• Journal of Microbiology and Biotechnology
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• 제27권10호
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• pp.1798-1807
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• 2017

The differentiations in nitrogen-converting activity and microbial community structure between granular size fractions in a continuous completely autotrophic nitrogen removal over nitrite (CANON) reactor, having a superior specific nitrogen removal rate of $0.24g/(g\;VSS{\cdot}h)$, were investigated by batch tests and high-throughput pyrosequencing analysis, respectively. Results revealed that a high dissolved oxygen concentration (>1.8 mg/l) could result in efficient nitrite accumulation with small granules (0.2-0.6 mm in diameter), because aerobic ammonium-oxidizing bacteria (genus Nitrosomonas) predominated therein. Meanwhile, intermediate size granules (1.4-2.0 mm in diameter) showed the highest nitrogen removal activity of $40.4mg/(g\;VSS{\cdot}h)$ under sufficient oxygen supply, corresponding to the relative abundance ratio of aerobic to anaerobic ammonium-oxidizing bacteria (genus Candidatus Kuenenia) of 5.7. Additionally, a dual substrate competition for oxygen and nitrite would be considered as the main mechanism for repression of nitrite-oxidizing bacteria, and the few Nitrospira spp. did not remarkably affect the overall performance of the reactor. Because all the granular size fractions could accomplish the CANON process independently under oxygen limiting conditions, maintaining a diversity of granular size would facilitate the stability of the suspended growth CANON system.

• KSBB Journal
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• 제10권3호
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• pp.249-256
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• 1995

${\gamma}$-Glutamylcysteine 생산에 있어서 재조합 대장 균 HB101/pGH501만을 이용한 단일세포반응계가 재조합 대장균과 효모를 이용한 흔합서l포반응계보다 반응시간이 짧고 생산농도가 높은 것으로 나타났다. 그러나 생산경제성 측면에서 ATP 재생공정을 위하 여 훈합세포반응계를 사용하였다. 재조합 대장균과 효모를 이용한 혼합세포반응계에서 대장균과 효모의 비율은 1:4가 적합함을 보였고, ATP 재생공정에 사용되는 glucose는 O.5M의 농도에서 가장 효율적 으로 나타났다. 재조합 대장균과 효모를 alginate를 이용하여 고정화하여 반응계로 사용하였을 경우 반 응에 필요한 시간이 걸어지고 생산놓도도 감소되냐 반응계의 안정성은 10% 정도 증가됨을 알 수 있었다. 실험결과 alginate로 고정화된 흔합세포반응계 를 사용하여 ${\gamma}$-glutamylcysteine를 연속 생산할 수 있음을 확인하였다.

• 한국식품위생안전성학회지
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• 제5권1호
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• pp.21-26
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• 1990

양송이의 감마선조사와 저장에 따른 미생물 생육새험에서 일반세균은 조사 직후 조사선량의 증가와 더불어 2~4 log cyles 정도의 격감을 가져왔으며, 저장 중 생육억제효과로 뚜렷하여 2~3kGy 조사구는 $9\;{\pm}\;1^{\circ}C$ 저장에서 비조사구에 비해 2주 이상 일반세균의 생육을 억제시킬 수 있었다. 효모 및 곰팡이의 생육변화는 저장초기 $10^{3}~10^{4}\;CFU/g$ 정도 오염된 것이 비조사구에서는 계속 증식하여 저장 4이경부터 외관상 버섯표면에 청회색의 포자가 형성되고 버섯균사인 솜털곰팡이가 버섯을 덮기 시작하였으나 2~3 kGy 조사구에서 저장 20일까지도 저장초기의 오염도보다 낮은 수치를 나타내었으며 외관상 곰팡이의 포자형성이 없었다. 대장균군은 저장초기 $10^3\;CFU/g$ 정도로 높게 오염되어 있었으나 2kGy 이상 조사로서 완전 사멸되어 식품위생적 측면에서도 감마선조사가 바람직함을 알 수 있었다. 따라서 감마선 조사는 양송이의 미생물상(microflora)에 대한 질적, 양적 변화를 가져옴으로써 버섯의 전반적인 저장성을 향상시켰다.

• 한국축산식품학회지
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• 제34권3호
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• pp.307-315
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• 2014

pH adjustment would be of advantage in improving the water holding capacity of muscle proteins. The objective of this study was to evaluate the addition of fish sarcoplasmic protein (SP) solution, which was adjusted to pH 3.0 or 12.0, neutralized to pH 7.0, and lyophilized to obtain the acid- and alkaline-treated SP samples, on the functional properties of the chicken myofibrillar protein induced by microbial transglutaminase (MTG). The solubility of alkaline-treated SP was higher than that of the acid counterpart; however, those values of the two pH-treated samples were lower than that of normal SP (p<0.05). All SP solutions were mixed with myofibrillar proteins (MP) extracted from chicken breast, and incubated with MTG. The shear stresses of MP with acid- and alkaline-treated SP were higher than that of normal SP. The thermal stability of MP mixture reduced upon adding SP, regardless of the pH treatment. The breaking force of MP gels with acid-treated SP increased more than those of alkaline-treated SP, while normal SP showed the highest value. The MP gel lightness increased, but cooking loss reduced, with the addition of SP. Smooth microstructure of the gel surface was observed. These results indicated that adjusting the pH of SP improved the water holding capacity of chicken myofibrillar proteins induced by MTG.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 1979년도 춘계학술대회
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• pp.113.2-114
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• 1979

