• Journal of Animal Science and Technology
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• v.51 no.3
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• pp.207-216
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• 2009

This experiment was conducted to investigate the effects of dietary supplementation of organic acid mixture on growth performance, cecal microflora, blood characteristics and immune response in broiler chicks and to prove the possibility of organic acid mixture as an alternative to antibiotics growth promotor. A total of four hundred eighty, 1-day-old male broiler chicks (Ross$\times$Ross 308) were randomly divided into 4 groups with 4 replicates of 30 birds each. The treatments were NC (free antibiotics), PC (basal diet with virginiamycin 10 ppm and salinomycin 60 ppm), 0.3% organic acid, and 0.5% organic acid. The final body weight and body weight gain were significantly higher in organic acid 0.5% than NC (P<0.05). The feed conversion ratio in all treated groups were significantly improved as compared to that of NC (P<0.05). The carcass rate and relative organs weight were not significantly difference among the groups. The relative weight and length of small intestine in PC were significantly decreased than the other groups. The numbers of cecal coliform bacteria and Salmonella in all treated groups were significantly lower than NC (P<0.05). The number of cecal lactic acid bacteria was not different among the groups. No significant differences among the groups were observed in the contents of total cholesterol, triglyceride, blood urea nitrogen (BUN), albumin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) in blood serum. The contents of total protein and globulin in blood serum of PC and organic acid treated groups were significantly increased as compared to those of NC (P<0.05). Therefore, albumin:globulin ratio of PC and organic acid treated groups was significantly lower than NC (P<0.05). The total white blood cell (WBC), heterophil, lymphocyte, and stress indicator (heterophil:lymphocyte ratio) were not significantly different among the groups. No significant difference was observed on the expression rate of splenic cytokines mRNA in organic acid treated groups compared to the control. Consequently, supplemental organic acid mixture improved the growth performance, and influenced positive effects on the intestinal microflora by inhibiting the growth of harmful bacteria without any adverse effects on relative weights of organs and blood biochemical parameters in broiler chicks.

• Journal of Bio-Environment Control
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• v.25 no.2
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• pp.83-88
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• 2016

In this study, previously reported surplus solar energy-related study result and current status of fan coil unit (FCU) for cooling and heating installed in the current sites were briefly examined and then a method to determine the number of FCUs required to recover surplus solar energy was schematically proposed to provide basic data for researchers and technical engineers in this field. The maximum, mean, and minimum outside temperatures during the experiment period were about $28.2^{\circ}C$, $4.4^{\circ}C$, and $-11.5^{\circ}C$, respectively. The horizontal surface solar radiation level outside the greenhouse was in a range of $0.8-20.5MJ{\cdot}m^{-2}$ and mean and total solar radiation were $10.8MJ{\cdot}m^{-2}$ and $1,187.5MJ{\cdot}m^{-2}$. The mean temperature and relative humidity in the greenhouse during the daytime were in a range of 18.8-45.5 and 53.5-77.5%. The total surplus solar energy recovered from the greenhouse during the experiment period was approximately 6,613.4MJ, which could supplement about 6.7% of the total heating energy 98,600.2 MJ. In addition, the number of FCUs installed for heating varies case to case, although similar FCUs are used. Thus, it is necessary to study the installation height, orientation and installation distance as well as the appropriate number of FCUs from the efficient and economical viewpoints. The required numbers of FCUs for surplus solar energy recovery were 8.4-10.9units and 6.1-8.0units based on air mass and circular flow rate that passed through the FCUs. Considering calculation methods and the risks such as efficiency and use environments of FCUs, it was found that about nine units (one unit per $24m^3$ approximately) needed to be installed. The required number of FCUs for surplus solar energy recovery was around one unit per $24m^3$ approximately.

