• Korean Journal of Microbiology
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• v.34 no.3
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• pp.126-131
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• 1998

Reduction of hexavalent chromium to its trivalent form by leachate microorganisms was studied in batch and bench-scale continuous stirred tank reactor. The inoculum was a culture of microorganisms in leachate and capable of providing up to 90% chromate reduction during 72 h batch assay with $20mg\;Cr(VI)\;L^{-1}$ in minimal media containing different levels of leachate (10 to 60%) and glucose (50 to 200 mM). Addition of glucose increased the efficiency of chromate reduction, but adverse effect was observed with increase of leachate probably due to the competitive inhibition between chromate and sulfate ions. The continuous culture experiment was conducted for 124 days using synthetic feed containing different levels of chromate (5 to $65mg\;L^{-1}$) at room temperature. With a hydraulic retention time of 36 h, chromate reduction efficiency was mostly 100% when Cr(VI) concentrations in the reactor were in the range of 5 to $50mg\;L^{-1}$ Specific rate of Cr(VI) removal was calculated as $3.492mg\;g^{-1}\;protein\;h^{-1}$ during the period of 101~124 days from the start-up which showed 81.2% of average reduction efficiency. The results indicate the potential application of using leachate microorganisms for detoxification of hexavalent chromium in various chromium-contaminated wastewater from landfill or tannery sites.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.183-187
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• 2000

Removal rate of nitrogen compound containing swine wastewater was 97 percent in case of high loading rate treatment of swine wastewater at studies for process development using soil microorganism. Minimum hydraulic retention time(HRT) for nitrification process was 11 days and solid retention time was 25 days. Nitrification was between 5 and 11 days but this time $NO_2-N$ was remained. Reactor condition was injured to nitrosomonas according to pH, $NO_2\;^--N$, and $NH_3\;^--N$ concentration but this condition was recover to pH controlling.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.2
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• pp.171-179
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• 2012

This study is focused on finding new natural materials that have antimicrobial activity. We found that 3 plants extracts, Magnolia sieboldii K. Koch (M. sieboldii K. Koch), Rhus chinensis (R. chinensis) and Metasequioa glyptostroboides (M. glyptostroboides), have antimicrobial activities by disk diffusion method. We determined the Minimum Inhibitory Concentation (MIC) of each and found that 0.3 ~ 0.35 % of M. glyptostroboides essential oil and 0.35 ~ 0.4 % of M. sieboldii K. Koch extracts inhibited fungal growth and 0.45 ~ 0.5 % of R. chinensis extracts inhibited bacterial growth. We isolated compounds from extracts and verified what have antimicrobial activity. As a result we found that caryophyllene oxide and caryophyllene isolated from M. glyptostroboides, costunolide and dehydrocostus lactone from M. sieboldii K. Koch and ethyl gallate, ethyl-3-gallate from R. chinensis have antimicrobial activities. In accordance with antimicrobial activity, O/W cosmetic emulsion containing mixture of 3 plants extracts showed preservative efficacy against both bacteria and fungi. Based on the above data we suggest that extracts from M. siebodii K. Koch, R. chinensis, and M. glyptostroboides, replace chemical synthetic preservatives and be applied as a natural preservative.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.4
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• pp.470-475
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• 2007

Antibacterial activities of Scutellaria baicalensis Georgi (SBG) extract were examined against spoilage bacteria isolated from commercial tofu and various pathogens such as Listeria monocytogenes ATCC 19115, Pseudomonas fluorescens ATCC 21541. Staphylococcus aureus ATCC 29737, Salmonella Typhimurium ATCC 11806, Vibrio parahaemolyticus ATCC 17802, and Aeromonas hydrophila KCTC 2358. Four kinds of spore forming organisms were isolated from commercial tofu and identified as Bacillus sp. KN-4, Bacillus sp. KN-6, Bacillus sp. KN-10 and Bacillus sp. KN-20 using API CHB kit. The SBG extract showed high antibacterial activities and significantly inhibited the growth of the isolated spoilage bacteria and pathogens. The inhibitory effects against the organisms increased as the concentration of the SBG extract increased. The antimicrobial activities of the SBG extract were maintained markedly after heat treatments $(80^{\circ}C/30\;min,\;100^{\circ}C/30\;min\;and\;121^{\circ}C/15min)$. The minimum inhibitory concentrations (MIC) of the SBG extract against the organisms ranged from 1,000 ppm to 5,000 ppm.

