• Food Science and Preservation
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• v.16 no.4
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• pp.562-566
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• 2009

We investigated the natural antimicrobial activities of Capsella bursa-pastoris water, methanol, and ethanol extracts. Antimicrobial activities of these extracts and sodium benzoate on Bacillus cereus, Staphylococcus aureus, and Escherichia coli were compared. The inhibition zone diameters of the methanol and ethanol extracts of Capsella bursa-pastoris were 13-20 mm and 12-20 mm, respectively, which were larger than those of sodium benzoate (11-15 mm). The minimum inhibitory concentrations of Capsella bursa-pastoris methanol and ethanol extracts were 12.5-20 mg/mL. These results indicate that Capsella bursa-pastoris methanol and ethanol extracts can be used as natural antimicrobial agents.

• YAKHAK HOEJI
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• v.41 no.4
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• pp.450-455
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• 1997

The preparation of Bacillus coagulans is used as a therapeutics for human intestinal disorders. However, the bacterium in the preparation is very susceptible to rifampic in and fluoroquinolones. When the preparation is taken with rifampicin or fluoroquinolones, its therapeutic effect can not be expected. So B. coagulans RFR17 resistant to rifampicin was obtained by treating the parent B. coagulans with N-methyl-N'-nitro-N-nitrosoguanidine. B. coagulans OFR17 was produced by serial passage of B. coagulans RFR17 on agar with 2-fold minimal inhibitory concentration of ofloxacin or ciprofloxacin. B. coagulans OFR17 was resistant to fluoroquinolones up to 16~64 fold higher than that for the original strain. B. coagulans OFR17 also exhibited identical characteristics with the parent strain when they were tested for lactic acid production and growth inhibition of E. coli MB4-01 and Shigella sonnei MB4-10411. From in vitro test, it was also identified that rifampicin and ofloxacin are not inactivated by certain factors of B. coagulans OFR17. Conclusively, B. coagulans OFR17 can be regarded as a promising strain which can be developed as the preparation for the treatment of the intestinal disorders of the tuberculosis patients under rifampicin and ofloxacin therapy.

• Journal of Microbiology and Biotechnology
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• v.31 no.7
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• pp.999-1010
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• 2021

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment. They are highly toxigenic and carcinogenic. Probiotic bacteria isolated from fermented foods were tested to check their ability to degrade and/or detoxify PAHs. Five probiotic bacteria with distinct morphologies were isolated from a mixture of 26 fermented foods co-cultured with benzo(a)pyrene (BaP) containing Bushnell Haas minimal broth. Among them, B. velezensis (PMC10) significantly reduced the abundance of BaP in the broth. PMC10 completely degraded BaP presented at a lower concentration in broth culture. B. velezensis also showed a clear zone of degradation on a BaP-coated Bushnell Haas agar plate. Gene expression profiling showed significant increases of PAH ring-hydroxylating dioxygenases and 4-hydroxybenzoate 3-monooxygenase genes in B. velezensis in response to BaP treatment. In addtion, both live and heat-killed B. velezensis removed BaP and naphthalene (Nap) from phosphate buffer solution. Live B. velezensis did not show any cytotoxicity to macrophage or human dermal fibroblast cells. Live-cell and cell-free supernatant of B. velezensis showed potential anti-inflammatory effects. Cell-free supernatant and extract of B. velezensis also showed free radical scavenging effects. These results highlight the prospective ability of B. velezensis to biodegrade and remove toxic PAHs from the human body and suggest that the biodegradation of BaP might be regulated by ring-hydroxylating dioxygenase-initiated metabolic pathway.

• Journal of Korean Medicine Rehabilitation
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• v.31 no.1
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• pp.47-57
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• 2021

Objectives This study was conducted to confirm the possibility of Clostridium difficile infection (CDI) treatment through natural herbal medicines. Methods After screening a total of 77 herbal medicines through the paper disc agar diffusion method, we selected the herbal medicines that showed a effectiveness compared to the positive control vancomycin. Afterwards, drugs that showed inhibitory effects compared to C. difficile without inhibition of Bifidobacterium bifidum and Lactobacillus plantarum, known as beneficial bacteria, were selected and minimal inhibitory concentration (MIC) was confirmed by applying the Broth microdilution method. Results The Coptidis Rhizoma, well known for its antimicrobial effect, was found to have antimicrobial effects on C. difficile, but also had inhibitory effects on the beneficial bacterium B. bifidum. 30% ethanol extraction Crataegi fructus, Corni fructus and Mume fructus had antimicrobial effects on C. difficile without inhibiting the beneficial bacteria B. bifidum and L. plantarum. The MIC values of 30% ethanol extraction Crataegi fructus, Corni fructus and Mume fructus were found to be 10 mg/mL, 20 mg/mL and 5 mg/mL, respectively. Conclusions Crataegi fructus, Corni fructus and Mume fructus were identified as candidate medicines for C. difficile. Further researchs will need to be done in vivo, and to find an optimal extraction method accompanied by economic evaluation.

