• Korean Journal of Microbiology
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• v.51 no.4
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• pp.407-418
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• 2015

This study is focused on establishing the optimal conditions to enhance the production of antilisterial substances by Lactobacillus paracasei BK57 isolated from Baikkimchi. In addition, the growth and in situ lactic acid and bacteriocin production of this strain were investigated during the manufacture of fresh cheese. And then the efficacy of using Lactobacillus starter as a protective culture to improve the safety of fresh cheese against Listeria monocytogenes KCTC 3569 was estimated. Maximum growth rate and activity of antibacterial substances were obtained in Lactobacilli MRS broth at $37^{\circ}C$ with controlled pH 6.0 after 30 h of incubation under aerobic condition. However, the growth rate and antimicrobial activity of bacteriocin produced in whole milk supplemented with yeast extract (2.0%) as a substrate were lower than those obtained in MRS broth. Live cells and cell-free culture supernatant of BK57 strain were effective in the suppression of L. monocytogenes in milk, whereas the inhibitory of the bacteriocin obtained from BK57 strain was higher in BHI broth than in milk. During storage at $4^{\circ}C$ and $15^{\circ}C$ for 6 days, no significant difference was found in the cell viability and antimicrobial activity of BK 57 strain in fresh cheese. In samples held at two temperatures, there was at least a 15% reduction in the numbers of the pathogen in fresh cheese artificially contaminated with approximately $10^5CFU/ml$ of L. monocytogenes within 6 days. Our results demonstrated the usefulness of L. paracasei BK57 having antilisterial activity as a biopreservative in the cheese making process.

• Korean Journal of Microbiology
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• v.52 no.4
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• pp.398-405
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• 2016

The Schizosaccharomyces pombe structural gene encoding bacterioferritin comigratory protein (BCP) was previously cloned using the shuttle vector pRS316 to generate the BCP-overexpressing plasmid pBCP10. The present work aimed to evaluate the thermoresistant properties of BCP against high temperature stress using the plasmid pBCP10. When the S. pombe cells were grown to the early exponential phase and shifted from $30^{\circ}C$ to $37^{\circ}C$ or $42^{\circ}C$, the S. pombe cells harboring pBCP10 grew significantly more at both $37^{\circ}C$ and $42^{\circ}C$ than the vector control cells. After 6 h of the shifting to higher incubation temperatures, they contained the lower reactive oxygen species (ROS) and nitrite content, an index of nitric oxide (NO), than the vector control cells. After the temperature shifts, total glutathione (GSH) content and total superoxide dismutase (SOD) activities were much higher in the S. pombe cells harboring pBCP10 than in the corresponding vector control cells. Taken together, the S. pombe BCP plays a thermoresistant role which might be based upon its ability both to down-regulate ROS and NO levels and to up-regulate antioxidant components, such as total GSH and SOD, and subsequently to maintain thermal stability.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.7
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• pp.974-981
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• 2002

Faba beans (vicia faba) (FB) and lupin seeds (Lupinus Albus) (LS) were dry roasted at three temperatures (110, 130, $150^{\circ}C$) for 15, 30 or 45 min to determine the effects of dry roasting on rumen degradation of crude protein and starch free organic matter ($^{PSF}OM$). Rumen degradation characteristics of $^{PSF}OM$ were determined by the nylon bag incubation technique in dairy cows fed 60% hay and 40% concentrate. Measured characteristics of $^{PSF}OM$ were undegradable fraction (U), degradable fraction (D), soluble fraction (S), lag time (T0), and the rate of degradation (Kd). Based on the measured characteristics, rumen availability ($RA^{PSF}OM$) and bypass $^{PSF}OM$ ($B^{PSF}OM$) were calculated. Dry roasting did not have a greater impact on rumen degradation characteristics of $^{PSF}OM$ (p>0.05). S varied from 32.1 (raw) to 30.0, 27.8, 30.8% (LS) and 15.4 (raw) to 14.4, 20.8, 20.9% (FB); D varied from 65.4 (raw) to 66.3, 66.9, 55.9% (LS) and 54.9 (raw) to 55.0, 51.0, 64.7% (FB); U varied from 2.6 (raw) to 7.3, 7.0, 7.7% (LS) and 29.7 (raw) to 30.6, 28.2, 14.4% (FB); Kd varied from 6.0 (raw) to 7.3, 7.0, 7.7% (LS) and 22.4 (raw) to 24.4, 21.1, 7.9% (FB); $B^{PSF}OM$ varied from 35.5 (raw) to 33.8, 36.6, 38.2% (LS) and 41.3 (raw) to 41.5, 39.7, 47.6% (FB) at 110, 130 and $150^{\circ}C$, respectively. Therefore dry roasting did not significantly affect $RA^{PSF}OM$, which were 353.7, 367.9, 349.6, 336.9 (g/kg DM) (LS) and 12.82, 127.0, 133.7, 117.1 (g/kg DM) (FB) at 110, 130 and $150^{\circ}C$, respectively. These results alone with our previously published reports indicate dry roasting had the differently affected pattern of rumen degradation characteristics of various components in LS and FB. It strongly increased bypass crude protein (BCP) and moderately increased starch (BST) with increasing temperature and time but least affected $^{PSF}OM$. Such desirable degradation patterns in dry roasted LS and FB might be beneficial to the high yielding cows which could use more dry roasted $^{PSF}OM$ as an energy source for microbial protein synthesized in the rumen and absorb more amino acids and glucose in the small intestine.

