• Microbiology and Biotechnology Letters
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• v.14 no.3
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• pp.209-212
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• 1986

$\alpha$-Amylase gene of Bacillus amyloliquetaciens was cloned on plasmid YEp13, S. cerevisiae-E. coli shuttle vector. Hybrid plasmid pTG17, carrying $\alpha$-amylase gene of B. amyloliquefaciens, was transformed to E. coli and the expression of it in yeast was investigated. This plasmid was unstable in E. coli and produced two minor plasmids, pTG17-1 and PTG17-2, which resulted from the segregation of it. Transformant of S. cerevisiae MC16 with pTG17-1 plasmid was not appeared on SD medium because of the Leu2 gene defection. S. cerevisiae could be transformed by the hybrid plasmid, and $\alpha$-amylase activity of the yeast transformant was detected by somogyi-Nelson method and agar diffusion method.

• 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.

• CELLMED
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• v.2 no.2
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• pp.20.1-20.5
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• 2012

$Gynura$ $segetum$ (Lour.) Merr. ($Compositae$) is a well recognized medicinal plant in Indonesia and Malaysia. It is believed to have an anticoagulant effect and is used in treating snake-bites, inflammations and other skin afflictions. This study was carried out to evaluate the antimicrobial effects of $Gynura$ $segetum$ leaves extracts and its fractions. The chemical compositions of the active extracts were also determined. The antimicrobial activities of different solvent extracts of leaves of $Gynura$ $segetum$ were evaluated using the agar well-diffusion method. The Minimum Inhibitory Concentration (MIC) of the active subfractions was determined by the tube dilution method. Gas Chromatography-mass spectrometry (GC-MS) analysis was carried out to identify the chemical compositions of the active extracts. The ethyl acetate fraction and its subfraction E4 performed potent antimicrobial activities and fifteen known chemical constituents were identified by GCMS analysis as 4-vinylphenol, 1-tetradecene, phenol, 2,4-bis(1,1-dimethylethyl), 1-hexadecene, E-15-heptadecenal, hexadecanoic acid, 1,2-benzenedicarboxylic acid, dibutyl ester, 1-docosene, octadecanoic acid, 1-eicosene, cyclotetracosane, 1,2-benzenedicarboxylic acid, bis(2-ethylhexyl)ester, butanedioic acid, monomethyl ester, niacin and 4-hydroxy-benzoic acid. The results of this study suggested a connection between the antimicrobial activities and the chemical structures. The plant may be used as a potential source for antimicrobial agents.

• Korean Journal of Microbiology
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• v.54 no.3
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• pp.244-253
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• 2018

This study was carried out to evaluate effects of antimicrobial substances produced by isolated soil bacteria. Among two thousands of bacterial isolates Paenibacillus elgii DS381 exhibited high antimicrobial activities against several microbial residents on human skin and pathogenic bacteria. DS381 showed 15.3~26.0 mm inhibition zone diameter against all target bacteria and yeast in agar well diffusion test. Antimicrobial peptide produced by DS381 indicated low minimum inhibitory concentration (0.039-5.000 mg/ml). DS381 produced biosurfactant such as lipopeptide, and surface tension of culture supernatant of DS381 reduced from 60.0 to 40.3 mN/m. DS381 also showed $1.56{\pm}0.13U/ml$ of chitinase activity. These results suggest that Paenibacillus elgii DS381 may be utilized as an efficient biocontrol agent against some important human skin microbes and pathogenic bacteria.

• 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.

• Journal of Applied Biological Chemistry
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• v.62 no.1
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• pp.19-23
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• 2019

The chemical compositions of the essential oil of Valeriana officinalis roots obtained by steam distillation method were analyzed by GC-MS. The 16 constituents were identified in the V. officinalis oil, and the most abundant compounds were patchouli alcohol (18.69%) and ${\beta}$-gurjunene (15.26%). Acaricidal effects of the V. officinalis oil were evaluated against Tyrophagus putrescentiae, Haemaphysalis longicornis larva and H. longicornis nymph by contact bioassay. The $LD_{50}$ values against T. putrescentiae, H. longicornis larva and H. longicornis nymph were 28.01, 178.26 and $207.98{\mu}g/cm^2$, respectively. Agar disc diffusion bioassay showed the antibacterial activity of the V. officinalis oil against foodborne pathogens, especially L. monocytogenes. These results showed that the essential oil of V. officinalis roots derived from USA has a potential for development as acaricide and antimicrobial.

• 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.

• KSBB Journal
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• v.9 no.5
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• pp.506-511
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• 1994

Antimicrobial activity of methanol extract and fraction from mugwort leaves(Artemisia princeps val. orientalis) was investigated for the screening of natural antiwucroblal components. By using agar diffusion method, ethyl acetate(EtOAc) layer fractionated from methanol extract of mugwort leaves showed the highest inhibitory effects against tested microorganisms. The ortho-coumaric acid(200∼600ppm) isolated from EtOAc layer showed strong antibacterial activities for Bacillus subtilis and Salmonella typhimurium. As derivatives of o-coumaric acid, antibacterial activity of para-coumaric acid was 1.2∼1.7 fold higher than that of o-coumaric acid. Three types of coumaric acids strong inhibited the growth of B. subtilis in the culture medium. Growth of S. tyhimurium, P. aeruginosa and S. aureus were effectively inhibited by o-, m- and p-coumaric acids, respectively. Minimum inhibitory dose of p-coumaric acid for B. subtilis was $\100∼200mu\textrm{g}$/paper disk.

• Microbiology and Biotechnology Letters
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• v.43 no.2
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• pp.97-104
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• 2015

Vinegar is a widely used acidic seasoning and can be manufactured using various methods and bases, including cereals, wheat, and fruits. Most studies on vinegar have been conducted to evaluate its antioxidant activity. In the present study, fermented dark vinegar (FDV) produced from unpolished rice was examined for its antimicrobial activity, biochemical content, including the amounts of sugar, total soluble sugar, organic acid, and free amino acids, and pH and physiological activity. The antimicrobial efficiency of FDV was assessed using the paper disc-agar diffusion method. FDV exhibited strong antimicrobial activity against the pathogenic bacteria and yeast strains that were tested. In fact, the activity of FDV was shown to be higher than that of the commercial antibiotics carbenicillin (50 µg/ml) and tetracycline (50 µg/ml) against Staphylococcus aureus, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella typhimurium, Yersinia enterocolitica, and Lodderomyces elongisporus. The antioxidant activity of FDV and ascorbic acid was evaluated. Using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method, we found that FDV has the highest activity of the antioxidants. After spreading FDV onto tryptic soy broth and yeast extract-peptone-dextrose agar media, the microbial strains were isolated and characterized through physiological and biochemical analysis. Based on 16S ribosomal DNA sequence analysis, the isolated microorganisms exhibited a close similarity to Acetobacter papayae, Acetobacter pasteurianus, and Acetobacter peroxidans.