• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1311-1322
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• 2021

Microbially induced calcium carbonate precipitation (MICP) has recently become an intelligent and environmentally friendly method for repairing cracks in concrete. To improve on this ability of microbial materials concrete repair, we applied random mutagenesis and optimization of mineralization conditions to improve the quantity and crystal form of microbially precipitated calcium carbonate. Sporosarcina pasteurii ATCC 11859 was used as the starting strain to obtain the mutant with high urease activity by atmospheric and room temperature plasma (ARTP) mutagenesis. Next, we investigated the optimal biomineralization conditions and precipitation crystal form using Plackett-Burman experimental design and response surface methodology (RSM). Biomineralization with 0.73 mol/l calcium chloride, 45 g/l urea, reaction temperature of 45℃, and reaction time of 22 h, significantly increased the amount of precipitated calcium carbonate, which was deposited in the form of calcite crystals. Finally, the repair of concrete using the optimized biomineralization process was evaluated. A comparison of water absorption and adhesion of concrete specimens before and after repairs showed that concrete cracks and surface defects could be efficiently repaired. This study provides a new method to engineer biocementing material for concrete repair.

• Mass Spectrometry Letters
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• v.12 no.4
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• pp.192-199
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• 2021

Alpine glaciers harbor a large quantity of bio-labile dissolved organic matter (DOM), which plays a pivotal role in global carbon cycling as glacial-fed streams are headwaters of numerous large rivers. To understand the complexity, origin, and fate of DOM in glaciers and downstream-linked streams and lakes, we elucidated the molecular composition of DOM in two different Tibetan Plateau glaciers, eight glacial-fed streams and five lakes, using an ultrahigh-resolution 15 Tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The compositional changes of the DOM samples revealed that glacier DOM mostly exhibited sulfur-containing organic compounds (CHOS species). We also found that aliphatic formulae contributed more than 50% of the total abundance of assigned molecules in glacier samples, and those compounds were significantly related to CHOS species. The CHO proportions of glacial-fed streams and lakes samples increased with increasing distance from glacial terminals. The relative contribution of terrestrial-derived organics (i.e., lignins and tannins) declined while microbial-originated organics (aliphatics) increased with increasing elevation. This suggested the gradual input of allochthonous materials from non-glacial environment and the degradation of microbe-derived compounds along lower elevations. Alpine glaciers are retreating as a result of climate change and they nourished numerous streams, rivers, and downstream-linked lakes. Therefore, the interpretations of the detailed molecular changes in glacier ice, glacial-fed streams, and alpine lakes on the Tibetan Plateau could provide broad insights for understanding the biogeochemical cycling of glacial DOM and assessing how the nature of DOM impacts fluvial ecosystems.

• Journal of Microbiology and Biotechnology
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• v.34 no.6
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• pp.1214-1221
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• 2024

The accumulating evidence substantiates the indispensable role of gut microbiota in modulating the pathogenesis of type 2 diabetes. Uncovering the intricacies of the mechanism is imperative in aiding disease control efforts. Revealing key bacterial species, their metabolites and/or metabolic pathways from the vast array of gut microorganisms can significantly contribute to precise treatment of the disease. With a high prevalence of type 2 diabetes in Inner Mongolia, China, we recruited volunteers from among the Mongolian population to investigate the relationship between gut microbiota and the disease. Fecal samples were collected from the Volunteers of Mongolia with Type 2 Diabetes group and a Control group, and detected by metagenomic analysis and untargeted metabolomics analysis. The findings suggest that Firmicutes and Bacteroidetes phyla are the predominant gut microorganisms that exert significant influence on the pathogenesis of type 2 diabetes in the Mongolian population. In the disease group, despite an increase in the quantity of most gut microbial metabolic enzymes, there was a concomitant weakening of gut metabolic function, suggesting that the gut microbiota may be in a compensatory state during the disease stage. β-Tocotrienol may serve as a pivotal gut metabolite produced by gut microorganisms and a potential biomarker for type 2 diabetes. The metabolic biosynthesis pathways of ubiquinone and other terpenoid quinones could be the crucial mechanism through which the gut microbiota regulates type 2 diabetes. Additionally, certain Clostridium gut species may play a pivotal role in the progression of the disease.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.254-262
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• 2003

