• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2509-2513
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• 2010

In order to increase protease stability of a novel Trp-rich model antimicrobial peptide, $K_6L_2W_3$ (KLWKKWKKWLK-$NH_2$)and investigate the effect of L-amino acid to peptoid residue conversion on biological functions, we synthesized its antimicrobial peptoid, $k_6l_2w_3$. Peptoid $k_6l_2w_3$ had similar bacterial selectivity compared to peptide $k_66L_2W_3$. The bactericidal rate of $k_6l_2w_3$ was somewhat slower than that of $K_6L_2W_3$. Peptoid $k_6l_2w_3$ exhibited very little dye leakage from bacterial outer-membrane mimicking PE/PG liposomes, as observed in $K_6L_2W_3$, indicating that the major target site of $K_6L_2W_3$ and $k_6l_2w_3$ may be not the cell membrane but the cytoplasm of bacteria. Trypsin treatment of $K_6L_2W_3$ completely abolished antimicrobial activities against Escherichia coli and Staphylococcus aureus. In contrast, the antimicrobial activity of $k_6l_2w_3$ was completely preserved after trypsin treatment. Taken together, our results suggested that antimicrobial peptoid $k_6l_2w_3$ can potentially serves as a promising therapeutic agent for the treatment of microbial infection.

• Journal of Microbiology and Biotechnology
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• 제24권1호
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• pp.87-96
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• 2014

In the present study, a yeast species isolated from CETP, Vellore, Tamilnadu was identified as Cryptococcus sp. VITGBN2 based on molecular techniques and was found to be a potent producer of acidic diacetate sophorolipid in mineral salt media containing vegetable oil as additional carbon source. The chemical structure of the purified biosurfactant was identified as acidic diacetate sophorolipid through GC-MS analysis. This sophorolipid was used as a stabilizer for synthesis of zinc oxide nanoparticles (ZON). The formation of biofunctionalized ZON was characterized using UV-visible spectroscopy, XRD, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy. The antimicrobial activities of naked ZON and sophorolipid functionalized ZON were tested based on the diameter of inhibition zone in agar well diffusion assay, microbial growth rate determination, protein leakage analysis, and lactate dehydrogenase assay. Bacterial pathogen Salmonella enterica and fungal pathogen Candida albicans showed more sensitivity to sophorolipid biofunctionalized ZON compared with naked ZON. Among the two pathogens, S. enterica showed higher sensitivity towards sophorolipid biofunctionalized ZON. SEM analysis showed that cell damage occurred through cell elongation in the case of S. enterica, whereas cell rupture was found to occur predominantly in the case of C. albicans. This is the first report on the dual role of yeast-mediated sophorolipid used as a biostabilizer for ZON synthesis as well as a novel functionalizing agent showing antimicrobial property.

• 한국식품저장유통학회지
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• 제18권4호
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• pp.429-435
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• 2011

The demand of packaged baby leaves has been increased for its convenient use as fresh-cut produce. This investigation was aimed to explore the effects of different sanitizers on the quality parameters of 'Tah Tasai' Chinese cabbage (Brassica campestris var. narinosa) baby leaves. Thirteen days old baby leaves were harvested and washed in tap water (TW), 100 ppm chlorine solution (Cl), 2 ppm ozonated water ($O_3$), 15 ppm chlorine dioxide solution ($ClO_2$) and washing with 0.2% citric acid solution followed by 50% ethanol spray (CA+Et). The samples were then packaged in 50 ${\mu}m$ polyethylene bags and stored at $5^{\circ}C$ for 10 days. Off-odor of packaged baby leaves was not detected during storage. There was no significant difference in color parameters among the treatments. Samples treated with $O_3$ showed substantially higher electrolyte leakage throughout the storage. This treatment also rendered a higher accumulation of $CO_2$ in the packages. Samples treated with Cl and CA+Et maintained good overall visual quality with higher scores compared to that of $O_3$ and $ClO_2$. Although Cl treatment showed lower number of total aerobic count at the beginning of storage, citric acid in combination with ethanol treatment was more effective until the end of storage. The combined treatment also showed comparatively lower coliform plate count. This result indicates that citric acid wash followed by ethanol spray could be an alternative to chlorine for environment friendly sanitization of baby leaves.

