• Journal of agriculture & life science
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• v.50 no.4
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• pp.27-34
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• 2016

Sclerotium rolfsii is a well known broad host range soil borne plant pathogenic fungus and caused serious damage to various vegetable crops. To develop an effective biological control agent for S. rolfsii, an isolate which showed strong inhibitory effect on the mycelial growth of S. rolfsii was selected among the antagonistic bacterial isolates collected from vinyl-house soil. The bacterial isolate was identified as Bacillus amyloliquefaciens KBC1009 based on the morphological, physiological characteristics and by 16S rRNA sequence analysis. The growth conditions for B. amyloliquefaciens KBC1009 were optimized in LB media(pH7) by culturing at 30℃ for 72 hrs. Glucose and yeast extract were confirmed as the best carbon and nitrogen sources, respectively. In order to test the inhibitory effect of B. amyloliquefaciens KBC1009 to stem rot of pepper, green house experiment was conducted. Drench of 1/500 diluted bacterial suspension of B. amyloliquefaciens KBC1009(5×108 cfu/ml) to each pepper plant 3 times with 10 days interval showed 66.7% control effectiveness. These results suggest that B. amyloliquefaciens KBC1009 is one of promising biocontrol agent to control stem rot caused by Sclerotium rolfsii.

• Journal of Food Hygiene and Safety
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• v.38 no.5
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• pp.287-296
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• 2023

Mushroom consumption is gradually growing annually worldwide for many centuries. Oyster mushrooms (Pleurotus ostreatus), button mushrooms (Agaricus bisporus), and enokitake (Flammulina filiformis) are mainly consumed in Korea. However, mushrooms can be contaminated with pathogenic microorganisms, such as Listeria monocytogenes, because antibacterial treatment during mushroom cultivation and processing is insufficient. Therefore, many cases of mushroom contamination-related foodborne illnesses and food recalls have been reported. Three representative treatments are used to prevent microbial contamination in mushrooms: chemical, physical, and combination treatments. Among the chemical treatments, chlorine compounds, peroxyacetic acid, and quaternary ammonium compounds are commercially used and ozone and electrolyzed water has recently been used. Additionally, physical treatments, including ultrasound, irradiation, and cold plasma, are being developed. Combination techniques include ultraviolet/chlorine compounds, ozone/organic acid, and ultrasound/organic acid. This review describes the domestically consumed mushroom types and their characteristics, and investigates the mushroom contamination levels. Additionally, effective antibacterial technologies for reducing microbial contamination in mushrooms are also discussed.

• Journal of Veterinary Science
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• v.25 no.3
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• pp.47.1-47.12
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• 2024

Importance: Staphylococcus aureus and Escherichia coli contribute to global health challenges by forming biofilms, a key virulence element implicated in the pathogenesis of several infections. Objective: The study examined the efficacy of various generations of cephalosporins against biofilms developed by pathogenic S. aureus and E. coli. Methods: The development of biofilms by both bacteria was assessed using petri-plate and microplate methods. Biofilm hydrolysis and inhibition were tested using first to fourth generations of cephalosporins, and the effects were analyzed by crystal violet staining and phase contrast microscopy. Results: Both bacterial strains exhibited well-developed biofilms in petri-plate and microplate assays. Cefradine (first generation) showed 76.78% hydrolysis of S. aureus biofilm, while significant hydrolysis (59.86%) of E. coli biofilm was observed by cefipime (fourth generation). Similarly, cefuroxime, cefadroxil, cefepime, and cefradine caused 78.8%, 71.63%, 70.63%, and 70.51% inhibition of the S. aureus biofilms, respectively. In the case of E. coli, maximum biofilm inhibition (66.47%) was again shown by cefepime. All generations of cephalosporins were more effective against S. aureus than E. coli, which was confirmed by phase contrast microscopy. Conclusions and Relevance: Cephalosporins exhibit dual capabilities of hydrolyzing and inhibiting S. aureus and E. coli biofilms. First-generation cephalosporins exhibited the highest inhibitory activity against S. aureus, while the third and fourth generations significantly inhibited E. coli biofilms. This study highlights the importance of tailored antibiotic strategies based on the biofilm characteristics of specific bacterial strains.

• Journal of Life Science
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• v.24 no.4
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• pp.352-360
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• 2014

We evaluated the growth performance, biochemical characteristics, and immune responses in weaning pigs given a diet containing MR-1 (0.2%/feed) or antibiotics (0.1%/feed) for 45 days. In vitro study showed that MR-1 has antibacterial activity against a variety of strains of pathogenic bacteria, especially a strain of cattle-derived Escherichia coli K99 (E. coli K99) by agar diffusion assay. In the in vivo model, 0.2% MR-1-given group clearly ameliorated the weight gain and feed efficiency in the growth performance of weaning pigs compared to the basal diet group (p<0.05). Additionally, 0.2% MR-1 induced an elevation in the levels of mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) and showed a similar pattern ($TNF{\alpha}$ and $IFN{\gamma}$ production) to the antibiotic treated pigs. Taken together, we suggest that 0.2% MR-1 makes probiotics an alternative to antibiotics in weaning pigs.

