• 한국환경과학회지
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• 제11권3호
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• pp.177-182
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• 2002

A biosurfactant-producing microorganism was isolated from activated sludge by enrichment culture when grown on a minimal salt medium containing n-hexadecane as a sole carbon source. This microorganism was identified as Pseudomonas sp. and it was named Pseudomonas sp. EL-G527. It's optimal culture condition is 2% n-hexadecane, 0.2% NH$_4$NO$_3$, 0.3% KH$_2$PO$_4$, 0.3% $K_2$HPO$_4$, 0.02% MgSO$_4$ㆍ7$H_2O$, 0.0025% CaCk$_2$ㆍ6$H_2O$, 0.0015% FeSO$_4$ㆍ7$H_2O$ in 1$\ell$ distilled water and initial pH 7.0. Cultivation was initiated with a 2% inoculum obtained from starter cultures grown in 30 $m\ell$ of the same medium in 250 $m\ell$ flask. They were cultivated at 3$0^{\circ}C$ in reciprocal shaking incubator and the highest biosurfactant production was observed after 4 days.

• The Plant Pathology Journal
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• 제27권1호
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• pp.20-25
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• 2011

Gibberella zeae (anamorph: Fusarium graminearum), a homothallic (self-ferile) ascomycete with ubiquitous geographic distribution, causes serious diseases in several cereal crops. Ascospores (sexual spores) produced by this fungal pathogen have been suggested as the main source of primary inoculum in disease development. Here, we report the function of a gene designated GzRUM1, which is essential for ascospore formation in G. zeae. The deduced product of GzRUM1 showed significant similarities to the human retinoblastoma (tumor suppressor) binding protein 2 and a transcriptional repressor, Rum1 in the corn smut fungus (Ustilago maydis). The transcript of GzRUM1 was detected during the both vegetative and sexual stages, but was more highly accumulated during the latter stage. In addition, no GzRUM1 transcript was detected in a G. zeae strain lacking a mating-type gene (MAT1-2), a master regulator for sexual development in G. zeae. Targeted deletion of GzRUM1 caused no dramatic changes in several traits except ascospore formation. The ${\Delta}$GzRUM1 strain produced perithecia (sexual fruit bodies) but not asci nor ascospores within them. This specific defect leading to an arrest in ascospore development suggests that GzRUM1, as Rum1 in U. maydis, functions as a transcriptional regulator during sexual reproduction in G. zeae.

• 한국균학회지
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• 제23권4호통권75호
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• pp.348-353
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• 1995

Poly (3-hydroxybutyrate)(PHB) 의 Penicillium pinophilum에 의한 생분해성을 변형 Sturm Test 법으로 조사하였다. 활성오니를 사용한 경우보다 PHB의 생분해성이 비교적 재현성있게 측정되었으며 PHB의 생분해를 가장 빠르게 진행시키는 최적 포자 접균량은 1 %(v/v)이었다. 생분해 속도는 시료의 표면적에 따라 증가하였으나 비례적으로 상승하지 않아 분해가 시료의 표면 뿐만 아니라 내부에서도 진행됨을 나타내었다. 반응 배지내의 질소원 함량에 따라 PHB의 생분해 속도는 증가하다가 점근값을 보여 질소원이 depolymerase 효소의 합성에 필요한 원소임을 보였다.

• Membrane and Water Treatment
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• 제10권3호
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• pp.213-221
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• 2019

Anaerobic digestion (AD) has been widely used to valorize food waste (FW) because of its ability to convert organic carbon into $CH_4$ and $CO_2$. Korean FW has a high content of fruits and vegetables, and efficient hydrolysis of less biodegradable fibers is critical for its complete stabilization by AD. This study examined the digestates from different anaerobic digesters, namely Rs, Rr, and Rm, as the inocula for the AD of vegetable waste (VW) and cellulose (CL): Rs inoculated with anaerobic sludge from an AD plant, Rr inoculated with rumen fluid, and Rm inoculated with anaerobic sludge and augmented with rumen fluid. A total of six conditions ($3\;inocula{\times}2\;substrates$) were tested in serial subcultures. Biogas yield was higher in the runs inoculated with Rm than in the other runs for both VW (up to 1.10 L/g VS added) and CL (up to 1.05 L/g VS added), and so was biogas production rate. The inocula had different microbial community structures, and both substrate type and inoculum source had a significant effect on the formation and development of microbial community structures in the subcultures. The overall results suggest that the bioaugmentation with rumen microbial consortium has good potential to enhance the anaerobic biodegradability of VW, and thereby can help more efficiently digest high fiber-content Korean FW.

