a genomic DNA. Our results revealed that Bacteroides coprosuis, which is common in pig excreta, and Sporanaerobacter acetigenes, which is a sulfur-reduced microbe, were continuously observed. During the early stages (0~2 weeks) of tissue decomposition, Clostridium cochlearium, Fusobacterium ulcerans, and Fusobacterium sp., which are involved in skin decomposition, were also observed. In addition, various microbes such as Turicibacter sanguinis, Clostridium haemolyticum, Bacteroides propionicifaciens, and Comamonas sp. were seen during the later stages (16~24 weeks). In particular, the number of existing microbial species gradually increased during the early stages, including the exponential phase, decreased during the middle stages, and then increased again during the later stages. Therefore, these results indicate that the decomposition of pigs continues for a long period of time and leachate is created continuously during this process. It is known that leachate can easily flow into the neighboring environment, so a long-term management plan is needed in burial locations for FMD-infected animals.

• 한국버섯학회지
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• 제19권2호
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• pp.103-108
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• 2021

본 시험은 재배과정 중 배지에서 분리한 미생물의 특성을 조사하여 이들 미생물과 버섯균의 생육과 연관관계를 밝히고자 하였다. 짚, 계분 등 배지 재료에서 분리한 미생물의 양송이 균주에 대한 억제 정도는 국내 육성 양송이 균주가 외국에서 수입한 양송이 균주 보다 생육 억제 정도가 낮은 경향을 보였다. 양송이 배지 발효 단계별 분리 미생물의 양송이 품종간 균사 생육 억제 정도는 국내 육성 품종인 새도가 다른 품종보다는 생육이 좋았다. 그리고 발효과정이 진행됨에 따라 버섯균에 대한 억제 정도는 약해지는 경향을 보였다. 양송이 배지에서 분리한 미생물을 합성배지(CDA)에 도말한 뒤 버섯균사를 접종하여 균사의 생육을 조사한 결과와 분리균을 도말하고 항온기에서 2일간 배양한 후 배지를 완전히 뒤집어 배지의 뒷면 중앙에 버섯 균사를 접종하여 균사 생육을 조사한 결과를 비교 분석한 결과 양송이균의 생육 정도가 비슷한 경향을 보이는 것으로 보아 양송이 배지에서 분리한 미생물은 분비성 물질을 통해서 버섯균의 생육과 증식에 영향을 미친다는 것을 알 수 있었다. 양송이 균의 생육을 촉진하는 미생물을 분리한 결과 21균주가 선발되었고 대부분 4차 뒤집기 이후에서 많이 선발되었다. 대표적인 균주로는 Alcaligenes faecalis B-4-28, Comamonas testosteroni B-4-31, Acinetobacter soli B-4-40 등이 있다.