• Research in Plant Disease
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• v.22 no.1
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• pp.18-24
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• 2016

This study was conducted to elucidate the cultural and pathogenic characteristics of Cladosporium cucumerinum PT1 and resistance of 81 commercial cucumbers (Cucumis sativus). Cucumber leaves and fruits appeared as scab were collected from a plastic film house located in Pyeongtaek, Gyeonggi-province, Korea in late March, 2015. A casual fungus was isolated from the diseased fruits on potato dextrose agar and it was identified as C. cucumerinum PT1 based on the morphological characteristics. To find out the effect of wounding and fruit size on the development of cucumber scab, small (<10 cm long), medium (10 to 20 cm long), and large (>20 cm long, commercially mature fruit) size cucumber fruits were harvested, C. cucumerinum PT1 pathogens were inoculated with a single droplet of suspension ($1{\times}10^5$ spores/ml) on wounded or unwounded cucumber fruits. Small fruits were completely damaged with showing severe water-soaking symptoms and fast pathogen growth regardless of wounded or unwounded. Meanwhile slight water-soaking symptoms on medium and large size fruits occurred and disease development into plant tissues was observed only on wounded fruits. Disease resistance of 81 commercial cucumber cultivars was evaluated on third-stage seedlings and small fruits by inoculating suspension ($1{\times}10^5$ spores/ml) of C. cucumerinum PT1. As a result, mini and pickling cultivar groups were resistant, 'Cheoeumcheoreom' cultivar was symptomless and the other cultivars were resistant to medium resistant. On the other hand, most of cucumber cultivars belonging to the other groups were susceptible. Disease resistance of cucumber against cucumber scab was significantly different among cultivars and a few cucumber cultivars showed different disease resistant responses to two bioassay methods using seedlings and small fruits. Therefore, to screen scab resistance in cucumber, a test using both fruits and seedlings is advisable. We think that the selected resistant cultivars can be used to control cucumber scab effectively under the farmhouse condition.

• Journal of Food Hygiene and Safety
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• v.35 no.6
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• pp.618-629
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• 2020

The purpose of this study was to optimize the fermentation condition of black bean by lactic acid bacteria (LAB) and to evaluate the quality characteristics of fermented black bean. Lactobacillus plantarum SU22 isolated from kimchi was selected as a starter for the fermentation of black bean because the strain exhibited strong antimicrobial activity against pathogenic bacteria and did not produce biogenic amines or a carcinogenic enzyme, β-glucuronidase. Fermentation was performed with broth containing puffed black bean (PBB) inoculated with 1% (v/v) of L. plantarum SU22 at 37℃ for 48h. The viable cell count of LAB was over 9 Log CFU/mL in PBB (20%) broth fermented with L. plantarum SU22. Fermentation of alcalase-treated PBB (20%) broth with L. plantarum SU22 was found to be the optimal condition, increasing viable cell count of LAB up to 10.30 Log CFU/mL. Under the optimal condition, the total polyphenol content (94.02 mg GAE/g) and DPPH radical scavenging activity (92.50%) were significantly increased, compared to non-fermented control (87.74 mg GAE/g, 83.14%).

• Journal of Food Hygiene and Safety
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• v.38 no.1
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• pp.1-11
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• 2023

Skin sanitizers are effective in killing or removing pathogenic microbial contaminants from the skin of food handlers, and the progressive growth of consumer interest in personal hygiene tends to drive product diversification. This review covers the advances in the application of efficacy tests for hand sanitizers to suggest future perspectives to establish an assessment system that is optimized to each product type (gel, liquid, and wipes). Previous research on the in vivo simulative test of actual consumer use has adopted diverse experimental conditions regardless of the product type. This highlights the importance of establishing optimal test protocols specialized for the compositional characteristics of sanitizers through the comparative analysis of test methods. Although the operational conditions of the mechanical actions associated with wiping can affect the efficacy of the removal and/or the inactivation of target microorganisms from the skin's surface, currently there is a lack of standardized use patterns for the exposure of hand sanitizing wipes to skin. Thus, major determinants affecting the results from each step of the overall assessment procedures [pre-treatment - exposure of sanitizers - microbial recovery] should be identified to modify current protocols and develop novel test methods. The ex vivo test, designed to overcome the limited reproducibility of in vivo human trials, is also expected to replicate the environment for the contact of sanitizers targeting skin microorganisms. Recent progress in the area of skin microbiome research revealed distinct microbial characteristics and distribution patterns after the application of sanitizers on hands to establish the test methods with the perspectives on the antimicrobial effects at the community level. The future perspectives presented in this study on the improvement of efficacy test methods for hand sanitizers can also contribute to public health and food safety through the commercialization of effective sanitizer products.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.4
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• pp.185-194
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• 2006

