• Food Science of Animal Resources
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• v.44 no.5
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• pp.1011-1027
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• 2024

Animal-derived foods, such as meat and dairy products, are prone to spoilage by psychrotrophic bacteria due to their high-water activity and nutritional value. These bacteria can grow at refrigerated temperatures, posing significant concerns for food safety and quality. Psychrotrophic bacteria, including Pseudomonas, Listeria, and Yersinia, not only spoil food but can also produce heat-resistant enzymes and toxins, posing health risks. This review examines the characteristics and species composition of psychrotrophic bacteria in animal-derived foods, their impact on food spoilage and safety, and contamination patterns in various products. It explores several nonthermal techniques to combat bacterial contamination as alternatives to conventional thermal methods, which can affect food quality. This review highlights the importance of developing nonthermal technologies to control psychrotrophic bacteria that threaten the cold storage of animal-derived foods. By adopting these technologies, the food industry can better ensure the safety and quality of animal-derived foods for consumers.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.3
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• pp.193-197
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• 2003

Psychrotrophic characteristics of Listeria monocytogenes YM-7 showed similar growth at $8^{\circ}C$ as L. monocytogenes ATCC 15313. But it showed different growth pattern at $4^{\circ}C.$ Thus the isolated strain from the Patient can not grow at $4^{\circ}C,$ while L. monocytogenes ATCC 15313 grow slowly. Number of the injured cells of L. monocytogenes YM-7 was higher at $-3^{\circ}C$ than at $-18^{\circ}C$ in phosphate buffer solution. The rate of the injured cell was higher in the TSB (tryptic soy broth) medium than in phosphate buffer solution at $-3^{\circ}C$ and $-18^{\circ}C.$ When L. monocytogenes YM-7 stored at $-18^{\circ}C$ in homogenized fish muscle, the cell numbers decreased by 2-3 log cycles in 12 weeks.

• Journal of Food Hygiene and Safety
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• v.12 no.1
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• pp.9-14
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• 1997

Vibrio mimicus is a closely related species with V. cholerae, and has been reported to be associated with gastrointestinal infections. Although extraintestinal infections of these vibrios have also been reported in Japan and Southeast Asia. But little research papers on V. mimicus was reported in Korea. Therefore, we tried to isolate V. mimicus from the environmental sea water from April to July in Pusan, Korea. Among the isolated strains, we selected the strongest hemolytic strain and then named V. mimicus SM-9. In this paper, we checked the antibiotic susceptibility and psychrotrophic characteristics of the isolated strain. Hemolytic activity of the hemolysin produced by the isolated strain was also measured. V. mimicus was not detected from the sea water samples in April and May, but its detection rate was relatively high in June and July in Pusan, Korea. The bacteriological characteristics of V. mimicus SM-9 were Gram-negative rods, motile, oxidase positive, Voges-Proskauer negative and sucrose negative. In 23 kinds of antibiotics susceptibility test, V. mimicus SM-9 showed susceptibility to the most of antibiotics submitted while it was resistive against lincomycin, oxacillin, rifampin and vancomycin. Hemolytic activity of the hemolysin produced by V. mimicus SM-9 was highest in stationary phase of the growth curve in BHI broth at 37$^{\circ}C$ and its activity was reached 18 HU per $m\ell$ of culture supernatant. For checking the psychrotrophic property of V. mimicus SM-9, the decreasing rate of the strain in phosphate buffer solution and yellowtail flesh homogenate was examined during the storage at 4, 0, -4 and -2$0^{\circ}C$. The decreasing rates of the selected strain stored in phosphate buffer solution were greater than those in fish homogenate. Decreasing rates of V. mimicus SM-9 stored in phosphate buffer solution were not significantly different by the storage temperatures. The viable cell counts of the strain were decreased as 5 log cycles after 120 hours at all the tested temperatures. While decreasing numbers of the strain in fish homogenates were 2*4 log cycles after 120 hours. The decreasing pattern of the strain numbers were very slow after 200 hours at all the stored temperatures.

