• Journal of Microbiology and Biotechnology
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• 제29권1호
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• pp.79-90
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• 2019

Lichens are generally known as self-sufficient, symbiotic life-forms between fungi and algae/cyanobacteria, and they also provide shelter for a wide range of beneficial bacteria. Currently, bacterial-derived biodegradable polyhydroxyalkanoate (PHA) is grabbing the attention of many researchers as a promising alternative to non-degradable plastics. This study was conducted to develop a new method of PHA production using unexplored lichen-associated bacteria, which can simultaneously degrade two ubiquitous industrial toxins, anthracene and naphthalene. Here, 49 lichen-associated bacteria were isolated and tested for PHA synthesis. During the GC-MS analysis, a potential strain of EL19 was found to be a 3-hydroxyhexanoate (3-HHx) accumulator and identified as Pseudomonas sp. based on the 16S rRNA sequencing. GC analysis revealed that EL19 was capable of accumulating 30.62% and 19.63% of 3-HHx from naphthalene and anthracene, respectively, resulting in significant degradation of 98% and 96% of naphthalene and anthracene, respectively, within seven days. Moreover, the highly expressed phaC gene verified the genetic basis of $PHA_{mcl}$ production under nitrogen starvation conditions. Thus, this study strongly supports the hypothesis that lichen-associated bacteria can detoxify naphthalene and anthracene, store energy for extreme conditions, and probably help the associated lichen to live in extreme conditions. So far, this is the first investigation of lichen-associated bacteria that might utilize harmful toxins as feasible supplements and convert anthracene and naphthalene into eco-friendly 3-HHx. Implementation of the developed method would reduce the production cost of $PHA_{mcl}$ while removing harmful waste products from the environment.

• 대한치과의사협회지
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• 제56권12호
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• pp.667-685
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• 2018

Objectives: Aim of this study was to evaluate bone regenerative efficacy of a chemically cross-linked porcine collagen membrane (CM) when used in combination with highly soluble biphasic calcium phosphate (BCP). Materials and methods: Physiochemical properties of the experimental collagen membrane were analyzed. Four circumferential defects with diameter of 8 mm were created in each calvarium of New Zealand white rabbits (n = 10). Defects were randomly allocated to one of following 4 groups: 1) BCP-CM (BCP (20% hydroxyapatite/80% ${\beta}$-tricalcium phosphate) covered with the prepared collagen membrane), 2) BCP (only BCP used), 3) CM (only the prepared collagen membrane used), and 4) C (control; only blood clot). After 2 weeks (n = 5) and 8 weeks (n = 5), histologic and histomorphometric analyses were performed. Results: The experimental collagen membrane exhibited dense and compact structure, relatively high tensile strength and lower degradability. Histologic analyses revealed that new bone increased rapidly at 2 weeks, while defect was preserved at 8 weeks. Histomorphometric analyses revealed that the new bone areas increased in the BCP-grafted groups over 8 weeks, with BCP-CM exhibiting greater total augmented area than that of BCP group both at 2 weeks ($27.12{\pm}3.99$ versus $21.97{\pm}2.27mm^2$) and 8 weeks ($25.75{\pm}1.82$ versus $22.48{\pm}1.10mm^2$) (P < 0.05). Conclusions: The experimental collagen membrane successfully preserved localized defect for 8 weeks despite early rapid resorption of BCP. Within the study limitations, combined use of the chemically cross-linked porcine collagen membrane and highly soluble BCP aided localized bone regeneration.

• 한국지반환경공학회 논문집
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• 제12권9호
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• pp.21-25
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• 2011

본 연구는 낙동강 준설사업 중 발견된 폐기물의 종류, 매립량, 지정폐기물 여부 및 안정화 상태를 파악하기 위하여 수행되었다. 발견된 폐기물의 정확한 분류는 향후 폐기물의 적정처리를 위해 필수적인 과정이다. 낙동강 중류지역 고수부지 내 굴착조사지점 159개 중 27곳에서 폐기물이 발견되었으며, 분석결과 이들 폐기물은 지정폐기물로 분류되지 않았다. 또한 60곳에서 점질토가 출토되었는데, 이들은 폐기물로 분류되지 않았고 일반토양과 같이 현장에서 재활용이 가능할 것으로 판단되었다. 일부 시료의 경우, 안정화되지 않고 유기물 분해가 일어나는 것으로 판명되었다.

