• Korean Journal of Veterinary Service
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• v.36 no.1
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• pp.37-44
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• 2013

The ecologically and economically important honeybee species are susceptible to infections by various pathogens. This study was investigated to detect infectious pathogens in honeybee colonies reared in eastern Gyeongbuk province by PCR in 2010~2011. A total of 11 infectious pathogens, including 6 viruses, 2 bacteria, 2 fungi, and 1 parasite, were investigated in honeybee colonies suffering from symptoms of sudden collapse, depopulation, or paralysis. The infectious pathogens and infection rates among 24 honeybee colonies detected were as follows: sacbrood virus (66.7%), deformed wing virus (4.2%), black queen cell virus (12.5%), Kashmir bee virus (29.2%), American foulbrood (41.7%), European foulbrood (12.5%), stonebrood (45.8%), chalkbrood (4.2%), and Nosema (33.3%), respectively. Since the coinfection rates of multiple pathogens were detected high in honeybee colonies reared in eastern Gyeongbuk province, large-scale investigation and appropriate control programs need to be established in this region.

• Biomolecules & Therapeutics
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• v.7 no.4
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• pp.385-389
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• 1999

The injibitory effect of Bacillus licheniformis AJ isolated from genitourinary normal flora as a new probiotics on the growth of diarrheal pathogens was studied. This B. licheniformis AJ inhibited the growth of E.coli O-157. Salmonella typhi and Shigella sonnei as well as the infectivity of rotavirus. However, it did not inhibit the growth of Helicobacter pyloriand human intestinal bacteria although it inhibited the harmful enzyme activity of human intestinal bacteria. B. licheniformis AJ seems to excret heat-lable growth-inhibitory protein, bacteriocin, into the media. These results suggest that B. lichenoformis AJ could be used as a new type of probiotics.

• Journal of Environmental Science International
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• v.28 no.2
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• pp.225-233
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• 2019

In this study, we investigated the in vitro anti-biofilm activities of plant extracts of chives (Allium tuberosum), garlic (Allium sativum), and radish (Raphanus sativus L.) against environment harmful bacteria (gram-positive Staphylococcus aureus and, gram-negative Salmonella typhimurium and Escherichia coli O157:H7). In the paper disc assay, garlic extracts exhibited the highest anti-biofilm activity. The Minimal Inhibitory Concentration (MIC) of all plant extracts was generally higher for gram-negative bacteria than it was for gram-positive bacteria. Gram-negative bacteria were more resistant to plant extracts. The tetrazolium dye (XTT) assay revealed that, each plant extract exhibited a different anti-biofilm activity at the MIC value depending on the pathogen involved. Among the plant extracts tested, garlic extracts (fresh juice and powder) effectively reduced the metabolic activity of the cells of food-poisoning bacteria in biofilms. These anti-biofilm activities were consistent with the results obtained through light microscopic observation. Though the garlic extract reduced biofilm formation for all pathogens tested, to elucidate whether this reduction was due to antimicrobial effects or anti-biofilm effects, we counted the colony forming units of pathogens in the presence of the garlic extract and a control antimicrobial drug. The garlic extract inhibited the E. coli O157:H7 biofilm effectively compared to the control antimicrobial drug ciprofloxacin; however, it did not inhibit S. aureus biofilm significantly compared to ciprofloxacin. In conclusion, garlic extracts could be used as natural food preservatives to prevent the growth of foodborne pathogens and elongater the shelf life of processed foods.

• The Plant Pathology Journal
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• v.27 no.3
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• pp.207-224
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• 2011

