• Korean Journal of Soil Science and Fertilizer
• /
• v.16 no.4
• /
• pp.358-367
• /
• 1983

Antibiotic-resistant strains of Salmonella typhimurium and Klebsiella pneumoniae died readily after their addition to raw sewage, but they grew in sterilized sewage. The decline was not a result of antibiotic stresses, and because the bacteria were able to survive in large numbers for at least 15 days in solutions containing no organic nutrients, it was not a result of competition. Toxin production, bacteriophages, and Bdellovibrio did not cause the disappearance of the two bacterial species. A decline was also evident if the sewage was first passed through a $3-{\mu}m$ filter or treated with cycloheximide or cycloheximide plus nystatin, but protozoa developed under these conditions. Little or no decline occurred if the sewage was filtered and treated with the eucaryotic inhibitors before adding S. typhimurium or K. pneumoniae, and protozoa were not detected. S. typhimurium increased in abundance if cycloheximide, streptomycin, and erythromycin or large amounts of glucose were added to sewage. Tetrahymena thermophilus did not significantly reduce the population of S. typhimurium in buffer when the density of the bacterium was about $10^4/ml$. However, when more than $10^8$ Enterobacter agglomerans cells per ml were added to the buffer, T. thermophilus reduced the abundance of E. agglomerans and S. typhimurium to $10^6$ and 10/ml, respectively. The density of S. typhimurium was further decreased by a second increment of E. agglomerans cells. The disappearance of S. typhimurium and K. pneumoniae from sewage thus is the result of predation by protozoa. It is proposed that predators will eliminate a prey species from a natural environment when an alternate prey is present at concentrations above the threshold number for active feeing by the predator and when the rate of growth of the prey is less than the rate of predation.

• The Korean Journal of Food And Nutrition
• /
• v.15 no.2
• /
• pp.89-96
• /
• 2002

The adsorption characteristics of sodium chloride into Ca-alginate beads have been investigated and the result were as follows: Sodium chloride uptake by Ca-alginate beads increased with time. The highest uptake volume of sodium chloride was 4.2g after 10 minutes. The uptake volume by Fe, Ca, Ba, and Sr-alginate beads was 5.6g, 4.2g, 4.2g and 4.0g, respectively but in case of Fe-alginate beads, the induced hydrogel beads were very fragile and the strength of Fe-alginate beads were weaker than Ca- and Ba-alginate beads. Mg-alginate bead was not formed and Ca-, Ba- and Sr-alginate beads had a similar uptake volume about 4.2g, respectively. The uptake volume of sodium chloride by CaCl$_2$concentration(0.1M. 0.2M and 1M), curing solution, was 4.8, 4.2g and 4.1g, respectively. The uptake volume by sodium alginate concentration(0.6%, 1% and 2%) was 2.8g, 4.0g, and 4.4g, respectively and Ca-alginate bead size was not effected in uptake sodium chloride. The uptake rate on initial sodium chloride concentration(4%, 8%, 12% and 16%) was 30%, 28%, 27% and 25%, respectively. The uptake rate on basic pH(10.0) was higher than when compared to other neutral pH(6.8) and acidic pH(4.0). The initial uptake velocity of sodium chloride from immobilization beads with salt resistant bacteria was lower than that of non-immobilization beads. The uptake rate of sodium chloride was decreased according to elongation of curing time. Reusability of Ca-alginate beads was possible but according to reutilization, the salt uptake volume of beads was also decreased. The uptake volume of sodium chloride from Doengjang by Ca-alginate beads on time course(3, 6, 12, and 24 hour) was revealed 5g, 6g, 7g and 7g, respectively.

