• Korean Journal of Microbiology
• /
• v.55 no.1
• /
• pp.46-51
• /
• 2019

This study was carried out to evaluate antimicrobial effects of a mixture of resin fractionated ethanol extract of Eucalyptus globulus, Yucca recurvifolia, and tea tree (Melaleuca alternifolia). The plant fraction mixture showed low minimum inhibitory concentration (0.24~3.32 mg/ml) against several bacteria and yeast that usually used as the target skin microbes in a cosmetic industry, and it was more effective than antibiotics, triclosan and ampicillin. In a time-kill assay the plant fraction mixture reduced more than 92% of microbial populations during 4 h, and significantly increased leakage of nucleotides from all microorganisms tested. Antimicrobial effect of the plant fraction mixture was not affected by divalent cation ($Mg^{2+}$ and $Ca^{2+}$). These results suggest that the fraction mixture of ethanol extracts of E. globulus, Y. recurvifolia, and M. alternifolia may be utilized as an efficient preservative in cosmetics to prevent contamination by human skin microbes.

• Toxicological Research
• /
• v.35 no.2
• /
• pp.137-154
• /
• 2019

Triclosan (TCS) is an antimicrobial compound used in consumer products. The purpose of current study was to examine toxicology and risk assessment of TCS based on available data. Acute toxicities of oral, transdermal and inhalation routes were low, and phototoxicity and neurotoxicity were not observed. Topical treatment of TCS to animal caused mild irritation. TCS did not induce reproductive and developmental toxicity in rodents. In addition, genotoxicity was not considered based on in vitro and in vivo tests of TCS. It is not classified as a carcinogen in international authorities such as International Agency for Research on Cancer (IARC). No-observed-adverse-effect level (NOAEL) was determined 12 mg/kg bw/day for TCS, based on haematoxicity and reduction of absolute and relative spleen weights in a 104-week oral toxicity study in rats. Percutaneous absorption rate was set as 14%, which was human skin absorption study reported by National Industrial Chemicals Notification and Assessment Scheme (NICNAS) (2009). The systemic exposure dosage (SED) of TCS has been derived by two scenarios depending on the cosmetics usage of Koreans. The first scenario is the combined use of representative cosmetics and oral care products. The second scenario is the combined use of rinse-off products of cleansing, deodorants, coloring products, and oral care products. SEDs have been calculated as 0.14337 mg/kg bw/day for the first scenario and 0.04733 mg/kg bw/day for the second scenario. As a result, margin of safety (MOS) for the first and second scenarios was estimated to 84 and 253.5, respectively. Based on these results, exposure of TCS contained in rinse-off products, deodorants, and coloring products would not pose a significant health risk when it is used up to 0.3%.

• Journal of the Korean Magnetic Resonance Society
• /
• v.22 no.4
• /
• pp.91-100
• /
• 2018

Benzisothiazolinone (BIT) is the preservative that is widely used in industrial and household products. In this study, zebrafish (Danio rerio) was exposed to BIT at different concentrations (control, 0.5 g/L, 1.0 g/L and 2.0 g/L) for 72 hours. The techniques of nuclear magnetic resonance (NMR) spectroscopy were applied to analyze the effects of BIT on zebrafish. The advantages of NMR are the minimal sample preparation and high reproducibility of experimental results. With the multivariate statistical analysis, dimethylamine, N-acetylaspartate, glycine and histidine were identified as an important metabolite in differentiating between the control and BIT-exposed group. This study will improve the understanding the metabolite changes in the zebrafish in response to BIT exposure.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.8
• /
• pp.1177-1183
• /
• 2019

