• Food Science and Biotechnology
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• v.17 no.5
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• pp.904-911
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• 2008

Covalent cross-links between a number of proteins and peptides explain why transglutaminase may be widely used by food processing industries. The objective of this work was optimization of the fermentation process to produce transglutaminase from a new microbial source, the Streptomyces sp. P20. The strategy adopted to modify the usual literature media was: (1) fractional factorial design (FFD) to elucidate the key medium ingredients, (2) central composite design (CCD) to optimise the concentration of the key components. Optimization of the medium resulted in not only an 86% increase in microbial transglutaminase activity as compared to the media cited in the literature, but also a reduction in the production cost. Optimal fermentation conditions - namely temperature and agitation rate - were also studied, using CCD methodology. Usual conditions of $30^{\circ}C$ and 100 rpm were within the optimal area. All other parameters for enzyme production were experimentally proven to be optimum fermentation conditions.

• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.83-91
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• 2015

Mine soil contamination by high levels of metal ions that prevents the successful vegetation poses a serious problem. In the study presented here, we used the microbial biocatalyst of urease producing bacterium Sporosarcina pasteurii or plant extract based BioNeutro-GEM (BNG) agent. The ability of the biocatalysts to bioremediate contaminated soil from abandoned mine was examined by solid-state composting vegetation under field conditions. Treatment of mine soil with the 2 biocatalysts for 5 months resulted in pH increase and electric conductivity reduction compared to untreated control. Further analyses revealed that the microbial catalysts also promoted the root and shoot growth to the untreated control during the vegetation treatments. After the Sporosarcina pasteurii or plant extract based BNG treatment, the microbial community change was monitored by culture-independent pyrosequencing. These results demonstrate that the microbial biocatalysts could potentially be used in the soil bioremediation from mine-impacted area.

• Food Science and Biotechnology
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• v.27 no.6
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• pp.1865-1869
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• 2018

This study examined the effects of alfalfa seed germination on growth of Salmonella enterica. We investigated the population changes of S. enterica during early sprout development. We found that the population density of S. enterica, which was inoculated on alfalfa seeds was increased during sprout development under all experimental temperatures, whereas a significant reduction was observed when S. enterica was inoculated on fully germinated sprouts. To establish a model for predicting S. enterica growth during alfalfa sprout development, the kinetic growth data under isothermal conditions were collected and evaluated based on Baranyi model as a primary model for growth data. To elucidate the influence of temperature on S. enterica growth rates, three secondary models were compared and found that the Arrhenius-type model was more suitable than others. We believe that our model can be utilized to predict S. enterica behavior in alfalfa sprout and to conduct microbial risk assessments.

• Journal of Food Hygiene and Safety
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• v.27 no.4
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• pp.442-448
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• 2012

This study investigated reduction of microbial population, water soluble pigment, capsanthin content, surface color (Hunter L, a, b, ${\Delta}E$), and sensory properties of pepper powder by LED (red, yellow, blue, green) treatments. LED (red, yellow, blue, green) treatment were conducted in 1,000 lux storage at $25^{\circ}C$ for 10 days. The total aerobic bacteria was no significant difference among the control and treated with LED during 10 days. In yellow LED treatment, yeast and molds were decreased about 1.76 log. Surface color such as lightness (L), redness (a), yellowness (b) were showed a decreasing tendency as the storage period. In the overall color difference (${\Delta}E$) of yellow LED treatment was lower less than 3.0. Water soluble pigment was no difference in control and LED treated samples during storage period. Capsanthin content was significantly decreased as storage period was increased, but no significant differences were observed among red and yellow LED treatments. Sensory properties of control was significantly reduced by storage period but yellow and green LED treatments were no significantly differences.

• Korean Journal of Environmental Agriculture
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• v.40 no.1
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• pp.49-59
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• 2021

BACKGROUND: Soil salinity causes reduction of crop productivity. Rhizosphere microbes have metabolic capabilities and ability to adaptation of plants to biotic and abiotic stresses. Plant growth-promoting bacteria (PGPB) could play a role as elicitors for inducing tolerance to stresses in plants by affecting resident microorganism in soil. This study was conducted to demonstrate the effect of selected strains on rhizosphere microbial community under salinity stress. METHODS AND RESULTS: The experiments were conducted in tomato plants in pots containing field soil. Bacterial suspension was inoculated into three-week-old tomato plants, one week after inoculation, and -1,000 kPa-balanced salinity stress was imposed. The physiological and biochemical attributes of plant under salt stress were monitored by evaluating pigment, malondialdehyde (MDA), proline, soil pH, electrical conductivity (EC) and ion concentrations. To demonstrate the effect of selected Bacillus strains on rhizosphere microbial community, soil microbial diversity and abundance were evaluated with Illumina MiSeq sequencing, and primer sets of 341F/805R and ITS3/ITS4 were used for bacterial and fungal communities, respectively. As a result, when the bacterial strains were inoculated and then salinity stress was imposed, the inoculation decreases the stress susceptibility including reduction in lipid peroxidation, enhanced pigmentation and proline accumulation which subsequently resulted in better plant growth. However, bacterial inoculations did not affect diversity (observed OTUs, ACE, Chao1 and Shannon) and structure (principle coordinate analysis) of microbial communities under salinity stress. Furthermore, relative abundance in microbial communities had no significant difference between bacterial treated- and untreated-soils under salinity stress. CONCLUSION: Inoculation of Bacillus strains could affect plant responses and soil pH of tomato plants under salinity stress, whereas microbial diversity and abundance had no significant difference by the bacterial treatments. These findings demonstrated that Bacillus strains could alleviate plant's salinity damages by regulating pigments, proline, and MDA contents without significant changes of microbial community in tomato plants, and can be used as effective biostimulators against salinity stress for sustainable agriculture.

