• 미생물학회지
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• 제46권1호
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• pp.33-37
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• 2010

근권토양에서 분리한 세균 Bacillus subtilis RFO41은 인산 가용화능이 높고 auxin 등의 식물호르몬을 생산한다. 이 균주를 이용하여 가시도꼬마리(Xanthium italicum Moore)의 생장 촉진 실험을 화천군 파로호의 호안나대지에서 수행하였다. 19주 경과 후 자라난 가시도꼬마리를 채취하여 줄기와 뿌리 길이를 측정하고 식물을 건조시켜 중량을 측정하였다. 균주를 처리한 접종군이 미접종 대조군보다 가시도꼬마리의 건조중량이 67.7%나 높았으며 또한 가시도꼬마리의 줄기 길이도 균주를 처리한 접종군이 미접종 대조군보다 21.1% 길었는데 모두 통계적 유의성을 가졌다. 접종균주의 동태를 denaturing gradient gel electrophoresis 방법으로 조사하였는데 나대지 토양에서 접종균주가 유지되고 있으며 토양의 고유 세균군집에는 큰 영향을 미치지 않는 것을 확인하였다. 따라서 척박한 호안나대지 토양에서 B. subtilis RFO41의 인산가용화능과 식물호르몬의 생성능 등의 식물생장촉진 효과가 가시도꼬마리의 생장에 직접적인 영향을 미치는 것으로 판단할 수 있다. 이러한 식물 생장 촉진효과는 친환경적 미생물비료, 특히 민감한 호안나대지 등의 미생물학적 식생복원방법으로서의 가치를 뒷받침하는 것이라 할 수 있다.

• 유기물자원화
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• 제11권3호
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• pp.67-74
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• 2003

본 연구의 목적은 토양미생물의 일종인 Pseudomonas putida 에서 추출한 탄소고갈 유전자로부터 starvation promoter를 분리한 후 starvation vector를 개발하여 이를 미생물로부터 유용물질의 생산 및 오염물질의 정화등에 활용하기 위한 것이다. Starvation 유전자란 영양분의 결핍시에만 특수하게 발현되는 유전자의 일종으로 본 유전자로부터 promoter를 분리한 후 특정 물질을 분해 또는 생성하는 유전자를 분리된 promoter에 유전자 재조합 방법에 의하여 연결시키면 영양분의 공급을 최소화하고 세균의 생장을 억제 시키는 동시에 promoter에 연결된 유전자의 발현 기능은 최대화 시킴으로써 그 목적을 달성할 수 있다 하겠다. 본 연구에서는 기 분리된 starvation gene으로부터 promoter를 분리한 후 이를 적절한 벡터에 연결시켜 starvation vector인 pYKS101을 완성하였다. 본 벡터의 성능을 시험하기 위하여 reporter gene으로 lacZ유전자를 벡터내에 클로닝하여 세균의 염색체에 삽입시킨후 그 성능을 조사하였다. 삽입된 유전자는 예상한 바와같이 세균이 영양분이 결핍되었을 때 충분한 영양분이 공급되었을 때보다 약 4배의 활성도를 나타냄으로써 본 벡터의 유용성을 입증할 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제16권5호
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• pp.704-715
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• 2006

Oil spill was found in 1999 from a diesel storage facility located near the top of Baekun Mountain in Uiwang City. Application of bioremediation techniques was very relevant in removing oil spills in this site, because the geological condition was not amenable for other onsite remediation techniques. For efficient bioremediation, bacterial communities of the contaminated site and the uncontaminated control site were compared using both molecular and cultivation techniques. Soil bacterial populations were observed to be stimulated to grow in the soils contaminated with diesel hydrocarbon, whereas fungal and actinomycetes populations were decreased by diesel contamination. Most of the dieseldegrading bacteria isolated from contaminated forest soils were strains of Pseudomonas, Ralstonia, and Rhodococcus species. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that the profiles were different among the three contaminated sites, whereas those of the control sites were identical to each other. Analysis of 16S rDNA sequences of dominant isolates and clones showed that the bacterial community was less diverse in the oil-contaminated site than at the control site. Sequence analysis of the alkane hydroxylase genes cloned from soil microbial DNAs indicated that their diversity and distribution were different between the contaminated site and the control site. The results indicated that diesel contamination exerted a strong selection on the indigenous microbial community in the contaminated site, leading to predominance of well-adapted microorganisms in concurrence with decrease of microbial diversity.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.244-244
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• 2017

