• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.3
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• pp.202-206
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• 2000

The genetically-engineered Escherichia coli strain, DPD2540, which contains a fabA:::luxCDAbefusion gene, gives a bioluminescent output when membrane fatty acid synthesis is needed. For more pactical application of this strain in the filed as biosensor, freezedrying was adopted. A 12% surcrose solution with Luria-Bertani (LB) broth, as determined by the viability after freeze-drying, was found to be most most effective composition for lyophilization solution among various compositions testitons tested. Rapid freezing with liquid nitrogen also gave the best viability after freeze-drying as compared to samples frozen at-7$0^{\circ}C$ and -2$0^{\circ}C$. The biosensing activities of the cells showed a greater sensitivity when the cells from the expontial phase were freeze-dried. Finally, the optimum temperature for use of the freeze-dried cells in the biodencor field was determined.

• Journal of Microbiology and Biotechnology
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• v.32 no.12
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• pp.1599-1604
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• 2022

Storage stability of freeze-dried lactic acid bacteria is a critical factor for their cost-effectiveness. Long-term storage of lactic acid bacteria enables microbial industry to reduce distribution costs. Herein, we investigated the effect of cold adaptation under supercooling conditions at -5℃ on the viability of Leuconostoc mesenteroides WiKim32 during the freeze-drying process and subsequent storage. Cold adaptation increased the thickness of exopolysaccharides (EPS) and improved the viability of freeze-dried Leu. mesenteroides WiKim32. Compared to non-adapted cells, cold-adapted cells showed a 35.4% increase in EPS thickness under supercooling conditions. The viability of EPS-hydrolyzed cells was lower than that of untreated cells, implying that EPS plays a role in protection during the freeze-drying process. Cold adaptation increased the storage stability of freeze-dried Leu. mesenteroides WiKim32. Fifty-six days after storage, the highest viability (71.3%) was achieved with cold adaptation at -5℃. When EPS-containing broth was added prior to the freeze-drying process, the viability further increased to 82.7%. These results imply that cold adaptation by supercooling pretreatment would be a good strategy for the long-term storage of Leu. mesenteroides WiKim32.

• Food Science of Animal Resources
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• v.34 no.4
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• pp.448-456
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• 2014

Studies on the flavour characteristics of meat-based broth, quantification of flavour-related and functional compounds, and factors affecting the availability of such compounds are minimal. The present study was designed to determine the effects of sex on flavor-related and functional compounds in freeze-dried broth (FDB) made from Korean native chickens (KNC). Male and female KNC from a commercial strain (Woorimatdag$^{TM}$) were reared under similar commercial conditions. FDB was separately prepared using male and female birds aged 100 d (six birds of each sex) and analyzed for nucleotide, free amino acid, betaine, carnitine, carnosine, anserine, and creatine contents, and fatty acid composition. The levels of betaine, carnitine and creatine in FDB were not significantly different between the two sexes (p>0.05) in KNC. Carnosine and anserine were not detected in FDB samples. However, FDB from female chickens had significantly higher inosine-5-monophosphate and arachidonic acid contents than did FDB from male chickens. FDB prepared with male KNC contained higher levels of inosine, linoleic acid, glycine, alanine, lysine, and serine (p<0.05). However, glutamic acid, oleic acid, and DHA were present in comparable amounts (p>0.05) in FDB made from male and female KNC. Our findings suggest that the sex of KNC has significant effect on the contents of flavor-related compounds, but not functional compounds.

• Korean Journal of Microbiology
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• v.36 no.1
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• pp.74-78
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• 2000

Vibrio, Photobacterium, Alteromonas and Xenorhabdus species are capable of emitting light, called bioluminescence. They exist in marine, freshwater and terrestrial environments. Bacterial bioluminescent reaction is that reduced riboflavin phosphates and a long-chain aldehyde are oxidized in the presence of molecular oxygen and enzyme luciferase. This experiment aims to develop the proper culture media and to optimize the storage condition for the recovery of bioluminescent activity in Photobacterium phosphoreum. The Luria broth (LB) medium was modified for cultivation of Photobacterium phophoreum, called as modified LB(mLB) medium. The mLB medium is LB fortified with 3% glycerol and 1.5% NaCl. In mLB medium. bacterial growth and bioluminescent activity are 25% higher than those in a Nutrient broth medium. When the cell stocks were stored at $-20^{\circ}C$, $-70^{\circ}C$ and LN2 for 3 months, cell growth and bioluminescent activity of culture after stored at $-20^{\circ}C$ were better than those of other treatments. The highest bioluminescent activity obtained at the late exponential phase in all treatments. When the cell stock was freeze-dried with 5% adonitol as a cryoprotectant, the recovery of cell was better than those of control and freeze-dried cell stock without addition of cryoprotectant.