• Animal Bioscience
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• v.36 no.4
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• pp.671-678
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• 2023

Objective: Previous studies isolated the thermophilic ammonium-tolerant (TAT) bacterium Bacillus sp. TAT105 that grew in composting swine manure with the assimilation of ammonium nitrogen and reduced ammonia emissions during composting. Those studies also investigated the potential for applications of TAT105 to composting. It was observed that the concentration of TAT bacteria, phylogenetically close to TAT105, increased during composting. The objectives of this study were to identify the phylogenetic placement of these TAT bacteria and investigate their distribution in various composts. Methods: The phylogenetic placement of TAT105 was examined based on the sequence of 16S ribosomal RNA gene. The genomic DNA homology between TAT105 and the type strains of bacterial species that were phylogenetically close to TAT105 were examined by DNA-DNA hybridization. Moreover, the tolerances of these strains to NH₄Cl and NaCl were analyzed using a cultivation method. Concentrations of TAT bacteria in various composts were evaluated using an agar medium specific to TAT bacteria and polymerase chain reaction followed by restriction fragment length polymorphism analysis. Results: TAT105 was most closely related to Bacillus thermolactis and Bacillus kokeshiiformis. Many variants of these species have been detected in various environments, including composts. The type strains of these species displayed TAT characteristics that were similar to those of TAT105. Among the composts examined in this study, TAT bacteria were detected at high concentrations (10⁵ to 10⁹ colony forming units per gram of dry matter) in most of the composts made from cattle manure, swine manure, bark, and excess sludge. Conclusion: TAT bacteria comprised B. thermolactis, B. kokeshiiformis, and their phylogenetically close relatives. They were considered to be adaptable to composting of some certain materials, and a favorable target for searching for strains with some useful function that could be applied to composting of these materials.

• The Plant Pathology Journal
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• v.39 no.4
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• pp.351-360
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• 2023

Citrus melanose, caused by Diaporthe citri, has been one of the serious diseases, and chemical fungicides were used for protection in many citrus orchards of Jeju Island. Establishing a disinfectant resistance management system and reducing pesticide usage would be important for contributing to safe agricultural production. In this study, monitoring of chemical resistance was performed with 40 representative D. citri isolates from many citrus orchards in Jeju Island. Four different fungicides, kresoxim-methyl, benomyl, fluazinam, and prochloraz manganese, with seven different concentrations were tested in vitro by growing the mycelium of the fungal isolates on the artificial medium potato dextrose agar. Among the 40 fungal isolates, 12 isolates were investigated as resistant to kresoxim-methyl which could not inhibit the mycelium growth to more than 50%. Especially isolate NEL21-2 was also resistant against benomyl, whose hyphae grew well even on the highest chemical concentration. However, any chemical resistance of fungal isolates was found against neither fluazinam nor prochloraz manganese. On the other hand, in vivo bio-testing of some resistant isolates was performed against both kresoxim-methyl and benomyl on young citrus leaves. Typical melanose symptoms developed on the citrus leaves pre-treated with both agrochemicals after inoculation with the resistant isolates. However, no or less symptoms were observed when the susceptible isolates were inoculated. Based on these results, it was suggested that some resistant isolates of D. citri occurred against both systemic fungicides, which may be valuable to build a strategy for protecting citrus disease.

• Journal of Microbiology and Biotechnology
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• v.34 no.5
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• pp.1135-1145
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• 2024

When cells are exposed to freezing temperatures, high concentrations of cryoprotective agents (CPA) prevent ice crystal formation, thus enhancing cell survival. However, high concentrations of CPAs can also cause cell toxicity. Exopolysaccharides (EPSs) from polar marine environments exhibit lower toxicity and display effects similar to traditional CPA. In this study, we sought to address these issues by i) selecting strains that produce EPS with novel cryoprotective activity, and ii) optimizing culture conditions for EPS production. Sixty-six bacteria producing mucous substances were isolated from the Ross Sea (Antarctic Ocean) using solid marine agar plates. Among them, Pseudoalteromonas sp. RosPo-2 was ultimately selected based on the rheological properties of the produced EPS (p-CY02). Cryoprotective activity experiments demonstrated that p-CY02 exhibited significantly cryoprotective activity at a concentration of 0.8% (w/v) on mammalian cells (HaCaT). This activity was further improved when combined with various concentrations of dimethyl sulfoxide (DMSO) compared to using DMSO alone. Moreover, the survival rate of HaCaT cells treated with 5% (v/v) DMSO and 0.8% (w/v) p-CY02 was measured at 87.9 ± 2.8% after freezing treatment. This suggests that p-CY02 may be developed as a more effective, less toxic, and novel non-permeating CPA. To enhance the production of EPS with cryoprotective activity, Response Surface Methodology (RSM) was implemented, resulting in a 1.64-fold increase in production of EPS with cryoprotective activity.

