• Korean Journal of Microbiology
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• 제51권2호
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• pp.156-168
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• 2015

The objective of this study is to investigate the anti-Helicobacter pylori and anti-cancer activities of the live cells (LC), cell-free culture supernatants (CFCS), and bacteriocin solution (BS) obtained from Lactobacillus acidophilus BK13 and Lactobacillus paracasei BK57 strains. After incubation for 30 h in MRS broth, the concentration of lactic acid produced by L. paracasei BK57 ($155.9{\pm}10.2mM$) was higher than in MRS broth using L. acidophilus BK13 ($126.8{\pm}7.9mM$). Maximum bacteriocin activity (128 AU/ml) of BK13 strain was observed after 30 h of cultivation at $37^{\circ}C$, however its magnitude was significantly lower than that of BK57 strain (256 AU/ml). The LC of L. acidophilus BK13 and L. paracasei BK57 were able to inhibit the growth of H. pylori ATCC 43504 at different incubation times, depending on the initial inoculum of the LAB. These CFCS and BS obtained from BK13 and BK57 strains dramatically inhibited the growth, adhesive ability, and enzymatic activity of H. pylori. Meanwhile, the anti-cancer effect of the lactic acid from L. acidophilus BK13 and L. paracasei BK57 strains on AGS cells had significant differences with the control group. Therefore, these antagonistic substances-producing strains are potentially useful as new potential antimicrobial agents for the management and prevention of H. pylori infections.

• Journal of Life Science
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• 제30권7호
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• pp.581-591
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• 2020

This study investigated the probiotic properties and physiological activities of Korean fermented foods such as sikhae, young radish kimchi, and bean-curd dregs. Among the isolated lactic acid bacteria, Pediococcus inopinatus BZ4, Lactobacillus plantarum SH1, Lactobacillus brevis SH14, Pediococcus pentosaceus YMT1, and Leuconostoc mesenteroides YMT6 demonstrated a greater than 60% survival rate at pH 2.5, along with an excellent survival rate even at 0.3% bile acid. These five bacteria showed strong flocculation ability in autoaggregation and coaggregation tests, indirectly clustering useful micro-organisms and inhibiting the attachment of pathogenic bacteria. In a cell surface hydrophobicity test, these bacteria showed adhesion to three solvents (ethyl acetate, chloroform, and xylene) and high hydrophobicity, thereby indicating excellent indirect cell adhesion to intestinal cells. The cell-free supernatants and intracellular extracts of the five lactic acid bacteria showed antioxidative activity in the form of 2,2-Diphenyl-1-picrylhydrazyl and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging ability and lipid peroxidation inhibition. Antimicrobial activities were also observed in four pathogenic bacteria, namely E. coli KCTC 2571, H. pylori HPKCTC B0150, L. monocytogenes KCTC 13064, and S. aureus KCTC 1916. These results demonstrate that these five lactic acid bacteria could be used as probiotics with antioxidant and antimicrobial properties.

• Journal of Life Science
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• 제27권4호
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• pp.430-434
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• 2017

Essential oils are fragrant oils extracted from the leaves, stems, peels, petals and roots of aromatic plants cultivated by natural means or using organic agricultural techniques. Essential oils have commonly been used as antibacterial and antifungal agents. In the present study, essential oil was extracted from lisianthus (Eustoma grandiflorum [Raf.] Shinn.) and tested for antifungal activities against three eumycetes (Penicillium pinophilum, Chaetomium glogosum and Aspergillus niger). Lisianthus essential oil showed high antifungal activities against three eumycetes, especially against Aspergillus niger, for which the resulting minimum inhibitory concentration (MIC) was 0.005 mg/ml. In addition, the extracted essential oil was shown to have antimicrobial activity against ten intestinal pathogenic bacteria (Escherichia coli, Salmonella typhimurium, Klebsiella pneumonia, Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Pseudomonas aeruginosa, Bacillus subtilis, Enterococcus faecalis and Vibrio parahaemolyticus) according to the disc diffusion method and was also shown to exhibit strong antibacterial activity against an additional three pathogenic bacteria (Bacillus subtilis, Listeria monocytogenes and Vibrio parahaemolyticus). These results indicate that lisianthus essential oil could be used as an antibiotic against harmful bacteria that produce intestinal illnesses. From the present study, we suggest that lisianthus extracts can be utilized as potential antifungal and antibacterial agents and for the development of pharmaceutical and cosmetic products.