• 미생물학회지
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• 제55권1호
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• pp.46-51
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• 2019

이 연구에서는 유칼립투스, 유카와 차나무의 ethanol 추출물의 수지를 이용한 분획 혼합물에 대한 항균활성을 평가하였는데 여러 인간 피부 상재균에 낮은 최소저해농도(0.24~3.32 mg/ml)를 나타내었고 항생제 triclosan과 ampicillin보다 우수한 활성을 나타내었다. Time kill assay에서 식물 추출분획 혼합물은 4시간 이내에 미생물 균주의 개체수를 92% 이상 감소시켰고, 모든 미생물 균주의 뉴클레오티드를 상당량 유출시켰으며, 항균 효과는 이가 양이온($Mg^{2+}$과 $Ca^{2+}$)에 영향을 받지 않았다. 이러한 결과는 Eucalyptus sp., Yucca sp., 및 tea tree의 ethanol 추출물의 수지분획 혼합물이 중요한 인간 피부 상재균을 억제하는 효율적인 화장품 방부제로 이용될 수 있음을 시사한다.

• The Journal of Advanced Prosthodontics
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• 제11권2호
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• pp.105-111
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• 2019

PURPOSE. Limited data is available regarding the differences for possible microleakage problems and fitting accuracy of zirconia versus titanium abutments with various connection designs. The purpose of this in vitro study was to investigate the effect of connection design and abutment material on the sealing capability and fitting accuracy of abutments. MATERIALS AND METHODS. A total of 42 abutments with different connection designs [internal conical (IC), internal tri-channel (IT), and external hexagonal (EH)] and abutment materials [titanium (Ti) and zirconia (Zr)] were evaluated. The inner parts of implants were inoculated with $0.7{\mu}L$ of polymicrobial culture (P. gingivalis, T. forsythia, T. denticola and F. nucleatum) and connected with their respective abutments under sterile conditions. The penetration of bacteria into the surrounding media was assessed by the visual evaluation of turbidity at each time point and the number of colony forming units (CFUs) was counted. The marginal gap at the implant- abutment interface (IAI) was measured by scanning electron microscope. The data sets were statistically analyzed using Kruskal-Wallis followed by Mann-Whitney U tests with the Bonferroni-Holm correction (${\alpha}=.05$). RESULTS. Statistically significant difference was found among the groups based on the results of leaked colonies (P<.05). The EH-Ti group characterized by an external hexagonal connection were less resistant to bacterial leakage than the groups EH-Zr, IT-Zr, IT-Ti, IC-Zr, and IC-Ti (P<.05). The marginal misfit (in ${\mu}m$) of the groups were in the range of 2.7-4.0 (IC-Zr), 1.8-5.3 (IC-Ti), 6.5-17.1 (IT-Zr), 5.4-12.0 (IT-Ti), 16.8-22.7 (EH-Zr), and 10.3-15.4 (EH-Ti). CONCLUSION. The sealing capability and marginal fit of abutments were affected by the type of abutment material and connection design.

• Membrane and Water Treatment
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• 제10권1호
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• pp.29-38
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• 2019

