• Korean Journal of Veterinary Service
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• v.36 no.4
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• pp.297-301
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• 2013

The present study was to investigate anti-microbial effects of curcumin on major bacterial pathogens for farmed fish, such as Aeromonas hydrophila, A. salmonicida subsp. masoucida, A. salmonicida subsp. salmonicida, Edwardsiella tarda, Vibrio vulnificus, V. paraheamolyticus using disk diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests. In disc diffusion test, curcumin exhibited concentration-dependent antimicrobial activities to all bacteria pathogens used in the study. Antimicrobial effects of curcumin was found differently depending on bacterial species when determined by MIC or MBC tests. For examples, E. tarda and A. hydrophila was respectively the most sensitive bacterium for bacteriostatic and bacteriocidal effect of curcumin. Collectively, curcumin could be a potential natural drug for controlling pathogenic bacteria in the aquaculture industry.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.20-26
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• 1986

Very little information is available in the literature on storage of fish sauce. Therefore, microbiological and chemical chracteristics during storage and quality of fish sauce were investigated and discussed to present data about the optimum storage condition. The chopped sardine meat was mixed with equal amount of water and $9\%$(w/w) of $75\%$ vital wheat gluten and then hydrolyzed by addition of commercial proteolytic enzymes such as bromelain, papaya protease, ficin and a enzyme mixture (Pacific Chem. Co.) for 4 hours at $52.5^{\circ}C$. The reaction mixture was heated for 30 min at $100^{\circ}C$ for enzyme inactivation, pasteurization and color development and then centrifuged for 20 min at 4,000 rpm. Table salt and benzoic acid were added for bacteriostatic effect and stored for 80 days at $15{\pm}1^{\circ}C$ and $30{\pm}1^{\circ}C$. The results were summarized as follows: 1. The amount of amino-nitrogen and pH of fish sauce were almost unchanged during storage. 2. Mininum concentration of salt for bacteriostatic activity was $9\%$(w/w) regardless of addition of benzoic acid. 3. the yields of amino-nitrogen were $63.1\%$ for the hydrolysate prepared without enzyme, $79.7\%$ for that with bromelain, $69.9\%$ with ficin, $74.3\%$ with papaya pretense, and $78.1\%$ with enzyme mixture, respectively. 4. The contents of amino-nitrogen were $4510.0mg\%$ on the dry basis for the product prepared by autolysis, $5483.2mg\%$ for that prepared with bromelain, $5305.7mg\%$ with ficin, $4994.1mg\%$ with papaya protease and $5582.3mg\%$ with the enzyme mixture, respectively. 5. The contents of crude protein were $51.35\%$ on the dry basis for the product prepared by autolysis and 55 to $59\%$ for prepared with commercial enzymes. 6. The hydrolysate prepared with the enzyme mixture revealed a little stronger meaty taste than any other products. 7. The level of crude protein in residues was still high ($69.5{\sim}77.2\%$ on the dry basis) and might be originated from the added vital wheat gluten.

• Journal of Veterinary Science
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• v.22 no.6
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• pp.41.1-41.14
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• 2021

Background: Our previously prepared ceftiofur (CEF) hydrochloride oily suspension shows potential wide applications for controlling swine Streptococcus suis infections, while the irrational dose has not been formulated. Objectives: The rational dose regimens of CEF oily suspension against S. suis were systematically studied using a pharmacokinetic-pharmacodynamic model method. Methods: The healthy and infected pigs were intramuscularly administered CEF hydrochloride oily suspension at a single dose of 5 mg/kg, and then the plasma and pulmonary epithelial lining fluid (PELF) were collected at different times. The minimum inhibitory concentration (MIC), minimal bactericidal concentration, mutant prevention concentration (MPC), post-antibiotic effect (PAE), and time-killing curves were determined. Subsequently, the area under the curve by the MIC (AUC_0-24h/MIC) values of desfuroylceftiofur (DFC) in the PELF was obtained by integrating in vivo pharmacokinetic data of the infected pigs and ex vivo pharmacodynamic data using the sigmoid E_max (Hill) equation. The dose was calculated based on the AUC_0-24h/MIC values for bacteriostatic action, bactericidal action, and bacterial elimination. Results: The peak concentration, the area under the concentration-time curve, and the time to peak for PELF's DFC were 24.76 ± 0.92 ㎍/mL, 811.99 ± 54.70 ㎍·h/mL, and 8.00 h in healthy pigs, and 33.04 ± 0.99 ㎍/mL, 735.85 ± 26.20 ㎍·h/mL, and 8.00 h in infected pigs, respectively. The MIC of PELF's DFC against S. suis strain was 0.25 ㎍/mL. There was strong concentration-dependent activity as determined by MPC, PAE, and the time-killing curves. The AUC_0-24h/MIC values of PELF's DFC for bacteriostatic activity, bactericidal activity, and virtual eradication of bacteria were 6.54 h, 9.69 h, and 11.49 h, respectively. Thus, a dosage regimen of 1.94 mg/kg every 72 h could be sufficient to reach bactericidal activity. Conclusions: A rational dosage regimen was recommended, and it could assist in increasing the treatment effectiveness of CEF hydrochloride oily suspension against S. Suis infections.