$\beta-Galactosidase$ is an enzyme which catalizes hydrolysis of lactose, a natural substrate, to glucose and galctose and transferring some monosac-charide units to active acceptors as sugar or alcohol. The occurence of $\beta-Galactosidase$ is known in various microorganisms, animals and higher plants and has been studied by many investigatigators. Especially, a great deal of articles for the enzyme of E. coli have been presented in genetic control mechanism and induction-repression effects of proteins, On the other hand, in the dairly products industry, it is important to hydrolyes lactosd which is the principal sugar of milk and milk products. During the last few years, the interest in enzymatic hydrolysis of milk lactose has teen increased, because of the lactose intolerence in large groups of the population. Microbial $\beta-Galactosidases$ are considered potentially most suitable for processing milk to hydrolyse lactose and, in recent years, the immobilized enzyme from yeast has been examined. Howev, most of the microbial $\beta-Gal$ actosidase are intracellular enzymes, except a few fungal $\beta-Gala-$ ctosidases, and extracellular $\beta-Galactosidase$ which may be favorable to industrial applieation is not so well investigated. On this studies, a mold producing a potent extracellular $\beta-Galactosidase$ was isolated from soil and identified as an imperfect fungus, Beauveria bassians. In this strain, both extracellular and intracellular $\beta-Galactosidases$ were produced simultaneously and a great increase of the extracellular production was acheved by improving the cultural conditions. The extracellular enzyme was purified more than 1, 000 times by procedures including Phosphocellulose and Sephadex G-200 chromatographies. Several characteristics of the enzymewas clarified with this preparation. The enzyme has a main subunit of molecular weight of 80, 000 which makes an active aggregate. And at neutral pH range, it has optimum pH for activity and stability. The Km value was determined to be 0.45$\times$10$^{-3}$ M for $o-Nitrophenyl-\beta-Galactoside.$ In any event, it is interesting to sttudy the $\beta-Galactosidase$ of B. bassiana for the mechanism of secretion and conformational structure of enzyme.

• 한국미생물·생명공학회지
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• 제48권4호
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• pp.491-505
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• 2020

A newly isolated strain, Proteus vulgaris OR34, from olive mill waste was found to secrete an alkaline extracellular lipase at 11 U·ml-1 when cultivated on an optimized liquid medium. This lipase was purified 94.64-fold with a total yield of 9.11% and its maximal specific activity was shown to be 3232.58 and 1777.92 U·mg-1 when evaluated using the pH-stat technique at 55℃ and pH 9 and Tributyrin TC4 or olive oil as the substrate. The molecular mass of the pure OR34 lipase was estimated to be around 31 kDa, as revealed by SDS-PAGE and its substrate specificity was investigated using a variety of triglycerides. This assay revealed that OR34 lipase preferred short and medium chain fatty acids. In addition, this lipase was stable in the presence of high concentrations of bile salt (NaDC) and calcium ions appear not to be necessary for its activity. This lipase was inhibited by THL (Orlistat) which confirmed its identity as a serine enzyme. In addition, the immobilization of OR34 lipase by adsorption onto calcium carbonate increased its stability at higher temperatures and within a larger pH range. The immobilized lipase exhibited a high tolerance to organic solvents and retained 60% of its activity after 10 months of storage at 4℃. Finally, the OR34 lipase was applied in biodiesel synthesis via oleic acid mediated esterification of methanol when using hexane as solvent. The best conversion yield (67%) was obtained at 12 h and 40℃ using the immobilized enzyme and this enzyme could be reused for six cycles with the same efficiency.

• Journal of Microbiology and Biotechnology
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• 제32권5호
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• pp.564-574
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• 2022

Microbial diversity in the soil is responsive to changes in soil composition. However, the impact of soil amendments on the diversity and structure of rare and abundant sub-communities in agricultural systems is poorly understood. We investigated the effects of different Chinese herb residue (CHR) soil amendments and cropping systems on bacterial rare and abundant sub-communities. Our results showed that the bacterial diversity and structure of these sub-communities in soil had a specific distribution under the application of different soil amendments. The CHR soil amendments with high nitrogen and organic matter additives significantly increased the relative abundance and stability of rare taxa, which increased the structural and functional redundancy of soil bacterial communities. Rare and abundant sub-communities also showed different preferences in terms of bacterial community composition, as the former was enriched with Bacteroidetes while the latter had more Alphaproteobacteria and Betaproteobacteria. All applications of soil amendments significantly improved soil quality of newly created farmlands in whole maize cropping system. Rare sub-communitiy genera Niastella and Ohtaekwangia were enriched during the maize cropping process, and Nitrososphaera was enriched under the application of simple amendment group soil. Thus, Chinese medicine residue soil amendments with appropriate additives could affect soil rare and abundant sub-communities and enhance physicochemical properties. These findings suggest that applying soil composite amendments based on CHR in the field could improve soil microbial diversity, microbial redundancy, and soil fertility for sustainable agriculture on the Loess Plateau.