• Journal of Microbiology and Biotechnology
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• 제33권4호
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• pp.419-429
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• 2023

Ultraviolet C (UV-C, 200-280 nm) light has germicidal properties that inactivate a wide range of pathogenic and spoilage microorganisms. UV-C has been extensively studied as an alternative to thermal decontamination of fruit juices. Recent studies suggest that the efficacy of UV-C irradiation in reducing microorganisms in fruit juices is greatly dependent on the characteristics of the target microorganisms, juice matrices, and parameters of the UV-C treatment procedure, such as equipment and processing. Based on evidence from recent studies, this review describes how the characteristics of target microorganisms (e.g., type of microorganism/strain, acid adaptation, physiological states, single/composite inoculum, spore, etc.) and fruit juice matrices (e.g., UV absorbance, UV transmittance, turbidity, soluble solid content, pH, color, etc.) affect the efficacy of UV-C. We also discuss the influences on UV-C treatment efficacy of parameters, including UV-C light source, reactor conditions (e.g., continuous/batch, size, thickness, volume, diameter, outer case, configuration/arrangement), pumping/flow system conditions (e.g., sample flow rate and pattern, sample residence time, number of cycles), homogenization conditions (e.g., continuous flow/recirculation, stirring, mixing), and cleaning capability of the reactor. The collective facts indicate the immense potential of UV-C irradiation in the fruit juice industry. Existing drawbacks need to be addressed in future studies before the technique is applicable at the industrial scale.

• The Plant Pathology Journal
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• 제21권1호
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• pp.68-72
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• 2005

The production of antibiotic substances by Serratia plymuthica A21-4 was greatly enhanced by modifying components of a growth medium. When the minimal medium containing $K_2HPO_4$ 0.7%, $KH_2PO_4$ 0.2%, $(NH_4)_2SO_4$ 0.1%, $MgSO_4$ 0.01% was used as basal medium, the best carbon source for antibiotic production was glycerol and the most favorable nitrogen source was ammonium sulfate. The modified medium for antibiotic production also increased colonization ability of A21-4 on pepper root and in the rhizosphere soil. When the cells of A21-4 were suspended in modified medium, the population density of A21-4 on pepper root was 10-100 times higher than that suspended in 0.1 M $MgSO_4$. The population density of A21-4 on root did not decrease under $10^6$ cfu/groot up to 21 days after treatment although the inoculum of A21-4 was reduced to $10^7$ cell/ml. Similar tendency was also observed in the rhizosphere soil. Consequently, Phytophthora blight of pepper was successfully controlled by A21-4 with $10^7$ cell/ml suspended in the modified buffer solution instead of $10^9$ cfu/ml suspended in 0.1 M $MgSO_4$.

• 한국균학회지
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• 제22권4호
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• pp.332-337
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• 1994

Under standard condition (Han, et al., 1990: glucose 1%-nitrate 0.1% minimal medium, 30 ml in 9 cm plate, $10^6$ cells of inoculum per plate), wild type of Aspergillus nidulans developed both sexual and asexual organs in ballance, while velA1 mutant developed asexual ones preferentially. Increase of glucose concentration did not significantly affect the asexual sporulation. However, development of sexual organs were largely affected. It was greatly enhanced when favorable nitrogen source, for example, casein hydrolysate was added, which is contrary to the case of Neurospora or Saccharomyces where limitation of N source induces sexual development. On most of moderate C sources asexual development in $velA^+$ strain was largely inhibited except acetate on which only asexual spores were produced, while that in velA1 mutant strain was not affected. Lactose promoted the sexual development even in velA1 mutant indicating that lactose itself or its metabolic intermediate may induce sexual development independent of allelic state of velA gene. On other moderate favorable C sources, glycerol, galactose and ethanol, asexual development was largely inhibited in $velA^+$ strain but not in velA1 mutant strain. Sexual organs were, however, never produced on acetate. These results suggested that asexual development of wild type is largely dependent on C sources and the velA gene is involved in the repression of asexual development in not-enough-grown (non-competent) thalli resulting in preferential progression of sexual development.

• Animal Bioscience
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• 제36권2호
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• pp.238-247
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• 2023

