• Microbiology and Biotechnology Letters
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• v.35 no.2
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• pp.98-103
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• 2007

To isolate probiotic lactic acid bacteria for animal, we have screened the microorganisms from chicken feces, by random selection and agar well diffusion assay. Among them, CPM-7 strain showing superior inhibitory activity against Escherichia coli was selected. By examining carbohydrates utilization, morphologic property and 16S rRNA gene sequence, CPM-7 strain was identified as Lactobacillus salivarius, then named L. salivarius CPM-7. L. salivarius CPM-7 produced thirteen enzymes in the test using API ZYM kit, and showed resistance to low pH and bile salts. It survived at pH 2 for 30 min. and pH 3 for 6 hr. And, it was able to grow in MRS medium containing 0.2% (w/v) bile salts. L. salivarius CPM-7 adhered to the jejunal epithelium cells of pig. Both the supernatant of L. salivarius CPM-7 and the its neutralized one showed high inhibitory activity against E. coli K88.

• Journal of Plant Biotechnology
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• v.47 no.1
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• pp.90-99
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• 2020

This study aimed to screen for plants with antimicrobial potential among the evergreen woody species of South Korea that are used for horticulture and landscaping and to provide basic information about plants with proven antimicrobial activity to underpin future research. The plant materials were extracted under various conditions, and the antimicrobial activities of the extracts were evaluated by agar diffusion assay. The screening tests demonstrated that the crude extracts of 43 species had inhibitory effects against S. aureus. The inhibitory activities of four species (Elaeocarpus sylvestris, Camellia japonica, Cleyera japonica, and Quercus salicina) were relatively higher than that of the synthetic antimicrobial agents methylparaben and phenoxyethanol. The highest inhibitory activity was observed with the leaf extracts (extracted with methanol for 30 minutes) of E. sylvestris, based on induction of the largest inhibition zone of 23.3 mm in size. In addition, solvent fractions of E. sylvestris were evaluated. The largest inhibitory zone of 23.1 mm was observed for the n-butanol fraction, which is likely to contain effective compounds that exhibit inhibitory activity against S. aureus. In contrast, n-hexane and residual aqueous fractions showed no antimicrobial activity. Overall, our findings confirm that evergreen woody plants native to South Korea have potential antimicrobial activity.

• Microbiology and Biotechnology Letters
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• v.50 no.4
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• pp.501-507
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• 2022

PET (Polyethylene terephthalate), a representative plastic material, has useful physicochemical properties such as high durability and economic feasibility, and is used in various industrial fields such as bottles, fibers, and containers. Due to the recent increase in plastic usage including disposable products, eco-friendly strategy using microorganisms have drawn attention differentiated from conventional landfill and incineration methods. In this study, a soil-derived Streptomyces javensis Inha503 containing a PETase gene was selected and the ability to hydrolyze PU (Polyurethane) was confirmed through agar plate diffusion assay. This strain was cultured with PET for a month, and PET decomposition ability was also confirmed through a scanning electron microscope. Moreover, cloning and heterologous expression of S. javensis Inha503 PETase gene exhibited PET activity in the PETase non-containing S. coelicolor, confirming for the first time the presence of functional PETase gene in Streptomyces species.

• Parasites, Hosts and Diseases
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• v.21 no.2
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• pp.270-280
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• 1983

Agar-gel Diffusion test (AGD), Counterimmunoelectrophoresis(CIEP) and Enzyme-Linked Immunosorbent Assay(ELISA) were examined with the sera of skin test positives for paragonimiasis. The crude antigen (Paragcnimus whole worm extracts: protein concentration, 7.56mg/m1) and human sera were used in AGD and CIEP. And in ELISA test, diluted antigen with 1:40, 000 of crude antigen and diluted sera with 1:100, 1:200 were used in the test. The positive identical ratio between AGD and CIEP reactions is 985 and negative identical ratio is 100%. One or three precipitin bands are observed in AGD. One to seven precipitin bands are also revealed in CIEP. Especially, deeply stained bands are observed in CIEP than those of AGD. The positive identical ratios between AGD and ELISA tests are 96% in 1:100 diluted sera, and 94% in 1:200 diluted sera. But the negative identical ratios between AGD and ELISA tests are 97% and 99% respectively in 1:100 and 1:200 diluted sera. The positive identical ratios between CIEP and ELIEA tests are 98% and 96% respectively in 1:100 and 1:200 diluted sera, but also 97% and 99% in 1:100 and 1:200. Control sera, such as clonorchiasis, amoebiasis and toxoplasmcsis, revealed all negatives with Paragonimus antigen in AGD, CIEP and ELISA tests. By above results, ELISA was mcst sensitive, next CIEP and AGD, But AGD test apprars to be more useful when used to crude antigen without cross rfacticn with other parasitic infections. CIEP test is basically equal in terms of precipitin reaction, but CIEP is able to be detected more sensitively and rapidly though less simple in handiwork than AGD. Consequently, three methods for inlmunological tests of paragonimiasis have gccd correlations with one another. Also, each of these has both merits and demerits in iymunolcgical test for paragonimiasis. But the ELISA test was proved to be the most sensitive and convenient tool for mass screening test, especially in cacti of using purified antigen.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1199-1202
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• 2011

Infection of surgical wounds is a severe problem. Conventional tissue reattachment methods have limits of incomplete sealing and high susceptibility to infection. Medical adhesives have several advantages over traditional tissue reattachment techniques, but still have drawbacks, such as the probability of infection, low adhesive strength, and high cytotoxicity. Recently, a new medical adhesive (new-adhesive) with high adhesive strength and low cytotoxicity, composed of aldehyded dextran and ${\varepsilon}$-poly(L-lysine), was developed. The antimicrobial activity of the new-adhesive was assayed using agar media and porcine skin. In the agar diffusion method, inoculated microorganisms that contacted the new-adhesive were inactivated, but this was not dependent on the amount of new-adhesive. Similar to the agar media results, the topical antimicrobial effect of new-adhesive was confirmed using a porcine skin antimicrobial assay, and the effect was not due to physical blocking based on comparison with the group whose wounds were wrapped.