Microbial community and composition in stormwater runoff from mixed land use land cover (LULC) catchment with ongoing land development was diverse across the hydrological stage due different environmental parameters (hydrometeorological and physicochemical) and source of runoff. However, limited studies have been made for bacterial composition in this catchment. Therefore, this study aims to: (1) quantify the concentration of fecal indicator bacteria (FIB), stormwater quality and bacterial composition and structure according to hydrological stage; and (2) determine their correlation to environmental parameters. The 454 pyrosequencing was used to determine the bacterial community and composition; while Pearson's correlation was used to determine the correlation among parameters-FIB, stormwater quality, bacterial composition and structure-to environmental parameters. Results demonstrated that the initial and peak runoff has the highest concentration of FIB, stormwater quality and bacterial composition and structure. Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes were dominant bacteria identified in this catchment. Furthermore, the 20 most abundant genera were correlated with runoff duration, average rainfall intensity, runoff volume, runoff flow, temperature, pH, organic matter, nutrients, TSS and turbidity. An increase of FIB and stormwater quality concentration, diversity and richness of bacterial composition and structure in this study was possibly due to leakage from septic tanks, cesspools and latrines; feces of domestic and wild animals; and runoff from forest, destroyed septic system in land development site and urban LULC. Overall, this study will provide an evidence of hydrological stage impacts on the runoff microbiome environment and public health perspective.

• Journal of Dairy Science and Biotechnology
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• 제41권4호
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• pp.203-210
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• 2023

Bacterial contamination negatively affects the quality, functionality, and safety of dairy products. Adherent populations of bacteria, referred to as biofilms, grow on the surfaces of dairy processing equipment and are the primary cause of dairy contamination. In addition, microorganisms present in the farm environment and dairy factory can contaminate the Clear-In-Place (CIP) line through raw milk transport pipes; therefore, exhaustive management is required. In dairy manufacturing facilities, biofilm formation is controlled using CIP systems that primarily require sodium hydroxide and nitric acid. However, the leakage or incomplete removal of these potently active compounds can be harmful to humans. In the present study, we compared the eradication of Escherichia coli and other bacteria using commercially available combinations of sodium hypochlorite (NaClO) and citric acid, which are recognized by the Korean Ministry of Food and Drug Safety (MFDS) as food disinfectants. When considered in the CIP system of the field manufacturing process, E. coli was not detected (compared to detection before treatment), and other bacteria were detected at 0-32 culture-forming units (CFU)/cm². The residual amount of chlorine ions after CIP treatment was similar to that in tap water, and there was no significant difference in the overall components of the fermented dairy products. Therefore, the NaClO/citric acid CIP system can be safely applied in dairy manufacturing processes.

• 동아시아식생활학회지
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• 제13권5호
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• pp.425-432
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• 2003

본 연구에서는 ethanol 과 일부 유기산(adipic acid, citric acid, acetic acid)을 첨가하였을 때 물김치 발효에 관여하는 미생물 생육의 변화를 측정하였으며 그 결과를 요약하면 다음과 같다. Ethanol 및 유기산의 첨가가 물김치 서식 미생물에 미치는 영향을 직접적으로 살펴보기 위하여 pH 4.3 의 buffer 용액에 ethanol 과 유기산을 농도별로 첨가하고 Lactobacillus plantarum, Leuconostoc mesenteroides, Kluyveromyces marxianus을 접종하여 균의 생육에 미치는 영향을 살펴 본 결과 L. plantarum 와 Leu. mesenteroides에서는 ethanol 농도가 높을수록 그리고 유기산 종류에서는 adipic acid를 첨가했을 때 성장 억제 효과가 가장 크게 나타났다. 비교 균주에서는 L. plantarum이 Leu. mesenteroides보다 유기산과 에탄올에 영향을 받아 생육이 더욱 억제되었다. Ethanol에 대해서는 L. plantarum이 Leu. mesenteroides보다 숙성 72 시간째에 40.0% 정도 생육이 억제되었으나 유기산의 경우에는 종류에 따라 생육억제 정도가 달랐다. Acetic acid의 경우 L. plantarumol 약 40.0% 정도, citric acid의 경우는 L. plantarum이 약 15.0% 정도 생육이 억제되었지만 adipic acid의 경우는 L. plantarum 와 Leu. mesenteroides 모두에게 억제 효과가 있어 무첨가군에 비해 50.0∼60.0% 정도 생육이 감소되었다. K. marxianus에서도 ethanol 농도가 높을수록 성장 억제에 효과적이나 유기산에 대해서는 차이를 보이지 않았다. Ethanol 및 유기산이 각 균에 어떠한 영향을 주었는가을 알기 위해 균체내 물질의 누출을 260nm에서의 흡광도를 측정하여 관찰한 결과 L. plantarum 에서는 ethanol 2.0% 첨가 에서와 adipic acid 0.1 를 첨가한 실험군에서 24 시간 후의 흡광도가 가장 많이 증가되었다. Leu. mesenteroides에서는 ethanol 첨가시 유의적인 차이가 보이지 않았고 유기산 중 adipic acid 첨가시 흡광도가 많이 증가되었다. K. marxianus 에서는 ethanol 농도가 높을수록 흡광도가 증가되었고 유기산 중 citric acid 에서 많이 증가되었다.

