• The Journal of the Korean Society for Microbiology
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• v.12 no.1
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• pp.11-18
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• 1977

A total of 665 strains of Escherichia coli isolated in Korea from stools of patients who were treated with antimicrobial drugs, doctors, and students were tested for the drug resistance and distribution of R plasmids. Approximately 25 to 41% of isolates were resistant to chloramphenicol, tetracycline, streptomycin, sulfisemidine and ampicillin(AP), and 9.5% were resistant to kanamycin. Nalidixic acid-resistant strains were only rarely encountered. The prevalence of resistant strains was significantly higher among patients than doctors and students. Strains multiply resistant to four or more drugs were significantly more prevalent among patient isolates than those from doctors and students, while no difference on the incidence of strains resistant to three or less drugs was noted among isolates from the three groups. The persons carrying strains resistant to four or more drugs were more frequently found among patients than doctors and students. Quite large proportions of drug-resistant strains transferred their resistance to drug-sensitive E. coli, with frequent transfer of whole resistance and AP resistance. Strains having higher multiplicity of resistance showed a tendency toward higher incidence of resistance transfer, irrespective of the origins of strains.

• Food Science of Animal Resources
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• v.29 no.1
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• pp.15-23
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• 2009

In order to develop a new starter for fermented milk, 2082 bacteria were isolated from raw milk. The strain that showed excellent acid forming and ${\gamma}$-aminobutyric acid (GABA) production ($711.40{\mu}g/g$ D.W) characteristics after incubation at $37^{\circ}C$ for 18 hr was selected and identified as Lactobacillus acidophilus by the result of API carbohydrate fermentation pattern and 16S rDNA sequence. L. acidophilus RMK567 was investigated for its physiological characteristics. RMK67 strain showed good GABA production compared with commercial lactic acid bacteria. The optimum growth temperature of L. acidophilus RMK567 was $40^{\circ}C$ and cultures took 15 hr to reach pH 4.3. L. acidophilus RMK567 showed higher sensitivity to penicillin-G, novobiocin, as compared to other 14 different antibiotics. However, it showed more resistance to kanamycin, neomycin, streptomycin. It showed higher leucine arylamidase and ${\beta}$-galactosidase activities compared to 16 other enzymes. It was comparatively tolerant to bile juice and able to survive at pH 2 for 3 hr. It showed resistence to Escherichia coli, Salmonella typhimurium and Staphylococcus aureus with rates of 29.2%, 39.1% and 51.4%, respectively. Based on these and previous results, L. acidophilus RMK567 could be an excellent starter culture for fermented milk with excellent GABA contents.

• Korean Journal of Veterinary Service
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• v.34 no.1
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• pp.45-54
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• 2011

This study was conducted to investigate the distribution of Salmonella spp. from pigs and cattle in slaughterhouse, the antimicrobial resistance pattern and the prevalence of resistance genes of isolates. A total of 640 fecal samples from pigs and cattle in slaughterhouse were collected for isolation of Salmonella spp.. Isolation rate was revealed as 15% in pigs and 1.6% in cattle. As result of serotyping, group B (56.6%) were identified as most common in pigs and cattle isolates, in order of group C (24.5%) and group E (15.1%). S. Typhimurium (50.9%) was most common serotype. The major serotypes were in order of S. Rissen and S. London (11.3%) and S. Riggil (7.6%). In antimicrobial test, all isolates were demonstrates susceptibility to nitrofurantoin. But isolates were revealed resistance other antibiotics in order of tetracycline (64.6%), streptomycin (68.3%), ampicillin and amoxicillin (56.3%) and spectinomycin (47.9%). With polymerase chain reaction, antimicrobial resistance gene strA (75.0%) and aadA1 (3.1%) were detected in streptomycin resistance isolates and tetA (94.3%) and tetB (11.3%) gene were detected in tetracycline resistant isolates, but tetG was not detected. Class 1 integron gene was detected in all Salmonella isolates.

• Korean Journal of Veterinary Research
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• v.40 no.4
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• pp.763-767
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• 2000

This study was performed to isolate and identify bacteria from uterus with pyometra and examine their susceptibility to antimicrobial agents. Uterus of 16 bitches with pyometra were surgically removed by ovariohysteroctomy and then bacteria were isolated and identified. Also, susceptibility test to 15 antimicrobial agents was performed. Out of 16 bitches, 11 strains of Escherichia coli, 2 strains of Serratia marcescens, and 1 strain of Staphylococcus aureus and Salmonella spp. were identified. In antimicrobial susceptibility test, the majority of isolates were susceptible to enrofloxacin, norfloxacin, chloramphenicol, nalidixic acid, gentamicin, trimethprim-sulfamethazole, tetracycline, and moderately susceptible to carbenicillin, amikacin, ampicillin, neomycin, but resistant to vancomycin, streptomycin, bacitracin and colistin. In conclusion, E coli was the most common bacteria isolated from bitches with pyometra and those susceptible antimicrobial agents could be recommended to medical therapy of pyometra.

