• Journal of Electrochemical Science and Technology
• /
• v.9 no.1
• /
• pp.44-50
• /
• 2018

The aims of this study were to determine the corrosion behavior of pure copper in the presence of Desulfovibrio sp. and also to investigate the effects of glutaraldehyde (GD) and isothiazolinone (ISO) on the corrosion behavior of pure copper in the presence of this sulfate-reducing bacteria (SRB) strain by using electrochemical techniques. Electrochemical measurements of pure copper were carried out at specified time intervals (0, 8, 24, 48, and 96 hr) over a period of exposure. Corrosion rates of pure copper from anodic and cathodic Tafel slopes and corrosion potential ($E_{corr}$) were determined. Biofilm and corrosion products on the copper surfaces were observed by Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-Ray Spectrometry (EDS) analyses. The effects of solution types (PC (Postgate's C medium) and SRB (Desulfovibrio sp.)) and exposure times of copper and biocides (ISO or GD) on the corrosion rates of pure copper were evaluated by statistical analyses. As a result of the FESEM analysis, biofilm formation was observed on the surfaces of pure copper exposed to the Desulfovibrio sp. cultures both with and without the biocides. The results show that the pure copper was corroded by Desulfovibrio sp. However, the addition of GD or ISO to the Desulfovibrio sp. culture resulted in a decrease in the corrosion rate of the pure copper. It was also observed that both of the biocides showed a similar effect on pure copper's corrosion rate caused by Desulfovibrio sp.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.21 no.6
• /
• pp.1564-1568
• /
• 2007

In this study fourteen ethanol extracts from Nepalese medicinal plants were screened for their in vitro antimicrobial and antiradical activity and their total phenolic content was evaluated. The antiradicalactivity was evaluated by free radical scavenging assay, using 2,2-diphenyl-1-picryl hydrazyl radical (DPPH). Plant extracts showed a wide range of radical scavenging activity, with $IC_50$ value ranging in between $5.38\; {\mu}g/\;mL$ - $429.61\;{\mu}g/mL$. Strong radical scavenging activity was shown by flower extract of Woodfordia fruticosa ($5.38\;{\mu}g/\;mL$) and stem bark extract of Azadirachta indica ($5.58 {\mu}g/\;mL$)that also contained high phenolic content. Most of the sample showed activity below the concentration of $100\; {\mu}g/mL$. For antimicrobial activity three test microorganisms namely Staphylococcus aureus, Streptococcus epidermidis, and Candida albicans were used. The minimum inhibitory concentration (MIC) of the plant extracts was determined. Most of the plant extracts were effective against bacterial strains only at higher concentration ($800\;-\;1,600\;{\mu}g/mL$) but none of these were effective against Candida albicans below $1,600\;{\mu}g/mL$.

• Advances in nano research
• /
• v.7 no.4
• /
• pp.241-248
• /
• 2019

Recent researches demonstrated well promising anticancer activities for antibiotics. Such effects would be significantly increased while nanoparticle based delivery systems were applied. In this study, the goal was aim to improve anticancer and antitoxic effects of Streptomycin by loading on special kind of dendrimer (anionic-linear-globular second generation). In the current study, Size and zeta potential as well as AFM techniques have been used to prove the fact that the loading was performed correctly. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the drug loaded on dendrimer nanoparticle were determined and compared with both of dendrimer alone and free drug with respect to staphylococcus aureus as the test microorganism. The anticancer activity among three groups including Streptomycin, Streptomycin -G2 dendrimer, and control was measured in vitro. In vitro studies showed that G2 anionic linear-globular polyethylene-glycol-based dendrimer, which loaded on Streptomycin was able to significantly improve the treatment efficacy over clinical Streptomycin alone with respect to proliferation assay. Maximal inhibitory concentration (IC50) was calculated to be $257{\mu}g/mL$ for streptomycin alone and $55{\mu}g/mL$ for Streptomycin -G2 dendrimer. In addition, Streptomycin -G2 dendrimer conjugate prevented the growth of MCF-7 cancerous cells in addition to enhance the number of apoptotic and necrotic cells as demonstrated by an annexin V-fluorescein isothiocyanate assay. Streptomycin -G2 dendrimer conjugate was able to increase Bcl-2/Bax ratio in a large scale compared with the control group and Streptomycin alone. Based on results a new drug formulation based nano-particulate was improved against S. aureus with sustained release and enhanced antibacterial activity as well as anticancer activity shown for functional cancer treatment with low side effects.