• Journal of Bio-Environment Control
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• v.17 no.3
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• pp.221-225
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• 2008

Lilium formolongi 'Fl August' plantlets with scale-leaves and scale-bulb were treated at 10, 15, 20, $25^{\circ}C$ for 15, 30, or 45 days and planted in February, March, April and May. In the April planting, flowering percentage was below 10% and in the May planting no flowering occurred. Sprouting and flowering percentages were lower at the late planting times. Days to flowering of the April planting was 110.8 days compared to 128 days for the February planting. Plant height and numbers of leaves were reduced to 7.2 in May planting, compared to 40.5 leaves in February planting, and almost no flowers emerged in either the April or May plantings. Plantlets exposed to 10 or $15^{\circ}C$ flowered at 80 percent or higher at all treatment durations, but at 20 or $25^{\circ}C$ flowering percentages were lower, with 30% or less in the $25^{\circ}C$ treatment. In the $15^{\circ}C$ treatment days to flowering were less than 100 days, while the number of flowers and flower bud differentiation were greatest in the $15^{\circ}C$ treatment. Cytokinin and auxin were analyzed in bulblets grown at 15, 20 and $25^{\circ}C$. T-zeatin content was three times greater in the $15^{\circ}C$ treatment than at $25^{\circ}C$, but the content of indoleacetic acid (IAA) was less at $15^{\circ}C$ than at 20 and $25^{\circ}C$. In the $15^{\circ}C$ treatment, T-zeatin content was about twice the IAA content in the scale- bulblet. The auxin and cytokinin balance may affect flower bud differentiation. $15^{\circ}C$ with 30 days was most effective for flowering in scale-bulblet and planting of February and March were effective for flowering too.

• Journal of Food Hygiene and Safety
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• v.29 no.3
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• pp.217-222
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• 2014

This study was performed to evaluate the sporicidal efficacy of a fumigation disinfectant containing 20% ortho-phenylphenol against Clostridium perfringens (C. perfringens) spores. In this research, efficacy test of fumigant against C. perfringens spores was carried out according to French standard NF T 72-281. C. perfringens spores working culture suspension number (N value), all the spore numbers on the carriers exposed with the fumigant (n1, n2, and n3), the number of bacterial spore suspensions by pour plate method (N1), the number of bacterial spore suspensions by filter membrane method (N2) and the mean number of bacterial spore recovered on the control-carriers (T value) were obtained from the preliminary test. In addition, the reduction number of C. perfringens spores exposed with the fumigant (d value) was calculated using T value, the mean number of bacterial spore in recovery solution (n'1) and the mean number of bacterial spore on carriers plated in agar (n'2). N value was $4.3{\times}10^7spores/mL$, and n1, n2, and n3 were higher than 0.5N1, 0.5N2 and 0.5N1, respectively. Additionally, T value was $4.9{\times}10^5spores/carrier$. In the sporicidal effect of the fumigant, the d value was 4.52log reduction. According to the French standard for the fumigant, the d value for the effective sporicidal fumigant should be over than 3log reduction. The results indicated that Fumagari $OPP^{(R)}$ had an efficient sporicidal activity against spores of C. perfringens, then the fumigant can be applied to disinfect food materials and kitchen appliances contaminated with bacterial spores.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.279-285
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• 2013

To establish sample preparation method for detection of food-borne pathogens from lettuce, perilla leaves, cucumber, pepper, and cherry tomato, the influences of diluent composition, processing time, and proportion of diluent to sample were examined. Each produce was inoculated with 6.0 log $CFU/cm^2$ of Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus. Each produce was treated with 0.1% peptone water, and D/E neutralizing broth. Processing time of produce was 30, 60, 90, and 120s, and the proportion of diluent to sample was 2 : 1, 4 : 1, 9 : 1, and 19 : 1. The number of bacteria after treatment of D/E neutralizing broth was higher than that of 0.1% peptone water (P<0.05). In cherry tomato, the population of S. typhimurium recovered from treated with D/E broth was higher than that recovered from treated with 0.1% peptone water by 1.05 log $CFU/cm^2$ (P<0.05). No difference in numbers of pathogens was observed in processing time. Optimum proportion of diluent to perilla leaf, iceberg lettuce, cucumber, green pepper, and tomato was 9 : 1, 4 : 1, 2 : 1, 2 : 1, and 2 : 1, respectively. These data suggest that D/E neutralizing broth should be recommend as diluent, and the diluent volume applied to produce should be determined in proportion to produce surface area per weight (g).