• 자원환경지질
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• 제41권6호
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• pp.657-672
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• 2008

본 연구의 목적은 금산 생활쓰레기 매립장을 대상으로 지하수의 수리지 화학적 특성과 통계분석을 통하여 침출수의 누출원인과 누출경로 및 영향범위를 파악하고, 매립지로부터 발생되는 오염물질인 침출수의 누출이 연구지역의 지하수환경에 미치는 위해요인에 대해 정량적으로 평가하는 것이다. 본 연구를 위해서 수질 검층, 침출수와 지하수 수질 분석 및 통계분석, 그리고 오염물질 이동모델링 기법 등을 이용하였다. 수질검층 결과 침출수 집수정 부근에서 침출수가 주변 대수층으로 누출되고 있었으며, 매립장과 인접한 하류부 관측정의 4-12m 깊이에서 지하수에 대한 침출수의 영향을 확인할 수 있었다. 침출수는 유출 범위는 매립장으로부터 70-100m 내외이며 오염된 지하수에서 전기전도도는 $400-750{\mu}S/cm$를 나타내었다. 주성분분석수행 결과 주성분 1과 2는 각각 침출수과 대수층의 매질 특성을 나타내었다. 주성분분석결과는 또한 침출수의 영향을 받는 지하수의 수질 변화에 의해 나타내어지는 양이온교환반응, 흡착 및 미생물 생분해 같은 자연저감과정을 나타내었다. 지하수 흐름 및 오염물 이동 모델링 결과 지하수는 매립장에서 서쪽으로 계곡을 따라 흐르며, 오염물질은 그에 따라 이동함을 알 수 있었다.

• 한국미생물·생명공학회지
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• 제9권3호
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• pp.159-164
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• 1981

부분적 항상성변이주인 Bacillus megaterium (KFCC 10029)가 생산하는 페니실린 아미다제를 예로하여 강화된 $Ca^{++}$-alginate gel에 의한 포괄방법을 이용하는 효소 고정화 방법을 제시하였다. 발효액으로 부터 celite 흡착법에 의해 효소를 분리한 후 alginate의 gellatin용액에 혼합하고 $Ca^{++}$ 용액에서 응고시키고 glutaraldehyde로 처리하여 성형하였다. 이렇게 하여 얻은 고정화효소의 최적 pH 및 온도는 각각 8.0과 6$0^{\circ}C$였다. Km value 와 6-APA 및 페닐초산에 의한 저해 상수는 각각 2.6mM, 7.4mM, 21.2mM이었다. Gel의 증가된 물리적 강도 때문에 반응조 조작중 흡착효소의 유실을 성공적으로 없앨수 있었다. 관형식 반응조에서의 고정화 효소의 반감기는 4$0^{\circ}C$와 3$0^{\circ}C$에서 각각 6일 및 30일이었으며, 이것은 흡착효소와 비교해 볼 때 6-8배의 증가치이다. 결론적으로 alginate gel 포괄방법에 의한 효소고정화 방법에 있어, 본 연구에서 개발된 개량된 방법을 사용함으로써 고정화효소의 물리적 강도 및 안정도를 크게 증가시킬 수 있었다.