• The Korean Journal of Community Living Science
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• v.18 no.2
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• pp.293-300
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• 2007

The antimicrobial activity of 10 different traditional medicinal herbs extracts against E. coli was determined using paper disc method. Caesalpinia sappan and Rhus javanica, extracts in 5 mg/ml, and Paeonia suffruticosa and Seutellaria baicalensis extracts in 10 mg/ml showed significant antimicrobial activity against E. coli. Minimum inhibitory concentrations of medicinal herbs extracts were in the range of $1.4{\sim}8mg/ml\;and\;1.2{\sim}12mg/ml$, for MeOH extracts and EtOH extracts, respectively. In addition, the antimicrobial activity of each solvent fraction was most significant with the EtOAc layer. Optical density at 620nm after 24 hours incubation of E. coli in the presence of 100, 300 or 500 ppm of Caesalpinia sappan extract ranged from 0.02 to 0.1 compared to 0.6 in the absence of Caesalpinia sappan extract, indicating that growth of E. coli was significantly inhibited within 24 hours by the addition of at least 300 ppm of Caesalpinia sappan extract. Optical density at 620 nm after 24 hours incubation of E. coli in the presence of 300 ppm of Rhus javanica extract ranged from 0.02 to 0.2 compared to 0.5 in the absence of Rhus javanica extract, indicating that growth of E. coli was also significantly inhibited within 24 hours by the addition of at least 500 ppm of Rhus javanica extract. In conclusion, these findings suggest that extracts from medicinal herbs may play important roles in antimicrobial activities against E. coli.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.8
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• pp.973-978
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• 2006

This study was conducted to investigate the solubility, antioxidative and antimicrobial activity of the freeze dried chitosan-ascorbate (CAs) and chitosan-acetate (CAc). In the results of solubility, CAs was soluble over 0.5% in distilled water, vinegar, green tea, soju (distilled liquor), beer and red wine, while it was not soluble in soy sauce, soy milk, milk, orange juice, coffee, sesame oil, soy milk and soybean oil. The solubility of CAc in the liquid foods was similar to those of CAs, but it was soluble less than 0.1% in beer, and formed curd in red wine. Electron donating activity, antioxidative activity and SOD activity of CAs were 48.2, 90.6 and 67.5%, respectively, while the activities of the CAc were 0, 40.0 and 10.0%, respectively. The minimal inhibitory concentrations of CAs and CAc were $200\;{\mu}g/disc$ against Bacillus circulans, Bacillus brevis, Bacillus licheniformis, Bacillus arabitane and Bacillus sterothermophillus, $400\;{\mu}g/disc$ against Escherichia coli O157, Listeria monocytogenous, Bacillus cereus and Bacillus subtilis. There was no significant difference in Hunter's L* value between CAs and CAc $(81.95{\sim}82.97)$, but Hunter's a* and b* values of the CAs was higher than those of CAc. While sour and bitter tastes of CAs were lower than those of CAc, there was no significant difference in astringent taste. From these results, it suggested that CAs has more extensive utility in liquid foods with antimicrobial and antioxidant activity as well as sensory quality compared to CAc.

• Korean Journal of Microbiology
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• v.54 no.3
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• pp.228-236
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• 2018

The aim of this study was to investigate the distribution of resistance genes in high-level streptomycin resistant Escherichia coli isolated from shellfish collected between April 2015 and March 2016 in Korea. From the 269 E. coli isolates obtained from shellfish samples, a total of 40 streptomycin-resistant isolates with MICs of > $1,024{\mu}g/ml$ were screened and the prevalence of streptomycin resistance determinants was analyzed by PCR. Among the isolates, strA-strB gene structure (77.5%) was the most frequent streptomycin resistance determinant, followed by aadA (30.0%). Six isolates (15.0%) simultaneously contained aadA and strA-strB determinants, whereas three of the isolates (7.5%) did not contain both resistance determinants examined in this work. The difference of MICs between the isolates having the same resistance gene was elucidated by real-time PCR results. The copy number of resistance genes differed considerably among the isolates, which solely harbored an aadA or strA-strB and showed different MICs.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.3
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• pp.316-322
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• 2019