• Tuberculosis and Respiratory Diseases
• /
• v.62 no.6
• /
• pp.506-515
• /
• 2007

Background: Nosocomial pneumonia in an intensive care unit (ICU) is associated with a high mortality rate. Diagnosing a respiratory tract infection in critically ill patients is still difficult but detailed information for the pathogens is needed to establish an adequate antimicrobial treatment. This study examined the causative organisms and their antimicrobial resistance using bronchoalveolar lavage (BAL) from patients suspected of having pneumonia in the ICU. Methods: From January 2004 to June 2006, ICU patients with diffuse lung infiltration were prospectively enrolled. The BAL was used to diagnose the respiratory infection, with 104 > or = organisms considered a positive result. The most common organisms and their antimicrobial resistances were analyzed from the quantitative BAL cultures in the burn ICU and non-burn ICU. Results: A total 72 patients were included, 35 (M 29, F 6) in the burn ICU and 37 (M 26, F 11) in the non-burn ICU. 27 patients (77.1%) in the burn ICU and 22 patients (59.5%) in the non-burn ICU met the criteria for a positive BAL culture. The major pathogens were Staphylococcus aureus, Acinetobacter species and Pseudomonas aeruginosa. All strains (100%) of Staphylococcus aureus isolated from BAL (9 cases) were methicillin-resistant (MRSA) in the burn ICU, but 5 strains (71.4%, 7 cases) were MRSA in the non-burn ICU. Regarding Pseudomonas aeruginosa, the rate of resistance to amikacin, ciprofloxacin, cefepime, imipenem, ceftazidime, piperacillin/tazobactam in the burn and non-burn ICU ranged from 45.5% to 90% and 25% to 50%, respectively. In addition, the rate of resistance of Acinetobacter species to the above drugs in the burn and non-burn ICU ranged from 81.8% to 100% and 62.5% to 100%, respectively. Conclusions: These results are expected to provide useful guidelines for choosing the effective empirical antimicrobial therapy in patients with lung infiltrations in the burn and non-burn ICU.

• Journal of Life Science
• /
• v.22 no.8
• /
• pp.1114-1119
• /
• 2012

Bacteria are frequently contaminated during the collection and processing procedures of boar semen. Of the contaminants, Stenotrophomonas (S.) maltophilia is a Gram-negative bacterium that is widely distributed in a variety of habitats. Although PCR assays have been developed for the detection of S. maltophilia, they cross-react with some species of Xanthomonas. In this study, we designed a primer set for the detection of S. maltophilia in order to target the chiA (GenBank accession no. NC_010943) gene. The specific PCR products were amplified from S. maltophilia only, not from other tested strains that are frequently found in semen. The detection limit of the PCR was $1.5{\times}10^3$ CFU/ml with pure-cultured S. maltophilia and $1.5{\times}10^4$ CFU/ml with S. maltophilia spiked in semen. Twenty-six (5.9%) S. maltophilia were isolated from 440 semen samples. The PCR results exhibited 98.9% agreement with a comparison of S. maltophilia isolation. Also, the sensitivity and specificity of the PCR were 100% and 98.7%, respectively. In the antimicrobial susceptibility test, S. maltophilia isolates were highly susceptible to enrofloxacin and florfenicol, while the majority of them were resistant to amoxicillin/clavulanic acid, apramycin, ceftiofur, penicillin, and spectinomycin. These results indicated that the PCR using the chiA gene was proven to be reliable and effective for the detection of S. maltophilia with high levels of sensitivity and specificity.