• Food Science and Preservation
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• 제14권5호
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• pp.445-450
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• 2007

This studies were engaged to investigate the potential us of Curcuma aromatica Salab. as a food ingredients. The antimicrobial activity of Curcuma aromatica Salab. extract (CE) and effect on shelf life of the cooked rice were examined. The antimicrobial activity of CE showed apparently against Bacillus cereus, B. subtilis and B. megaterium. The minimum inhibitory concentration (MIC) of CE was 0.15% for B. cereus md 0.2% for B. subtilis and B. megaterium. The antimicrobial activity of CE remained relatively high after heat treatments(30 min at 80 and $100^{\circ}C$, 15 min at $121^{\circ}C$). The shelf life of cooked rice containing above 0.05% CE increased more 1 or 2 days than that of control at $30^{\circ}C$, The texture of cooked rice was improved by addition of above 0.01% CE. The sensory quality of cooked rice with CE did not show significant difference between 0.00% and 0.05% in taste and overall acceptability but decreased above 0.10% in taste, color, flavor and overall acceptability.

• Journal of Life Science
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• 제29권6호
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• pp.712-723
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• 2019

Chemically synthesized compounds are widely used in oral hygiene products. However, excessively long-term use of these chemicals can cause undesirable side effects such as bacterial tolerance, allergy, and tooth discoloration. To solve these issues, significant effort is put into the search for natural antibacterial agents. The aim of this study was to assess the extracts of foreign native plants that inhibit the growth and biofilm formation of Streptococcus mutans. Among the 300 foreign plant extracts used in this study, Chesneya nubigena (D. Don) Ali extract had the highest antimicrobial activity relatively against S. mutans with a clear zone of 9 mm when compared to others. This plant extract also showed anti-biofilm activity and bacteriostatic effect (minimal bactericidal concentration [MBC], 1.5 mg/ml). In addition, the plant extracts of 19 species decreased the ability of S. mutans to form biofilm at least a 6-fold in proportion to the tested concentrations. Of particular note, C. nubigena (D. Don) Ali extract was found to inhibit biofilm formation at the lowest concentration tested effectively. Therefore, our results reveal that C. nubigena (D. Don) Ali extract is a potential candidate for the development of antimicrobial substitutes, which might be effective for caries control as well, as demonstrated by its inhibitory effect on the persistence and pathogenesis of S. mutans.

• Korean Journal of Food Science and Technology
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• 제53권4호
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• pp.495-500
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• 2021

This study investigated the prevalence, serotypes, virulence genes, and antimicrobial resistance patterns of Listeria monocytogenes isolates collected from salmon products. A total of 16 out of 65 salmon products (24.6%) were positive for L. monocytogenes. Bacteria were most frequently identified in smoked salmon products (15/53, 28.3%). Serological tests revealed that serotype 1/2b (62.5%) was the predominant serotype of L. monocytogenes, followed by 1/2a (37.5%). All isolates harbored 10 virulence-associated genes (inlA, inlB, plcA, plcB, hlyA, actA, prf, fbpA, iap, and mpl), confirming their potential pathogenicity. The isolates of L. monocytogenes showed resistance to cefotetan (100%), cefotaxime (87.5%), cefepime (31.3%), erythromycin (6.3%), and tetracycline (6.3%); however, most of the strains were susceptible to antimicrobials except cephalosporins. These results provide useful information regarding the contamination of salmon products with L. monocytogenes, which may have implications for public health.

• Journal of Life Science
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• 제33권7호
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• pp.538-548
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• 2023

The research has been conducted on the isolation of antimicrobial compounds from plant natural extracts and their potential application in oral health care products. This study aimed to investigate the antimicrobial mechanism by analyzing the changes in gene expression of Streptococcus mutans, a major oral pathogen, in response to complex compounds extracted from Aralia continentalis and Arctii Semen using organic solvents. Transcriptome analysis (RNA-seq) revealed that both natural extracts commonly upregulated or downregulated the expression of various genes associated with different metabolic and physiological activities. Three genes (SMU_1584c, SMU_2133c, SMU_921), particularly SMU_921 (rcrR), known as a transcription activator of two sugar phosphotransferase systems (PTS) involved in sugar transport and biofilm formation, exhibited consistent high expression levels. Additionally, component analysis of the A. continentalis extract was performed to compare its effects on gene expression changes with the A. Semen extract, and two active compounds were identified through gas chromatography-mass spectrometry (GC-MS) analysis of the active fraction. The n-hexane fraction (ACEH) from the A. continentalis extract exhibited antibacterial specificity against S. mutans, leading to a significant reduction in the viable cell counts of Streptococcus sanguinis and Streptococcus gordonii among the tested multi-species bacterial communities. These findings suggest the broad-spectrum antibacterial activity of the A. continentalis extract and provide essential foundational data for the development of customized antimicrobial materials by elucidating the antibacterial mechanism of the identified active compounds.