Diseases caused by plant pathogenic bacteria constitute an emerging threat to global food security. Xanthomonas is a large genus of Gram-negative bacteria that cause disease in several host plants leading to considerable losses in productivity and quality of harvests. Despite the ranges of controlling techniques available, the microbiological safety of economically important crops and crop plants including fruits and vegetables continues to be a major concern to the agriculture industry. On the other hand, many of the currently available antimicrobial agents for agriculture are highly toxic, non-biodegradable and cause extended environmental pollution. Besides, the use of antibiotics has provoked an increased resistance among the bacterial pathogens and their pathovars. Thus, novel efficient and safe remedies for controlling plant bacterial diseases are necessary. There has been an increasing interest worldwide on therapeutic values of natural products such as essential oils, hence the purpose of this review is to provide an overview of the published data on the antibacterial efficacy of essential oils that could be considered suitable for application in agriculture as biocontrol measures against plant pathogenic bacteria of Xanthomonas species. The current knowledge on the use of essential oils to control Xanthomonas bacteria in vitro and in vivo models has been discussed. A brief description on the legal aspects on the use of essential oils against bacterial pathogens has also been presented. Through this review, a mode of antibacterial action of essential oils along with their chemical nature and the area for future research have been thoroughly discussed.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.2
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• pp.107-114
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• 2015

Endophytes provide multifarious benefits such as promotion of plant growth and yield, suppression of phyto-pathogens, phosphate solubilising and fixation nitrogen. A study has been carried out to explore growth promotion and antifungal activities of endophytes of mulberry (Morus spp.). Endophytic bacteria were isolated from mulberry plants and studied their cultural, morphological characters, growth promotion as well as their antifungal activity against Rhizoctonia bataticola and Fusarium oxysporum , two mulberry root rot associated pathogens. Except two isolates, all bacteria were colourless and the colony size of eight isolates was small. The margin of five isolates was irregular and the consistency of three isolates was creamy, six isolates was slimy and one was mucoid. Texture of seven isolates was convex and others were flat. Eight isolates were gram positive and the rest Gram negative, five were cocci and others were bacilli (rod shaped). Four isolates were motile and all were catalase positive and only three isolates were oxidase positive. Spore staining was positive only for two isolates. The growth promotion study showed that there was significant difference in root length and seedling length. The antagonistic effect of the bacterial isolates was tested against R. bataticola showed significant (p <0.05) influence of the bacteria, days after inoculation and their interaction on the inhibition of fungal growth. The isolate En-7 completely inhibited the fungus followed by En-5 (66.67%). The bacterial isolates significantly (p <0.05) inhibited growth of F. oxysporum in PDA. The mean inhibition was higher (70.45%) in case of En-7 followed by En-8 (68.65%) and En-10 (66.44%). The study reveals that some endophytic bacteria associated with mulberry have growth promotion and antifungal activity and could be explored for promotion of mulberry growth and managing root rot disease.

• Journal of Food Hygiene and Safety
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• v.30 no.1
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• pp.98-102
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• 2015

Oleanolic acid and its derivatives are pentacyclic triterpene acids, which are produced in many plants and herbs. These are considered safe and thus, oleanolic acid is now used for cosmetic and pharmaceutical industry. Oleanolic acid affects peptidoglycan in cell wall of bacteria. Hence, the antimicrobial activity of oleanolic acid is not very obvious to Gram-negative bacteria such as Escherichia coli, Yersinia enterocolitica, Shigella flexneri, and Shigella sonnei because the peptidoglycan is covered with outer membrane. However, oleanolic acid derivatives showed improved antimicrobial activity to Gram-negative bacteria. For Gram-positive bacteria such as Staphylococcus aureus and Listeria monocytogenes, oleanolic acid was very effective on reducing the cell counts of the pathogens. In addition, the cytotoxicity of oleanolic acid for human cell lines was minimal. Therefore, oleanolic acid should be considered as an antimicrobial food additive and a therapeutic agent to control foodborne pathogens.

• International Journal of Oral Biology
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• v.43 no.4
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• pp.217-222
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• 2018

Phagocytosis is a fundamental process in which phagocytes capture and ingest foreign particles including pathogenic bacteria. Several oral pathogens have anti-phagocytic strategies, which allow them to escape from and survive in phagocytes. Impaired bacteria phagocytosis increases inflammation and contributes to inflammatory diseases. The purpose of this study is to investigate the influences of various agents on oral pathogenic phagocytosis. To determine phagocytosis, Streptococcus mutans, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis were stained with 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE), and was measured using flowcytometery and confocal microscopy. The influencing factors on phagocytosis were evaluated through the pretreatment of ROS inhibitor (N-acetyl-L-cysteine (NAC)), lysozyme, potassium chloride (KCI) and adenosine triphosphate (ATP) in THP-1 cells. Expression of pro-inflammatory cytokines was determined by enzyme-linked immunosorbent assay (ELISA). The phagocytosis of various bacteria increased in a MOI-dependent manner. Among the tested bacteria, phagocytosis of P. gingivalis showed the highest fluorescent intensity at same infection time. Among the tested inhibitors, the NAC treatment significantly inhibited phagocytosis in all tested bacteria. In addition, NAC treatment indicated a similar pattern under the confocal microscopy. Moreover, NAC treatment significantly increased the bacteria-induced secretion of $IL-1{\beta}$ among the tested inhibitors. Taken together, we conclude that the phagocytosis occurs differently depending on each bacterium. Down-regulation by ROS production inhibited phagocytosis and lead increased of oral pathogens-associated inflammation.