• Journal of Microbiology and Biotechnology
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• v.8 no.3
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• pp.229-236
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• 1998

6-Substituted derivatives of 1-［(2-hydroxyethoxy)methyl］-6-(phenylthio)thymine (HEPT) were synthesized by introducing alkyl groups with the aid of chlorotrimethylsilane, and then purified ranging 40 to 81 % of yield. Because of their peculiar structures, we presumed that HEPT derivatives would contain extra biological activities other than their already known anti-human immunodeficiency viral (HIV -1) activities. In this study, we investigated the possible effects of the HEPT derivatives on bacterial growth and found their selective antibiotic activities against gram-positive strains. We could not observe the corresponding activity from a disc-zone test, but confirmed the activity by liquid cultivation. Since the growth rate of cells was easily recovered, the antibiotic function was suggested to be bacteriostatic. We also suggested that the intracellular fate of HEPT derivatives would be fast. A HEPT derivative f-3 was shown to synergize unidirectionally toward chloramphenicol (Chr). With 0.1 mM f-3, the Chr-directed growth-inhibitory curve appeared 4 hours earlier than found without the additive. Interestingly, from the data of SDS-polyacrylamide gel electrophoresis (PAGE), we found that a membrane-bound protein having a molecular weight of 70-kDa was overexpressed by f-3 in S. aureus.

• Journal of Aquaculture
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• v.14 no.3
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• pp.157-163
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• 2001

The antibacterial effect of fish diet soaked in the extract of Salvia miltiorriza was tested to determine its levels of antibacterial activity, minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC). The extract showed strong activity against gram positive bacteria, but was weak against gram negative bacteria. Concentration levels of 13.4~40.3 and 67.2~403.0 $\mu\textrm{g}$/ml were determined as the MIC and MBC, respectively. However, levels above 403.0 $\mu\textrm{g}$/ml was neither bacteriostatic nor bactericidal against Edwardsiella tarta, a gram negative strain. The fish diet, soaked in the extract of Salvia miltiorriza, inhibited the growth of all strains of Streptococcus genus and Vibrio anguillarum. The relationship formula between weight of fish diet and Salvia miltiorriza extract absorbed into the fish diet was Y＝2.4953X＋3.3276 ($R^2$= 0.9999). The antibacterial activity of the fish diet, soaked in the extract, was stable from 10 to 35$^{\circ}C$ during the storage period of 28 days.

• Food Science of Animal Resources
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• v.31 no.3
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• pp.413-419
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• 2011

The antimicrobial effects of the natural flavonoids kaempferol, quercetin, apigenin, and naringenin as well as a novel flavonoid 7-O-butyl naringenin against the growth of four meat-born Staphylococcus aureus strains were evaluated. First, the flavonoids were screened for inhibitory effects against the growth of each strain using the paper disc diffusion method. Second, the growth inhibitory effects of flavonoids that showed antimicrobial activity were measured using the microplate method. Third, the bactericidal effects of flavonoids were evaluated in a 0.8% (w/v) NaCl solution. All flavonoids showed bacteriostatic effects at >20 mM. Among the flavonoids studied, quercetin was more effective than the others tested. However, the inhibitory effect of 7-O-butyl naringenin on growth of S. aureus KCCM 32395 was greater than that of quercetin at the same concentration. Additionally, 7-O-butyl naringenin exhibited significant bactericidal effects at >25 ${\mu}M$. When bacterial cells were examined using scanning electron microscopy, it appeared that the S. aureus membranes were damaged or morphologically changed when treated with quercetin and 7-O-butyl naringenin at 200 ${\mu}M$.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.9
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• pp.1374-1383
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• 2003