• Journal of Korean Dental Science
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• 제14권1호
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• pp.12-25
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• 2021

Purpose: (i) To evaluate the biologic properties of a bi-layered 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride-cross-linked collagen membrane (CCM) in vitro. (ii) To assess the efficacy of CCM for localized bone regeneration in vivo. Materials and Methods: Biodegradation of CCM compared to a native collagen membrane (NCM) was assessed in vitro. In vivo, twelve male New Zealand White rabbits were used. Four calvarial, circular defects (diameter 8 mm) were created in each animal. The sites were randomly allocated to i) CCM+biphasic calcium phosphate (BCP) (CCM-BCP group), ii) CCM alone (CCM), iii) BCP alone (BCP) and, iv) negative control (control). Animals were sacrificed at 2 (n=6) and 8 weeks (n=6). Outcome measures included: micro-computed tomography (μCT) analysis (total augmented volume [TAV], new bone volume) and histomorphometry (total augmented area [TAA], newly formed bone, remaining membrane thickness [RMT]). Result: CCM was more resistant to degradation than NCM. μCT analysis showed CCM-BCP (196.43±25.30 mm³) and BCP (206.23±39.13 mm³) groups had significantly (P<0.01) larger TAV than the control (149.72±12.28 mm³) after 8 weeks. Histomorphometrically, CCM-BCP group (17.75±5.97 mm²) had significantly (P<0.01) greater TAA compared to the CCM group (7.74±2.25 mm²) and the control (8.13±1.81 mm²) after 8 weeks. After 8 weeks, RMT was reduced by 67%. Conclusion: CCM can be a favorable choice of barrier membrane when performing guided bone regeneration (GBR) in localized bone defects. CCM has better resistance to degradation than the natural collagen membrane, in vitro. In vivo, CCM provides an advantageous integration of prolonged barrier function and biocompatibility for GBR.

• 멤브레인
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• 제31권6호
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• pp.393-403
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• 2021

생체 내 변화에서 효소는 중요한 촉매이다. 효소의 안정성과 재사용성은 촉매 과정에서 중요한 요소이다. 적합한 기질에 효소 고정화는 특정 미세환경의 조성을 통해 효소 활동성을 높인다. 다양한 종류의 분리막이 각각의 생체적합성과 막 표면의 친수성/소수성 조절 용이도에 따라 기질로 사용되었다. 본 논문에서는 셀룰로스, 폴리아크릴로니트릴(PAN), 폴리디메틸실록산(PDMS), 폴리비닐리덴플루오라이드(PVDF), 폴리에테르설폰(PES) 고분자 분리막이 소개되고 토의되었다. 고정화 효소를 이용한 유기오염물의 생물적 분해는 제약 회사 및 섬유 회사 등에서 발생하는 오염물질을 친환경적으로 감소할 수 있는 방법이다. 효소 고정화 생물반응기(EMBR)로 기름의 가수분해를 제어할 수 있고 이를 통해 탄소 배출량 감소 및 환경오염을 줄일 수 있다. EMBR로 만들 수 있는 바이오에탄올과 바이오디젤은 화석 연료의 대체제이다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권spc호
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• pp.34-50
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• 2022

Principal component analysis (PCA) was conducted using hydrochemical data in four testbeds (A to D) built for the development of site characterization technologies to assess the hydrochemical processes controlling the hydrochemistry in each site. The PCA results indicated the nitrogen loading to deep bedrock aquifers through permeable fractures in Testbed A, the chemical weathering enhanced with the biodegradation of petroleum hydrocarbons in Testbed B, the reductive dechlorination in Testbed C, and the different hydrochemistry depending on the depth to bedrock in Testbed D, consistent with the characteristics of each site. In Testbeds B and D, outliers seemed to affect the PCA result probably due to the small number of samples, whereas the PCA result was still consistent with site characteristics. This study result indicates that the PCA is widely applicable to hydrochemical data for the assessment of major hydrochemical processes in contamination sites, which is useful for site characterization when combined with other site characterization technologies, e.g., geological survey, geophysical investigation, borehole logging. It is suggested that PCA is applied in contaminated sites to interpret hydrochemical data not only for the distribution of contamination levels but also for the assessment of major hydrochemical processes and contamination sources.

• 한국해양바이오학회지
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• 제14권2호
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• pp.133-142
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• 2022

The increased production and consumption of polyethylene terephthalate (PET)-based products over the past several decades has resulted in the discharge of countless tons of PET waste into the marine environment. PET microparticles resulting from the physical erosion of general PET wastes end up in the ocean and pose a threat to the marine biosphere and human health, necessitating the development of new technologies for recycling and upcycling. Notably, enzyme-mediated PET degradation is an appealing option due to its eco-friendly and energy-saving characteristics. PETase, a PET-hydrolyzing enzyme originating from Ideonella sakaiensis, is one of the most thoroughly researched biological catalysts. However, the industrial application of PETase-mediated PET recycling is limited due to the low stability and poor reusability of the enzyme. Here we developed the whole-cell catalyst (WCC) in which functional PETase is attached to the outer membrane of Escherichia coli. Immunoassays are used to identify the surface-expressed PETase, and we demonstrated that the WCC degraded PET microparticles most efficiently at 30℃ and pH 9 without agitation. Furthermore, the WCC increased the PET-degrading activity in a concentration-dependent manner, surpassing the limited activity of soluble PETase above 100 nM. Finally, we demonstrated that the WCC could be recycled up to three times.

