• Korean Journal of Microbiology
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• v.8 no.2
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• pp.53-64
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• 1970

In order to study ecology of microorganisms during Takju brewing, microflora changes were examined fromm the start to the sixth day of Takju fermentation in 24 hours intervals. Takju made from rice, flour and dried sweet potato in a liter volume open container at the laboratory and a sanple of Takju brewing factory were studied for their microflora and their changes during fermentationl together with a sample of Kokja. Results obtained were as follows ; 1. The followings were the identified microorganisms in Kokja. The molds ; Absidia spinosa, Aspergillus parasiticus. The yeasts ; Candida melinii, Candida Solani, Hansenula anomala. The bacteria ; Luctobacillus casei, Leuconostoc mesenteroides, Bacillus subtilis, Bacillus pumilus. 2. Torulopsis inconspicua, Lactobacillus casei, Leuconotoc mesenteroides, Bacillus subtilis, Bacillus pumilus were isolated from main mash of laboratory-made Takju samples. The yeast, Torupsis inconspicua which was not present in Kokja and, probably of a contaminant yeast, dominated the yeast flora of Takju mash of rice, flour and sweet potato of labotatory brewing. The laboratory brewing lost also always showed large population of lactic acid bacteria flora. 3. None of the wild yeasts which were present in Kokja appeared in Takju mashes. The Kokja appears to be of no use as the yeast source for Takju fermentation. Also the Kokja appears to be of not so effective amylolytic and proteolytic enzyme sources considering the microflora characteristics. Probably the major role of Kokja in Takju fermentation may be to contribute in taste formation. 4. Inoculation of Sacharomyces cerevisiae into the mash to the level of $10^7$ ml at the start of fermentation greatly changed the ecological aspects eliminating conditions of rather slow rising of natural contaminant yeast populaiton and fermentation which might give rise to prosperity of lactic acid and Bacillus bacteria that would be avoidable. 5. Examination of microflora of the large factory scale Takju fermentation showed the quite similar pattern of microflora and their changes to that of the cultured yeast-inoculated laboratory batch Takju fermentation. The cultured yeast dominated as the only predominant microflora, and the lactic acid bacteria flora were completely suppressed and aerobic bacteria, greatly. Probably this may be the regular microflora pattern of normal Takju fermentation. The role of lactic acid bacteria and aerobic bacteria in Takju fermentation may not be clear yet from this experiment alone.

• Journal of the FoodService Safety
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• v.4 no.1
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• pp.7-20
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• 2023

This study was conducted to investigate the impact of refrigerator type and temperature fluctuations on the quality changes of refrigerated foods. Phycochemical and sensory quality, as well as microbial growth, were measured for various foods stored in open- or door-type refrigerators set at 5℃ during storage. The average temperatures recorded were 11.50±1.14℃ in an open refrigerator, and 6.34±0.97℃ in a closed refrigerator. The average surface temperatures of the food items were 9.60±1.20 and 6.00±0.80℃ for open and closed refrigerators, respectively. Significant changes in color and appearance quality were observed in lettuce, mackerel, ground beef, and cut pineapples when stored in open refrigerators. Ready-to-Eat foods such as gimbap and sandwiches exhibited higher levels of microbiological proliferation when stored in open refrigerators compared to closed refrigerators. Processed foods, such as sterilized milk and packaged tofu, did not show significant differences in quality among various types of refrigerators. The installation of refrigerator doors can effectively minimize temperature fluctuations caused by external factors, thereby reducing variations in food quality. These findings provide essential insights into the quality changes associated with the implementation of refrigerator doors, serving as fundamental data for ensuring optimal food preservation.

• Journal of Microbiology
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• v.45 no.2
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• pp.146-152
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• 2007

A mutant exhibiting decreased cytotoxic activity toward INT-407 intestinal epithelial cells and carrying a mutation in the rtx gene cluster that consists of rtxCA and rtxBDE operons was screened from a library of V. vulnificus mutants. The functions of the rtxA gene, assessed by constructing an isogenic mutant and evaluating its phenotypic changes, demonstrated that RtxA is essential for the virulence of V. vulnificus in mice as well as in tissue cultures.

• Culinary science and hospitality research
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• v.8 no.3
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• pp.249-257
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• 2002

Gamma irradiation(1~10 kGy) was applied to chicken for the evaluation of their microbiological safety. In 3kGy-irradiated sample, the initial level of microbial contamination in chicken was 1.8$\times$10$^4$CFU/g (Coliforms), 2.2$\times$10$^3$CFU/g(Salmonella) and 2.7$\times$10$^3$CFU/g(Listeria), All kinds of contaminated microorganism were sterilized by 7kGy-irradiation. Also, irradiation followed by freeze storage at the same time was very effective in inhibiting bacterial growth. The pH was slightly increased during storage period and titratable acidity decreased. However, no significant changes in pH and acidity were observed by gamma irradiation.

