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Ahn J.-Y.,Chungbuk National University | Min J.,Chonbuk National University | Lee S.-H.,Chungbuk National University | Jang A.,Sungkyunkwan University | And 4 more authors.
Toxicology and Environmental Health Sciences | Year: 2013

Kimchi fermentation is complex process which really depends on the composition of microfloa under the optimum ripening environment such as salt concentration, acidity, pH and temperature conditions. Most kinds of bacteria belonging to Lactobacillus group have been identified in kimchi, which continuously produce lactic acids after ripening and cause the change of kimchi tasty and physical texture. Green tea extract as a natural preservative was investigated on the antimicrobial activity and the change of pH, in terms of retardation of kimch fermentation. Minimal Inhibitory Concentration (MIC), paper disc assay, bacterial growth, and pH change were tested against four microorgasnisms, Leuconostoc mesenteroides, Lactobacillus sake, Lactobacillus plantarum, and Weissella koreensis. 2 mg/mL of green tea extract completely inhibited the growth of test organisms after 5-7 hours. Furthermore, it showed the maximized clear zone (24-34 mm) was observed at the 2mg/disc concentration. pH change resulted in a slow downward drift for fermentation period. Moreover, green tea extract showed long-term buffer effects for over 35 days (5 weeks) at 4°C. © 2013 Korean Society of Environmental Risk Assessment and Health Science and Springer Science+Business Media Dordrecht. Source


Park J.-M.,Chungbuk National University | Kim M.,Chungbuk National University | Park H.-S.,Institute of Mine Reclamation Technology | Jang A.,Sungkyunkwan University | And 2 more authors.
International Journal of Biological Macromolecules | Year: 2013

Chitosan (CS) nanofibers with a diameter of 150-200. nm were fabricated from a mixed chitosan/poly (vinyl alcohol) (PVA) solution by the electrospinning method. The nascent CS/PVA nanofibers were treated with 0.5. M NaOH solution to make stable CS nanofibers by removing PVA under aqueous conditions. Hen egg-white lysozyme was immobilized on electrospun CS nanofibers via cross-linked enzyme aggregates (CLEAs) and used for effective and continuous antibacterial applications. The maximum amount of lysozyme immobilized on the CS nanofibers was determined to be 62.3. mg/g of nanofibers under the optimum conditions. The immobilized lysozyme-CLEA retained more than 75.4% of its initial activity after 80 days of storage at room temperature, while the free lysozyme lost all of its activity under the same conditions. In addition, the immobilized lysozyme-CLEA retained more than 76% of its activity after 100 consecutive uses. Finally, the durability of the lysozyme-CLEA immobilized CS nanofibers showed bacteriostasis ratios of 82.4%, 79.8%, 83.4%, and 84.1% after 10 cycles against 4 pathogenic bacteria, viz. Staphylococcus aureus, Bacillus subtilis, Shigella flexneri, and Psedomonas aeruginosa, respectively. These results demonstrated that lysozyme-CLEA immobilized CS nanofibers could be used as a promising material for enhanced and continuous antibacterial applications. © 2012 Elsevier B.V.. Source


Park J.H.,University of Queensland | Edraki M.,University of Queensland | Mulligan D.,University of Queensland | Jang H.S.,Institute of Mine Reclamation Technology
Journal of Cleaner Production | Year: 2014