• Oncology Letters
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• v.17 no.3
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• pp.3589-3598
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• 2019

Colorectal cancer (CRC) is a complex disease involving numerous genetic abnormalities. One of the major characteristics of CRC is enhanced Wnt signaling caused by loss-of-function mutations in the adenomatous polyposis coli (APC) gene. Previously, it has been demonstrated that the majority of malignant phenotypes following APC deletion in adult murine small intestines could be rescued when Myc, a downstream target of the Wnt pathway, was deleted. This indicated that Myc is a critical regulator of CRC development following APC loss. Previous studies reported that cyclic adenosine 3',5'-monophosphate (cAMP) can influence the AKT/mammalian target of rapamycin (mTOR) survival pathway in cancer and Myc is a critical downstream molecule of AKT/mTOR signaling. Phosphodiesterase 4D (PDE4D), a member of the cAMP-specific PDE4 family, has been associated with drug resistance in CRC. However, the association between PDE4D and Myc remains unclear. To investigate the potential role of PDE4D in Myc regulation in CRC, the present study evaluated the expression levels of PDE4 subtypes in DLD-1 CRC cells. Additionally, the effects of PDE4 inhibitors on Myc expression and oncogenic properties were analyzed by western blot analysis, reverse transcription-quantitative polymerase chain reaction, colony formation and soft agar assays. It was demonstrated that cAMP/PDE4D signals serve a critical role in regulating Myc expression in DLD-1 CRC cells. Furthermore, PDE4D was identified to be a main hydrolyzer of cAMP and suppression of PDE4D using selective inhibitors of PDE4 increased intracellular cAMP levels, which resulted in a marked decrease in the oncogenic properties of DLD-1 cells, including colony formation, cell proliferation and anchorage-independent growth. Notably, the current data imply that cAMP represses Myc expression via the downregulation of AKT/mTOR signaling, which was abolished by high PDE4D activities in DLD-1 cells. Additionally, a natural polyphenol resveratrol in combination with forskolin elevated the concentration of cAMP and enhanced the expression of Myc and the malignant phenotype of DLD-1 cells, reproducing the effect of known chemical inhibitors of PDE4. In conclusion, the present study identified that cAMP/PDE4D signaling is a critical regulator of Myc expression in DLD-1 and possibly other CRC cells.

• Korean Journal of Food Science and Technology
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• v.45 no.5
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• pp.583-589
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• 2013

We investigated the delay of kimchi fermentation by the addition of plant extracts. Fifteen plant extracts were screened for inhibitory activity aginst Lactobacillus plantarum by using an agar well diffusion assay, and determined the minimal inhibitory concentration (MIC) and minimal lethal concentration (MLC) were determined. The lowest MIC for grapefruit seed extract (GFSE; 0.0313 mg/mL) was determined, followed by Caesalpinia sappan L. extract (CSLE; 0.25 mg/mL), and oregano essential oil (OREO; 1.0 mg/mL). GFSE, CSLE, and OREO were individually added to kimchi, and incubated the samples at 10 for up to 20 days. Results showed that the addition of GFSE (0.3 and 0.5%), CSLE (0.1, 0.3, and 0.5%), or OREO (0.5 and 1.0%) led to a significant increase in the pH of kimchi, and also a significant reduction in the numbers of lactic acid bacteria. Taken together, the addition of natural antimicrobial agents can delay kimchi fermentation.

• Journal of Food Hygiene and Safety
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• v.16 no.4
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• pp.264-273
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• 2001

Antimicrobial activities of ave different probiotics (Lactobacillus reuteri, L. acidophillus, L. bulgaricus, L. casei and Bifidobacterium longum) against 8 bacterial pathogens were determined on the Mueller Hinton Agar containing supernatant of probiotics obtained from 3 different growth conditions (MRS without glycerol, MRS with 0.5 M glycerol or 0.25 M glycerol solution). Though antimicrobial activity of L. reuteri in the first two conditions was not better than the others', the activity was significantly higher than that of others in 0.25 M glycerol solution. This prominent effect might be attributable to reuterin, produced by L. reuteri using glycerol. We could detect the presence of reuterin in the supernatant of 0.25 M glycerol solution with 500 MHz Nuclear Magnetic Resonance (NMR). The result of minimum bactericidal concentration (dilution fold) has revealed that reuterin showed pan-bactericidal effects against 8 major food-borne pathogens. To examine any changes of antimicrobial activities of the probiotics, the probiotics were treated with different pH conditions, pepsin or trypsin digestion. Antimicrobial activity of reuterin was not entirely affected by any of these treatments, while the activities of the other probiotics were significantly decreased.