• Asian-Australasian Journal of Animal Sciences
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• v.20 no.3
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• pp.378-384
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• 2007

Three microorganisms and one chemical preservative were tested for their effects on the fermentation and aerobic stability of whole-crop wheat, sorghum and maize silages. Wheat at the early dough stage, sorghum at the late milk stage and maize at the one-third milk line stage were harvested and ensiled in 1.5-l anaerobic jars untreated or after the following treatments: control (no additives); Lactobacillus plantarum (LP) at $1.0{\times}10^6$ colony-forming units (CFU)/g of fresh forage; L. buchneri (LB) at $1.0{\times}10^6$ CFU/g; Propionibacterium acidipropionici (PA) at $1.0{\times}10^6$ CFU/g; and a formic acid-based preservative (FAP) at 3 ml/kg of fresh forage weight. Three jars per treatment were sampled on d 90 after ensiling, for chemical and microbiological analysis. At the end of the ensiling period, 90 d, the silages were subjected to an aerobic stability test lasting 5 d. In this test, $CO_2$ produced during aerobic exposure was measured along with chemical and microbiological parameters which serve as spoilage indicators. The silages inoculated with LP had higher concentration of lactic acid compared with the controls and the other treated silages (p<0.05). The controls and LP-inoculated silages spoiled upon aerobic exposure faster than LB, PA and FAP-treated silages. The controls and LP-inoculated silages spoiled upon aerobic exposure faster than LB, PA and FAP-treated silages due to more $CO_2$ production (p<0.05) in these two groups and development of yeasts unlike the other groups. In the experiment, the silages treated with LB, PA and FAP were stable under aerobic conditions. However, the numbers of yeasts was higher in the LP-inoculated wheat, sorghum and maize silages compared with the LB, PA and FAP-treated silages. The LB, PA and FAP improved the aerobic stability of the silages by causing more extensive heterolactic fermentation that resulted in the silages with high levels of acetic and propionic acid. The use of LB, PA and FAP as silage additives can improve the aerobic stability of whole-crop wheat, sorghum and maize silages by inhibition of yeast activity.

• Korean Journal of Environmental Biology
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• v.28 no.3
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• pp.172-178
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• 2010

The bloom of the genus Stephanodiscus was gradually extinguished after 18 April. Counts of bacterial population were increased as the diatom bloom was disappeared. Numbers of the heterotrophic nanoflagellates and ciliates were also increased during the disappearance of the bloom. The densities of the mesozooplankton, the major predator of the diatoms, started to increase in April. However, their growth was suppressed during the bloom period of the diatoms (from January to March). During the bloom period of the diatoms, the monthly average value of the basic productivity amounted up to 11,765.7 mgC $m^{-2}day^{-1}$, which is relatively high value considering the low temperature and light during that period. The growth rate of phytoplankton in March, when the bloom was beginning to be supressed was 0.007. The growth rate of phytoplankton was negative value in April when the decreasing of the algal density was started.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.106-118
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• 2001

The chemistry of porewater and exchangeable nutrients of sediment was determined to define potential influence of sediment nutrients on the water quality and the phytoplankton growth in Taechong Reservoir in March and May of 2000. The sediment-water interface showed almost anoxic state, < 0.5 mg $O_2/l$. Conductivity of the porewater was higher 1.9${\sim}$2.6 fold than that of sediment, and its variation was greater in the shallow water. Eh ranged from -12mV to -148 mV and bulk density from $1.17\;g/cm^3$ to $1.30\;g/cm^3$ and they did not differ among stations. The water content in the sediment ranged from 58% to 72% and organics from 8% to 13%, and they were higher toward the lower part of reservoir. Soil texture was in the order of sand>clay>silt and sandy sediment accounted for 97% of the total sediment. The total bacterial numbers and diatom abundance were high in the downstream of the reservoir. In porewater and exchangeable nutrients of sediment, nitrogen and phosphorus were mostly consist of the particulate form. Inorganic nitrogen was mostly composed of $NH_4$. Nitrogen of porewater was mostly an inorganic form while exchangeable nutrients were composed an organic form. However, phosphorus was composed of dissolved organic fraction in the porewater while inorganic fraction in the exchangeable nutrients. Silicon content of sediment was much exchangeable nutrients with 63%, and it was higher than in the porewater. In summary, the sediments of Taechong Reservoir were mostly composed of organics and assessed to be a eutrophic state.