Dental caries has a multifactorial aetiology in which there is an interplay of three principal factors: the host(saliva and teeth), the microflora(dental plaque) and the substrate(diet), and a fourth factor time. There is no single test that takes into consideration all these factors and can accurately predict an individual's susceptibility to dental caries. The risk of dental caries can be evaluated by analysing and integrating several causative factors. The objective of the study was to clarify the relationship between caries activity and the status of caries of primary teeth and the relationship between the quantity of S. mutans in the dental plaque and the status of dental caries. Forty nine children ages 5 were examined with caries indices, Dentocult-SM and quantity of S. mutans. The results were as follows: All the survey results were similar with national means of 5-6 years Korean preschool children. The deft index of subjects was 5.46 and defs index was 9.81. There was 8.6% of negative, 10.9% of mild, 28.1% of moderate and 52.3% of active results at screening strip test. 8.6% was negative, 17.2% was mild, 33.6% was moderate and 40.6% was active in site strip test. The Spearman correlation coefficient was 0.775, and overall kappa index was 0.496 between screening strip test and site strip test. There also was a high correlation between caries incidence, Dentocult-SM test, and quantity of S. mutans. Dentocult-SM test as a caries activity test is a reliable method for measuring the status of dental caries in primary teeth.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4B
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• pp.253-259
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• 2012

Wastewater-adapted microalgae such as Chlorella vulgaris AG10032, Ankistrodesmus gracilis SAG278-2 and Scenedesmus quadricauda AG10308 are useful biological resources for recovering biofuel and other bio-based materials from wastewater because of their efficient removals of nitrogen and phosphorus from wastewater and their high fatty acid contents in biomass. Although the concentrations of phosphorus typically vary in wastewater environment, very little is known about the effect of phosphorus concentration, especially phosphorus starvation, on microalgal fatty acid synthesis. This is partially due to the lack of methodological establishment for algal fatty acid analysis. In this study, we compared the analysis performances of microalgal fatty acids by two different methods; one is a non-polar GC (gas chromatography) column based method, which is generally used for microbial fatty acids, and the other is a polar WAX-type GC column method, which is typically used for plant fatty acids. And then, we explored the effect of phosphorus concentration levels on fatty acid production in microalgae cultivated from wastewater. As results, the polar WAX-type column method has better ability to separate poly unsaturated fatty acids (PUFA) including $C_{18:3}$ (linolenic acid), and was found to be more applicable in analyzing fatty acids from wastewater-cultivated microalgae than the non-polar column method. The fatty acid characterization by the WAX-type column method revealed little effect of phosphorus starvation on the quantity and composition of fatty acids from wastewater-cultivated microalgae.

• Journal of Korea Soil Environment Society
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• v.4 no.3
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• pp.45-56
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• 1999

A biofilter was established to remove the ammonia, which is representative nitrogen-contained malodorous gas. in a compost factory. Removal efficiency of ammonia and hydrogen sulfide also was investigated. A quantity of malodor gas produced in a compost factory was affected greatly by the weather. compost states and working condition of a fertilizing mixer, and the produced gas concentrations doubled by above various parameters. By operating a water scrubbing system for removing water-soluble malodorous gases effectively. we could improve the removal efficiency over three times. We investigated long-term stability of biofilter under continuous gas flow(SV=500h-1) for 100 days. The results showed 30 days of microbial retention time. After the days, deodorization efficiency of biofilter was kept steady state. and the removal efficiency was kept over 95% for ammonia and 97% for hydrogen so]fide. respectively. The electric consumption of the biofilter, which could treat malodorous gas of 100$\textrm{m}^3$/min, applied in the compost factory was evaluated about 80u0day and water consumption was 80~100$\ell$/day. These results concluded that the biofilter is a excellent deodorization technology as well as cost-effective for removing malodorous gas produced in a compost factory.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.5
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• pp.667-672
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• 2003

Low-fat, precooked high quality Wanjajun was prepared by treating natural antioxidant herbs and hydrocolloids for quantity production of cook/chill system in foodservice. The proposed Wanjajun was formulated under the consideration of flavor and fat level. Wanjajun was prepared with hydrocolloid such as sodium alginate, car-boxymethyl cellulose (CMC), carrageenan and xanthan gum. Cooking yield, fat retention and water holding capacity of Wanjajun containing hydrocolloidal gums were higher than those of control. L-value of raw product was low in comparison with cooked product, but a-value was higher than that of other cooked product. Colors of raw and cooked products were not different among five kinds of products. pH value of cooked product was higher than that of raw product pH range of cooked products revealed to 6.10~6.23. There was no considerable change in pH value during storage. The coliform group and Staphylococus aureus were not detected during storage. Total bacteria1 counts were close to microbial guidelines for safe condition. Hardness, springness, cohesiveness, gumminess and brittleness of low-fat products were generally lower than those of control product. Hardness, gumminess and brittleness of reheated products were higher than those of preheated products. Flavor, tenderness, juiciness and overall quality were not different between precooked and reheated products. Textural characteristics of products were superior in the order of sodium alginate, xanthan gum, CMC, carrageenan and control product.

