• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.929-935
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• 2002

The 5-stage biological nutrient removal (BNR) process with step feed system showed a very stable organic carbon and nutrient removal efficiency ($87\%\;COD\,;79\%\;nitrogen,\;and\;87\%$ phosphorus) for an operation period of 2 years. In each stage at the pilot plant, microbial communities, which are important in removing nitrogen and phosphorus, were investigated using fluorescence in-situ hybridization (FISH) and 165 rDNA characterization. All tanks of 5-stage sludge had a similar composition of bacterial communities. The totat cell numbers of each reactor were found to be around $2.36-2.83{\times}10^9$ cells/ml. About $56.5-62.0\%$ of total 4,6-diamidino-2-phenylindol (DAPI) cells were hybridized to the bacterial-specific probe EUB388. Members of ${\beta}$-proteobacteria were the most abundant proteobacterial group, accounting for up to $20.6-26.7\%$. The high G+C Gram-positive bacterial group and Cytophaga-Flexibacter cluster counts were also found to be relatively high. The beta subclass proteobacteria did not accumulate a large amount of polyphosphate. The proportion of phosphorus-accumulating organisms (PAOs) in the total population of the sludge was almost $50\%$ in anoxic-1 tank. The high G+C Gram-positive bacteria and Cytophaga-Flexibacter cluster indicate a key role of denitrifying phosphorus-accumulating organisms (dPAOs). Both groups might be correlated with some other subclass of proteobacteria for enhancing nitrogen and phosphorus removal in this process.

• Parasites, Hosts and Diseases
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• 제49권4호
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• pp.349-356
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• 2011

The existence of symbiotic relationships between Acanthamoeba and a variety of bacteria is well-documented. However, the ability of Acanthamoeba interacting with host bacterial pathogens has gained particular attention. Here, to understand the interactions of Escherichia coli K1 and E. coli K5 strains with Acanthamoeba castellanii trophozoites and cysts, association assay, invasion assay, survival assay, and the measurement of bacterial numbers from cysts were performed, and nonpathogenic E. coli K12 was also applied. The association ratio of E. coli K1 with A. castellanii was 4.3 cfu per amoeba for 1 hr but E. coli K5 with A. castellanii was 1 cfu per amoeba for 1 hr. By invasion and survival assays, E. coli K5 was recovered less than E. coli K1 but still alive inside A. castellanii. E. coli K1 and K5 survived and multiplied intracellularly in A. castellanii. The survival assay was performed under a favourable condition for 22 hr and 43 hr with the encystment of A. castellanii. Under the favourable condition for the transformation of trophozoites into cysts, E. coli K5 multiplied significantly. Moreover, the pathogenic potential of E. coli K1 from A. castellanii cysts exhibited no changes as compared with E. coli K1 from A. castellanii trophozoites. E. coli K5 was multiplied in A. castellanii trophozoites and survived in A. castellanii cysts. Therefore, this study suggests that E. coli K5 can use A. castellanii as a reservoir host or a vector for the bacterial transmission.

• The Korean Journal of Ecology
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• 제23권5호
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• pp.369-375
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• 2000

도시에서 토양을 보존하고 합리적으로 이용하기 위하여 도시 토양을 과학적으로 이해하는 것이 필요하지만 아직까지 이처럼 과도하게 관리되고 교란된 토양의 특성에 대하여 집중적으로 연구되지 않았다. 본 연구에서 조사된 인천의 산림, 잔디밭, 가로수, 나지 및 포장 밑 토양에서 답압에 의한 견밀화에 의하여 토양 가밀도가 높았다. 또한 다양한 도시 토양에서 수분함량은 전원지 산림 토양에 비하여 적었고 지온은 높았다. 화학적으로는 도시 토양에서 pH가 중성에 가깝고 유기물 함량이 적었다. 도시 토양의 총세균수는 전원지 산림 토양의 단지 5∼50% 수준이었다. 단계식 다중회귀분석의 결과, 토양 유기물함량이 총세균수에 영향을 미치는 주요한 요인으로서 선정되었다. 대부분의 도시 토양에서 탈수소효소 활성도는 전원지 산림 토양과 유의한 차이가 없었으나, 아스팔트 포장 밑 토양에서는 낮았다 그러므로 견밀한 도시 토양에서 낮은 유기물함량이 물질 순환에 관여하는 미생물 수에 악영향을 미친다고 판단되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제13권7호
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• pp.918-921
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• 2000