• Journal of Microbiology and Biotechnology
• /
• v.32 no.1
• /
• pp.46-55
• /
• 2022

Clostridioides difficile infection (CDI) is a significant cause of hospital-acquired and antibiotic-mediated intestinal diseases and is a growing global public health concern. Overuse of antibiotics and their effect on normal intestinal flora has increased the incidence and severity of infections. Thus, the development of new, effective, and safe treatment options is a high priority. Here, we report a new probiotic strain, Bacillus amyloliquefaciens (BA PMC-80), and its in vitro/in vivo anti-C. difficile effect as a prospective novel candidate for replacing conventional antibiotics. BA PMC-80 showed a significant anti-C. difficile effect in coculture assay, and its cell-free supernatant (CFS) also exhibited a considerable anti-C. difficile effect with an 89.06 ㎍/ml 50% minimal inhibitory concentration (MIC) in broth microdilution assay. The CFS was stable and equally functional under different pHs, heat, and proteinase treatments. It also exhibited a high sensitivity against current antibiotics and no toxicity in subchronic toxicity testing in hamsters. Finally, BA PMC-80 showed a moderate effect in a hamster CDI model with reduced infection severity and delayed death. However, further studies are required to optimize the treatment condition of the hamster CDI model for better efficacy and identify the antimicrobial compound produced by BA PMC-80.

• Journal of Microbiology and Biotechnology
• /
• v.32 no.4
• /
• pp.504-513
• /
• 2022

Chitin deacetylase (CDA) inhibitors were developed as novel antifungal agents because CDA participates in critical fungal physiological and metabolic processes and increases virulence in soil-borne fungal pathogens. However, few CDA inhibitors have been reported. In this study, 150 candidate CDA inhibitors were selected from the commercial Chemdiv compound library through structure-based virtual screening. The top-ranked 25 compounds were further evaluated for biological activity. The compound J075-4187 had an IC50 of 4.24 ± 0.16 µM for AnCDA. Molecular docking calculations predicted that compound J075-4187 binds to the amino acid residues, including active sites (H101, D48). Furthermore, compound J075-4187 inhibited food spoilage fungi and plant pathogenic fungi, with minimum inhibitory concentration (MIC) at 260 ㎍/ml and minimum fungicidal concentration (MFC) at 520 ㎍/ml. Therefore, compound J075-4187 is a good candidate for use in developing antifungal agents for fungi control.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.10
• /
• pp.1353-1360
• /
• 2011