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.272-278
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• 2013

To evaluate the effect of surface contaminated with Escherichia coli O157:H7 (E. coli O157:H7) on the microbiological safety of lettuce, this study was conducted to investigate the attachment, biofilm producing, survival, and cross-contamination of E. coli O157:H7 on stainless steel and polyvinyl chloride (PVC). The attachment rate of E. coli O157:H7 on PVC was 10 times higher than that on stainless steel after exposure 1 h in cell suspension. However, there was not a difference between two types of surface after exposure for 6 h and 24h. The biofilm producing of E. coli O157:H7 was TSB > 10% lettuce extracts > 1% lettuce extracts > phosphate buffer. When two kinds of materials were stored at various conditions ($20^{\circ}C$ and $30^{\circ}C$, relative humidity (RH) 43%, 69%, and 100%), the numbers of E. coli O157:H7 at $30^{\circ}C$, RH 43% or RH 69% were reduced by 5.0 log CFU/coupon within 12 h regardless of material type. Conversely, the survival of E. coli O157:H7 at RH 100% was lasted more than 5 days. In addition, the reduction rate of E. coli O157:H7 was decreased in the presence of organic matter. The transfer efficiency of E. coli O157:H7 from the contaminated surface to lettuce was dependent upon the water amount of the surface of lettuce. Especially, the transfer rate of E. coli O157:H7 was increased by 10 times in the presence of water on the lettuce surface. From this study, the retention of E. coli O157:H7 on produce contact surfaces increase the risk cross-contamination of this pathogen to produce. Thus, it is important that the surface in post harvest facility is properly washed and sanitized after working for prevention of cross-contamination from surface.

• The Journal of the Korean Society for Microbiology
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• v.15 no.1
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• pp.19-32
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• 1980