• Journal of Life Science
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• 제30권3호
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• pp.298-303
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• 2020

This study aimed to investigate possible applications of Rodgersia podophylla in the food and cosmetic industry. Ethanol extracts of leaves (RP-L), branches (RP-B), and root (RP-R) were prepared, and their antimicrobial, antioxidant, and anti-diabetic activities were evaluated. The polyphenol content in the RP-R, RP-L, and RP-B extracts was 79.6, 30.4, and 16.9 mg/g, respectively. An antimicrobial activity assay showed that the RP-L and RP-R extracts exhibited strong growth inhibition of pathogenic and food spoilage Gram-positive bacteria. Furthermore, the RP-R extract inhibited the growth of the Gramnegative E. coli and P. vulgaris bacteria. All extracts showed strong scavenging activity for DPPH, ABTS, nitrite, and reducing power determined by A 700 nm. In particular, the RC₅₀s of the RP-R extract for the DPPH anion and ABTS cation were 23.0-29.7 and 15.0-18.2 ㎍/ml, respectively, which are comparable to those of vitamin C (9.8 and 8.0 ㎍/ml, respectively). An activity assay of α-glucosidase and β-amylase suggested a high potential for the RP-R extract as an anti-diabetic agent. Its inhibition levels of α-glucosidase and β-amylase at 0.5 mg/ml were 6.9 and 48.5%, respectively. This is the first report of the antimicrobial and anti-diabetic activities of R. podophylla. Our results suggest that RP-L and RP-R extracts could be developed as novel cosmeceutical and functional food resources.

• Journal of Life Science
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• 제21권3호
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• pp.375-384
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• 2011

This study was performed to evaluate the antioxidant and antimicrobial activity of methanol extract from Rosmarinus officinalis L. and its fractions. The ethyl acetate fraction of rosemary had a higher antioxidant activity in both DPPH ($3.22\;{\mu}g/ml$) and ABTS ($5.05\;{\mu}g/ml$) compared to other extracts and fractions. Based on the results of the FRAP assay, the ethyl acetate fraction of rosemary showed a value of $5.9{\pm}0.3\;{\mu}M/{\mu}g$, and buthanol fraction and rosmarinic acid exhibited values of $4.8{\pm}0.2\;{\mu}M/{\mu}g$ and $5.1{\pm}0.1\;{\mu}M/{\mu}M$, respectively. Measurements of the antimicrobial activities of the extracts, fraction against gram positive, negative bacteria revealed that the methanol extract, hexane, ethyl acetate, and chloroform fraction of rosemary caused Staphylococcus aureus and Escherichia coli to form clear zones greater than 12 mm. Furthermore, the methanol extract and chloroform fraction showed high antibacterial activity, with inhibition zone exceeding 13 mm. The methanol extract and chloroform fraction of rosemary had broad antimicrobial spectrums and low MIC values. Therefore, methanol extracts of rosemary could serve as potential antibacterial agents to inhibit pathogen growth in food and hand sanitizers.

• Journal of Life Science
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• 제27권11호
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• pp.1276-1289
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• 2017

This study isolated and purified the antimicrobial peptide McSSP-31 from an acidified hemocyte extract of a Mytilus coruscus. The antimicrobial peptide was purified by using a $C_{18}$ reversed-phase high-performance liquid chromatography (HPLC). The peptide was determined to be 3330.549 Da by matrix assisted-laser desorption ionization time-of-flight mass spectrophotometer (MALDI-TOF/MS). The N-terminus of a 14 amino-acid sequence was identified as P-S-P-T-R-R-S-T-S-R-S-K-S-R by Edman degradation method. The acquired sequence showed a 93% similarity with the sperm-specific protein Phi-1, which is from M. californianus. The identified open-reading frame (ORF) of peptide was 306 bp encoding 101 amino acids, which was analyzed by rapid amplification of cDNA ends (RACE), cloning and sequencing analysis. We compared the full sequence with other known proteins that reveal the sperm-specific protein Phi-1 (93.5%) of M. californianus. Synthesized antimicrobial peptide (McSSP-31) showed antibacterial activity against gram-positive bacteria including B. subtilis, S. mutans, S. aureus and gram-negative bacteria including E. coli, K. pneumoniae, P. mirabilis, P. aeruginosa and fungi, C. albicans. Also, synthesized peptide showed strong antibacterial activity against antibiotic-resistant strains, including S. aureus. The cytotoxicity of the peptide was determined by using the HUVEC human cell line. The peptide did not exhibit any significant cytotoxic effects on the normal human cell line, and it had very low hemolytic activity with flounder hemoglobin. The results demonstrated that peptide purified from the hemocyte of a M. coruscus exhibits antibacterial activity against various bacteria and has the potential to be an alternative antibiotic agent.