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.66-73
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• 1993

Psychrotrophic bacterial strains utilizing crude oil as their sole carbon and energy sources were isolated from Antarctic soil and sea sediments. One of the strains named AI-I showed the hightest activity for emulsification of crude oil and the best growth. This strain was identified as Acinetobacter calcoaceticus. A. calcoaceticus AI-I strain contains a plasmid (OCT plasmid) which was related to the utilization of alkane compounds. The molecular weight of this plasmid was estimated to be about 110 Md by agarose gel electrophoresis. The cured strain of A. calcoaceticus AI-I strain (OCT ) was not able to utilize normal hydrocarbon compounds ($C_6C_{17}$) as carbon and energy sources. A. ca/coaceticus AI-1 was resistant to ampicillin and sensitive to streptomycin, kanamycin, chloramphenicol, tetracycline. The results suggested that this strain carries a plasmid (OCT) responsible for oil utilization which is quite stable and might be concerned with antibiotics resistancy.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1066-1075
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• 2023

Kimchi is a traditional Korean fermented vegetable that is stored and fermented at low temperatures. However, kimchi lactic acid bacteria (LAB) are typically isolated under mesophilic conditions, which may be inappropriate for isolating the diverse LAB. Therefore, this study investigated the suitable conditions for isolating various LAB from kimchi. Here, LAB were isolated from four kimchi samples using MRS, PES, and LBS media and varying isolation temperatures (30, 20, 10, and 5℃). Then, MRS was selected as the suitable medium for LAB isolation. A comparison of culture-dependent and culture-independent approaches indicated that 5℃ was not a suitable isolation temperature. Thus, the number and diversity of LAB were determined at 30, 20, and 10℃ using 12 additional kimchi samples to elucidate the effect of isolation temperature. With the exception of two samples, most samples did not substantially differ in LAB number. However, Leuconostoc gelidum, Leuconostoc gasicomitatum, Leuconostoc inhae, Dellaglioa algida, Companilactobacillus kimchiensis, Leuconostoc miyukkimchii, Leuconostoc holzapfelii, and Leuconostoc carnosum were isolated only at 10 and 20℃. The growth curves of these isolates, except Leu. holzapfelii and Leu. carnosum, showed poor growth at 30℃. This confirmed their psychrotrophic characteristics. In Weissella koreensis, which was isolated at all isolation temperatures, there was a difference in the fatty acid composition of membranes between strains that could grow well at 30℃ and those that could not. These findings can contribute to the isolation of more diverse psychrotrophic strains that were not well isolated under mesophilic temperatures.

• Journal of the East Asian Society of Dietary Life
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• v.6 no.2
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• pp.187-194
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• 1996

Changes of the growth of microorganisms, pH, and TBA values were examined for chickens treated with 5% potassium sorbate, 5% sodium acid pyrophosphate, and mixture of 2.5% potassium sorbate and 2.5% sodium acid pyrophosphate solution during 15 days at 4$^{\circ}C$. Treatment of the mixture solution inhibited synergistically the growth of mesophilic and psychrotrophic bacteria and suppressed effectively enteric bacilli. Potassium sorbate treatment was the most effective on inhibition of the growth of yeast and mold. The extension of lag phase for psychrotrophic bacteria and enteric bacilli was observed by the treatment of the mixture solution of potassium sorbate plus sodium acid pyrophosphate and the potassium sorbate solution. PHs of chickens were increased during the storage, which might induce the decline of antimicrobial effect. Sodium acid pyrophosphate was expected to give antioxidant effect as well as antimicrobial effect for high fat foods because the lowest increase of TBA value for chickens treated nth sodium acid pyrophosphate was measured.

• Food Science of Animal Resources
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• v.34 no.6
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• pp.815-821
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• 2014

The effects of ultraviolet (UV) radiation were investigated with regards to the microbial growth inhibitory effect on the shelf life of Korean native cattle (Hanwoo) beef prior to refrigerated storage. The Hanwoo samples were exposed to UV radiation ($4.5mW/cm^2$) for 0, 5, 10, 15, and 20 min. The UV-irradiated beef that was exposed for 20 min showed significantly reduced mesophilic and psychrotrophic bacterial populations to the extent of approximately 3 log cycles, as compared to that of non-irradiated beef. About 2.5 Log CFU/g of mesophilic bacteria were different compared with UV-irradiated and non-irradiated meat. UV irradiation showed the most significant growth inhibition effects on mesophilic and psychrotrophic bacteria. Coliform and Gram-negative bacteria were also reduced by 1 log cycle. The population of L. monocytogenes, S. Typhimurium, and E. coli O157:H7 decreased significantly to 53.33, 39.68, and 45.76% after 10 min of UV irradiation. They decreased significantly to 84.64, 80.76, and 84.12%, respectively, after 20 min of UV irradiation. The results show that UV irradiation time and the inhibitory effect were proportional. These results verified that UV radiation prior to refrigeration can effectively reduce the number of pathogenic bacteria on the surface of meat and improve the meat's microbial safety.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.506-515
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• 1995