• 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.

• Journal of fish pathology
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• v.22 no.3
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• pp.253-262
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• 2009

We conducted bacteriological and histopathological analysis for olive flounder Paralichthys olivaceus after experimental infection with Streptococcus parauberis (FP2284) isolated from diseased olive flounder under different stress conditions. Experimental challenge was performed in healthy flounder (40.4 g in average body weight) by intraperitoneal (i.p.) injection with $2{\times}10^{8}$ CFU/fish under normal (no stress) or netting (for 2 min, twice/day) stress condition. The cumulative mortalities of no-stress and netting stress group were 70% and 95%, respectively. The most prevalent changes observed in experimentally infected flounder were darkness of skin and inflammation of the heart. Severe pericarditis, myocarditis and fibrosis were observed in the heart of the affected flounder. The results of viable counts showed the number of bacteria of the heart tissue was maintained over the $10^{4}$ CFU $g^{-1}$ heart for 3 weeks after inoculation. Histological lesions of the heart was more extensive and gradual decrease in bacterial numbers of heart tissue was delayed under stress condition.

• Korean journal of food and cookery science
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• v.25 no.1
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• pp.8-15
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• 2009

This study was carried out to examine changes in the quality characteristics of Aralia continentalis Kitagawa (AcK) Jangachi made with different $CaCl_2$ and seasoning treatments during storage at $4^{\circ}C$ for 6 months. The results exhibited there were no significant changes in pH, acidity, and salinity in the various samples. The numbers of total bacterial counts and lactic acid bacteria increased slowly during the early storage period and then increased rapidly in the third month. In the fifth month they reached their highest level near $6.6{\times}10^{6}cfu/ml$ and then decreased thereafter. The sample treated with $CaCl_2$ exhibited a higher degree of hardness than the untreated sample. Finally, the sensory characteristics of the AcK Jangachi were highly acceptable during the entire storage period in terms of color, smell, bitterness, texture, and general preference regardless of the $CaCl_2$ treatments.

• Korean Journal of Veterinary Research
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• v.24 no.2
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• pp.183-193
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• 1984

In this study lactating female rabbits and strains of coliforms previously isolated from the cases of acute and chronic mastitis in dairy cattle were employed. The pathological changes were observed on the mastitis experimentally induced with the coliform strains and the mamary glands after infusions of E. coli suspension together with dexamethasone, dextran iron or transferrin were grossly and microscopically observed. From the results reported, the following points are concluded. In the bacterial suspension-infused groups by E. coli, K. pneumoniae and Ent. aerogenes, respectively, the affected quarters of udder showed grossly swelling, hyperemia, hemorrhage, focal necrosis and firmness. The microscopic findings of early stage of the mastitis were appearance of large numbers of heterophils in the glandular lumina and ducts accompanied by degeneration, necrosis and desquamation of epithelial cells and also infiltration of heterophils, hemorrhage and edema in the interstitial tissue and destruction of alveoli. Later, proliferation of fibroblasts, plasma cells, lymphocytes, eosinophils and macrophages appeared in the glandular tissue and with these cells necrotic foci of glandular tissue were surrounded by highly proliferated connective tissue. In addition, granulomatous inflammatory changes could be observed in the glandular tissue from the 7th day after infusion. The difference of the inflammatory response among the groups did not recognized. In the groups infused with dexamethasone and E. coli suspension the inflammatory response was slighter at the inflammatory change with alveolar destruction and hemorrhage was more rapid and severer than E. coli alone. Also in the groups infused with dextran iron and E. coli suspension the inflammatory change was more rapid and severer than E. coli alone and the histological changes were not recognized in the groups infused with dextran iron alone. Reaction of the iron staining was diffusely strong positive within the glandular alveolar lumina in the groups of dextran iron alone, hut was slightly positive toward epithelial cells in the groups of dextran iron and E. coli infusion. In the group infused with transferrin and E. coli suspension, the inflammatory response was tighter, but the peroxidase activity of the heterophils in the glandular lumina was more or less stronger than E. coli alone.