• Korean Journal of Microbiology
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• v.40 no.4
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• pp.320-327
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• 2004

Three hundreds thirty two bacterial colonies which were able to degrade crude oil were isolated from soil sam­ples that were contaminated with oil in Daejeon area. Among them, one bacterial strain was selected for this study based on its higher oil degrading ability, and this selected bacterial strain was identified as Acinetobactor sp. B2 through physiological-biochemical tests and analysis of its 16S rRNA sequence. Acinetobactor sp. B2 was able to utilize various carbohydrates but did not utilize trehalose and mannitol as a sole carbon source. Acinetobactor sp. B2 showed a weak resistance to antibiotics such as kanamycin, streptomycin, tetracycline and spectinomycin, but showed a high resistance up to mg/ml unit to heavy metals such as Ba, Li, Mn, AI, Cr and Pb. The optimal growth temperature of Acinetobactor sp. B2 was $30^{\circ}C.$ The lipase produced by Acinetobactor sp. B2 was purified by ammonium sulfate precipitation, DEAE-Toyopearl 650M ion exchange chromatography and Sephadex gel filtration chromatography. Its molecular mass was about 60 kDa and condition for the optimal activity was observed at $40^{\circ}C$ and pH 10, respectively. The activation energy of lipase for the hydrolysis of p­nitrophenyl palmitate was 2.7 kcal/mol in the temperature range of 4 to $37^{\circ}C,$ and the enzyme was unstable at the temperature higher than $60^{\circ}C.$ The Michaelis constant $(K_m)\;and\;V_{max}$ for p-nitrophenyl palmitate were 21.8 uM and $270.3\;{\mu}M\;min^{-1}mg^{-1},$ respectively. This enzyme was strongly inhibited by 10 mM $Cd^{2+},\;Co^{2+},\;Fe^{2+},\;Hg^{2+},$ EDTA and 2-Mercaptoethalol.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.352-364
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• 2016

In this study, we examined in vitro the potential probiotic properties of lactic acid bacteria (LAB) obtained from the fish intestine and their ability to degrade histamine through the production of diamine oxidase (DAO) enzymes and bacteriocin. Among 97 LAB strains isolated from the intestine of croaker, flatfish, pollack, and rockfish, CIL08, CIL16, FIL20, FIL31, PIL45, PIL49, PIL52, and RIL60 isolates exhibited excellent survival rates under simulated gastrointestinal tract conditions, high adhesion ability to HT-29 epithelial cells, and resistance to the antibiotics such as amoxicillin, ampicillin, erythromycin, penicillin G, streptomycin, tetracycline, or vancomycin. In addition, these strains did not produce histamine in decarboxylating broth containing histidine. In particular, 4 strains (CIL08, FIL20, PIL52, and RIL60) that may produce DAO were significantly able to degrade histamine. The bacteriocins produced by FIL20, FIL31, and PIL52 LAB inhibited the growth and histamine production of Enterococcus aerogenes CIH05, Serratia marcescens CIH09, Enterococcus faecalis FIH11, Pediococcus halophilus FIH15, Lactobacillus sakei PIH16, Enterococcus faecium PIH19, Leuconostoc mesenteroides RIH25, or Aeromonas hydrophilia RIH28. Histamine-producing strains isolated from fish intestine were found to reduce histamine accumulation during co-culture with CIL08, FIL20, PIL52, and RIL60 LAB showing histamine degradation or bacteriocin production ability. The probiotic strains preventing histamine formation were identified as Pediococcus pentosaceus CIL08, Lactobacillus plantarum FIL20, Lactobacillus paracasei FIL31, Lactobacillus sakei PIL52, and Leuconostoc mesenteroides RIL60 with high similarity based on 16S rRNA gene sequencing.

• The Journal of the Korean Society for Microbiology
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• v.21 no.4
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• pp.461-471
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• 1986

Shigella strains isloated in the Teagu area during the period from 1973 to 1985 were studied for species distribution, drug resistance, and R plasmids. Approximately 1,200 strains were isolated during this period, and most of them were classified into Shigella flexneri, S. sonnei occupied less than 20%, and S. dysenteriae and S. boydii were very rarely isolated. More than 95% of them were resistant to one or more of these drugs; chloramphenicol (Cm), tetracycline (Tc), streptomycin (Sm), sulfisomidine (Su), ampicillin (Ap), and trimethoprim (Tp). Strains resistant to kanamycin, nalidixic acid (Na), and rifampin (Rf) were rare, and no strain was resistant to cephaloridine, gentamicin, and amikacin. Approximately half of the isolates were resistant to drugs in 1973, but the rate of resistant strains increased to more than 95% from 1977. Strains resistant to the four drugs (Cm, Tc, Sm, and Su) occupied the majority of resistant strains until 1977, but the most prevalent multiplicity of drug resistance increased to six drugs (Cm, Tc, Sm, Su, Ap, and Tp) from 1978 with the marked increase of Ap- and Tp-resistant strains. Approximately 75% of them transferred resistance to Escherichia coli by conjugation, and the resistance was considered to be mediated by R plasmids. Almost all of them transferred the complete patterns of resistance to drugs except Na and Rf. However, among some strains of recent isolates, small numbers of segregants of transferred resistance were observed. The R plasmids in Shigella were mostly classified into Inc FII, and only small numbers into Inc B. Segregants were in most cases unclassified.