A comparative study on rumen bacterial and protozoal population and fungal zoospores in cattle (Brahman$\times$Native) and swamp buffalo (Bubalus bubalis) was conducted. Forty animals, twenty of each, with same sex and similar age which were raised under similar condition in the Northeast of Thailand, were used. Rumen digesta were sampled immediately post slaughtering for total microscopic counts of bacteria, protozoa and fungal zoospores. It was found that total bacterial population were higher in swamp buffalo that those in cattle (1.6 vs $1.36{\times}10^{8}cells/ml$) having more population of cocci, rods and ovals. Lower rumen protozoal pupulation in swamp buffalo with lower numbers of Holotrichs and Entodiniomorphs were found as compared to those in cattle. Significant higher fungal zoospore counts were in swamp buffalo than those in cattle being 7.30 and $3.78{\times}10^6$, respectively. Study under electron microscope, revealed Anaeromyces sp. with acuminate apex were more predominant in the rumen of swamp buffalo. With these findings, cattle and swamp buffaloes showing differences in rumen bacterial, protozoal population and fungal zoospore counts, offer new additional information as why swamp buffaloes exhibit conditionally better than cattle especially during long dry season without green grass.

• 대한지하수환경학회지
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• 제5권4호
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• pp.215-222
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• 1998

지하수 세균 군집에 미치는 환경요인의 영향을 분석하기 위하여, 서울 시내에서 음용수로 사용하는 2개 정점과 음용수외 생활용수로 사용하고 있는 8개 정점을 대상으로 조사하였다. 물리.화학적 환경요인과 중금속의 농도, 및 세균 군집의 분포 등 40개 변수를 분석한 결과, 음용수로 사용하는 정점을 제외한 나머지 정점에서 질산성 질소와 암모니아가 용수목적별 수질기준의 기준치 이상으로 측정되었다. 총세균은 5.1~41.4$\times$$10^{5}$cells/ml 범주로, 종속영양세균과 기능성 세균군집은 0.01~29.6$\times$$10^4$cfu/ml의 범주로 조사되었다. 세포외 효소의 활성도는 0.005~11.3$\mu$M/l/hr 의 범주로 나타났고, lipase, phophatase, $\beta$-glucosidase, cellulase, chitinase, amylase 순으로 활성도가 나타났다. 정점별로 조사된 세균 군집에 미치는 환경요인의 상호관계는 대응분석(correspondence analysis)과 다차원 척도법 분석(multidimensional scaling; MDS)으로 하였으며, 그 결과 4개의 집단으로 구분되었으며, 세균 군집에 미치는 주요한 환경요인은 정점별 잠재오염원과 일치하는 양상을 보였다.다.

• Journal of Ginseng Research
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• 제40권4호
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• pp.453-461
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• 2016

Background: This study aims to describe the characterization of Paenibacillus polymyxa GBR-1 (GBR-1) with respect to its positive and negative effects on plants. Methods: The morphological characteristics of GBR-1 were identified with microscopy, and subjected to Biolog analysis for identification. Bacterial population and media optimization were determined by a growth curve. The potential for GBR-1 as a growth promoting agent, to have antagonistic activity, and to have hydrolytic activity at different temperatures was assessed. The coinoculation of GBR-1 with other microorganisms and its pathogenicity on various stored plants, including ginseng, were assessed. Results: Colony morphology, endospore-bearing cells, and cell division of GBR-1 were identified by microscopy; identification was performed by utilizing the Biolog system, gas chromatography of fatty acid methyl esters (GC-FAME). GBR-1 showed the strongest antagonistic activity against fungal and bacterial pathogens. GBR-1 cell numbers were relatively higher when the cells were cultured in brain heart infusion (BHI) medium when compared with other media. Furthermore, the starch-hydrolytic activity was influenced by GBR-1 at higher temperature compared to low temperatures. GBR-1 was pathogenic to some of the storage plants. Coinoculation of GBR-1 with other pathogens causes differences in rotting on ginseng roots. A significant growth promotion was observed in tobacco seedlings treated with GBR-1 suspensions under in vitro conditions, suggesting that its volatile organic compounds (VOCs) might play a role in growth promotion. Conclusion: The results of this study indicate that GBR-1 has both positive and negative effects on ginseng root and other stored plants as a potential biocontrol agent and eliciting in vitro growth promotion.

• Journal of Microbiology and Biotechnology
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• 제23권1호
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• pp.76-84
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• 2013

A polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique followed by sequencing of the 16S rDNA fragments eluted from the bands of interest on denaturing gradient gels was used to monitor changes in the bacterial microflora of two commercial kimchi, salted cabbage, and ingredient mix samples during 30 days of fermentation at $4^{\circ}C$ and $10^{\circ}C$. Leuconostoc (Lc.) was the dominant lactic acid bacteria (LAB) over Lactobacillus (Lb.) species at $4^{\circ}C$. Weissella confusa was detected in the ingredient mix and also in kimchi samples throughout fermentation in both samples at $4^{\circ}C$ and $10^{\circ}C$. Lc. gelidum was detected as the dominant LAB at $4^{\circ}C$ in both samples. The temperature affected the LAB profile of kimchi by varing the pH, which was primarily caused by the temperature-dependent competition among different LAB species in kimchi. At $4^{\circ}C$, the sample variations in pH and titratable acidity were more conspicuous owing to the delayed growth of LAB. Temperature affected only initial decreases in pH and initial increases in viable cell counts, but affected both the initial increases and final values of titratable acidity. The initial microflora in the kimchi sample was probably determined by the microflora of the ingredient mix, not by that of the salted cabbage. The microbial distributions in the samples used in this study resembled across the different kimchi samples and the different fermentation temperatures as the numbers of LAB increased and titratable acidity decreased.