• 한국환경농학회지
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• 제42권4호
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• pp.259-268
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• 2023

Rhodococcus sp. 3-2 strain has been reported to degrade benzimidazole-based pesticides, such as benomyl and carbendazim. Therefore, this study aimed to optimize culture medium composition and culture conditions to achieve cost-effective and efficient large-scale production of the Rhodococcus sp. 3-2 strain. The study identified that the optimal media composition for mass culture comprised 0.5% glucose, 0.5% yeast extract, 0.15% NaCl, 0.5% K₂HPO₄, 0.5% sodium succinate, and 0.1% MgSO₄. Additionally, a microbial agent was developed using a 1.5-ton fermenter, with skim milk (20%), monosodium glutamate (15%), and vitamin C (2%) as key components. The storage stability of the microbial agent has been confirmed, with advantages of low temperature conservation, which helps to sustain efficacy for at least six months. We also assessed the benomyl degradation activity of the microbial agent within field soil. The results revealed an over 90% degradation rate when the concentration of viable cells exceeded 2.65 × 10⁶ CFU/g after a minimum of five weeks had elapsed. Based on these findings, Rhodococcus sp. 3-2 strain can be considered a cost-effective microbial agent with diverse agricultural applications.

• 한국환경농학회지
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• 제39권1호
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• pp.65-74
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• 2020

BACKGROUND: Soil carbon sequestration has been investigated for a long time because of its potential to mitigate the greenhouse effect. No- or reduced tillage, crop rotations, or cover crops have been investigated and practiced to sequester carbon in soils but the roles of soil biota, particularly microorganisms, have been mostly ignored although they affect the amount and stability of soil organic matters. METHODS AND RESULTS: In this study we analyzed the organic matter and microbial community in organically cultivated corn field soils where no-tillage (NT) or conventional tillage (CT) had been practiced for about three years. The amounts of organic matter and recalcitrant carbon pool were 18.3 g/kg dry soil and 4.1 g C/kg dry soil, respectively in NT soils, while they were 12.4 and 2.5, respectively in CT soils. The amounts of RNA and DNA, and the copy numbers of bacterial 16S rRNA genes and fungal ITS sequences were higher in NT soils than in CT soils. No-tillage treatment increased the diversities of soil bacterial and fungal communities and clearly shifted the bacterial and fungal community structures. In NT soils the relative abundances of bacterial phyla known as copiotrophs, Betaproteobacteria and Bacteroidetes, increased while those known as oligotrophs, Acidobacteria and Verrucomicrobia, decreased compared to CT soils. The relative abundance of a fungal phylum, Glomeromycota, whose members are known as arbuscular mycorrhizal fungi, was about two time higher in NT soils than in CT soils, suggesting that the higher amount of organic matter in NT soils is related to its abundance. CONCLUSION: This study shows that no-tillage treatment greatly affects soil microbial abundance and community structure, which may affect the amount and stability of soil organic matter.

• 대한환경공학회지
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• 제34권1호
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• pp.49-54
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• 2012

본 연구에서는 수 환경 내에서 일어나는 주요 자연분획변환 과정 중 생분해 시 변화하는 용존 유기물질의 특성이 중금속 결합특성에 미치는 영향을 조사하고자 하였다. 각각 호수와 하천 기원을 대표하는 Pony lake fulvic acid와 Suwannee river fulvic acid를 포함한 다양한 유기물을 대상으로 2주간 배양실험을 하여 변화하는 농도, 성상 및 중금속 구리 결합특성을 조사한 결과 각 시료 내 DOC농도는 감소하고 SUVA 값은 증가하였다. 특히 포도당 및 단백질계 탄소구조 함유비율이 높을수록 미생물에 의한 DOC 농도 분해율은 증가하였다. 포도당과 휴믹물질의 혼합비를 고려한 경우 배양 후 예측되는 혼합액의 DOC 감소율은 실제 측정값과 유사하였다. 그러나 SUVA값은 오히려 더 높게 나타나 생분해성 물질과 휴믹물질이 혼재할 경우 탄소 구조 변화로 인한 휴믹화의 진행이 더 크게 나타날 수 있음을 보였다. Synchronous 형광스펙트럼 결과 배양 후 Pony lake fulvic acid의 경우 휴믹산계 형광특성이, Suwannee river fulvic acid에서는 펄빅산계 형광특성이 크게 증가하였다. 포도당 시료에서는 배양 전 관찰되지 않았던 단백질계와 펄빅산계 형광특성이 관찰되었다. 중금속 구리와의 결합정도를 나타내는 log K 값은 미생물 배양 전과 후 휴믹물질 종류에 따라 변화가 없거나 혹은 약간 감소하는 경향을 나타냈다. 본 실험 결과는 미생물에 의한 휴믹물질 관련 형광구조의 증가가 중금속 결합력 강화에 영향을 미치지 않거나 오히려 감소시키는 것으로 보인다.