• Journal of Microbiology
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• v.44 no.1
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• pp.1-10
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• 2006

Adaptation to any undesirable change in the environment dictates the survivability of many microorganisms, with such changes generating a quick and suitable response, which guides the physiology of bacteria. During nutritional deprivation, bacteria show a stringent response, as characterized by the accumulation of (p)ppGpp, resulting in the repression of stable RNA species, such as rRNA and tRNA, with a concomitant change in colony morphology. However, genes involved in amino acid biosynthesis become over-expressed to help bacteria survive under such conditions. The survivability of pathogenic bacteria inside a host cell also depends upon the stringent response demonstrated. Therefore, an understanding of the physiology of stringent conditions becomes very interesting in regulation of the growth and persistence of such invading pathogens.

• Korean Journal of Microbiology
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• v.29 no.5
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• pp.270-277
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• 1991

A mutational alteration in the signal sequence of ribose-binding protein (RBP) of Escherichia coli, rbsB103, completely blocks the export of the protein to the periplasm. Intragenic suppressors for this mutation have been selected on minimal medium with ribose as a sole carbon source. Six suppressor mutations were characterized in detail and were found to have single amino acid wubstitution in the mature portion of RBP, which resulted in the mobility shift of the proteins on SDS polyacrylamide gel. Amino acid changes of these suppressors were localized in several peptides which are packed to form the N terminal domain of typical bilobate conformation of RBP. The involvement of SecB, a molecular chaperone, was investigated in the suppression of signal sequence mutation. Translocation efficency was found to be increased by the presence of SecB for all suppressors. It is likely that the folding characteristics of RBP altered by the suppressor mutations affect the affinity of interaction between SecB and RBP.

• Korean Journal of Microbiology
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• v.1 no.1
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• pp.19-25
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• 1963

The studies could be summarized as follows: 1. Standard Rf Values were made as Table II for the identification of amino acids. 2. Amounts of free amino nitrogen in eggs were increased about 0.03% (Table IV) while the amounts of total nitrogen (Table III) were increased lower percentage during the ten days of development. 3. Three unknown substances were found newly during the development. 4. Eight ninhydrine positive amino acids were present, in the fresh embryonic eggs, but the numbers increased to eighteen after fifty days of development. 5. Through the development, there were large amounts of glutamic acid, aspartic acid and alanine. 6. After fifty days development, the amount of amides, such as asparagine, glutamine and alanine were increased very large which were very small amount before it and the amount of asparagine were more than that of glutamine. 7. Tryptophane, Cystine , Histidine were detected after 50 days of development. This is very remarkable fact.

• Korean Journal of Microbiology
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• v.7 no.4
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• pp.143-152
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• 1969

This investigation was proceeded to define the effects of gibberellic acid on the growth of Chlorella by determining the contents of chlorphyll and changes in various components in Chlorella cells according to the concentration of treated GA. The growth of Chlorella was accelerated with telative low concentrations of GA(10, 40 ppm) and was restrained with relative high concentrations of GA(70, 100, 200 ppm). The synthetic ability of chlorophyll of GA was inhibited generally in proportion to the concentration of treated-GA and the higher the concentration of GA was applied, the longer time was required in the restoration. The contents of RNA, protein and soluble carbohydrate were increased PCA-soluble amino acid and polysacharide were decreased in those cell components between the accelerated and restrained group. Consequently, the effect on accelerated growth in relative low concentrations of GA is considered to be caused by the powerful effet on expansion growth of GA. It is presumed that the effect of restrained growth in relative high concentrations of GA is due to the inhibitory effect on the chlorophyll synthesis.

• Journal of Dairy Science and Biotechnology
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• v.31 no.2
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• pp.195-200
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• 2013

The ripening of cheese allows for the development of characteristic taste and flavour, nutritional substances, bio-active components and texture, helping to improve quality. Many different microbiological, biochemical and nutritional changes occur during the process depending on the quality of raw milk, added cultures and enzymes, as well as specific processing and ripening conditions. During the ripening lactose is hydrolyzed to lactic, propionic and acetic acid, helping to reduce potential effects of the problem of lactose intolerance. Fat is hydrolyzed to butyric, propionic and conjugated linoleic acid, which function as bio-active substances. Protein is hydrolyzed to different peptides and amino acids which all show various bio-activities. However, errors of cheese ripening can happen and affect the quality of the product. To guarantee good quality cheese the process needs to be managed carefully with the right microbes used and ensuring cleanliness of processing facilities, staff, ventilation and hazard analysis and critical control points (HACCP). Research into and controlling of ripening technology is crucial for producing high quality cheeses.

• Journal of Microbiology
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• v.34 no.3
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• pp.220-224
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• 1996

Ultrastructural organization of encysting zoospores of Allomyces macrogynus was examined using the methods of cryofixation and freeze substitution. During enxcystment, obvious changes were observed at the surface of the plasma membrane and in the structure of gamma particles. Many multivesicular bodies associated with the plasma membrane were observed at early stages of encystment. After induction of encystment, vesicles were found within the gamma particles. These vesicles appeared to leave gamma particles after forming multivesicular bodies. This study suggests that the cell wall formation during encystment is mediated by the fusion of multivesicular bodies with the plasma membrane.