• Applied Biological Chemistry
• /
• v.13 no.1
• /
• pp.1-27
• /
• 1970

The process of the forced aging of flue-cured tobacco leaves were studied extensively from various scientific points of view. The Flue-cured tobacco leaves were inoculated and fermented with nicotine resistant Hansenula yeast, or the leaves were subjected under simple forced aging. The above two processes of forced aging were studied from the summarized points of microbiology, physics, chemistry, and biochemistry, and the resulted products ware compared in their physical, chemical and biochemical quality determining factors with that of raw material tobacco leaves (dried-tobacco leaves) and 2 years aged high quality tobacco leaves. The summary results were as follows. 1) The Korean flue-cured tobacco leaves, were forcedly aged under the basic optimum aging condition, temperature $40^{\circ}C$, moisture contents 18%, relative humidity 74%. It was found that this aging condition was the best in bringing the quality of forcedly aged tobacco leaves to the utmost state. 2) Under this optimum temperature and moisture condition of forced aging in about 20 days the forcedly aged tobacco leaves both with yeast inoculation and without yeast inoculation showed the equivalent tobacco qualities comparable with that of more than 2 years aged tobacco leaves. 3) The forcedly aged tobacco leaves both with and without yeast inoculation under $40^{\circ}C$ temperature and $74^{\circ}C$ relative humidity achieved the necessary quality determining physical and chemical changes in about 20 days. 4) The microbial changes during the forced aging were as follows. The population of yeasts and bacteria increased until to 15 days of aging, then decreased thereafter. Whereas the molds grew continously until the end of fermentation. 5) The tobacco quality determing physico-chemico-properties of yeast inoculated aged and simple forcedly aged tobacco leaves, progressed as the follows in time. As the forced aging progresses, swelling and combustibility properties were improved. The pH, total reducing materials, total sugars, alkaloids contents decreased. The contents of organic and ether extractable materials increased. The total nitrogen, protein, crude fiber, ash contents showed no changes. The color properties, excitation purity, luminance, main wave length, showed equivalent changes comparable with that of 2 years aged tobacco leaves. 6) The changes in chemical components in yeast treated and simple forcedly aged tobacco leaves during $15{\sim}20{\;}days$ of forced aging were as follows. The following chemical components decreased as the aging. Sugars-sucrose. rhamnose, glucose. Pigments-chlorophyll, carotenes, xanthophyll and violax anthine. Polyphenols-rutin, chlorogenic and, coffeic acid. Organic acids-iso-butylic, crotonic, caprylic, galacturonic, tartaric, succinic, citric acid. Alkaloids-nicotine, nornicotine. The following components increased as the forced aging progressed. Sugars-frutose, maltose, raffinose. Amino acids-proline, cystine. Organic acids-formic, acetic, propionic, n-butyric, iso-valeric, n-valeric, malic, oxalic, malonic, ${\alpha}-ketoglutaric$, fumaric, glutaric acid. 7) During the forced aging of tobacco Leaves the oxygen-uptake decreased gradually. The enzyme activities of polyphenol oxidase, ${\beta}-amylase$ ${\alpha}-amylase$ decreased gradually. The activities of the enzymes, catalase, and invertase increased once then decreased at the later stage.

• Proceedings of the Korea Society of Poultry Science Conference
• /
• 2003.07b
• /
• pp.37-54
• /
• 2003

It has been recognized that the hen. like its mammalian counterparts. provides young chicks with antibodies as protection against hostile invaders. This system facilitates the transfer of specific antibodies from serum to egg yolk. and provides a supply of antibodies called immunoglobulin Y(IgY) to the developing embryo and the hatched chick. The protection against pathogens that the relatively immuno-incompetent newly hatched chick has. is through transmission of antibodies from the mother via the egg. Egg yolk. therefore. can be loaded with a large amount of IgY against pathogens which can immobilize the existing or invading pathogens during the embryo development or in day-old chicks. Thus. the immunization of laying hens to various pathogens results in production of different antigen-specific IgY in eggs. Egg yolk contains 8~20 mg of immunoglobulins (IgY) per $m\ell$ or 136~340 mg per yolk suggesting that more than 30 g of IgY can be obtained from one immunized hen in a year. By immunizing laying hens with antigens and collecting IgY from egg yolk. low cost antibodies at less than ＄10 per g compared to more than ＄20.000 per g of mammalian IgG can be obtained. This IgY technology opens new potential market applications in medicine. public health veterinary medicine and food safety. A broader use of IgY technology could be applied as biological or diagnostic tool. nut-raceutical or functional food development. oral-supplementation for prophylaxis. and as pathogen-specific antimicrobial agents for infectious disease control. This paper has emphasized that when IgY-loaded chicken eggs are produced and consumed. the specific antibody binds. immobilizes and consequently reduces or inhibits the growth or colony forming abilities of microbial pathogens. This concept could serve as an alternative agent to replace the use of antibiotics. since today. more and more antibiotics are less effective in the treatment of infections. due to the emergence of drug-resistant bacteria.