• International Journal of Oral Biology
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• v.43 no.4
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• pp.171-175
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• 2018

Quorum sensing (QS) is a cell density-dependent communication mechanism between bacteria through small signaling molecules. When the number of QS signaling molecules reaches a threshold, they are transported back into the cells or recognized by membrane-bound receptors, triggering gene expression which affects various phenotypes including bioluminescence, virulence, adhesion, and biofilm formation. These phenotypes are beneficial for bacterial survival in harsh environments. This review summarizes the application of QS inhibitors for control of biofilm formation and virulence expression of periodontal pathogens.

• Journal of Veterinary Clinics
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• v.14 no.2
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• pp.215-222
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• 1997

Enrofloxacin-colistin combination, widely used in Gram negative infections in veterinary sector, was investigated in terms of MIC and initial killing rate using E coli k 88ab, Salmonella typhimurium, Pasteurella multocida type A, Bordetella bronchiseptica and Staphylococcus aureus as test organisms. On the basis of MICs of enrofloxacin-colistin combination against the above bacteria, killing rates of the combination of enrofloxacin and colistin at the ratio of 5:0, 4:1, 3:2, 1:1, 2:3, 1:4 and 0:5, indicated high and rapid antibacterial acitivities against all but Staphylococcus aureus R-209, with the number of bacteria reducing to less than one percent within two hours. At the MIC of enrofloxacin or colistin, both antibacterials showed the highest killing rates during 2-4 hours against Gram negatives such as E coli K88ab,Pasteurella multocida type A and Bodetella bronchiseptica but allowed the regrowth of the same pathogens thereafter. On the while, the combination of two antibacterials at a fourth MIC resulted in high killing rate without bacterial regrowth during 24 hours, suggesting the synergistic antivacterial effects. The combination, however, did not show favourable activity against Gram negatime S typhimurium and Gram positive S aureus ergistic antibacterial activity against Gram negatime pathogens but also colistin showed LPS-neutraization, we could suggest the combination should provide clinically positive therapeutic armarium in Gram negative infections.

• Food Science of Animal Resources
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• v.42 no.6
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• pp.1009-1019
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• 2022

In recent years, biocontrol of foodborne pathogens has become a concern in the food industry, owing to safety issues. Listeria monocytogenes is one of the foodborne pathogens that causes listeriosis. The major concern in the control of L. monocytogenes is its viability as it can survive in a wide range of environments. The purpose of this study was to isolate lactic acid bacteria with antimicrobial activity, evaluate their applicability as a cheese starter, and evaluate their inhibitory effects on L. monocytogenes. Lactococcus lactis strain with antibacterial activity was isolated from raw milk. The isolated strain was a low acidifier, making it a suitable candidate as an adjunct starter culture. The commercial starter culture TCC-3 was used as a primary starter in this study. Fresh cheese was produced using TCC-3 and L. lactis CAU2013 at a laboratory scale. Growth of L. monocytogenes (5 Log CFU/g) in the cheese inoculated with it was monitored during the storage at 4℃ and 10℃ for 5 days. The count of L. monocytogenes was 1 Log unit lower in the cheese produced using the lactic acid bacteria strain compared to that in the cheese produced using the commercial starter. The use of bacteriocin-producing lactic acid bacteria as a starter culture efficiently inhibited the growth of L. monocytogenes. Therefore, L. lactis can be used as a protective adjunct starter culture for cheese production and can improve the safety of the product leading to an increase in its shelf-life.