Grapefruit seed extract (GSE) is a safe and effective preservative that is used widely in the food industry. However, there are few studies addressing the anti-biofilm effect of GSE. In this study, the anti-biofilm effect of GSE was investigated against biofilm-forming strains of Staphylococcus aureus and Escherichia coli. The GSE minimum inhibitory concentration (MIC) for S. aureus and E. coli were $25{\mu}g/ml$ and $250{\mu}g/ml$, respectively. To investigate biofilm inhibition and degradation effect, crystal violet assay and stainless steel were used. Biofilm formation rates of four strains (S. aureus 7, S. aureus 8, E. coli ATCC 25922, and E. coli O157:H4 FRIK 125) were 55.8%, 70.2%, 55.4%, and 20.6% at $1/2{\times}MIC$ of GSE, respectively. The degradation effect of GSE on biofilms attached to stainless steel coupons was observed (${\geq}1$ log CFU/coupon) after exposure to concentrations above the MIC for all strains and $1/2{\times}MIC$ for S. aureus 7. In addition, the specific mechanisms of this anti-biofilm effect were investigated by evaluating hydrophobicity, auto-aggregation, exopolysaccharide (EPS) production rate, and motility. Significant changes in EPS production rate and motility were observed in both S. aureus and E. coli in the presence of GSE, while changes in hydrophobicity were observed only in E. coli. No relationship was seen between auto-aggregation and biofilm formation. Therefore, our results suggest that GSE might be used as an anti-biofilm agent that is effective against S. aureus and E. coli.

• Microbiology and Biotechnology Letters
• /
• v.47 no.3
• /
• pp.337-342
• /
• 2019

We published that bacterial heme was over-produced in a recombinant Corynebacterium glutamicum expressing 5-aminolevulinic acid synthase ($hemA^+$) under control of a constitutive promoter ($P_{180}$) and the heme-producing C. glutamicum had commercial potentials; as an iron feed additive for swine and as a preservative for lactic acid bacteria. To enhance the heme production, the $hemA^+$ gene was expressed under controls of various promoters in the recombinant C. glutamicum. The $hemA^+$ expression by $P_{gapA}$ (a constitutive glycolytic promoter of glyceraldehyde-3-phosphate dehydrogenase) led 75% increase of heme production while the expression by $P_{H36}$ (a constitutive, very strong synthetic promoter) resulted in 50% decrease compared with the control ($hemA^+$ expression by $P_{180}$ constitutive promoter). The $hemA^+$ expression by a late log-phase activating $P_{sod}$ (an oxidative-stress responding promoter of superoxide dismutase) led 50% greater heme production than the control. The $hemA^+$ expression led by a heat-shock responding chaperone promoter ($P_{dnaK}$) resulted in 121% increase of heme production at the optimized heat-shock conditions. The promoter strength and induction phase are discussed based on the results for the heme production at an industrial scale.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.9
• /
• pp.14-19
• /
• 2019

In this study, the possibility of using marine life for cosmetic materials was assessed by establishing a fermentation process of seaweed, such as Ecklonia cava, Enteromorpha prolifera, Chondria crassicaulis, Eiseniabicyclis, Codium fragile, Seaweed furcata, Gloiopeltis tenax, Grateloupia elliptica, Undaria pinnatifida, and Saccharina japonica. Lactobacillus sakei isolated from Kimchi was used for effective fermentation and whole milk powder was used as an additive. 2.0 % of crushed seaweed and 1.0 % of whole milk powder were added and afterwards, 1.0 % Lactobacillus sakei was added after cooling to $40^{\circ}C$. After cooling and filtering the fermented product, butylene glycol, glycerine, and 1,2-hexandiol, which have the effect of a preservative, were added to mix and complete the final product. Among the ten kinds of seaweeds, the process was found to be highly effective in the fermentation of Ecklonia cava, Codium fragile, Undaria pinnatifida, and Saccharina japonica. The amount of fermentable substances in cosmetics was determined and the safety of the raw material was verified using the HET-CAM (The Hen's egg test-Chorioallantoic membrane) test.

• Journal of the Korean Wood Science and Technology
• /
• v.47 no.1
• /
• pp.21-32
• /
• 2019

In order to investigate the decay process of wood treated with preservative, waterproofing agent and their compound systems, a full-cell process was applied to impregnate the sapwood of poplar (Populus cathay) at paraffin wax emulsion concentrations of 0.5% and 2.0%, Copper Azole (CA) concentrations of 0.3% and 0.5%, and their four compound systems, respectively. Leaching tests and laboratory decay resistance against the white-rot fungus Corious versicolor (L.) Murrill for treated wood were carried out according to the America Standard E11-06 and China Standard GB/T 13942.1-2009. At certain time intervals during the decay test, samples were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction technique (XRD) to investigate the time-dependent changes of chemical components and crystalline structure, thus clarifying the decay mechanisms. The results suggested that white-rot fungi degrade hemicellulose and lignin in the wood cell wall first, followed by a simultaneous degradation of polysaccharides and lignin. Besides, CA could not only slower the decomposition of both hemicellulose and lignin, but also reduce the degradation amount of hemicellulose. However, paraffin wax emulsion at high concentration had a negative effect on the impregnation of CA for the compound system treated wood.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.2
• /
• pp.488-496
• /
• 2021