• Toxicological Research
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• 제30권3호
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• pp.211-220
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• 2014

Resveratrol has received considerable attention as a polyphenol with various biological effects such as anti-inflammatory, anti-oxidant, anti-mutagenic, anti-carcinogenic, and cardioprotective properties. As part of the overall safety assessment of HS-1793, a novel resveratrol analogue free from the restriction of metabolic instability and the high dose requirement of resveratrol, we assessed genotoxicity in three in vitro assays: a bacterial mutation assay, a comet assay, and a chromosomal aberration assay. In the bacterial reverse mutation assay, HS-1793 did not increase revertant colony numbers in S. typhimurium strains (TA98, TA100, TA1535 and TA1537) or an E. coli strain (WP2 uvrA) regardless of metabolic activation. HS-1793 showed no evidence of genotoxic activity such as DNA damage on L5178Y $Tk^{+/-}$ mouse lymphoma cells with or without the S9 mix in the in vitro comet assay. No statistically significant differences in the incidence of chromosomal aberrations following HS-1793 treatment was observed on Chinese hamster lung cells exposed with or without the S9 mix. These results provide additional evidence that HS-1793 is non-genotoxic at the dose tested in three standard tests and further supports the generally recognized as safe determination of HS-1793 during early drug development.

• 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.

• 상하수도학회지
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• 제27권6호
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• pp.689-701
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• 2013

잔류염소 농도가 상당히 낮은 수돗물에서 유기탄소(organic carbon)와 인(phosphorus)의 증가가 세균 생장에 미치는 영향과 세균에 의한 유기탄소와 인의 소모를 fed-batch 실험조건($20^{\circ}C$ 수온)에서 조사하였다. 수돗물에서 단지 인의 증가만으로는 부유성 세균의 현저한 수적 증가는 나타나지 않았다. 그러나 유기탄소의 증가는 부유성 세균을 $10^3CFU/mL$ 수준까지 증가시켰으며, 특히 유기탄소와 함께 동반된 인의 증가는 부유성 세균을 $10^5CFU/mL$ 수준까지 증가시켰다. 이러한 효과들은 polyethylene (PE) slide 표면에 형성된 생물막 세균과 생물량 측정에서도 동일하게 나타났다. 유기탄소와 함께 인 농도가 높은 수돗물에서 PE slide 표면에 형성된 생물막 세균과 세포외 중합체(extracellular polymeric substance) 구성 성분으로 측정된 생물량은 각각 $7.6{\times}10^5CFU/cm^2$와 $5.3{\mu}g/cm^2$로 가장 높았다. 세균 생장과 더불어, 수돗물에서 유기탄소와 인의 증가는 세균에 의한 탄소와 인의 이용 패턴에 영향을 미치는 것으로 나타났다. 전형적인 세균의 C/P 소모비율(100:1)과 비교했을 때, 상대적으로 높은 C/P 소모비율(590:1)은 유기탄소 농도가 높은 수돗물에서, 그리고 상대적으로 낮은 C/P 소모비율(40:1)은 인 농도가 높은 수돗물에서 관찰되었다. 또한 유기탄소와 함께 인 농도가 높은 수돗물에서도 상대적으로 낮은 C/P 소모비율(80:1)이 관찰되었다. 주어진 실험조건에서는 수돗물과 생물막내 세균 생장이 인의 증가보다는 유기탄소의 증가에 더욱 민감하게 반응하는 것으로 나타났다. 수돗물에서 인의 증가는 세균의 낮은 C/P 소모비율을 가져오지만, 세균 생장에 미치는 인의 영향은 세균이 쉽게 이용할 수 있는 유기탄소의 존재와 밀접하게 관련되어 있는 것으로 보인다. 그러므로 수돗물에 자연적으로 존재하는 낮은 농도의 인만으로도 세균 생장을 위해 필요한 인 요구량을 만족시킬 수 있기 때문에, 수돗물에서 세균 생장의 최소화를 위해서는 인보다는 유기탄소의 외부적인 유입을 제어하는 것이 더욱 중요한 것으로 판단된다.