• Korean Journal of Microbiology
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• v.44 no.2
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• pp.147-155
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• 2008

The diversity of sulfate reducing bacteria was investigated in different depths of sediments in Lake Sihwa, Korea and Lake Aha, China by PCR amplification, denaturing gradient gel electrophoresis (DGGE) and clone libraries targeting dissimilatory sulfite redectase (dsr) gene. In the analysis of DGGE band patterns, the community compositions of dsr gene in the sediments of both lakes were significantly different whereas bands in all depths of each environment revealed similar patterns. Bands from Lake Sihwa were produced much more than those from Lake Aha, demonstrating a higher diversity of dsr gene in Lake Sihwa. Total 68 clones containing dsr gene were obtained to analyze their sequences. Sequences from the sediment of Lake Sihwa were affiliated to Deltaproteobacteria, the Gram-positive thermophilic sulfate reducers belonging to the genus Desulforomaculum and archaeal thermophilic SRB belonging to the genus Archaeoglobus, whereas sequences from the sediments of Lake Aha were related to genus Desulfotomaculum. Clones retrieved from sediment of Lake Sihwa revealed a higher numbers than those of Lake Aha, demonstrating a higher diversity of dsr gene in Lake Sihwa. Most of clones (59%) were distantly related to the known cultivated SRB with $60\sim65%$ of similarity, which were clustered only the sequences from the environments showed less than 90% similarity. These habitat specific sequences suggested that the clustered dsr sequences represent species or groups of species that were indigenous to these environments. This study showed that these lakes have a specific bacterial communities having dsr gene distinct from those in other environments such as soil and marine ecosystems around the world.

• Korean Journal of Environmental Biology
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• v.24 no.1 s.61
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• pp.38-45
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• 2006

Ecological characteristics of microbial populations inhabiting heavy metal polluted soil were investigated. The samples were collected from 293 sites around an factory and industry at Gyeoungsangbuk-do. We measured the contents of seven heavy metal elements (Cd, Cu, As, Hg, Pb, $Cr^{6+}$, CN), seven sites have been seriously contaminated by mercury and chrome. A quantitative evaluation of microbial populations in mercury and chrome contaminated soil was examined by using plate count method. Bacterial numbers in polluted soil samples ranged from $7.4X10^5\;to\;9.3X10^7\;cfu\;g^{-1}$, about $10\sim100$ fold less than the count for the unpolluted soil. Moulds were not detected in chrome polluted soil. The log values of actinomycetes of each contaminated soil samples were log ranged from 6.18 to 7.52. The ratio of actinomycetes was similar to unpolluted soil. The investigation showed actinomycetes to be the major microbial population inhabiting the mercury and chrome polluted soil. Thirty-one isolates among the total isolates were examined for antibacterial activity. These isolates were identified based on a phylogenetic analysis using 16S rRNA gene nucleotide sequences, they were categorized in three major phylogenetic groups, belong to the Streptomyces (6 strains), Saccharopolyspora (3 strains), Nocardiodes (1 strain). On the phylogenetic tree, the clade consisting of five isolates were distantly related to all of the established Streptomycetes genera, indicating the possibility as members of new species.

• Korean Journal of Environmental Biology
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• v.20 no.1
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• pp.85-90
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• 2002

In an artificial pH-gradient batch culture system, the author analyzed the effects of acidification on the species composition of heterotrophic bacteria. As the result of this study, it was found that the numbers of total bacteria were not affected by acidification and that the population size of heterotrophic bacteria decreased as pH became lower. The heterotrophic bacteria isolated from all of the pH gradient were 12 genera and 22 species, and among them, gram negative and gram positive bacteria were 04% and 30%, respectively. As pH decreased, the distribution rate of gram negative bacteria increased while that of gram positive bacteria decreased. Regarding to distribution rate of genuses in each pH gradient, 13 genuses appeared at pH 7 while only 5 genuses appeared at pH 3, which means that the diversity of genera decrease as pH decreased. The activities of extracellular enzyme showed the ranges of $0.008-0.292\;\mu{M}\ell^{-1}\;hr^{-1}$ in bioreactor system. The enzymatic activities decreased rapidly below pH 5 and then sustained 5-38% at the lower pH values.