In this study, a study was conducted to utilize Orostachys japonica A. Berger EtOAc fraction extract as an antibacterial activity and cosmetic ingredient. As a result of measuring the antimicrobial activity of Orostachys japonica A. Berger EtOAc, the growth of S. aureus, S. epidermidis, and P. aeruginosa was inhibited. Among them, S. aureus was an extract of 18.35 ± 1.5 mm Orostachys japonica A. Berger EtOAc fraction at a concentration of 0.5 g / mL, showing superior antibacterial activity than methyl paraben (16.83 ± 1.0 mm), and was shown as a positive control. As a result of evaluating the MIC of the Orostachys japonica A. Berger EtOAc fraction extract through MIC measurement, the remaining strains excluding Candida. A showed a MIC of 17.5 mg/mL. As a result of evaluating the cosmetic preservation effect through the challenge test applied to the cosmetic emulsion formulation, the growth inhibitory effect of S. aureus in the emulsion containing 0.3% Orostachys japonica A. Berger EtOAc fraction extract 7 days after microbial inoculation was 100%.

• Food Science of Animal Resources
• /
• v.41 no.4
• /
• pp.701-714
• /
• 2021

In this study, the microbial community succession and the protein hydrolysis of donkey meat during refrigerated (4℃) storage were investigated. 16S rDNA sequencing method was used to analyze the bacteria community structure and succession in the level of genome. Meanwhile, the volatile base nitrogen (TVB-N) was measured to evaluate the degradation level of protein. After sorting out the sequencing results, 1,274,604 clean data were obtained, which were clustered into 2,064 into operational taxonomic units (OTUs), annotated to 32 phyla and 527 genus. With the prolonging of storage time, the composition of microorganism changed greatly. At the same time, the diversity and richness of microorganism decreased and then increased. During the whole storage period, Proteobacteria was the dominant phyla, and the Photobacterium, Pseudompnas, and Acinetobacter were the dominant genus. According to correlation analysis, it was found that the abundance of these dominant bacteria was significantly positively correlated with the variation of TVB-N. And Pseudomonas might play an important role in the production of TVB-N during refrigerated storage of donkey meat. The predicted metabolic pathways, based on PICRUSt analysis, indicated that amino metabolism in refrigerated donkey meat was the main metabolic pathways. This study provides insight into the process involved in refrigerated donkey meat spoilage, which provides a foundation for the development of antibacterial preservative for donkey meat.

• Korean Journal of Metals and Materials
• /
• v.49 no.3
• /
• pp.237-242
• /
• 2011

The effect of shearing speed on the shear force and energy of Sn-0Ag-0.5Cu solder ball was investigated. Various UBM (under bump metallurgy)'s on Cu pads were used such as ENEPIG (Electroless Nickel, Electroless Palladium, Immersion Gold; Ni/Pd/Au), ENIG (Electroless Nickel, Immersion Gold; Ni/Au), OSP (Organic Solderability Preservative). To fabricate a shear test specimen, a solder ball, $300{\mu}m$ in diameter, was soldered on a pad of FR4 PCB (printed circuit board) by a reflow soldering machine at $245^{\circ}C$. The solder bump on the PCB was shear tested by changing the shearing speed from 0.01 m/s to 3.0 m/s. As experimental results, the shear force increased with a shearing speed of up to 0.6 m/s for the ENIG and the OSP pads, and up to 0 m/s for the ENEPIG pad. The shear energy increased with a shearing speed up to 0.3 m/s for the ENIG and the OSP pads, and up to 0.6 m/s for the ENEPIG pad. With a high shear speed of over 0 m/s, the ENEPIG showed a higher shear force and energy than those of the ENIG and OSP. The fracture surfaces of the shear tested specimens were analyzed, and the fracture modes were found to have closer relationship with the shear energy than the shear force.