A fungal strain of Trichoderma having strong chitinolytic activity was isolated from field soil enriched with crabshell for several years. Based on 5.8S rRNA, partial 18S, 28S rRNA genes, ITS1, ITS2 sequence analysis and morphological characteristics, the fungus was identified as Trichoderma asperellum and named as Trichoderma asperellum T-5 (TaT-5). The fungus released lytic enzymes such as chitinase and ${\beta}$-1, 3-glucanse, and produced six antifungal substances in chitin broth medium. To demonstrate the protective effect of TaT-5 against damping-off in cucumber plant caused by Rhizoctonia solani, TaT-5 culture broth (TA), chitin medium (CM) and distilled water (DW) were applied to each pot at 10 days after sowing, respectively. Then, the homogenized hyphae of R. solani were infected to each pot at 1 week after TaT-5 inoculation. During experimental period, fresh weight of shoot and root in cucumber plant more increased at TA treatment compared to other treatments. PR-proteins (${\beta}$-1, 3-glucanase and chitinase) activities in cucumber leaves markedly increased at CM and DW treatments, but the activity slightly increased and then decreased at TA treatment at 3 days after infection of R. solani. The activity of PR-proteins activities in cucumber roots at all treatments decreased with time where the degree of decrement was more alleviated at TA treatment than CM and DW. These results suggest that the lytic enzymes (chitinase and ${\beta}$-1, 3-glucanse) and antifungal substances produced by TaT-5 can reduce the pathogenic attack by R. solani in cucumber plants.

• Journal of fish pathology
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• v.28 no.2
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• pp.63-69
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• 2015

The biological characteristics of Bacillus sp.CPB-St as a probiotic strain to control fish streptococcosis was determined. Based on 16S rRNA sequencing, Bacillus sp.CPB-St was identified as Bacillus pumilus and named B. pumilus CPB-St (Abbreviated as CPB-St). Growth inhibitory activity of CPB-St against Streptococcus spp. was examined at three different incubation temperatures ($20^{\circ}C$, $25^{\circ}C$, and $30^{\circ}C$) and three culture media (NA, TSA, and BHIA) based on the diameter of inhibition zone. Its activity (inhibition zone of 11~29 mm) at $20^{\circ}C$ was higher than that (12~21 mm) at $30^{\circ}C$. Its activity (29 mm) in NA media was the same as that (29 mm) in TSA media. However, it was higher than that (22 mm) in BHIA media. The inhibitory activity of CPB-St against Streptococcus spp. was high at pH7. However, its activity was the same at salinity of 0.5% to 3%. CPB-St showed maximum growth after incubation at $25^{\circ}C$ for 48 h. To use CPB-St as probiotics, settlement studies in fish intestine and its efficacy through feeding are needed. CPB-St was highly resistant to gastric juice at pH4 and flounder's bile salt as well as deoxycholic acid at $300{\mu}g/ml$. CPB-St showed optimal viability in 1% NaCl. It showed similar growth in 0% to 7% NaCl. CPB-St could tolerate $-20^{\circ}C$ and $-70^{\circ}C$ for 45 min. There was no difference in the growth of the strain between room temperature and $4^{\circ}C$. Fish diet supplemented with CPB-St could be stored at low temperature without cell loss. Therefore, CPB-St might be used as probiotics to control streptococcosis of fish.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.4
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• pp.271-277
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• 1993

An antagonistic bacteria was isolated from rhiaosphere of pepper and corn and identified as Bacillus (B.) subtilis. These B. subtilis B-5 was transformed and marked with the plasmid pCPP4 which possess neomycine resistan. gene. The marked stranins showed growth inhibition to Rhizoctonia (R.) solani, Fusarium (F.) solani, and F. oxysporum in vitro, and were used in studying growth promoting effects on sesame and cabbage. All the identified strains utilize glucose, sucrose, fructose, lactose, mannitol and sorbitol as carbon source, but not rhamnose, and the marked strains also showed characteristics similar to wild-type strains. Germination rate of chinese cabbage and sesame seeds was increased by about 10% or more in the plot to which these strains were inoculated and the effect was higher in soil than in petri dish. The early growth promoting effects of these strains appeared higher, as compared with control plot, in the plots to which B. subtilis B-5 and pathogenic fungi was inoculated together. When the marked strains, B. subtilis B-5NEOr, were inoculated in the rhizosphere of chinese cabbage and sesame with $1.1{\times}10^8CFU/g$ dry soil, the number of inoculated strain was decreased slowly to the level of $10^5{\sim}10^6CFU/g$ dry soil after 4 weeks and the number of Pseudomonas spp. maintanied the level of $10^5CFU/g$ dry soil throught total period, but the number of fungi was decreased rapidly from the early level of $10^8CFU/g$ dry soil to $10^3CFU/g$ dry soil after 4 weeks.