Besides the benefits of antimicrobial agents in the control of various infectious diseases, widespread and prolonged use of particular antimicrobial agents has brought about the increase of drug-resistant strains in a community and the profound changes in the pattern of infectious diseases. In Korea, there are some remote villages where no clinics and drug stores are available and the residents in those areas are assumed to have fewer chances to contact with antimicrobial agents. In the present study, the differences in susceptibilities to 14 antimicrobial agents between the isolates from rural areas(R) and Seoul National University Hospital(SNUH, H) were studied. The isolates and their numbers were Staphylococcus aureus, R;55, H;68), Enterococci(R;28, H;30), Escherichia coli(R;40, H;40), Enterobacter aerogenes(R;25, H;21) and Klebsiella pneunoniae(R;58, H;67). Minimal inhibitory concentrations(MIC's) of penicillin, ampicillin, carbenicillin, cephalexin, tetracycline, oxytetracyline, doxycycline, minocycline, gentamicin, kanamycin, streptomycin, erythromycin, troleandomycin and co-trimoxazole were determined by agar dilution method. I. Comparison of MIC's and resistant strain proportions between isolates from SNUH and rural areas. MIC's and/or resistant strain proportions of the isolates from SNUH were significantly higher than those of the isolates from rural areas in the cases of 1. S. aureus to doxycycline, streptomycin and kanamycin. 2. E. coli to penicillin, ampicillin, carbenicillin, tetracycline, oxytetracycline, doxycycline, minocycline, streptomycin, kanamycin, erythromycin and co-trimoxazole. 3. E. aerogences to carbenicillin, tetracycline, oxytetracycline, doxycycline, minocycline, streptomycin, kanamycin, genaamicin and co-trimoxazole. 4. K pneunoniae to penicillin, ampicillin, tetracycline, oxytetracycline, doxycycline, monocycline, streptomycin, kanamycine, gentamicin and co-trimoxazole. However, the mean MIC and resistant strain proportion of S. aureus to tetracycline were higher in isolates from rural areas than in those from SNUH and Enterococci showed no differences in susceptibilities to the antimicrobial agents between isolates from rural areas and from SNUH. Therefore, in general, differenes in susceptibility to these antimicrobial agents between the isolates from rural areas and SNUH were remarkably greater and broader in gram negative enteric bacteria. II. Multiple drug resistance pattern. Patterns and incidences of multiple drug resistance were studied with penicillin, ampicillin, tetracycline, cephalexin, gentamicin, streptomcin, kanamycin and co-trimoxazole in Enterococci, E. coli, E. aeroges and K. pneumoniae. There appeared significant differences in the incidence of multiply drug-resistant strains and multiple drug resistance patterns between the isolates from SNUH and rural areas in Enterococci, E. coli, E. aerogenes and K. pneumoniae. However, there was no difference in the incidence of multiply drug-resistant strains between isolates of S. aureus from SNUH and rural areas but the pattern of multiple resistance of the SNUH strains of S. aureus was diverse, while that of the rural strains was predominantly confined to penicillin-tetracycline combination. The incidence of multigly drug-resistant strains and diversity of their patterns were the highest in E. coli strains isolated from SNUH and there were no multiply drug resistant strrains in Enterococci and K. pneumoniae strains isolated from rural areas. The number of drug-resistance determinants was also different between the isolates from rural areas and SNUH. Most of the multiply drug-resistant strains of E. coli, E. aerogenes and K. pneumoniae isolated from SNUH were resistant to more than 3 kinds of antimicrobial agents, most frequently to ampicillin, tetracycline and streptomycin, while multiply drug-resistant strains from rural areas were resistant to 2 kinds of antimicrobial agents among ampicillin, tetracycline and streptomycin. With drug-resistant E. coli strains, resistance to tetracycline which was used most widely since 1951 was most frequently involved as a part of mutliple drug-resistance, followed by resistance to ampicillin and streptomycin. This strongly suggests that emergence of drug-restant strains in a community is directly dependent on the selective pressure exerted by the antimicrobial agent used. III. Cross resistance. Cross resistance of bacteria was studied among tetracycline penicillin, aminoglycoside and macrolide derivatives by analyzing correlation coefficients of sucseptibilities using the least square method. In this study, there were high correlations among the susceptibilities to related derivatives. It appears that the relatively low correlations in susceptibilities present in some cases are due to intrinsic resistance of E. aerogenes to penicillin, Enterococci to aminoglycoside and E. coli E. aerogenes and K. pneumoniae to macrolide derivatives.

• The Journal of the Korean Society for Microbiology
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• v.7 no.1
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• pp.29-41
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• 1972

To grow Myocbacterium leprae in cultured mouse peritoneal macrophages, studies were made with trypsin-purified Myco. laprae on 1) the dynamics of infection of mouse peritonal macrophages in vivo with Myco. leprae by intraperitoneal inoculation, 2) growth experiment of Myco. leprae in cultured mouse peritoneal macrophages by in vivo infection and in vitro cultivation and 3) the observation of pathological changes in spleens of mice induced by intraperitoneal inoculation of Myco. leprae. Results are summarized as follows; 1. Continuing and significant decreases were observed in the numbers of both acid-fast bacilli in cultured macrophage and of macrophages harboring.acid-fast bacilli by the length of inter vats between the time of intraperitoneal inoculation of Myco. leprae and the time of initiation of macrophage culture. 2. No evidence of multiplication of Myco. leprae in the peritoneal macrophages in vivo was found up to 5 months after intraperitoneal inoculation. 3. With cultures of macrophages made 24 hours and 1 week after intraperitoneal inoculation of Myco. leprae and maintained in vitro up to 2 to 3 months, microscopic examination of the stained preparations of cultured macrophages indicated that an apparent increase in the number of acid-fast bacilli in the macrophages did occur. 4. Quantitative experiment with in vivo infected-in vitro cultured macrophages revealed certain features of increase in the number of total acid-fast bacilli in the cultured macrophages 7 and 9 weeks after initiation of the cultures. 5. Pathological changes in the spleens mice inoculated with Myco. leprae were of mainly degenerative nature in the red pulp. No multiplication of Myco. leprae was observed in the spleens of mice up to 5 months after intraperitoneal inoculation.