• 패션비즈니스
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• 제26권4호
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• pp.100-111
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• 2022

After the corona pandemic, when consumers choose clothes, the issue of sustainability has become a more important selection criterion. The eco-friendly functional fiber used in the study is a smartcell, which has functions such as UV protection, decomposition of harmful substances, deodorization, antibacterial and biodegradation. This eco-friendly functional fiber was dyed using five kinds of natural dyes to examine the color change according to dyeability and dyeing conditions. As natural dyes, gardenia, turmeric, sappan wood, lac, and indigo were used. For comparison with smartcell, rayon, a cellulose regenerated fiber, and wool fiber, a protein fiber, were dyed under the same conditions to compare dyeability and color. The study results are as follows. It was found that smartcell had superior dyeability compared to rayon and wool in gardenia dye and showed lower dyeability than wool when dyeing turmeric, sappan wood, and lac dyes, but showed superior or similar dyeability than rayon. In case of indigo dyeing, the dyeability of smartcell was the best when dyed once, but it was found that smartcell had a lower effect on repeated dyeing compared to wool or rayon. Therefore, smartcell has superior dyeability compared to rayon fiber in gardenia, turmeric, sappan wood, and lac dyeing, and in case of indigo dyeing, it is suitable for light dyeing. When smartcell is produced as textile fashion products, natural dyeing is actively introduced and commercialized, and it is hoped that this study can be a reference material.

• Journal of Microbiology and Biotechnology
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• 제32권12호
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• pp.1561-1572
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• 2022

Plastic pollution has been recognized as a serious environmental problem, and microbial degradation of plastics is a potential, environmentally friendly solution to this. Here, we analyzed and compared microbial communities on waste plastic films (WPFs) buried for long periods at four landfill sites with those in nearby soils to identify microbes with the potential to degrade plastics. Fourier-transform infrared spectroscopy spectra of these WPFs showed that most were polyethylene and had signs of oxidation, such as carbon-carbon double bonds, carbon-oxygen single bonds, or hydrogen-oxygen single bonds, but the presence of carbonyl groups was rare. The species richness and diversity of the bacterial and fungal communities on the films were generally lower than those in nearby soils. Principal coordinate analysis of the bacterial and fungal communities showed that their overall structures were determined by their geographical locations; however, the microbial communities on the films were generally different from those in the soils. For the pulled data from the four landfill sites, the relative abundances of Bradyrhizobiaceae, Pseudarthrobacter, Myxococcales, Sphingomonas, and Spartobacteria were higher on films than in soils at the bacterial genus level. At the species level, operational taxonomic units classified as Bradyrhizobiaceae and Pseudarthrobacter in bacteria and Mortierella in fungi were enriched on the films. PICRUSt analysis showed that the predicted functions related to amino acid and carbohydrate metabolism and xenobiotic degradation were more abundant on films than in soils. These results suggest that specific microbial groups were enriched on the WPFs and may be involved in plastic degradation.

• 한국미생물·생명공학회지
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• 제50권4호
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• pp.501-507
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• 2022

대표적인 플라스틱 소재인 PET (Polyethylene terephthalate)는 높은 내구성, 경제성과 같은 유용한 물리화학적 특성으로 병, 섬유, 용기 등 다양한 산업 분야에 사용되고 있다. 최근 일회용품을 비롯한 플라스틱 사용량 증가로 인해, 이를 처리하기 위한 방법이 필요한 상황이다. 기존의 매립, 소각 등과 같이 자연상태에 노출되는 방법과 달리 최근 미생물을 이용한 친환경적인 방법이 주목받고 있다. 본 연구에서는 PETase 유전자를 가지고 있는 토양 유래 방선균 Streptomyces. javensis Inha503를 선별하고, agar plate diffusion assay를 통해 PU (Polyurethane) 가수분해 능력을 확인하였다. 해당 균주를 PET과 함께 한달 간 배양하였고, 주사전자현미경을 통해 PET 분해능력을 확인하였다. 또한, S. javensis Inha503 유전체 탐색에서 선별된 PETase 유전자를 PET 분해능이 없는 이종숙주 S. lividans와 S. coelicolor 균주에 도입하여 PET 분해능을 확인함으로써, 방선균 유래 PETase 유전자의 활성을 최초로 확인하였다.