• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.567-578
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• 2013

A microbial fuel cell (MFC) is a bio-electrochemical device that converts chemical energy in the chemical bonds in organic compounds to electrical energy through catalytic reactions of microorganisms under anaerobic conditions. Power density and Coulombic efficiency are significantly affected by the types of microbe in the anodic chamber of an MFC, configurations of the system and operating conditions. The achievable power output from MFC increased remarkably by modifying their designs such as the optimization of MFC configurations, the physical and chemical operating conditions, and the choice of biocatalysts. This article presents a critical review on the recent advances made in MFC research with the emphasis on MFC configurations, optimization of important operating parameters, performances and future applications of MFC.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 1996.06a
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• pp.33-33
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• 1996

Interests in the field of rapid methods and automation in microbiology have been growing steadily on an international scale in recent years. International meetings concerned this problem have been held in elsewhere in the world countries since the past twenty years. But, unfortunately in the field of microbial examination in food hygiene, this problem have not yet been developed so much as in the field of clinical microbiology. Today, I would like to introduce you here present aspects of rapid and automation technologies, those which are manly carrying in milk and meats industries. My illustration will be given recent improved technologies using automatic apparatus and instruments along with process of microbial count procedure. Recent direct microbiological counting system (ChemeScan \ulcorner) as real time ultrasensitive analysis created by Cheminex Ltd., France is now most evolutional instrument to provide direct microbial counts, down to one cell, within 30 minutes. The results from these evaluations how a good correlation between the ChemScan system and the standard plate count method. This system will be successful application for not only in the field of pharmacology but also food microbiology. In addition, current identification of microbes by sophisticated instruments suitable for food microbiology, one of which Biology is manual system (BIOLOG\ulcorner), provides reference-level capability at a modes price. For the manual system, the color reactions in the microplate are read by eye and manually keyed into personal computer. Species identification appears on the computer screen within seconds, along with biotype patterns, a list of closely related species, and other useful statistics. In present this is useful application for microbial ecology and epidemiological survey. RiboPrinter system newly produced by DuPont is now focusing among microbiologists in the world, and is one of the biggest microbial characterization system using a DNA-based approach. The technology analyzer is bacterial culture for its genetic fingerprint or riboprint pattern. Finally Bio-cellTracer system for automatic measurement of fungal growth and Fukitori-Maseter, a Surface Hygiene Monitoring Kit by using swabe procedure in food processing environment are briefly illustrated in this presentation.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.04a
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• pp.115.4-116
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• 1979

Acetone-dried cells of Arthrobacter simplex were entrapped in several preparations of hydrophilic urethane prepolymers and their steroid converting ability was examined. SeVeral solvents, such as methanol and propylone glycol, wereeffective for the conversion of hydrocortisone to prednisolone. The stability of the immobilized cells during storage and on repeated reactions was also examined. Thisconvenient entrapping method was also applicable for the immobilization of cellular organelles. yeast peroxisomes. The entrapped peroxi-somessh owed the activities of alcohol oxidase and catalase.

• Microbiology and Biotechnology Letters
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• v.34 no.2
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• pp.101-108
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• 2006

YNB54 strain which shows inhibitory activities specific to the plant pathogenic Phytophthora sp. on potato dextrose agar medium was screened among lots of strains isolated from Korean soils. To identify taxonomy of the Phytophthora specific antagonistic bacteria YNB54, 165 rDNA sequence, MIDI fatty acid composition, DNA-DNA hybridization, GC content, and commercial multitest systems such as API 20E and Biolog GN were performed. Results of commercial kits including lots of biochemical and physiological reactions showed that this strain was closely related to taxa including Enterobacter cloacae and Enterobacter cancerogenus species than other genera(Citerobacter Klebsiella, Leclercia). Also, analysis of its MIDI, G+C contents, and DNA-DNA hybridization suggests that this strain was more similiar to the Genus Enterobacter than other genera (Citerobacter Klebsiella, Leclercia). This strain was potentially identified as Enterobacter sp. by these results. But our 16S ribosomal DNA sequences (rDNA) analysis confirmed that it was more closely related to the cluster of Citerobacter freundii ATCC 29935 than any other Enterobacter species. In the absence of defined phylogenetic critia for delineating genera, the results observed with Citrobacter and Enterobacter species suggest that further studies are needed to clarify their relationships. This investigation demonstrates that YNB54 strain is genetically diverse and potentially more taxonomically complex than hitherto realized. Further study is necessary to confirm their taxonomic positions.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.247-259
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• 2015