Soil salinity due to accumulation of salts particularly sodium chloride affects agricultural lands and their vegetation. Generally, rice is a moderately sensitive plant with some cultivars with varying tolerance to salinity. Though there are physiological differences between salt-sensitive and salt-tolerant rice cultivars, both are still affected especially during high salinity and prolonged exposure. This also ultimately affects their indigenous bacterial endophytes particularly those that inhabit the rice seed endosphere. This study investigates the dynamic structure of seed bacterial endophytes of salt-sensitive and tolerant rice cultivars grown in different levels of soil salinity. Endophytic bacterial diversity was studied Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis. Results revealed a very interesting pattern of diversity and shifts in community structure of bacterial endophytes in the rice seeds. There is a general decrease in diversity for the salt-sensitive rice cultivar, IR29 as soil salinity increases. For the salt-tolerant cultivars, IC32 and IC37, diversity interestingly increased at moderate salinity then decreased at high soil salinity. The patterns of community structure is also strikingly different for the salt-sensitive and salt-tolerant rice cultivars. IR29 has a more even distribution of abundance, but under soil salinity, the community shifted where Curtobacterium, Pantoea, Flavobacterium and Microbacterium become the more dominant bacterial communities. For IC32 and IC37, the dominant bacterial groups under normal stress conditions were also the dominant bacterial groups during salt stress conditions. Their seed bacterial community is dominated by endophytes belonging to Microbacterium, Flavobacterium, Pantoea, Kosakonia and Enterobacter. Stenotrophomonas and Xanthomonas have not changed in terms of abundance under different salinity stress level in the salt-sensitive and salt-tolerant rice cultivars. This study showed that soil salinity greatly influenced the seed bacterial communities of rice seeds irrespective of their physiological tolerance to salinity.

• 한국임상수의학회지
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• 제29권4호
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• pp.352-355
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• 2012

Hypospadias is a rare congenital malformation of the urethra reported in cattle. The urethral lumen of male indigenous Korean calf is open along the ventral aspect of the penis in the perineal region. Renal abscess and renal stone formation causing urinary tact infection has not been reported in hypospadia calves. The objective of this study was investigation for renal abscess and renal stone formation through autopsy. Histopathological examination and laboratory tests were performed. At autopsy, the pustules were formed on the right renal cortex, and the renal medulla abscess were formed on right and left part of the renal pelvis. Histopathological finding, this case was diagnosed as severe acute suppurative and necrotizing pyelonephritis, and severe chronic interstitial nephritis with fibrosis and moderate multifocal acute cystitis with edema. Milky exudate of the kidney has been identified as Actinomyces meyeri using the VITEK-2 system for identification of bacteria, and the stone has been identified as carbonate apatite using FT-IR system for quantification analysis. This case report describe the hypospadias complicated with urinary tract infection due to carbonate apatite stones and Actinomyces meyeri.

• Journal of Microbiology
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• 제34권4호
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• pp.320-326
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• 1996

To analyze the effects of host versus plasmid on survival of 2, 4-degrading bacteria in environmental samples, strains Pseudomonas cepacia/pJP4, Alcaligenes JMP228/pJP4, P. cepacia/p712, and Alcaligenes JMP228/p712 were separately inoculated into samples of field soil, paddy soil, lake water, and river water, and then the changes of their populations were measured. The strains used contained a 2, 4-D degradative plasmid, either pJP4 conferring fast-growing property to the host or p712 conferring slow-growing property, and were resistant to antibiotics such that the inoculated strains could be enumerated against the indigenous microbial populations. In sterile environmental samples, these strains were stably maintained at the levels used for inoculation, except in sterile paddy soil where Alcaligenes JMP228 strains died drapidly. In natural soil samples for four strains declined steadily with time, but in naturla water samples their polulations fell rapidly at the early phase and then remained almost constant. When the environmentla samples were treated with 2, 4-D, P. cepacia/pJP4 and P. cepacia/p712 maintained significant numbers, while Alcaligenes JMP228/pJP4 and Alcaligenes JMP228/p712 declined significantly in most of the samples. The results indicated that the survivability of genetically modified microorganisms could vary depending on the environments and that their abundance in the environments under s2, 4-D selection was markedly influenced by the nature of the 2, 4-D degradative plasmid as well as type of the host strain.

• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.602-608
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• 2010

An atrazine-degrading bacterium, strain KU001, was obtained from a sugarcane field at the Cane and Sugar Research and Development Center at the Kasetsart University, Kamphaeng Saen Campus, Thailand. Strain KU001 had a rod-to-coccus morphological cycle during growth. Biolog carbon source analysis indicated that the isolated bacterium was Arthrobacter histidinolovorans. Sequence analysis of the PCR product indicated that the 16S rRNA gene in strain KU001 was 99% identical to the same region in Arthrobacter sp. The atrazine degradation pathway in strain KU001 consisted of the catabolic genes trzN, atzB, and atzC. Strain KU001 was able to use atrazine as a sole nitrogen source for growth, and surprisingly, atrazine degradation was not inhibited in cells grown on ammonium, nitrate, or urea, as compared with cells cultivated on growth-limiting nitrogen sources. During the atrazine degradation process, the supplementation of nitrate completely inhibited atrazine degradation activity in strain KU001, whereas ammonium and urea had no effect on atrazine degradation activity. The addition of strain KU001 to sterile or nonsterile soils resulted in the disappearance of atrazine at a rate that was 4- to 5-fold more than that achieved by the indigenous microbial community. The addition of citrate to soils resulted in enhanced atrazine degradation, where 80% of atrazine disappeared within one day following nutrient supplementation.