• Food Science of Animal Resources
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• v.29 no.4
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• pp.437-444
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• 2009

${\gamma}-Aminobutyric$ acid (GABA) producing lactic acid bacteria, Lactobacillus acidophilus RMK567 was cultivated in 50 L of sterilized MRS broth using a fermenter at $40^{\circ}C$ for 24 h. The cell number was increased to $10.04{\pm}0.13$ Log CFU/mL with a growth rate constant (k) of 0.454 generation/h and a generation time (g) of 2.303 h after a lapse of a lag phase (L) of 5.16 h. A total of 487 g of cell paste with 40.5% moisture was harvested with viable cell number of 12.48 Log CFU/g cell paste. The cell pastes after preparation with glycerol, glucose, and polydextrose as cryo-protectants were lyophilized under a vacuum of 84 m torr. A total of 408 g of freeze dried (FD) cell powders were mixed with a commercial strain of Streptococcus thermophilus to prepare of three types FD starter cultures with the viable cell numbers of 12.42 (FDA-GY), 12.60 (FDBGG) and 12.91 (FDC-GP) Log CFU/g. During preservation the FD cultures at -$18^{\circ}C$, the cell viability of the FD starter cultures were rapidly dropped to below 3.24% of the day of storage. No significant difference was found in the cell viabilities among three types of FD starters cultures, but significant difference (p<0.01) was found in storage periods. Yoghurts fermented through FD starter culture of L. acidophilus RMK567 were determined to contain $155.16{\pm}8.53$ ppm, $243.82{\pm}4.27$ ppm, and $198.64{\pm}23.46$ ppm of GABA, respectively. This study shows that GABA production activity of L. acidophilus RMK567 is not affected during the freeze drying process and would be available for commercial production of yoghurt containing high GABA content.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.38-49
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• 2011

Bioaerosols generated from wastewater treatment plants may create health risks for plant workers and nearby residents. To determine the levels of culturable airborne bacteria and fungi in bioaerosols, samples were seasonally collected above and near the aeration tanks of one feces-urine and three sewage treatment plants in Ulsan, Korea with an impaction-type sampler. In the feces-urine treatment plant, concentrations of heterotrophic bacteria were between $1.3({\pm}0.2){\times}10^3$ and $2.6({\pm}1.2){\times}10^4$ MPN/$m^3$ above the aeration tank and between $1.7({\pm}1.0){\times}10^2$ and $7.2({\pm}2.2){\times}10^3$ MPN/$m^3$ near the aeration tank. Coliform bacteria were detected both above and near the aeration tank. In cases of sewage treatment plant, the numbers of heterotrophic bacteria ranged from $1.9({\pm}1.2){\times}10^1$ to $1.8({\pm}1.2){\times}10^4$ MPN/$m^3$ above the aeration tank and from $5.0({\pm}2.8){\times}10^0$ to $6.6({\pm}2.0){\times}10^3$ MPN/$m^3$ near the aeration tank. At reference sites, the concentrations of heterotrophs in ambient air were measured between $7.0{\times}10^0$ and $2.7{\times}10^1$ MPN/$m^3$. When we isolated and tentatively identified heterotrophic bacteria, Pseudomonas luteola was the most dominant species in bioaerosols from wastewater treatment plants, whereas the most abundant one in reference samples was Micrococcus sp. When we measured fungal concentrations in bioaerosols, they were rather similar regardless of sampling locations and seasons, and such genera as Cladosporium, Alternaria, and Penicillium were commonly identified.