This study was performed to investigate the application of dark $H_2$ fermentation to two-stage bioprocesses for organic waste treatment and energy production. We reviewed information about the two-stage bioprocesses combining dark $H_2$ fermentation with $CH_4$ fermentation, photo $H_2$ fermentation, microbial fuel cells (MFCs), or microbial electrolysis cells (MECs) by using academic information databases and university libraries. Dark fermentative bacteria use organic waste as the sole source of electrons and energy, converting it into $H_2$. The reactions related to dark $H_2$ fermentation are rapid and do not require sunlight, making them useful for treating organic waste. However, the degradation is not complete and organic acids remain. Thus, dark $H_2$ fermentation should be combined with a post-treatment process, such as $CH_4$ fermentation, photo $H_2$ fermentation, MFCs, or MECs. So far, dark $H_2$ fermentation followed by $CH_4$ fermentation is a promising two-stage bioprocess among them. However, if the problems of manufacturing expenses, operational cost, scale-up, and practical applications will be solved, the two-stage bioprocesses combining dark $H_2$ fermentation with photo $H_2$ fermentation, MFCs, or MECs have also infinite potential in organic waste treatment and energy production. This paper demonstrated the feasibility of two-stage bioprocesses combining dark $H_2$ fermentation as a novel system for organic waste treatment and energy production.

• Korean Journal of Microbiology
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• v.48 no.4
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• pp.254-261
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• 2012

The purpose of this research was to optimize electric current production of sediment microbial fuel cells by injecting glucose and to investigate its impact on microbial communities involved. It was shown that injection of proper concentration of glucose could increase electric current generated from sediment microbial fuel cells. When 1,000 mg/L of glucose, as opposed to higher concentrations, was injected, electric current increased up to 3 times. This increase is mainly attributed to the mutual relationship between fermenting bacteria and exoelectrogenic bacteria. Here the organic acids generated by fermenting bacteria could be utilized by exoelectrogenic bacteria, removing feedback inhibition caused by the organic acids. When glucose was injected, the population of Clostridium increased as to ferment injected glucose. Glucose fermentation can have either a positive or negative effect on electric current generation. When exoelectrogenic bacteria may readily utilize the end-product, electric current could increase. However, when the end-product was not readily removed, then detrimental chemical reactions (pH decrease, methane generation, organic acids accumulation) occurred: exoelctrogenic bacteria population declined and non-microbial fuel cell related microorganisms prospered. By injecting a proper concentration of glucose, a mutual relationship between fermenting bacteria, such as Clostridium, and exoelectrogenic bacteria, such as Geobacter, should be fulfilled in order to increase electricity production in mixed cultures of microorganisms collected from the aquatic sediments.

• Journal of Microbiology and Biotechnology
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• v.26 no.1
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• pp.120-129
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• 2016