• Journal of Life Science
• /
• v.27 no.2
• /
• pp.202-210
• /
• 2017

As an effort to find a potential biopreservative, we isolated bacterial strains producing bacteriocin from fermented foods. A strain was finally selected and characteristics of the bacteriocin were investigated. The selected strain was identified as Bacillus subtilis E9-1 based on the 16S rRNA gene analysis. The culture supernatant of B. subtilis E9-1 showed antimicrobial activity against Gram-positive bacteria. Subtilisin A, ${\alpha}$-chymotrypsin, trypsin and proteinase K inactivated the antimicrobial activity, which means its proteinaceous nature, a bacteriocin. The bacteriocin activity was fully retained at the pH range from 2.0 to 8.0 and stable at up to $100^{\circ}C$ for 60 min. Solvents such as ethanol, isopropanol and methanol had no effect on the antimicrobial activity at the concentration of 100% but acetone and acetonitrile reduced the activity at up to 100% concentration. Cell growth of four indicator strains was dramatically decreased in dose-dependent manner. Listeria monocytogenes was the most sensitive, but Enterococcus faecium was the most resistant. Bacillus cereus and Staphylococcus aureus showed the medium sensitivity. The bacteriocin showed its antimicrobial activity against B. cereus and L. monocytogenes via bactericidal action. The number of viable cells of L. monocytogenes started to reduce after addition of bacteriocin to the minced beef. The bacteriocin was purified through acetone concentration, gel filtration chromatography and RP-HPLC. The whole purification step led to a 6.82 fold increase in the specific activity and 6% yield of bacteriocin activity. The molecular weight of the purified bacteriocin was determined to be 3.3 kDa by MALDI-TOF/TOF mass spectrometry.

• Microbiology and Biotechnology Letters
• /
• v.35 no.3
• /
• pp.238-244
• /
• 2007

To identify the useful biological activities and the superiority in quality of Korean traditional liquors, we prepared the alcohol-free concentrates from different types of commercial traditional liquors, Takju ($T1{\sim}T3$), Yakju/Cheongju ($Y-1{\sim}Y-5$), Fruit wine (F-1) and Soju (S-1, S-2), respectively. We investigate their compositions as well as antimicrobial, antioxidant, and anti-thrombosis activity. Among the 11 traditional liquors, Y-3, Y-4, Y-5 and F-1 showed higher total-polyphenol, total-flavonoids and reducing sugars than the others. The strong antibacterial and anti-thrombosis activities were identified in Y-3, Y-4, Y-5 and F-1, and a minor antioxidant activity was found in F-l. The antibacterial activity of the Y-3, Y-4, Y-5 and F-1 alcohol-free concentrates showed a broad-spectrum, and growth inhibition was found in gram-positive, gram-negative, and ampicillin-resistant bacteria. The sequential solvent fractionation of Y-3, Y-4, Y-5 and F-1, and following analysis showed that ethyl acetate fractions of Y-3, Y-4, Y-5 and F-1 possess strong antibacterial and anti-thrombosis activity. Especially, the ethyl acetate fractions of Y-3, Y-4 and F-1 showed superior anti-thrombosis activity compared than that of aspirin. Our results suggest that the useful substances are produced from substrates and edible plant added during the fermentation, and the Korean traditional liquors could be developed as strong antibacterial and anti-thrombosis agents.

