• Fisheries and Aquatic Sciences
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• v.6 no.1
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• pp.27-33
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• 2003

A lactic acid bacterium showing antimicrobial activity against fish pathogen was isolated from gastrointestinal tract of flounder for the purpose of use as an aquaculture probiotics. From the analysis of morphological and physiological characteristics, the isolated strain was named as Lactococcus sp. HM58. Antimicrobial substance (AMS) from Lactococcus sp. HM58 showed strong growth inhibitory activity against Streptococcus sp., which is a fish pathogenic bacterium. AMS was presumed a proteinaceous compound with stability in heat and wide pH range from 2 to 10. It was started to produce in exponential growth phase and was not produced any more in stationary phase. It showed comparatively broad antimicrobial spectrum against most of gram positive bacteria used for this study. About $84\%$ of Lactococcus sp. HM58 was able to survive in the artificial gastric juice though it was low to the extent in the artificial bile juice. In the sensitivity test for various antibiotics, this strain was highly sensitive for doxycycline, erythromycin, amoxicillin clavu1anic acid and ampicillin.

• Journal of Veterinary Clinics
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• v.4 no.1
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• pp.409-421
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• 1987

For the epidemiological studies of the respiratory infection from 1,918 heads of adult rabbits from January 1980 to December 1985 at an integrated farm, the causative agents were. Isolated samples 92 from of lungs and nasal discharges, and identified by serological and non-serololgical tests, the loss rates by the infection were also investigatyed, and the antimicrobial sensitivities of the isolates were determined. The results obtained were as fellows : 1. The loss rate by respiratory infection was 11.9% among 1,819 heads which raised and 41.7% among 518 heads which lost by diseases, and the rate increased annually. 2. The loss rate of rabbits in Spring (45.0%), Summer (45.5%) and Winter (53.5%) showed significantly higher (P < 0.01) than that in Autumn(29.1%). 3. The loss rate of Rex (56.3%) showed significantly higher (P<0.05) than New Zealand White (40.7%) and Californian (42.0% ). 4. P. multocida.(37.9%), B. brouchiseptica (16.0%), E. coli (10.6%) and so forth were isolated from 92 samples of lungs and nasal discharges. 5. Sixty fours trains of P. multocida were typed by serological or non-serological tests and their all serotypes were A type (62 strains) except 2 strains of untypable. 6. In antimicrobial sensitivity test for 64 isolates of P. multocida, all the strains tested were highly sensitive to chloramphenicol(95.3%), colistin (95.3%), gentamicin (92.2%), kanamycin (90.6%), neomycin (82.8%) and tetracycline (81.3%), but exhibited low sensitivity to streptomycin (26.6%), and all strains were resistant to lincomycin. 7 Twenty seven isolates of B. brouchiseptica showed higher sensitivity to cephalothin (100%), erythromycin (100% ), gentamicin (100%). trimethoprim+sulfamethoxazole (100%), chloramphenicol(88.9%), kanamycin(88.9%), neomycin (88.9%) and colistin (85.2%), but lower sensitivity to nitrofurantoin (18.5%), penicillin(18.5%). streptomycin(18.5%) and ampicillin (14.8%), and all strains were resistant to lincomycin.

• Microbiology and Biotechnology Letters
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• v.48 no.1
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• pp.12-23
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• 2020

Edible films containing antimicrobial agents can be used as safe alternatives to preserve food products. Essential oils are well-recognized antimicrobials. However, their low water solubility, volatility and high sensitivity to oxygen and light limit their application in food preservation. These limitations could be overcome by embedding these essential oils in complexed product matrices exploiting the encapsulation efficiency of β-cyclodextrin. This study focused on the maximization of β-cyclodextrin production using cyclodextrin glucanotransferase (CGTase) and the evaluation of its encapsulation efficacy to fabricate edible antimicrobial films. Response surface methodology (RSM) was used to optimize CGTase production by Brevibacillus brevis AMI-2 isolated from mangrove sediments. This enzyme was partially purified using a starch adsorption method and entrapped in calcium alginate. Cyclodextrin produced by the immobilized enzyme was then confirmed using high performance thin layer chromatography, and its encapsulation efficiency was investigated. The clove oil/β-cyclodextrin inclusion complexes were prepared using the coprecipitation method, and incorporated into chitosan films, and subjected to antimicrobial testing. Results revealed that β-cyclodextrin was produced as a major product of the enzymatic reaction. In addition, the incorporation of clove oil/β-cyclodextrin inclusion complexes significantly increased the antimicrobial activity of chitosan films against Staphylococcus aureus, Staphylococcus epidermidis, Salmonella Typhimurium, Escherichia coli, and Candida albicans. In conclusion, B. brevis AMI-2 is a promising source for CGTase to synthesize β-cyclodextrin with considerable encapsulation efficiency. Further, the obtained results suggest that chitosan films containing clove oils encapsulated in β-cyclodextrin could serve as edible antimicrobial food-packaging materials to combat microbial contamination.