• Microbiology and Biotechnology Letters
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• v.26 no.3
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• pp.200-205
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• 1998

A probiotic-strain of Lactobacillus sp. was cultured in bovine blood plasma-based (BBPB) medium and freeze-dried to prepare a probiotic product as an animal feed additive. The cell mass produced in the medium, $5.2{\times}10^9$ CFU/ml, was high enough to be commercialized and was 74% of that in MRS medium. The survival rate of tactobacillus sp. against freeze-drying was affected by the conditions for treatment of cultured BBPB broth before freeze-drying such as pH adjustment, volume reduction and freezing rate. It was also found that the blood protein hydrolysate remaining in broth also enhanced the survival rate. Among various protective substances, sucrose showed a high stabilizing effect with 10% (w/v) addition, by which the maximum survival rate (48.3%) and viable cell count ($3.0{\times}10^{10}$ CFU/g) were obtained.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.390-393
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• 2000

In this work, effects of trehalose on the recovery of bioluminescence and viability of luxAB-containing recombinant bacteria were investigated. In case of a recombinant, UV2, only 2.5% of bioluminescence and 2.7% of cell viability were restored after 3.5hr of freeze-drying without trehalose, which implies that cells were heavily damaged during the dehydration. To improve these losses, trehalose was added before freeze-drying on different modes. Trehalose increased the bioluminescence and viability of freeze-dried UV2 in all conditions tested and it was observed that addition of trehalose into the broth(final concentraion, 0.08M) for 15min before the freeze-drying resulted in 45% of bioluminescence and 50% of cell viability. For the other luminescent recombinant, YH9, trehalose showed a similar efficacy.

• Journal of Environmental Health Sciences
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• v.35 no.2
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• pp.95-99
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• 2009

This study was performed to investigate the possible effect of garlic produced in Korea on the inhibition/reduction of growth of A. parasiticus, a toxigenic strain. The effect was studied using different concentrations of freeze-dried garlic in potato-dextrose agar (PDA) and/or in yeast-extract sucrose (YES) broth at $25^{\circ}C$ for 15 days. While inhibition of the fungal growth due to increasing the concentration of garlic was observed, the more remarkable effect was observed on the ninth day. Reduction of fungal diameter as a result of addition of garlic on PDA was observed to range between 3.4% to 20.1 % while reduction of mycelial weight in YES broth ranged from 9.9% to 30.5%. The 0.5% and 1.0% concentrations of garlic significantly reduced fungal diameter in PDA on the 9th day, while 0.1 %, 0.5%, and 1.0% concentrations of garlic significantly reduced the mycelial weight in YES broth (p<0.05). Dose-response relationships were observed between the concentration of garlic and inhibition of growth both in solid culture and in liquid culture. This study indicates that garlic could be an effective inhibitor at a human consumption level of the growth of A. parasiticus. More research is needed to study the inhibitory effects of the main active component of garlic.

• Korean journal of applied entomology
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• v.54 no.2
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• pp.55-62
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• 2015

'Bt-Plus' has been developed by mixing spores of Bacillus thuringiensis (Bt) and culture broth of Xenorhabdus nematophila (Xn). Despite its high toxicity, it has some imitation to broaden its efficacy against diverse insect pest spectrum. This study focuses on enhancement of Bt-Plus toxicity against semi-susceptible insect, Spodoptera exitgua, by addition of Xn metabolites. Two main Xn metabolites, oxindole (OI) and benzylideneacetone (BZA), are known to enhance the Bt insecticidal activities. The addition of OI or BZA significantly increased Bt-Plus pathogenicity. However, when the freeze-dried Xn culture broth was added to Bt-Plus, much less amount was enough to enhance the toxicity compared to the amount of OI or BZA. An HPLC analysis indicated that there were more than 12 unidentifed bacterial metabolites in Xn culture broth. These suggest that there are potent biological response modifiers in Xn metabolites other than OI and BZA.

• Microbiology and Biotechnology Letters
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• v.29 no.1
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• pp.56-61
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• 2001

For the development of probiotics in aquaculture of marine organisms, three strains having psychrophilic and salt tolerant characteristics were isolated from Kimchi. Amng the isolated strains. MG19, MG89 and MG208 were identified as Lactobacillus brevis, Enterococcus faecium and Lactobacillus plantarum, respectively. The neutralized culture broth of isolated strains were tested in order to evaluate the antibactrial activity, 조초 showed high antibacterial activity against Edwardsiella tarda, Vibrio cholerae andPseudomonas fluorescens. In mixed culture of pathogens and isolated strain,pathogens were signifi-cantly inhibited after 2 days of cultivation but the isolated strains showed normal growth. When the Edwardsiella tarda was cultured with three isolated strains, its growth was completely inhibited after 254 hours of cultivation. The effect of isolated three strains as probiotics was investigated based on the changes in body weight of aquacultured flounder. After 50 days feeding trial, it was found that the mean body weight gain of the tested group fed freeze-dried isolated cells was significantly greater than that of the control group. These results suggest that these isolated strains can play an important role as probiotics in aquaculture.

• The Korean Journal of Food And Nutrition
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• v.17 no.3
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• pp.286-293
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• 2004

Extract of Eleutherococcus senticosus, Lycium chinensis, Angelica acutiloba and Schizandra chinensis were investigated to determine whether its addition may inflict on growth of lactic acid bacteria, freeze dry and cell viability during the storage. In cultivation with herbal extract, all strains tested did not demonstrate a significant reduction in their cell population, particularly Lactobacillus. acidophilus, L. bulgaricus, L. paracasei. But Schizandra chinensis extract inhibited growth of several strains. Immediately after freeze-drying using the skim milk 10%(w/v), sucrose 5%(w/v) with herbal extract 2.5%(v/v), the percentage viability was about 81.7%, 63.8%, 73.2%, 78.1 % in L. acidophilus, L. bulgaricus, L. paracasei, L. casei respectively. The protective effect of herbal extract to cell damage from freeze-drying was weak in comparison with control. During accelerated storage of freeze-dried lactic acid bacteria, those survival rate decrease rapidly, reaching 8 -18% in one month. But addition of Eleutherococcus senticosus extract in freeze dry of L. acidophilus showed a positive activity in storage.