This study was performed to investigate the antimicrobial effects against food-borne pathogens and antioxidant activity of Rhododendron brachycarpum ethanol-extract. The antimicrobial activity of the extract was determined using a paper disc-diffusion method, and the diameter of the clear zone was measured. The diameter of the clear zone in the presence of 10 mg of extract was maximal against Bacillus cereus among the three tested Gram-positive bacteria and against Escherichia coli O157:H7 among the five tested Gram-negative bacteria. Analysis of the minimum inhibitory concentration (MIC) showed that the extract exhibited a similar efficacy as that of sorbic acid, a well-known chemical preservative. The growth inhibitory effects of the extract at concentrations of 250, 500, 1,000, and 2,000 mg/L on food-borne pathogens were determined against Staphylococcus aureus, Listeria monocytogenes, Salmonella Typhimurium, and Escherichia coli O157:H7. Growth of the microorganisms was not affected by the extract at concentrations up to 250 mg/L, but it was significantly (p<0.05) inhibited by the extract at concentrations higher than 1,000 mg/L. The antioxidant effects of the extract were examined via measurement of DPPH radical scavenging activity, inhibition of reactive oxygen species (ROS) generation using fluorescent dichlorofluorescien (DCF) assay, and prevention of peroxyl radical- and hydroxyl radical-induced supercoiled DNA breakage. The $IC_{50}$ of the extract for DPPH radical scavenging activity was about half that of ${\alpha}$-tocopherol, which was used as a positive control. DCF fluorescence intensity decreased as the concentration of the extract increased, demonstrating that ROS generation was inhibited in a concentration-dependent manner. The ROS inhibitory effect of the extract was higher than that of ascorbic acid. The extract prevented supercoiled DNA strand breakage induced by peroxyl radical and hydroxyl radical. Thus, the results of the present study demonstrate that the extract exhibits antimicrobial effects against food-borne pathogens as well as potent antioxidant capacity, suggesting that R. brachycarpum could be used as a natural antibacterial agent and effective antioxidant in food.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.45 no.7
• /
• pp.1017-1025
• /
• 2016

This study was performed in order to investigate changes in platycosides, as well as antimicrobial activities of bronchus diseases-inducing bacteria (Corynebacterium diphtheriae, Klebsiella pneumoniae, Staphylococcus aureus, and Streptococcus pyogenes) of Platycodon grandiflorum root (PGR) fermented by lactic acid bacteria (Leuconostoc mesenteroides N12-4, Leuc. mesenteroides N58-5, Lactobacillus plantarum N76-10, L. plantarum N56-12, Lactobacillus brevis N70-9, and L. brevis E3-8). Growth of L. plantarum on PGR was most active during lactic acid fermentation using different strains. Total platycoside, platycoside E, platycodin A, polygalacin $D_2$, polygalacin D, and diapioplatyco-side E contents of PGR fermented for 96 h at $37^{\circ}C$ by Leuc. mesenteroides and L. plantarum increased, whereas contents of platycodin D and platycodin $D_3$ were reduced. The antimicrobial activity on PGR fermented by L. plantarum N56-12 exhibited strong microbial proliferation for all four kinds of bronchus disease-inducing bacteria and was higher than that of non-fermented PGR extract. MIC of fermented PGR extract by L. plantarum N56-12 on C. diphtheriae, K. pneumoniae, S. aureus, and S. pyogenes were 45, 10, 50, and 25 mg/mL, respectively. Thus, this result shows that the antimicrobial activities of bronchus disease-inducing bacteria and platycoside content of PGR by L. plantarum N56-12 were higher than that of non-fermented PGR extract.

• Food Engineering Progress
• /
• v.21 no.2
• /
• pp.143-149
• /
• 2017

This study was carried out to investigate antimicrobial activity and characteristics of Asparagus cochinchinenesis which was steamed and fermented with lactic acid bacteria. A. cochinchinensis was prepared to steaming process which was washed and freeze dried. A. cochinchinensis was steamed at $95^{\circ}C$ for 12 h and dried by hot air at $50^{\circ}C$ for 24 h. After steaming process, A. cochinchinensis was fermented with lactic acid bacteria (Leuconostoc mesenteroides 4395, Lactobacillus sakei 383 and Lactobacillus plantarum KCCM 11322). Ethyl acetate extracts of fermented A. cochinchinensis had antimicrobial activities for the respiratory disease bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli). A. cochinchinensis had highest antimicrobial activity for the P. aeruginosa which fermented with L. mesenteroides 4395. The minimum inhibition concentration (MIC) of A. cochinchinensis fermented with L. mesenteroides 4395 was 10 mg/mL for S. aureus, S. epidermidis, E. coli and 5 mg/mL for P. aeruginosa. The MIC of A. cochinchinensis fermented with L. sakei 383 and A. cochinchinensis fermented with L. plantarum KCCM 11322 were the same. Total sugar was decreased from $863.33{\pm}17.47mg/mL$ to $722.67{\pm}5.51mg/mL$ during the steaming process. But reducing sugar was increased from $99.36{\pm}1.32mg/mL$ to $109.29{\pm}2.71mg/mL$ during the steaming process. Total sugar was decreased to 301.50-361.42 mg/mL and reducing sugar was decreased to 27.39-62.20 mg/mL during the fermentation process.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.12
• /
• pp.1745-1752
• /
• 2010