• Korean Journal of Microbiology
• /
• v.28 no.3
• /
• pp.210-218
• /
• 1990

The survival and transfer of chromosomal genes coding for the synthesis of amino acids (threonine, tryptophan, histidine, leucine, methionine) and of plasmid-borne genes coding for resistance to antibiotics (chloramphenicol, kanamycin, erythromycin) by transformation in sterile and nonsterile soil (the soil was amended to 12% vol/vol with the clay mineral, montmorillonite) was studied. In pure culture, the numbers of vegetative cells of the Bacillus subtilis strains decreased by 1 to 1.5 orders of magnitude within one week, but spores of each strain showed lesser decreases. In sterile soil, the populations of vegetative cells and spores decreased by 1.5 to 3 orders of magnitude within 2 to 4 days and then showed little additional decreased. The transformation frequencies (number of transformants/numbers of donors and recipients) of individual amino acid-genes invitro ranged from $1.3{\pm}0.6{\times}10^{-6}$ to $6.0{\pm}2.36{\times}10^{-6}$, of two amino acid-genes from $8.5{\pm}0.7{\times}10^{-8}$ to $3.1{\pm}0.6{\times}10^{-7}$, and of the antibiotic-resistance genes from $1.5{\pm} 0.2{\itmes} 10^{-7}$ to $1.4{\pm} 0.4{\times} 10^{-5}$ . In sterile soil, the frequencies of transfer of individual amino acid-genes ranged from $2.0{\times} 10^{-7}$ to $2.0{\times} 10^{-5}$ and of the antibiotic-resistance genes from $2.0{\times} 10^{-7}$ to $9.4{\pm} 4.7{\times} 10^{-6}$. The transfer of two amino acid-genes in sterile soil was detected at a frequency of $2.0{\times} 10^{-6}$ to $4.5{\times} 10^{-6}$, but only in three instances. The transformation frequencies of antibiotic-resistance genes in nonsterile soil were essentially similar to those in sterile soil. However, to detect transformants in nonsterile soil, higher concentrations of antibiotics were needed, as the result of the large numbers of indigenous soil bacteria resistant to the concentration of antibiotics used in the sterile soil and in vitro studies. The results of these studies show that genes can be transferred by transformation in soil and that this mechanism of transfer must be considered in risk assessment of the release of genetically engineered microorganisms to the environment.

• Childhood Kidney Diseases
• /
• v.9 no.1
• /
• pp.46-55
• /
• 2005

Purpose : Recurrent urinary tract Infection(UTI) in primary vesicoureteral reflux(VUR) may lead to serious renal scarring, a major cause of childhood hypertension and end-stage renal disease. To prevent recurrent UTI, low-dose long--term antibiotic prophylaxis has been recommended. However, recurrent UTI still develops during antibiotic prophylaxis, the efficacy of which is now being disputed. The emergence of resistant bacteria has also raised concerns. To evaluate the effect of antibiotic prophylaxis, we investigated recurrent UTI during prophylactic antibiotic use in children with primary VUR Materials : The incidence and risk factors of recurrent UTI were retrospectively evaluated in ninety-one children with primary VUR on trimethoprim- sulfamethoxazole(TMP/SMX) prophylafis during the year following their index febri]e UTI. Results : Recurrent UTI occurred in 31.9%(29/91) children and comprised 0.32 episodes/patient year. Febrile UTI was 0.26 episode/patient year and afebrile UTI was 0.07 episodes/patient year. The recurrent rate of UTI in male patients with phimosis was 37.2%(19/51), which was significantly higher than in males without phimosis 0%(0/5)(P=0.025). In the logistic regression analysis for recurrent UTI, renal scar was the significant risk factor for recurrent UTI [RR 3.8(95% CI 1.0-14.1) P=0.04]. For other well-known risk factors such as sex, age, degree of VUR, APN, and voiding dysfunction, the differences were not significant. Conclusion : TMP/SMX prophylaxis did not prevent recurrent UTI in children with primary VUR. Phimosis and renal scars were the risk factors for recurrent UTI but the grade of primary VUR was not. In VUR without phlmosis and renal scar, a randomized controlled study without antibiotic prophylaxis is required. (J Korean Soc Pediatr Nephrol 2005;9:46-55)