• Korean Journal of Veterinary Research
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• v.58 no.1
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• pp.17-25
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• 2018

This study aimed at determining the current knowledge, attitude, and practices (KAP) of layer and pig farmers to antimicrobial usage and its consequences. Description of such KAP could provide insights useful for promoting the rational use of antimicrobials in livestock. From May 2014 to February 2016, a survey involving 251 respondents in Chiang Mai, Lamphun, and Chonburi provinces, Thailand, was conducted by using a validated questionnaire. More than half (51.0%) of the respondents incorrectly believed that antimicrobial drug efficacy could not be reduced by using sub-recommended dosages, 61.2% had misconceptions about non-therapeutic antimicrobial use, and 66.9% inaccurately felt that antimicrobials were also effective for virus and fungi. Over half (50.6-55.2%) did not see the need to follow instructions or advice of veterinarians. Moreover, only 10.4% regularly relied on responses to drugs sensitivity tests when evaluating the effectiveness of antimicrobials. Overall, assessment of KAP regarding antimicrobial usage indicated that the majority of respondents had low levels of knowledge of antimicrobials, neutral rather than positive attitudes, and employed poor practices in the use of antimicrobials. The results indicate improvements in KAP could be helpful in developing more effective interventions by farmers, reduce antibiotic usage, and slow the growth of antimicrobial resistance.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.87-96
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• 2014

In the present study, a yeast species isolated from CETP, Vellore, Tamilnadu was identified as Cryptococcus sp. VITGBN2 based on molecular techniques and was found to be a potent producer of acidic diacetate sophorolipid in mineral salt media containing vegetable oil as additional carbon source. The chemical structure of the purified biosurfactant was identified as acidic diacetate sophorolipid through GC-MS analysis. This sophorolipid was used as a stabilizer for synthesis of zinc oxide nanoparticles (ZON). The formation of biofunctionalized ZON was characterized using UV-visible spectroscopy, XRD, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy. The antimicrobial activities of naked ZON and sophorolipid functionalized ZON were tested based on the diameter of inhibition zone in agar well diffusion assay, microbial growth rate determination, protein leakage analysis, and lactate dehydrogenase assay. Bacterial pathogen Salmonella enterica and fungal pathogen Candida albicans showed more sensitivity to sophorolipid biofunctionalized ZON compared with naked ZON. Among the two pathogens, S. enterica showed higher sensitivity towards sophorolipid biofunctionalized ZON. SEM analysis showed that cell damage occurred through cell elongation in the case of S. enterica, whereas cell rupture was found to occur predominantly in the case of C. albicans. This is the first report on the dual role of yeast-mediated sophorolipid used as a biostabilizer for ZON synthesis as well as a novel functionalizing agent showing antimicrobial property.

• Food Science of Animal Resources
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• v.31 no.6
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• pp.843-850
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• 2011

This study investigated the effect of low dose ${\gamma}$-irradiation on the damage of the cell envelopes and antibiotic sensitivity profiles of Bacillus cereus, Escherichia coli, and Salmonella Typhimurium. The bacteria suspension in tryptic soy broth was exposed to the ${\gamma}$-irradiation doses of 0, 1, 1.5, 3, and 5 kGy, and then stored at $0^{\circ}C$ for 24 h. A viability test, an antimicrobial sensitivity profile, and an electron microscopy were performed to observe the effects due to ${\gamma}$-irradiation treatment. B. cereus could survive the ${\gamma}$-irradiation up to 5 kGy while E. coli and S. Typhimurium were all deactivated at 1.5 kGy and 5 kGy, respectively. At 5 kGy, the cell count of B. cereus was significantly reduced, and the survived bacteria cells retained their important features. There were no significant changes observed in the antimicrobial sensitivity profile (p>0.05) for the recovered bacteria after irradiation treatment. Low dose ${\gamma}$-irradiation below 3 kGy was found to be insufficient to achieve decontamination of B. cereus and S. Typhimurium. Cell envelope damage and deactivation of different bacteria did not occur in the same manner; thus, deferent doses of ${\gamma}$-irradiation may be required for deactivation of different bacteria.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.313-318
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• 2008