Objective: Recently, indigenous Korean grass Sasa quelpaertensis Nakai (SQ) has garnered much interest as a roughage source for livestock to mitigate its adverse effects on habitat diversity. Thus, the objective of the present study was to evaluate the ruminal fermentation, palatability, and nutrient digestibility of SQ for Korean native beef cattle (Hanwoo) using in vitro rumen fermentation, in situ rumen degradability, and in vivo feeding trials. Methods: Using in vitro tests with rumen fluid as the inoculum for 48 h, ruminal fermentation of SQ was evaluated and compared with that of other roughage sources commonly used in Korea (i.e., rice straw, Timothy hay, and Italian ryegrass [IRG]). Additionally, an in situ trial 96 h was performed using three cannulated Hanwoo steers. Further, an in vivo trial was performed using eight Hanwoo steers to compare the palatability of SQ with rice straw in total mixed ration (TMR) and forage-concentrate separate feeding conditions. Finally, an in vivo digestibility trial of SQ fed as TMR of two particle sizes was performed with four Hanwoo steers. Results: In vitro and in situ trials revealed that SQ was comparable or superior to rice straw in terms of the ruminal fermentation characteristics of pH, gas production, total volatile fatty acid content, and effective ruminal dry matter digestibility (DMD), although its fermentability was lower than that of Timothy hay and IRG. In the palatability test, steers showed a greater preference for SQ when given as TMR. The total tract DMD of SQ fed as TMR was 75.9%±1.37%, and it did not differ by particle size. Conclusion: The feed value of SQ as a roughage source for Hanwoo steers is comparable or superior to that of rice straw, particularly when provided as TMR.

• 식물조직배양학회지
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• 제21권2호
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• pp.91-97
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• 1994

고구마 현탁배양세포로부터 POD 고생산세포주로 선발한 SP-47세포주를 사용하여 POD생산성을 향상시키기 위하여 식물생장조절제 및 탄소원의 종류와 농도, 세포접종량 등의 배양조건을 적정화하였다. 30 g/L Surcrose, 1 mg/L 2,4-D가 첨가된 LS배지 50mL을 함유한 30 mL Erlenmeyer flask에 세포생중량 1 g을 접종하여 $25^{\circ}C$ 암소에서 100 rpm으로 진탕배양하였을 때 세포생장은 배양 후 15일에 절정에 달하였으나 단위세포당 POD 활성(unit/g dry cell wt)은 배양 25일에 약 6,800으로 이는 실생 서양겨자무뿌리의 것보다 약 30배 높았다. 배양시기별 단위세포당 단백질 함량은 계대배양후 약간 높았다가 감소한 후, 배양 25일까지는 거의 일정한 값을 유지하다가 계속 배양함에 따라 감소하였으나 POD 비활성(unit/mg protein)은 배양후 12일부터 배양말기 (40일)까지 계속하여 증가하였다. 배양시기별 POD 동위효소의 패턴은 배양시기에 관계없이 거의 일정하였으나 배양 25일이후 산성의 주요 동위효소들의 활성이 약간 증가하였다. 이러한 결과로부터 고구마 세포배양의 POD는 세포생장 및 계대배양과 배지고갈로 인한 배양스트레스와 밀접한 관련 이 있을 것으로 간주된다. 본 연구에서 확립한 SP-47세포주는 하나의 동위효소가 강하게 발현되어 높은 활성을 보임으로써 새로운 POD 대량생산 시스템에 활용될 수 있을 것으로 기대된다.

• 원예과학기술지
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• 제32권2호
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• pp.217-226
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• 2014

2012년 충남 부여에서 뿌리혹선충(Meloidogyne incognita, M. arenaria 및 M. javanica)에 대한 저항성 유전자 Mi를 가지고 있는 토마토 '유니콘' 품종에서 뿌리혹선충병이 크게 발생하였다. 이로부터 분리한 뿌리혹선충은 종 특이적 프라이머 2개에 의한 분석한 결과, M. incognita로 동정되었다. 이 선충에 의한 감수성 1개와 저항성 3개 토마토 품종의 뿌리혹선충병 발생을 조사하였는데, 실험한 모든 온도 조건에서 실험한 품종 모두는 높은 감수성을 보였다. 그리고 시판 중인 토마토 33개 품종(뿌리혹선충 저항성 25개와 감수성 8개)의 이 선충에 대한 저항성 정도를 조사한 결과, 실험한 모든 품종들은 각 품종의 뿌리혹선충 저항성과 관계없이 유사한 정도의 높은 감수성을 나타냈다. 본 논문은 우리나라에서 Mi 저항성 토마토 품종에 뿌리혹선충병을 일으키는 M. incognita 발생을 처음으로 보고하는 것이다. 한편, 새로운 저항성 육종 소재를 찾기 위한 효율적인 저항성 검정 방법을 확립하기 위하여, 이 선충의 접종 농도, 토마토 생육 시기 및 이식 시기 등의 다양한 발병 조건에 따른 토마토 4개 품종의 뿌리혹선충병 발생을 조사하였다. 접종원의 접종 농도가 증가할수록 토마토의 뿌리혹선충병 발생은 농도 의존적으로 증가하였다. 하지만 토마토의 생육 시기 및 이식 시기에 따른 토마토의 뿌리혹선충병 발생은 유의성 있는 차이가 없었다. 이들 결과들을 바탕으로 Mi-virulent M. incognita에 대한 토마토의 저항성 정도를 검정하기 위한 효율적인 방법을 제안하는 바이다.