• Journal of Food Hygiene and Safety
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• v.32 no.2
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• pp.154-162
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• 2017

The purpose of this study was to investigate the microbial reduction effect of chlorine dioxide and sodium hypochlorite in Korean chive. Korean chive inoculated with foodborne pathogens at the level of approximately 7~8 log CFU/g was treated with various concentration of chlorine dioxide (3, 4, 10, 25 and 100 ppm and sodium hypochlorite (100, 150 and 200 ppm) for 5, 10, 30 and 60 minutes. The treatment of 150 ppm sodium hypochlorite and 50 ppm chlorine dioxide for 30 min reduced the number of total bacteria in Korean chive up to 2.0 log CFU/g. Reduction of microbial levels was observed for all concentrations of sanitizers but their effectiveness did not correspond to their concentration. Due to the quality degradation, 50 ppm chlorine dioxide was not appropriate for Korean chive. Most effective reduction of microbial levels was observed when Korean chive were treated with 9 times more sanitizer in volume. For field application, the treatment of 150 ppm sodium hypochlorite showed 2.7 and 4.0 log CFU/g reductions for numbers of total bacteria and coliforms, respectively. Therefore, washing with sodium hypochlorite of a ratio of 1:9 (Korean chive : 150 ppm sodium hypochlorite (w/v)) for 30 minutes can reduce the number of foodborne pathogen in Korean chive.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.757-762
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• 2016

The group of Fe(III) oxide-reducing bacteria includes exoelectrogenic bacteria, and they possess similar properties of transferring electrons to extracellular insoluble-electron acceptors. The exoelectrogenic bacteria can use the anode in microbial fuel cells (MFCs) as the terminal electron acceptor in anaerobic acetate oxidation. In the present study, the anodic community was compared with the community using Fe(III) oxide (ferrihydrite) as the electron acceptor coupled with acetate oxidation. To precisely analyze the structures, the community was established by enrichment cultures using the same inoculum used for the MFCs. High-throughput sequencing of the 16S rRNA gene revealed considerable differences between the structure of the anodic communities and that of the Fe(III) oxide-reducing community. Geobacter species were predominantly detected (>46%) in the anodic communities. In contrast, Pseudomonas (70%) and Desulfosporosinus (16%) were predominant in the Fe(III) oxide-reducing community. These results demonstrated that Geobacter species are the most specialized among Fe(III)-reducing bacteria for electron transfer to the anode in MFCs. In addition, the present study indicates the presence of a novel lineage of bacteria in the genus Pseudomonas that highly prefers ferrihydrite as the terminal electron acceptor in acetate oxidation.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.9
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• pp.1219-1227
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• 2000

Rumination behavior, in vivo digestibility of cell wall constituents, particle size reduction in the rumen, and retention time in the digestive tract of sheep were examined using rice and oat straw as roughage sources. The in sacco digestibility, rumen fermentation, and microbial population and internal adenosine 5-triphosphate (ATP) content were also determined under feeding conditions of high-roughage and high-concentrate diets. Chewing number and time in rumination behavior were higher with rice straw than with oat straw, while the in sacco and in vivo DMD of rice straw were consistently lower than those of oat straw. Rice straw also showed higher frequency of thinner and longer particles in the rumen contents and lower retention time in the whole digestive tract as compared to those of oat straw. Rice straw was more effective to maintain the ruminal pH than oat straw, being reflected in higher internal ATP content of large-type protozoa on the high- concentrate diet. Changes in the ruminal microflora by shifting from the low- to the high- concentrate diet were also different between rice and oat straw.

• Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.59-65
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• 2014

We measured the reductions in size and solubility of mackerel muscle that was freeze-dried, deoiled by supercritical carbon dioxide (SC-$CO_2$), or roasted. The percent size reduction and solubility were high in SC-$CO_2$-treated muscle compared with freeze-dried and roasted muscle. We used oil-free residues to test for heavy metals and determine microbial safety. The SC-$CO_2$, hexane, and ethanol were used to separate oil from muscle. The concentrations of cadmium (Cd) in all treated muscles were less than the values reported in the literature, as were the concentrations of lead in SC-$CO_2$- and hexane- treated muscle. In contrast, concentrations of arsenic and mercury in muscles were greater than the reported values regardless of treatment. Zinc and iron, which are beneficial for health, were found in high levels after all treatments of muscle tissue. After 6 months of storage at different temperatures, SC-$CO_2$-and ethanol-treated muscle showed few bacterial colonies, and none were found after 4 months of storage at $-20^{\circ}C$. These results will be useful to food-processing industries for maintaining high-quality, safe mackerel muscle.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.12
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• pp.682-688
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• 2015

Effect of electrode spacing on the performance of microbial electrolysis cells(MECs) for treating sewage sludge was investigated through lab scale experiment. The reactors were equipped with two pairs of electrodes that have a different electrode spacing (16, 32 mm). Shorter electrode distance improved the overall performance of MEC system. With the 16 mm of electrode distance, the current density was $3.04{\sim}3.74A/m^3$ and methane production was $0.616{\sim}0.804Nm^3/m^3$, which were higher than those obtained with 32 mm of electrode spacing ($1.50{\sim}1.82A/m^3$, $0.529{\sim}0.664Nm^3/m^3$). The COD removal was in the range of 34~40%, and the VSS reduction ranged 32~38%. As the current production increased, VSS reduction and methane production were increased possibly due to the improved bioelectrochemical performance of the system. Methane production was more affected by current density than VSS reduction. These results imply that the reducing the electrode spacing can enhance the methane production and recovery from sewage sludge with the decreased internal resistance, however, it was not able to improve VSS reduction of sewage sludge.