This study was conducted to investigate the antimicrobial activity of 70% ethanol (EtOH) extract and the five fractions of the crude extract from Sasa borealis leaves against seven food poisoning bacteria, Staphylococcus aureus, Micrococus luteus, Listeria monocytogens, Bacillus subtilis, Escherichia coli, Salmonella Typhimurium, and Pseudomonas aeruginosa. The yield of 70% EtOH extract was 11.4% and those of n-hexane, chloroform, ethyl acetate, n-butanol, and aqueous fractions were 3.0%, 1.1%, 0.6%, 1.3%, and 5.1%, respectively. The 70% EtOH extract and the four fractions except aqueous fraction demonstrated antimicrobial activity against all the seven food poisoning bacteria at a concentration of 0.5%, although it was less compared to benzoic acid. Minimal inhibitory concentration (MIC) of the 70% EtOH extract against all the food poisoning bacteria except S. aureus was $50{\mu}L$/disc. Moreover, chloroform fraction was $35{\mu}L$/disc against 3 food poisoning bacteria and $50{\mu}L$/disc against the other 4 food poisoning bacteria; ethyl acetate fraction was $50{\mu}L$/disc against all the food poisoning bacteria. In addition, n-butanol fraction was $50{\mu}L$/disc against all the food poisoning bacteria except S. aureus. Aqueous fraction, which did not show antimicrobial activity at 5%, was $200{\mu}L$/disc against only S. aureus and L. monocytogen. The 0.25%, and 0.5% of ethyl acetate fraction inhibited the growth of all the food poisoning bacteria 8 to 12 hours and 24 hours, respectively. These results indicate that the Sasa borealis leaves may be useful as a natural antimicrobial substance.

• Korean Journal Plant Pathology
• /
• v.1 no.2
• /
• pp.128-135
• /
• 1985

Responses to the 14 fungicides added in PSA of penicillium expansum isolated froms the four major apple growing areas in Korea were examined. Degrees of the fungal tolerance were various with little difference by area and with great difference by kind and concentration of fungicide. Fall isolates of the fungus grew at higher fungicide concentration than did the spring isolates. $ED_{50}$ and MIC to mycelial growth of genomyl, garbenda, polydong, polyoxin and thiophanate methyl were $0.1{\mu}g-41.7{\mu}g/ml\;and\;100{\mu}g-2,250{\mu}g/ml,$, respectively, indicating high fungicide effects on the fungus isolated from decayed apples in storages and infected apples in orchards with low fungal tolerance; of captafol, captan, iprodione and mancozeb were $2.6{\mu}g - 750{\mu}g/ml\;and\;638{\mu}g-40,500{\mu}g/ml$, respectively, indicating medium degree of both fungicidal effects and fungal tolerance; and of chlorothalonil, folpet, oxidong, propineb and triademefon were $27.8{\mu}g-8,354{\mu}g/ml\;and\;2,625{\mu}g-150,357{\mu}g/ml$, respectively, indicating low fungicide effects and high fungal tolerance. Fungicidal inhibitory effects on conidia formation exhibited a similar trend as on mycelial growth whereas those on conidia germination showed an opposite trend to the mycelial growth with the exception of polyoxin and triademefon.