• Research in Plant Disease
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• v.19 no.2
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• pp.95-101
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• 2013

Black rot caused by Xanthomonas campestris pv. campestris (Xcc) is one of the most serious diseases of crucifers world-wide. To establish the efficient screening method for resistant cabbage to Xcc, different inoculation methods, inoculation positions, growth stages of seedlings, and incubation temperatures after inoculation were investigated with the seven cabbage cultivars showing different resistance degrees to the pathogen. Clipping with mouse-tooth forceps was better inoculation method than piercing with 18 pins or cutting with scissors to distinguish the level of resistance and susceptibility. In inoculation using mouth-tooth forceps, clipping the edges of the leaves near veins is more effective than injuring the veins of the leaves directly. In addition, the inoculated plants kept at $22^{\circ}C$ showed more clear resistant and susceptible responses than those kept at 26 or $30^{\circ}C$. On the basis of the results, we suggest that an efficient screening method for resistance of cabbage cultivars to black rot is to clip the edges of the leaves near veins of the four-week-old seedlings with mouth-tooth forceps dipped in a suspension of Xcc at a concentration of $7{\times}10^7$ cfu/ml and incubate the inoculated plants in a growth room at $22^{\circ}C$ with 12-hr light a day.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.2
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• pp.77-83
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• 2020

A series of foamed plastic sheets containing biomass (as HMR container) were developed via different foaming process temperatures, and their density, porosity, WVTR, and pore morphology were evaluated. Thermal stability of samples during re-heating the food in oven, change in morphology, density, porosity, and WVTR were investigated using a simulated thermal shock process according to MIL-STD-883E assay. As such, the pore size of samples was generally increased with increasing temperature of the foaming process. It can be explained that as foaming temperature increased, the viscosity of molten resins and the repulsive force against pore expansion decreased. In addition, an increase in the thermal shock cycle reduced the pore size and WVTR, while density increased because high temperature treatment that softened the sheet matrix was followed by a low temperature incubation, which contracted the matrix, thereby changing the physical and morphological properties of samples. However, an insignificant change in density was observed and WVTR tended to be decreased, indicating that as-prepared foamed plastic sheets could be used as a high thermal stable container for HMR application. Therefore, it found that the properties of newly developed HMR containers containing biomass were dependent on the foaming process temperature. Moreover, to better understanding of these newly developed containers, further investigations dealing with foaming process temperature based on various food items and cooking conditions are needed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.1
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• pp.1-8
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• 2012

The objective of the present study was carried out to clarify the effects of deep sea water on the growth and maturation of $Porphyra$ (Rhodophyta, Bangiales). Foliose thalli for indoor culture were collected from Yeongok ($P.$ $okamurae$) in Gangwon Prefecture, Tongyeong ($P.$ $suborbiculata$ f. $latifolia$) and Namhae ($P.$ $yezoensis$ f. $narawaensis$) in Gyongnam Prefecture respectively. Monospores were cultured at five temperatures (5, 10, 15, 20 and $25^{\circ}C$) with a photon irradiance of $80{\mu}m^{-2}s^{-1}$ under photoperiods of 14L:10D and 10L:14D in surface, deep and mixed seawater in respectively. The fast growth of foliose thalli were observed in $P.$ $suborbiculata$ f. $latifolia$ cultured at deep seawater under $15^{\circ}C$ and 10L:14D. In three species, the optimum growth occurred at 10 and $15^{\circ}C$ under deep and mixed seawater and short day-length. In general, monospores from the cultured thalli were liberated within three weeks after incubation under $10-25^{\circ}C$ and both photoperiods. From the result of this study, deep seawater is considered that the natural species of the genus $Porphyra$ can be useful for the development as the new cultivars.