Coal combustion by-products (CCBs) generated from coal-fired power plants have been considered in some circumstances and in some applications as alternatives for natural materials. This review focused on the beneficial use of CCBs for mine sites. The alkaline pH of CCBs has been shown to play a neutralising role for acid mine drainage and the consequent precipitation of metals from solution, mainly as metal hydroxides. Coal combustion by-products have also been used for soil restoration, having been shown to improve one or more of the physical, chemical and biological properties of degraded soils which in turn has led to improvements in revegetation outcomes. In addition, fly ash has been used as a one of the materials in engineered covers that are constructed to encapsulate and isolate potentially hazardous mine wastes. The use of CCBs for mine void backfilling has been considered an opportunity for the bulk utilization of CCBs. Backfilling of underground mine voids with these materials presents the potential to reduce acid mine drainage, limit the risk of land subsidence and minimise and control the likelihood of mine fires. Even though the proactive use of CCBs may eliminate or reduce an environmental burden that remains if separate storage or disposal of these otherwise 'waste' materials is required, there may be adverse side effects that could occur through such uses of CCBs, such as the leaching of deleterious elements. Therefore, in the case of their use in mine backfilling, for example, possible environmental impacts need to be assessed and monitored during a testing phase in the context of other variables, and before backfilling with such materials is used on a large-scale. There is still a lack of well-researched information on the practical use of CCBs, and their potential environmental and health effects, and in their use for mine site rehabilitation purposes, effective guidelines and regulations are also limiting factors. In most countries, government regulations regard CCBs as a waste but not a hazardous waste. However, given the high potential CCBs have in a number of roles and functions relating to mine rehabilitation and mine closure, more research at the practical level, and more engagement at a government level, is required. © 2014 Elsevier Ltd. All rights reserved. Source


Ahn J.-Y.,Chungbuk National University | Min J.,Chonbuk National University | Lee S.-H.,Chungbuk National University | Jang A.,Sungkyunkwan University | And 5 more authors.
Toxicology and Environmental Health Sciences | Year: 2014

Metagenome analysis was used to monitor changes in microbial population during the industrial-scale batch fermentation period (0, 15 days and 2 years). Genomic DNA was extracted from Bachu-Kimchi samples and was sequenced using GS Junior Titanium system, which yielded a total 6886, 6271, and 6621 reads from 0, 15 days and 2 years samples, respectively. Phylogenetic analysis based on 16S rRNA sequences showed clearly that microbial population was changed depending on the fermentation process (initial, rancid, and over-ripening stage). Wessella sp. and Leuconostoc sp. became the predominant group in microbial community at the optimum-rancid stage (15 days), but as the fermentation progressed more, the abundance of Lactobacillus sp. and Bacillus sp. increased (2 years). Moreover, the specific kimchi microbes in the industrial-scale fermentation process were isolated: Leuconostoc mesenteroides, Lactobacillus sakei, Lactobacillus plantarum, and Weissella koreensis. © 2014 Korean Society of Environmental Risk Assessment and Health Science and Springer Science+Business Media Dordrecht. Source


Sekhon S.S.,Chungbuk National University | Park J.-M.,Chungbuk National University | Ahn J.-Y.,Chungbuk National University | Park T.S.,Chonbuk National University | And 4 more authors.
Molecular and Cellular Toxicology | Year: 2014

The para-nitrobenzyl esterase (PNBE) was successfully immobilized onto electrospun polystyrene/poly(styrene-co-maleic anhydride) (PS/PSMA) nanofibers as cross-linked enzyme aggregates (CLEA). The maximum amount of PNBE immobilized on the PSPSMA nanofibers was determined to be 56.4 mg/g of nanofibers. The variation of pH and temperature has been observed to affect the enzymatic activity of the free and immobilized PNBE-CLEA. The immobilized PNBE-CLEA has been observed to show improved stability as compared to the native one. PNBE-CLEA has been found to retain more than 63% activity after 60 consecutive reuses. Finally, the immobilized PNBECLEA presented a high decomposition efficiency of cephalexin tosylate PNB ester. The durability determination of PNBE-CLEA immobilized nanofibers showed 70% of de-esterification after 10 cycles. These results demonstrate that PNBE-CLEA immobilized nanofiber could be used as an economical and environment friendly system for the catalytic process of paranitrobenzyl esters in pharmaceutical synthesis. © 2014 The Korean Society of Toxicogenomics and Toxicoproteomics and Springer Science+Business Media. Source

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