• Asian-Australasian Journal of Animal Sciences
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• v.28 no.5
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• pp.620-631
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• 2015

A total of 59 lactic acid bacteria (LAB) strains were isolated from corn stover silage. According to phenotypic and chemotaxonomic characteristics, 16S ribosomal DNA (rDNA) sequences and recA gene polymerase chain reaction amplification, these LAB isolates were identified as five species: Lactobacillus (L.) plantarum subsp. plantarum, Pediococcus pentosaceus, Enterococcus mundtii, Weissella cibaria and Leuconostoc pseudomesenteroides, respectively. Those strains were also screened for antimicrobial activity using a dual-culture agar plate assay. Based on excluding the effects of organic acids and hydrogen peroxide, two L. plantarum subsp. plantarum strains ZZU 203 and 204, which strongly inhibited Salmonella enterica ATCC $43971^T$, Micrococcus luteus ATCC $4698^T$ and Escherichia coli ATCC $11775^T$ were selected for further research on sensitivity of the antimicrobial substance to heat, pH and protease. Cell-free culture supernatants of the two strains exhibited strong heat stability (60 min at $100^{\circ}C$), but the antimicrobial activity was eliminated after treatment at $121^{\circ}C$ for 15 min. The antimicrobial substance remained active under acidic condition (pH 2.0 to 6.0), but became inactive under neutral and alkaline condition (pH 7.0 to 9.0). In addition, the antimicrobial activities of these two strains decreased remarkably after digestion by protease K. These results preliminarily suggest that the desirable antimicrobial activity of strains ZZU 203 and 204 is the result of the production of a bacteriocin-like substance, and these two strains with antimicrobial activity could be used as silage additives to inhibit proliferation of unwanted microorganism during ensiling and preserve nutrients of silage. The nature of the antimicrobial substances is being investigated in our laboratory.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.281-286
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• 2002

Detection of Vibrio vulnificus in fish farm and searching for the bactericidal methods on this bacteria were studied. To detect this microorganism in sea water, mud, fish and mussels, selective isolation methods and detection of vvhA gene were used from January to October,2000. V. vulnificus was detected from May when the water temperature was over $17^{\circ}C$. From June to September, higher than $19^{\circ}C$, this bacteria could be isolated from most of the samples. Freezing and refrigerating did not inhibit the growth of V. vulnificus. Citric acid did not show the bactericidal effect, but more than 500 mg/l of EDTA did. With the aid of UV and photocatalyst, $TiO_{2}$ showed bactericidal effect after 15 minute treatment. Photocatalytic system consisted of glass bead coated with $TiO_{2}$ and UV illumination showed bactericidal effect on V. vulnificus at the turnover rate of 0.2/min.

• Journal of fish pathology
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• v.13 no.1
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• pp.67-73
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• 2000

This study was carried out to elucidate the preliminary ecosystem of the heterotrophic bacterial flora in Kunsan Bay located in western costal area of Korea. Samples were collected at 5 sampling stations. Among 123 bacterial isolates, 9 genera of bacteria were appeared as follows; Vibrio spp.(44 isolates/35.7%), Pseudomonas spp.(42 isolates/34.1%), Aeromonas spp.(11 isolates/8.9%), Moraxella spp.(9 isolates/7.3%), Enterobacteria spp.(6 isolates/4.8%), Bordetella spp.(3 isolates/2.4%), Alkaligenesis spp.(3 isolates/2.4%), Flavobacterium spp.(2 isolates/1.6%), and Staphylococcus spp.(3 isolates/2.4%) respectively. Total viable heterotrophic bacteria was ranged from $5{\times}10^3$ to $1{\times}10^5$ CFU/ml and the most abundant viable counts of bacterial population were showed at the stations 2 and 3. This result indicates that the coastal area around Kunsan bay is getting to contaminate far more by municipal wastewaters and industrial byproducts. and so the outbreak of the bacterial diseases will be increased in fish farms.

• Korean Journal of Veterinary Research
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• v.40 no.4
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• pp.701-706
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• 2000

This study was carried out to select the lactic acid bacteria(Lactobacillus, Streptococcus and Bifidobacterium) and yeast for probiotic use in pigs. Acid-tolerant 536 strains were isolated from the feces of 30 pigs. To select useful strains, the first screened strains were treated with strong acid solution(pH 2.5 to 3.0) for 3 hours and subsequentely treated with the anaerobic diluent solution containing 0.15% Oxgall for 3 hours. Among these strains, 151 strains showed strong tolerance to both acid and bile. Lactobacillus and Streptococcus tolerant to the acid and bile were treated with heat at $80^{\circ}C$ for 15 min, and at $70^{\circ}C$ for 5 min in Bifidobacterium and yeast. As a result of heat treatment, 38 strains were obtained as heat-tolerant strains. All of heat-tolerant strains were tested for antibiotic resistance against virginiamycin, sulfathiazole, aureomycin, neomycin, linsmycin, tiamulin and ASP250 which were used as feed additives for growth promotion in pigs. Finally, one strain each from Lactobacillus, Streptococcus, Bifidobacterium and yeast that showed resistance to acid, bile, heat and antibiotics was selected for probiotic use in pigs.