An industrial complex in Wonju, contaminated with trichloroethene (TCE), was one of the most problematic sites in Korea. Despite repeated remedial trials for decades, chlorinated ethenes remained as sources of down-gradient groundwater contamination. Recent efforts were being made to remove the contaminants of the area, but knowledge of the indigenous microbial communities and their dechlorination abilities were unknown. Thus, the objectives of the present study were (i) to evaluate the dechlorination abilities of indigenous microbes at the contaminated site, (ii) to characterize which microbes and reductive dehalogenase genes were responsible for the dechlorination reactions, and (iii) to develop a PCE-to-ethene dechlorinating microbial consortium. An enrichment culture that dechlorinates PCE to ethene was obtained from Wonju stream, nearby a trichloroethene (TCE)-contaminated industrial complex. The community profiling revealed that known organohalide-respiring microbes, such as Geobacter, Desulfuromonas, and Dehalococcoides grew during the incubation with chlorinated ethenes. Although Chloroflexi populations (i.e., Longilinea and Bellilinea) were the most enriched in the sediment microcosms, those were not found in the transfer cultures. Based upon the results from pyrosequencing of 16S rRNA gene amplicons and qPCR using TaqMan chemistry, close relatives of Dehalococcoides mccartyi strains FL2 and GT seemed to be dominant and responsible for the complete detoxification of chlorinated ethenes in the transfer cultures. This study also demonstrated that the contaminated site harbors indigenous microbes that can convert PCE to ethene, and the developed consortium can be an important resource for future bioremediation efforts.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3349-3354
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• 2012

Understanding exoelectrogenic reactions of the bioanode is limited due to its complexity and the absence of analytics. Impedance and thermodynamics of bioanode, abiotic anode, and riboflavin-amended anode were evaluated. Activation overpotential of the bioanode was negligible compared with that of the abiotic anode. Impedance spectroscopy shows that the bioanode had much lower charge transfer resistance and higher capacitance than the abiotic anode in low frequency reaction. In high frequency reaction, the impedance parameters, however, were relatively similar between the bioanode and the abiotic anode. At open-circuit impedance spectroscopy, a high frequency arc was not detected in the abiotic anode in Nyquist plot. Addition of riboflavin induced a phase angle shift and created curvature in high-frequency arc of the abiotic anode, and it also drastically changed impedance spectra of the bioanode.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.2
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• pp.75-88
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• 2001

In this paper, the microbial production of riboflavin is reviewed and includes descriptions of riboflavin overproducers, and the biosynthesis and details of the key-enzyme genes related to riboflavin. There kinds of riboflavin overproducers are known; Bacillus subtilis and Candida famate utilize glucose as a carbon source, but the fungus Ashbya gossypii requires plant oil as its sole carbon source. The starting material in ribofalvin biosynthesis is guanosine triphospate (GTP), which is converted to riboflavin through six enzymatic reactions. Though Bacillus subtilis, Candida famate, and Ashbya gossypii operate via different pathways until GTP, they follow the same pathway from GTP to riboflavin. From the metabolic viewpoint, with respect to improved riboflavin production, the supplementation of GTP, aprocess-limiting precursor must be considered. The GTP fluxes originate from three sources, serine, threonine and glyoxylate cycles. The development of pathways to strengthen GTP supplementation using biotechnological techniques remains an issue fro future research.

• Biomolecules & Therapeutics
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• v.29 no.3
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• pp.263-267
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• 2021

Periodontal disease is primarily associated with bacterial infection such as dental plaque. Dental plaque, an oral biofilm harboring a complex microbial community, can cause various inflammatory reactions in periodontal tissue. In many cases, the local bacterial invasion and host-mediated immune responses lead to severe alveolar bone destruction. To date, plaque control, non-surgical, and surgical interventions have been the conventional periodontal treatment modalities. Although adjuvant therapies including antibiotics or supplements have accompanied these procedures, their usage has been limited by antibiotic resistance, as well as their partial effectiveness. Therefore, new strategies are needed to control local inflammation in the periodontium and host immune responses. In recent years, target molecules that modulate microbial signaling mechanisms, host inflammatory substances, and bone immune responses have received considerable attention by researchers. In this review, we introduce three approaches that suggest a way forward for the development of new treatments for periodontal disease; (1) quorum quenching using quorum sensing inhibitors, (2) inflammasome targeting, and (3) use of FDA-approved anabolic agents, including Teriparatide and sclerostin antibody.