• Preventive Nutrition and Food Science
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• v.1 no.2
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• pp.269-277
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• 1996

Bacteriocins are proteins produced by a heterogeneous group of bacteria that have a bactericidal effect on closely related organisms. Recently, bacteriocins from lactic acid bacteria and other food-related organisms have been the subject of much research because of their potential as food biopreservatives. Various modifications of agar plate diffusion assays are the most widely used methods even though the limitations of such assays are generally recognized. The ability to obtain a concentrated crude preparation on bacteriocin by optimizing production parameters greatly simplifies recovery of bacteriocin on subsequent purification steps. Some studies performed to optimize bacteriocins have been purified to homogeneity, and the amino acid sequences of many of these purified bacteriocins have been determined. Obtaining characterization data on purified bacteriocin will minimize the risk of overlapping of research and confusion on identification of these compounds. Several me-chanisms leading to cell death have been hypothesized. These include depletion of the proton motive force(PMF) across the cell membrane: RNase and/or DNase activity within the sensitive cell; and pore formation and lysis of sensitive cells at the cell membrane.

• Journal of Pharmaceutical Investigation
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• v.3 no.1_2
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• pp.16-22
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• 1973

Biological determination of Pivampicillin hydrochloride was examined and an available method has been established. Unhydrolyzed Pivampicillin hydrochloride has no antibacterial activity, but it exhibits an antibacterial activity hydrolyzed with liberation of ampicillin by nonspecific enzymes present in blood and tissues from various species in vitro and in vivo. Using these properties, Pivampicillin hydrochloride can be determined as ampicillin by use of an agar-diffusion method with Bacillus subtilis as the assay organism.

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.619-623
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• 1991

To investigate nisin production and resistance of Lactococcus lactis ssp. tactis ML (L. lactis $ML_8$, effects of medium, pH of culture broth, and cell growth on the nisin activity, and effect of nisin with or without $Ca^[2+}$ ion on the growth of L. lactzs were analyzed. In the bio-assay of nisin by the agar diffusion method, inhibition-zone diameter of Micrococcus Javus was propotional to the logarithm of nisin concentration ranged 0.5~20 unitlml (12.5~500 ng/mf). Nisin activity of the pasteurized culture filtrates of L. lactis MLs was high at pH 2!3 but was inactivated completely at pH over 6.0. Nisin production of the L. lactis $ML_8$ cultured on LTB broth increased at late logarithmic phase and reached 10.5 unitlml after 16 hr. The cell growth of L. lactis LM 0230, a plasmid free and nisin sensitive strain, was inhibited on agar medium containing 7 unitlrnl of nisin, while L. lactis $ML_8$ showed high survival ability at 20 unitld of nisin. When 40 mM $Ca^[2+}$ ion was added to Elliker broth with 8 unitlml of nisin, the growth pattern of L. lactis $ML_8$ was similiar to that on control medium which did not contain nisin and $Ca^[2+}$ ion, and this suggested that $Ca^[2+}$ increased the nisin resistance of the L. lactis.

• Korean Journal of Food Science and Technology
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• v.43 no.4
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• pp.446-452
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• 2011

Total 480 lactic acid-producing bacteria were isolated from five kinds of kimchi, and their antibacterial activity was tested against Salmonella enterica serovar Typhimurium, Bacillus subtilis, and Pseudomonas aeruginosa using an agar diffusion assay. Among them, 340 isolates showed a halo on MRS agar against one or more indicator strains, which were identified using multiplex PCR, an API 50CHL kit, and a 16S rDNA sequence analysis. As a result, 169 Lactobacillus plantarum, 20 Lactobacillus fermentum, two Lactobacillus paracasei ssp. paracasei, two Lactobacillus sp., and 15 Pediococcus sp. were identified. This may be the first report on the isolation of antibacterial Lactobacillus fermentum from kimchi.

• Journal of Microbiology and Biotechnology
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• v.27 no.7
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• pp.1242-1248
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• 2017

Several medicinal plants are ethnomedically used in Korea as agents for treating infection, anti-inflammation, and pain relief. However, beyond typical inhibitory effects on cell growth, little is known about the potential anti-biofilm activity of these herbs, which may help to prevent cavities and maintain good oral health. This study aimed to investigate the antimicrobial and anti-biofilm activities of the methanol extracts of 37 Korean medicinal plants against dental pathogens Streptococcus mutans and Candida albicans, which synergize their virulence so as to induce the formation of plaque biofilms in the oral cavity. The antimicrobial activities were investigated by broth dilution and disk diffusion assay. The anti-biofilm and antioxidant activities were evaluated based on the inhibitory effect against glucosyltransferase (GTase) and the DPPH assay, respectively. Among 37 herbs, eight plant extracts presented growth and biofilm inhibitory activities against both etiologic bacteria. Among them, the methanol extracts (1.0 mg/ml) from Camellia japonica and Thuja orientalis significantly inhibited the growth of both bacteria by over 76% and over 83% in liquid media, respectively. Minimum inhibitory concentration (MIC) values of these methanol extracts were determined to be 0.5 mg/ml using a disk diffusion assay on solid agar media. Biofilm formation was inhibited by more than 92.4% and 98.0%, respectively, using the same concentration of each extract. The present results demonstrate that the medicinal plants C. japonica and T. orientalis are potentially useful as antimicrobial and anti-biofilm agents in preventing dental diseases.