• BMB Reports
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• v.33 no.4
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• pp.326-331
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• 2000

Acidic chitinases from the gizzards of a broiler were purified to homogeneity, using precipitation with $(NH_{4})_{2}SO_{4}$, ion exchanger chromatography, gel filtration, chromatofocusing and hydrophobic interaction chromatography. The enzymes, GAC1 and GAC2, were purified 180- and 194- folds with a recovery of 4.9% and 2.7%, respectively. The molecular mass of GAC1 and GAC2 were 48.2 kDa and 57.8 kDa, respectively. Chromatofocusing resulted in a pI of 3.1 for both enzymes. The purified enzymes were endochitinases that were devoid of ${\beta}-N-acetylglucosaminidase$ and lysozyme activity. Kinetic studies using $[^3H]chitin$ indicate that GAC1 has a $K_m$ and $V_{max}$ of 1.97 mg/ml and 185 mg/mg protein/h, respectively. The GAC2 has a $K_m$ and $V_{max}$ of 0.42 mg/ml and 92.3 mg/mg protein/h, respectively at optimal pH and temperature (pH 5.0 and $60^{\circ}C$). When the pentamer and hexamer of N-acetylglucosamine (GlcNAc) were used as a substrate, the major product by GAC1 was the dimer of GlcNAc with a differential accumulation of the monomer and trimer, depending upon the substrate. However, the GAC2 produced the dimer and trimer in an equal quantity, regardless of the substrate used. The first 9 $NH_2-terminal$ amino acid residues of the purified gizzard chitinase GAC1 and GAC2 shared a 100% homology. The first 25 $NH_2-terminal$ amino acid residues of GAC1 also shared 55-60% homology with animal chitinases and some animal proteins, such as whey protein and oviduct-specific proteins. However, little homology was found with either microbial and plant chitinases, or egg white lysozyme.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.4
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• pp.269-273
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• 2007

We studied anti-microbial and anti-oxidant activities of bio-active components in stem of Juniperus chinensis L. and leaf of Abies koreana Wilson. Those plants of needle leaf tree family were reported to contain anti-cancer compounds. The anti-bacterial activity was tested by Broth dilution method against Escherichia coli and Staphylococcus aureus. As results, Juniperus chinensis L. and Abies koreana Wilson extracts showed 17.0% and 8.5% higher anti-bacterial activity than methyl paraben, respectively. The free radical scavenging activity of Juniperus chinensis L. and Abies koreana Wilson extracts showed 45 % and 44 % at 5,000 ppm. We measured polyphenol (catechin equivalent) and flavonoids quantity. The Juniperus chinensis L. extract contained 312 mg/g of polyphenol and 105 mg/g of flavonoids. The Abies koreana Wilson extract contained 280 mg/g of polyphenol and 103.8 mg/g of flavonoids. The cytotoxicity of extracts was measured by neutral red assay. Extracts did not affect the viability of CCK-986sk cells up to a concentration of 1,250 ppm. In conclusion, these data suggest that extracts of needle leaf trees would be usefull as antiseptic agents and anti-oxidants for cosmetic products.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.91-101
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• 1996

In recent years, phytoremediation, the use of plants to detoxify hydrocarbons, has been a promising new area of research, particularly in situ cleanup of large volumes of slightly contaminated soils. There is increasing need for a mathematical model that can be used as a predictive tool prior to actual field implementation of such a relatively new technique. Although a number of models exist for solute-plant interaction in the vegetated zone of soil, most of them have focused on ionic nutrients and some metals. In this study, we developed a mathematical model for simulation of bioremediation of hydrocarbons in soil, associated with plant root systems. The proposed model includes root interactions with soil-water and hydrocarbons in time and space, as well as advective and dispersive transport in unsaturated soil. The developed model considers gas phase diffusion and liquid-gas mass exchanges. For simulation of temporal and spatial changes in root behavior on soil-water and with hydrocarbons, time-specific distribution of root quantity through soil was incorporated into the simulation model. Hydrocarbon absorption and subsequent uptake into roots with water were simulated with empirical equations. In addition, microbial activity in the rhizosphere, a zone of unique interaction between roots and soil microorganisms, was modeled using a biofilm theory. This mathematical model for understanding and predicting fate and transport of compound in plant-aided remediation will assist effective application of plant-aided remediation to field contamination.