• Korean Journal of Food Science and Technology
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• v.27 no.1
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• pp.74-79
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• 1995

Autoclaved juices of common vegetables including cabbage were growth inhibitory to various microorganisms. Sensitivity of microorganisms to antimicrobial action of autoclaved vegetable juices was different depending on microbial strains. Lactic acid bacteria and Gram negative bacteria were less sensitive while non-lactic Gram positive bacteria and yeasts were very much sensitive to antimicrobial action of autoclaved cabbage juice(ACJ). Staphylococcus aureus and Candida utilis whose growth were completely inhibited in ACJ could grow in ACJ diluted with distilled water. This suggests that microorganisms were not able to grow in ACJ because of growth inhibitory compounds produced during heating but not because of the lack of nutrients. Cabbage juice heated at $100^{\circ}C$ for up to 30 min was not inhibitory while that heated at $121^{\circ}C$ for 5 min was. Heating temperature was an important parameter in generating growth inhibitory compound in heated cabbage juice.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.5
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• pp.518-523
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• 2018

This study analyzed the food safety in processing process of simple-processed fishery products. A total of 88 samples analyzed for the presence of pathogenic bacteria and physicochemical hazards. No major foodborne pathogenic bacteria, such as Salmonella sp., Listeria monocytogenes and Escherichia coli O157:H7, were detected in any of the samples. However, Bacillus cereus (12 samples, 13.6%) and Staphylococcus aureus (15 samples, 17.0%) were frequently detected in both the intermediate processing stages and the final products, although cell populations were not high. Very small amounts of heavy metals and histamine were detected in some samples, in quantities that did not exceed the safe guidelines according to Korean Government regulations. Similarly, no other physical hazards such as foreign material were observed in any of the samples. We concluded that there are no significant pathogenic bacteria or physicochemical food hazards in simply processed fish products from Korea. The present study strongly suggests that increased food sanitation measures should be implemented to decrease the prevalence of S. aureus in simple-processed fishery products.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.191-195
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• 2007

Four bacteria producing viscous exopolysaccharides (EPSs) were isolated from Korean fermented vegetables (Cucumber kimchi, Young radish kimchi, Green onion kimchi) using a selection medium intended for isolating bacteria with tannin-degrading activity. They were identified phylogenetically by 16S rDNA sequence analysis and found to be very close to Enterobacter cowan ii, Escherichia senegalensis, Enterobacter asburiae, and Enterobacter ludwigii. Strain CK31, the most efficient EPS-producer, produced a heteropolysaccharide with an approximate molecular weight of 420 kDa. The neutral sugar fraction of the EPS was composed of rhamnose, fucose, arabinose, mannose, galactose, and glucose.

• KSBB Journal
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• v.15 no.6
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• pp.594-599
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• 2000

The adsorption of the antimicrobial agents and their heat-resistance were investigated for the packaging film manufacture, wherein, the antimicrobial agents were adsorbed on a ceramic component. The naturally sourced antimicrobial agents were produced by methylotropic actinomycetes strains MO-16 and MO-17, extracted with ethylacetate. Antimicrobial action was stable to $121^{\circ}C$ and 1 atm. for 30 min., showing wide-ranging activity to the Gram(+) and the Gram(-) bacteria. Antimicrobial agents, adsorbed on ceramic Ce-1, retained activity to the Gram(+) and the Gram(-) species at $105^{\circ}C$ and $230^{\circ}C$ heat treatment, and methanol extracted antimicrobial agents from Ce-1 treated at $230^{\circ}C$ for 30min., retained activity to Gram(+) bacteria. In the presence of oxygen during the heat treatment process, antimicrobial agents adsorbed on ceramic Ce-1 showed antimicrobial activity to Gram(+) and the Gram(-) bacteria.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.733-741
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• 2021

Jeju island is the largest island of South Korea, and has a relatively warm climate due to its geographical characteristics. These features have fostered development of various fermented foods distinct to Jeju island. Therefore, the functional activity of the lactic acid bacteria (LAB) isolated from the Jeju region's traditional fermented foods, including Kimchi and Jeotgal was characterized in this study. Fifteen strains were isolated from 6 types of fermented food. These strains include Enterococcus spp., Lactoplantibacillus spp., and Weisella spp. Several experiments were carried out to assess functional characteristics including acid resistance, bile resistance, hemolysis, DPPH and ABTS radical scavenging activity, and cholesterol-lowering activity. Three isolated strains (J-4, J-6 and J-10) exhibited high acid resistance, while the other 3 isolates (J-1, J-4 and J-6) showed high bile salt resistance. The strains displayed varied DPPH and ABTS radical scavenging activity: 71.14-86.42% among the first 3 strains, and 50.11-75.11% among the remaining 3 strains. Cholesterol-lowering activities were in the range 15.74-82.90% for all isolated strains. In conclusion, these studies suggest that isolated LAB strains from Jeju island traditional fermented foods possess the potential for broader application in the food industry.

• Journal of Microbiology
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• v.41 no.3
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• pp.252-258
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• 2003

The carbon utilizations of Bacillus species and Pythium species were investigated by using a Biolog$^{(R)}$ microplate assay to determine if there are differences in the carbon utilizations of selected strains of these species. It may be possible to afford a competitive advantage to bacterial biological control agents by providing them with a substrate that they can readily use as a carbon source, for example, in a seed coating formulation. Microplates, identified as SFP, SFN and YT were used to identify spore-forming bacteria, nonspore-forming bacteria, and yeast, respectively. Bacterial and mycelial suspensions were adjusted to turbidities of 0.10 to 0.11 at 600 nm. One hundred microliters of each of the bacterial and mycelial suspension were inoculated into each well of each of the three types of microplates. L-arabinose, D-galactose, D-melezitose and D-melibiose of the 147 carbohydrates tested were found to be utilized only by bacteria, and not by Pythium species, by Biolog$^{(R)}$ microplate assay, and this was confirmed by traditional shake flask culture. Thus, it indicated that the Biolog$^{(R)}$ microplate assay could be readily used to search for specific carbon sources that could be utilized to increase the abilities of bacterial biological control agents to adapt to contrived environments.