• Journal of Life Science
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• v.14 no.4
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• pp.664-669
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• 2004

The contamination of Bacillus cereus was investigated in 240 RTE (ready-to-eat) food samples including 118 seafoods, 82 Korean packaged meals and 40 other RTE foods. Many B. cereus presumptive strains were isolated from the enrichment culture in Tryptic Soy Broth (TSB) added polymyxin, followed by selective culture in Mannitol Egg Yolk Polymyxin (MYP) agar and Gram staining. A total of 36 strains (16 in seafoods, 17 in Korean pack-aged meals and 3 in other RTE foods) were identified as B. cereus by the analysis of 61 biochemical tests of the API 50CHB/20E system test and supplementary tests of $\beta$-hemolysis, rhizoid growth, motility and oxidase activity. The 28 strains out of 36 B. cereus isolates produced diarrhoeal enter-otoxin in Brain Heart Infusion (BHI) broth. All isolates were resistant to ampicillin and penicillin antibiotics, and most of them were susceptible to gentamicin, vancomycin, bacitracin, chloram-phenicol, kanamycin and streptomycin. The growth of B. cereus was affected by environmental temperature and incubation time. Culture with temperature under 1$0^{\circ}C$ effectively restricted the growth of B. cereus.

• Journal of Life Science
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• v.18 no.1
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• pp.84-90
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• 2008

Bacterial colonies which were able to oxidize the manganese were isolated from six soil samples in Byungchon area. Among them, one bacterial strain was selected for this study based on its high manganese oxidation activity. This selected bacterial strain was identified as Pseudomonas sp. MN5 through physiological-biochemical test and analysis of its 16s rRNA sequence. This selected bacterial strain was able to utilize fructose and maltose, but they doesn't utilizing various carbohydrates as a sole carbon source. Pseudomonas sp. MN5 showed a very sensitive to antibiotics such as kanamycin, chloramphenicol, streptomycin and tetracycline, but a high resistance up to mg/ml unit to heavy metals such as lithium, manganese and barium. Optimal manganese oxidation condition of Pseudomonas sp. MN5 was pH 7.5 and manganese oxidation activity was inhibited by proteinase K and boiling treatment. The manganese oxidizing protein produced by Pseudomonas sp. MN5 was purified by ammonium sulfate precipitation, HiTrap Q FF anion exchange chromatography and G3000sw $_{XL}$ gel filtration chromatography. By sodium dodecyl sulfate polyacrylamide gel electrophoresis, three manganese oxidizing protein with estimated molecular weights of 15 kDa, 46.7 kDa and 63.5 kDa were detected. Also, it was estimated that manganese oxidizing protein produced by Pseudomonas sp. MN5 were a kind of porin proteins through internal sequence and N-terminal sequence analysis.

• Journal of Life Science
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• v.25 no.7
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• pp.733-739
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• 2015

Microalgae are a renewable natural resource that requires only sunlight, carbon dioxide, phosphorus, and nitrogen for rapid growth. They produce a broad variety of basic chemical substances―such as vitamins, fatty acids and carotenoids―that have high added value potential for the pharmaceutical and food industries. The aim of this study was to develop axenic culture and to establish a cell growth assay for microalgae. A further experiment was carried out to determine the yield of astaxanthin derived from microalgae. The axenic culture was developed using a mixture of antibiotics [ampicillin (100 ${\mu}g/ml$), streptomycin (10 ${\mu}g/ml$), chloramphenicol (10 ${\mu}g/ml$), penicillin (10 ${\mu}g/ml$), neomycin (50 ${\mu}g/ml$), gentamycin (50 ${\mu}g/ml$), kanamycin (10 ${\mu}g/ml$), and nystatin (1.5 ${\mu}g/ml$)] and then used to extract a variety of useful components from the microalgae. The optimal concentration for the antibiotic mixture was 1-3 percent. A spectrophotometric cell growth assay was also established. Astaxanthin was extracted from Haematococus lacustris with a yield of $1.9{\times}10^{-3}{\mu}g/l$ per 1 ml of culture medium. In conclusion, the axenic culture method developed here allows extraction of high-quality astaxanthin and other useful components from microalgae.