Helicobacter pylori, a gram-negative bacterium, is one of the risk factors that induces gastritis and gastric cancer. Therefore, much attention has been paid to the compounds that inhibit bacterial growth or eradicate bacteria. Evodiae fructus (EF), the fruit of Evodia rutaecarpa, has been used for treating diarrhea and abdominal pain. EF extract was already found to inhibit the growth of H. pylori. However, to the best of our knowledge, the effect of EF on the virulence factors of H. pylori has not been reported. In this study, when comparing the minimum inhibitory concentration (MIC) of the different methanol concentration extracts, the 95% methanol extract (EF95) showed the lowest MIC value. EF95 extract suppressed the expressions of cagA, vacA and ureB, but interestingly, it up-regulated the expression of ureA. A decrease in production of ammonia in the culture medium and the cell lysates indicated that EF95 inhibited the urease activity in H. pylori, which was the result of EF95 inhibiting the ureB expression. Although the mechanism by which EF95 extract regulates the virulence factors in H. pylori needs further study, EF95 could be used for treatment of gastric troubles induced by H. pylori.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.657-663
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• 2011

$Bacillus$ $cereus$ is widely distributed on various foods and is known to cause clinical infections, food poisoning toxin induced diarrhea and vomiting. In this study, $B.$ $cereus$ group detected and analyzed rice, rice bran, and biofilm characterization of $B.$ $cereus$ confirmed. $B.$ $cereus$ was identified in approximately 34.6% of brown rice and 50.0% of rice bran. $B.$ $thuringiensis$ was detected in 3.9% of brown rice and 23% of rice bran, and $B.$ $mycoides$ was isolated from rice bran. The microtiter plate assay detected differences in biofilm-forming ability among $B.$ $cereus$ group isolates. Biofilm of $B.$ $cereus$ seemed to increase the MIC values of antimicrobial agent and antibiotic compounds compared with planktonic cells. Therefore, sufficient attention should be given to good manufacturing practice and good agriculture practice to avoid contamination of $B.$ $cereus$ group raw material including rice.

• Journal of Korean society of Dental Hygiene
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• v.18 no.1
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• pp.9-18
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• 2018

Objectives: Pleurotus eryngii is used both for edible and medicinal purposes, and has a physiological activity. The purpose of this study is to investigate the antibacterial effect of Pleurotus eryngii against six oral pathogens (Staphylococcus aureus, Streptococcus criceti, Streptococcus mutans, Streptococcus ratti, Streptococcus sobrinus, and Actinomyces viscosus). Methods: The antibacterial activities of various extracts of Pleurotus eryngii were examined by disc diffusion assay and minimum inhibitory concentration (MIC). The disc diffusion assay was performed by putting a paper disc soaked in extracts on plates inoculated bacterial cultures. The MIC of these extracts was determined by using a broth microdilution assay at a concentration ranging between 0.03 mg/ml to 15.00 mg/ml. The growth inhibition effect of extracts was measured at 600 nm for 24 hrs. Results: The antibacterial activity was confirmed against all six tested bacteria at Pleurotus eryngii ethyl acetate extract by the disc diffusion method. Acetone extract showed the antibacterial activity only against 4 strains containing Streptococcus criceti, Streptococcus mutans, Streptococcus ratti, and Actinomyces viscosus. In ethanol extract, no activity was observed against other strains except Staphylococcus aureus. MIC values of ethyl acetate extract were the same, 7.50 mg/ml in all tested bacteria. Conclusions: Pleurotus eryngii exhibited the antibacterial activity against oral pathogens (Staphylococcus aureus, Streptococcus criceti, Streptococcus mutans, Streptococcus ratti, Streptococcus sobrinus, and Actinomyces viscosus). Thus, Pleurotus eryngii may be considered as a natural antibacterial agent for treatment of dental diseases.