The cultural characteristics of 60 strains of psychrotrophic lactic acid bacteria which were isolated from kimchi, a Korean traditional fermented vegetable food, and identified as Leuconostoc mesenteroides subsp. mesenteroides, Leu. mesenteroides subsp. dextranicum, Leu. paramesenteroides, Leu. lactis, Lactobacillus bavaricus and Lac. homohiochii were tested. All strains grew at $5^{\circ}C,\;10^{\circ}C\;and\;37^{\circ}C$ in tomato glucose broth, but not at $45^{\circ}C$. The optimum growth temperature of Leu. mesenteroides and Lactobacillus sp. were $33{\sim}34^{\circ}C\;and\;34{\sim}36^{\circ}C$, respectively. All strains of Leu. mesenteroides and Lactobacillus sp. grew at 4.8 and 4.2 of initial pH, but not at 4.0. The final pH of Leu. mesenteroides and Lactobacillus sp. in glucose broth were $3.84{\sim}4.10\;and\;3.82{\sim}3.99$, respectively. None of the 60 strains clotted milk nor reduced litmus in litmus milk. All strains of Leu. mesenteroides and Lactobacillus sp. grew in tomato glucose broth containing 7% ethanol or 6.5% NaCl, but not in the broth containing 15% ethanol or 10% NaCl. All strains grew in tomato glucose broth containing 40% bile juice and survived in the artificial gastric juice of pH 3.5. Furthermore, all strains of Leu. mesenteroides survived in the artificial gastric juice of pH 3.0. Since many strains of lactic acid bacteria tested in this study showed differences in several physiological characteristics from those described in Bergey's Manual of Systematic Bacteriology, it was considered that further tests would be necessary to clarify their positions in taxonomic system.

• Journal of Microbiology
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• v.41 no.1
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• pp.58-62
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• 2003

An extracellular pretense of Bacillus amyloliquefaciens S94 was purified to apparent homogeneity. The enzyme activity was strongly inhibited by general inhibitor for serine protease, PMSF, suggesting that the enzyme is a serine pretense. The purified enzyme activity was inhibited by leucine peptidase inhibitor, bestatin, suggesting that the enzyme is a leucine endopeptidase. The maximum proteolytic activity against different protein substrates occurred at pH 10, 45$^{\circ}C$ (protein substrate) and pH 8, 45$^{\circ}C$ (synthetic substrate). The purified enzyme was specific in that it readily hydrolyBed substrates with Leu or Lys residues at P$_1$ site. The pretense had characteristics of a cold-adapted protein, which was more active for the hydrolysis of synthetic substrate in the range of 15$^{\circ}C$ to 45$^{\circ}C$, specially at low temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1153-1156
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• 2012

Daegwallyeong area to be formed along the mountainous terrain more above 800 m of sea level is known as the cold zone to occur frequently wind, rain and fog. This study to evaluate the stability of crop production and agricultural production potential in the Daegwallyeong was calculated for the low temperature frequency of occurrence and potential evapotranspiration changes with announce the release of Korea Meteorological Administration (KMA) from 1972 to 2009 up to 38 years. Evapotranspiration calculated FAO and other international standard method authorized under the PENMAN-MONTEITH Method was used, and the low temperature onset and frequency of the Gumbel probability density function was used. As a result, the variation of day evaporation for 38 years were showed to respectively width of variation from maximum $9mm\;day^{-1}$ to minimum $0.5mm\;day^{-1}$. The frequency of reappearance to first emergence day that lasts more than 5 days with temperature $5^{\circ}C$ over is 3 April a 50-year frequency, 10 April a 25-year frequency, 20 April a 10-year frequency, 28 April a 5-year frequency, 8 May a 2-year frequency. Psychrotrophic crop to growth temperature more than $5^{\circ}C$ can be secured to stable production with planting after May 8, prior to planting for normal growth can be seen that the risk of growth.