• 한국동물위생학회지
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• 제33권1호
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• pp.29-35
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• 2010

This study was performed to test the hypothesis that Brucella abortus strain RB51 (SRB51) might protect Korean indigenous mongrel dog against challenge with either virulent B. abortus biotype 1 or B. canis. A total of 12 Korean mongrel dogs were divided into four groups (Group A, B, C and D). Dogs belonging to Group A and C were inoculated subcutaneously with $1{\times}10^9$ CFU of SRB51 in 1ml of sterile phosphate buffered saline (PBS). Dogs of Group B and D were inoculated subcutaneously with 1ml of sterile PBS as control. At 12 weeks post vaccination, dogs of Group A and B were challenged by oral inoculation of virulent strain of B. canis ($5.0{\times}10^9$ CFU) and dogs of Group C and D were challenged by oral inoculation of virulent strain of B. abortus biotype 1 ($4.4{\times}10^{10}$ CFU). The serum antibodies titers in all dogs were monitored at regular interval for eight weeks after challenge (AC) by standard tube agglutination test, plate agglutination test, rose bengal test, 2-mercaptoethanol rapid slide agglutination test and 2-mercaptoethanol tube agglutination test. No antibody titers in Group A and C was detected. Also, the challenge strains were not found from blood of all dogs of Group A and C from 1 week AC till the end of the experiment by culture and modified AMOS-PCR, whereas B. canis and B. abortus challenge strains were detected from blood of Group B and D, respectively. In addition, neither of two challenge bacteria was recovered from liver, spleen, kidneys, lymph nodes and reproductive tracts of Group A and C dogs after postmortem. However, B. canis and B. abortus challenge strains were isolated from these tissues of Group B and D, respectively. These data suggest that SRB51 could be a promising vaccine candidate for immunizing dogs to control canine brucellosis caused by B. canis or B. abortus.

• The Korean Journal of Ecology
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• 제18권1호
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• pp.109-120
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• 1995

As the genetically modified microorganisms (GMMs) and their recombinant plasmid DNAs could be released into natural environments, their stabilities and impacts to indigenous microorganisls have become very importhant research subjects concerning with environmental and ecological aspects. In this study, the genetically modified E. coli CU103 and its recombinant pCU103 plasmid DNA, in which pcbCD genes involving in degradation of biphenyl and 4-chlorobiphenyl were cloned, were studied for their survival and stability in several different waters established under laboratory conditions. E. coli CU103 and its host E. coli XL1-Blue survived longer in sterile distilled water (SDW) and filtered autoclaved river water (FAW) than in filtered river water (FW). A lot of extracellular DNAs were released from E. coli CU103 by lytic action of phages in FW and the released DNAs were degraded by DNase dissolved in the water. Such effects of the factors in FW on stability of the recombinant pCU103 plasmid were also observed in the results of gel electrophoresis, quantitative analysis with bisbenzimide, and transformation assay. Therefore, the recombinant plasmids of pCU103 were found to be readily liberated from the genetically modified E. coli CU103 into waters by normal metabolic processes and lysis of cells. And the plasmid DNAs were quite stable in waters, but their stabilities could be affected by physicoKDICical and biological factors in non-sterile natural waters.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권2호
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• pp.16-24
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• 2014

To test the potential effects of extracellular electron shuttles (EES) on the rate and extent of heavy metal release from contaminated soils during microbial iron reduction, we created anaerobic batch systems with anthraquinone-2,6-disulfonate (AQDS) as a surrogate of EES, and with contaminated soils as mixed iron (hydr)oxides and microbial sources. Two types of soils were tested: Zn-contaminated soil A and As/Pb-contaminated soil B. In soil A, the rate of iron reduction was fastest in the presence of AQDS and > 3500 mg/L of total Fe(II) was produced within 2 d. This suggests that indigenous microorganisms can utilize AQDS as EES to stimulate iron reduction. In the incubations with soil B, the rate and extent of iron reduction did not increase in the presence of AQDS likely because of the low pH (< 5.5). In addition, less than 2000 mg/L of total Fe(II) was produced in soil B within 52 d suggesting that iron reduction by subsurface microorganisms in soil B was not as effective as that in soil A. Relatively high amount of As (~500 mg/L) was released to the aqueous phase during microbial iron reduction in soil B. The release of As might be due to the reduction of As-associated iron (hydr)oxides and/or direct enzymatic reduction of As(V) to As(III) by As-reducing microorganisms. However, given that Pb in liquid phase was < 0.3 mg/L for the entire experiment, the microbial reduction As(V) to As(III) by As-reducing microorganisms has most likely occurred in this system. This study suggests that heavy metal release from contaminated soils can be strongly controlled by subsurface microorganisms, soil pH, presence of EES, and/or nature of heavy metals.