• Journal of Food Hygiene and Safety
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• v.28 no.2
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• pp.174-180
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• 2013

This study investigated the microbiological contamination of tomato in cultivation and distribution stage. Growth of Escherichia coli O157:H7 and Listeria monocytogens examined in tomato extracts (0.1, 1.0, and 10.0%) and incubation temperatures (5, 15, 25, and $35^{\circ}C$). In cultivation stage of tomato, total aerobic bacteria were 7.77 log CFU/g in gloves of APC (Agricultural Products Processing Center) worker and Bacillus cereus were 0.33 log CFU/g at nutrient tank, respectively. And Staphylococcus aureus, Salmonella spp., were not detected. After APC stage, total aerobic bacteria were significantly higher compared with before-APC stage. Among of general, pesticide-free and organic produce in tomato were no significant difference in microbial contamination. Coliforms of tomato in small vinyl package were significantly higher when compared to tomato in whole boxes package. There was no significant difference in bacteria count between unwashed tomato and washed tomato using tap water for one minute. The growth of E. coli O157:H7 and L. monocytogens in tomato extracts were decreased significantly as the concentration increased, and the microbial population was reached the lowest point during storage in 10% tomato extracts concentration for 72h at $5^{\circ}C$. However, the population of E. coli O157:H7 and L. monocytogens were gradually increased at 7.33~8.51 and 7.73~8.60 log CFU/ml during storage at $15{\sim}35^{\circ}C$ for 72h, respectively.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.313-318
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• 2016

Bacteria in the viable but nonculturable (VBNC) state fail to produce colonies on routine bacteriological media, but are still alive in the state of very low metabolic activity. The aim of the present study was to induce the VBNC state of the Edwardsiella tarda using sea water microcosm under starvation conditions at $10^{\circ}C$ and to investigate resuscitation of the VBNC cells in temperatures changed from 10 to $25^{\circ}C$, with and without additives. E. tarda entered into the VBNC state within about 42-84 days of incubation in the microcosm. Throughout this period, the total cell counts as determined using acridine orange direct counting remained near the original inoculum level of ${\sim}10^8cells/ml$. The live cell counts measured with direct viable counting, on the other hands, declined to ${\sim}10^4cells/ml$. When the VBNC cells were incubated with addition of yeast extract, fish muscle extract or serum at $25^{\circ}C$, the ratios of resuscitated samples were 37%, 23%, and 37%, respectively. The characteristics of resuscitated E. tarda were consistent with those of the original E. tarda. When the resuscitated E. tarda were intraperitoneally injected into olive flounders, all fishes died within 5 days, indicating that the VBNC E. tarda might retain its pathogenic potential. Therefore, E. tarda under starvation conditions in the winter enter into the VBNC state and the VBNC E. tarda cells resuscitated at summer and autumn seawater temperature are considered to be pathogen continuously to olive flounder on the southern coast of Korea.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.484-489
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• 1997

The characteristics of growth and esterase activity of bacterial strains isolated from acid hydrolysed soybean protein were examined. All the isolated strains having decomposition activity of p-hydroxybenzoic acid butyl ester and esterase producing activity were identified as Bacillus sp. by morphological and biochemical methods. The specific growth rates, esterase activities and p-hydroxybenzoic acid butyl ester decomposition activities of isolated strains were $0.844{\sim}1.213\;h^{-1}$, $21{\sim}222\;mU/ml$ and $5.4{\sim}8.1\;mU/ml$, respectively. In the fermentation of Bacillus sp. KB8 strain which had the highest esterase producing activity, growth, extracellular excretion and intracellular synthesis of esterase were inhibited by adding NaCl in the culture broth. Esterase producing activity gradually increased after late exponential growth phase, until maximum value of 420 mU/ml reached after 64 hours culture period. Esterase of Bacillus sp. KB8 strain was stable up to $50^{\circ}C$ for 30 minutes, but was inactivated by heating for 30 minutes at $70^{\circ}C$. The enzyme activity exponentially decreased during the incubation time at the temperatures of $60^{\circ}C$ and $65^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.120-126
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• 1989

Streptococcus diacetylactis and Leuconostoc cremoris were isolated from commercial culture and the effects of culture conditions on the diacetyl production by these strains and their mixture(1:1) were investigated. Optimum temperatures and culture times for the diacetyl production by Str. diacetylactis, Leu, cremoris and their mixture were 60hr at $22^{\circ}C$(diacetyl content, 2.24ppm), 48hr at $22^{\circ}C$(2.29ppm) and 48hr at $22^{\circ}C$ (2.21ppm), respectively Optimum initial pH for the diacetyl production by Str. diacetylactis, Leu. cremoris and the mixture were all 4.8(4.32, 6.66, 7.30ppm, respectively) and optimum sodium citrate concentrations(%, w/v) were 0.30(2.58ppm), 0.1(2.54ppm) and 0.1(2.52ppm), respectively. The diacetyl contents were gradually increased according as inoculation rates(%, w/v) were increased. The amounts of diacetyl produced under optimum conditions at 24hr incubation by Str. diacetylactis, Leu. cremoris and the mixture were 4.40, 6.59 and 7.25ppm, respectively. The most effective factor affecting diacetyl production under optimum condition was pH.