This study was conducted to evaluate in vitro antioxidative and antimicrobial properties of ethanolic extracts from Allium victoriallis L. var. platyphyllum (AVP) with 6 different parts. The antioxidative activities of these samples were determined using the 4 separate methods that involved reducing power, DPPH, hydrogen radical scavenging, and lipid peroxidation with use of a $\beta$-carotene/linoleic acid system. The leaf part ethanolic extracts (1,000 ppm) showed the strongest inhibitory potential for reducing power, DPPH, and hydroxyl radicals to 99.8, 49.4, and 52.8%, respectively. Inhibition values of linoleic oxidation were calculated as 58.0, 39.5, and 38.0% for seed, flower, and leaf ethanolic extracts (1,000 ppm), respectively, from AVP. In addition, the ethanolic extracts of the root part showed the most effective antimicrobial activity. The inhibition zones of the root ethanolic extracts ($200\;{\mu}g/disc$) of AVP against Bacillus cereus and Staphylococcus aureus were 17 and 14 mm, respectively. In a micro-dilution assay, B. cereus, S. aureus, and Vibrio parahaemolyticus exhibited sensitivity to root part ethanolic extracts with an minimum inhibition concentration (MIC) value of 20, 28, and 18 mg/mL, respectively. Therefore, the AVP extracts may be suitable as antimicrobial and antioxidative agents in the food industry.

• Korean Journal of Veterinary Research
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• v.44 no.1
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• pp.151-157
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• 2004

Samples of milk were collected from 425 halves of 216 dairy goats in Chonnam province over a period of January through August 2003. Bacterial isolation was carried out on those samples, and their antimicrobial susceptibility was tested. Bacteria were isolated from 166 milk samples (39.1%), either singly (74.7%) or in combination (25.3%). Of the 220 isolates, Staphylococcus spp. was the most prevalent (82.6%), followed by Streptococcus spp. (2.7%), Corynebacterium spp. (1.8%), Enterococcus spp. (1.8%), and Pasteurella spp. (1.8%). Of the 11 species identified from the 182 isolates of Staphylococcus spp., the most frequent species identified were S. epidermidis (28.6%) followed by S. chromogens (14.8%), S. haemolyticus (12.6%), S. aureus (12.1%), S. capitis (8.2%), S. lentus (8.2%), S. hyicus (4.4%), S. simulans (4.4%), S. caprae (2.8%), S. hominis (2.8%) and S. warneri (1.1%). Antimicrobial sensitivity test revealed that most isolates were highly susceptible to 11 antimicrobial agents (96.4 ~ 80.9%), while most isolates were resistant to penicillin.

• Journal of Life Science
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• v.34 no.9
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• pp.632-638
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• 2024

The antimicrobial activity of Bacillus amyloliquefaciens JFP-02 against nine fish pathogenic bacteria isolated from olive flounder aquaculture farms on Jeju Island was assessed under various medium compositions, pH levels, and incubation temperatures. The fish pathogenic bacteria isolated were Flexibacter maritimus, Staphylococcus caprae, Edwardsiella tarda, Streptococcus parauberis, Photo-bacterium damselae, Vibrio harveyi, Vibrio campbellii, Vibrio alginolyticus, and Vibrio anguillarum. The antibiotic susceptibility testing results for the fish pathogenic bacteria indicated the highest sensitivity to florfenicol, followed by gentamycin and neomycin. The bacteria exhibited the greatest resistance to penicillin, with amoxicillin and erythromycin showing the next highest levels of resistance. B. amyloliquefaciens JFP-02 exhibited the highest growth activity at pH 9, while the greatest antimicrobial activity was observed at pH 6. Likewise, although the highest growth occurred at 30℃, the most significant antimicrobial effect was observed at 20℃. Among the various medium components, the antimicrobial activity of B. amyloliquefaciens JFP-02 was highest when dextrin was used as the carbon source, leading to the greatest growth and antimicrobial activity. Additionally, among the nitrogen sources, the addition of yeast extract resulted in the highest growth and antimicrobial activity. For inorganic salts, although the highest growth activity was observed with MgSO₄·7H₂O and FeSO₄·7H₂O, the greatest antimicrobial effect was observed with KH₂PO₄.

• Microbiology and Biotechnology Letters
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• v.29 no.4
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• pp.253-257
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• 2001

Essential oil of Chamaecyparis obtusa showed antimicrobial on relatively broad spectrum of bacterial and fungal species. Staphylococcus epidermidis was highly sensitive to the essential oil but Streptococcus aureus and Streptococcus mutans were not. Vibro parahemolyticus, Pseudomoas aeruginosa and Pseudomoas putida showed sensitivity at the concentration higher that 400 ppm, Thegrowth of a pathogenic yeast Candida albicans was inhibited by the essential oil above 200ppm. The radialgrowth of several filamentous fungi was also inhibited The antifungal activity of the essential oil was effective on two plant pathogens Fusarium oxysporum and Altenaria mali. These results sug-gest that essential oil of Chamaecyparis obtusa has an antimicrobial activity by inhibiting bacterial and fungal species.