The effect of applying edible coating and addition of antioxidants (butylated hydroxyanisole (BHA) plus butylated hydroxytoluene (BHT) in a 1:1 ratio) on pork patties were investigated prior to achieve desired physico-chemical, microbiological and sensory qualities. For this, five treatments were conducted as (i) control (neither coated nor antioxidants treated); (ii) coated without antioxidants treated; (iii) coated and antioxidants added in the batter mix only (100 ppm); (iv) coated and antioxidants added in meat mix (100 ppm) only; and (v) coated and antioxidants added both in the batter mix (50 ppm) and the meat mix (50 ppm). Addition of antioxidants both in the batter mix and the meat mix significantly (p<0.05) reduced the microbial loads and thiobarbituric acid (TBA) values. The TBA values significantly (p<0.05) increased up to day 14 and then progressively increased with the advancement of each interval of storage days up to 28 days. Total plate count significantly (p<0.05) increased with the increase in storage days.Coliform and Staphylococcus aureus were absent throughout the storage days in all samples. Staphylococcus aureus however, were present in the control group at day 14 and in enrobed (coated) patties (without antioxidants treated) at 28th day. Addition of antioxidants to batter mix and meat mix did not substantially enhance bacteriostatic activity. Application of coatings and antioxidants retarded the loss of firmness, flavor, changes in appearance and color, and also other sensory attributes. Control patties were better with respect to microbial quality and TBA values but had poorer sensory quality than coated patties.

• The Plant Pathology Journal
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• v.35 no.3
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• pp.234-242
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• 2019

Thirty-four strains of bacteria were isolated from Phellodendron amurense. Using Nectria haematococca as an indicator strain, the best strain, B18, was obtained by the growth rate method. The morphological, physiological and biochemical characteristics of strain B18 and its 16S DNA gene sequence were identified, and the biocontrol effect of strain B18 was assessed in pot and field tests, as well as in a field-control test. Drilling methods were used to determine the antibacterial activity of metabolites from strain B18 and their effects on the growth of pathogen mycelia and spores. The best bacteriostatic rate was 85.4%. B18 can hydrolyse starch and oxidize glucose but does not produce gas; a positive result was obtained in a gelatine liquefaction test. According to 16S DNA gene sequencing, strain B18 is Bacillus methylotrophicus (GenBank accession number: MG457759). The results of pot and field-control trials showed 98% disease control when inoculating $10^8cfu/ml$ of the strain. The disease control effect of the B18 culture liquid (concentrations of $10^8$, $2{\times}10^6$, $10^6$, $5{\times}10^5$ and $2.5{\times}10^5cfu/ml$) in the field-control test was higher than 80%, and the cure rate of the original delivery solution was 96%. Therefore, in the practical forestry production, a $2.5{\times}10^5cfu/ml$ culture liquidshould be applied in advance to achieve good control effects.

• Journal of Microbiology and Biotechnology
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• v.32 no.10
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• pp.1234-1244
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• 2022

Oral streptococci are considered as an opportunistic pathogen associated with initiation and progression of various oral diseases. However, since the currently-available treatments often accompany adverse effects, alternative strategy is demanded to control streptococci. In the current study, we investigated whether short-chain fatty acids (SCFAs), including sodium acetate (NaA), sodium propionate (NaP), and sodium butyrate (NaB), can inhibit the growth of oral streptococci. Among the tested SCFAs, NaP most potently inhibited the growth of laboratory and clinically isolated strains of Streptococcus gordonii under anaerobic culture conditions. However, the growth inhibitory effect of NaP on six different species of other oral streptococci was different depending on their culture conditions. Metabolic changes such as alteration of methionine biosynthesis can affect bacterial growth. Indeed, NaP enhanced intracellular methionine levels of oral streptococci as well as the mRNA expression level of methionine biosynthesis-related genes. Collectively, these results suggest that NaP has an inhibitory effect on the growth of oral streptococci, which might be due to alteration of methionine biosynthesis. Thus, NaP can be used an effective bacteriostatic agent for the prevention of oral infectious diseases caused by oral streptococci.

• Korean Journal of Food Science and Technology
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• v.18 no.4
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• pp.249-254
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• 1986

An experiment was performed to investigate the combined effect of preservatives and the synergistic effect of sodium chloride to them on the inhibition of bacterial growth. Escherichia coli and Salmonella typhimurium were cultured with or without shaking in liquid media (pH 6) of tryptone-glucose-yeast extract or tryptic soy broth which contained 0.1% potassium sorbate and/or 0.03% sodium benzoate, equivalent to half of the maximum permissible levels, respectively. The growth of E. coli was more inhibited with one or both of the two preservatives by shaking culture than by non-shaking culture. For S. typhimurium the single treatment of the preservatives did not show inhibitory effect whereas the combined treatment of them showed bacteriostatic effect in shaking culture and a prolongation of lag phase in non-shaking culture. Addition of 2% sodium chloride to either potassium sorbate or potassium sorbate plus sodium benzoate remarkably increased the growth inhibition of E. coli for non-shaking cultivation but no effect observed for shaking cultivation. S. typhimurium was more sensitive to the addition of sodium chloride than E. coli in both shaking and non-shaking culture to show lower viable cell counts than initial numbers.