• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.452-459
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• 2003

In previous study, we have isolated Lactobacillus spp. from healthy human vagina and examined various characteristics such as antimicrobial substance production and exopolysaccharide (EPS) production. It is known that an EPS is an important factor of Lactobacillus spp. to adhere to epithelial cell. We have selected L. paracasei KLB58 having high antimicrobial activity and EPS production. In this study, we performed NTG (1-Methyl-3-nitro-1-nitrosoguanidine) mutagenesis to isolate an EPS deficienct mutant of KLB58 showing high cell surface hydrophobicity (CSll) compared to wild type strain. By monitoring the kinetics of the partition with hexadecane the EPS mutant was found to be far more hydrophobic than the wild type strain ; the CSH of the EPS mutant was 0.5-fold higher than the wild type strain.

• KSBB Journal
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• v.23 no.1
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• pp.18-22
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• 2008

Various probiotic Lactobacillus spp. are known to produce exopolysaccharide (EPS) which has potential health promoting functionality. A Lactobacillus paracasei strain producing EPS was isolated from healthy human. This strain, named L. paracasei KLB58, was grown on modified MRS medium. Experiments were conducted under various growth conditions to optimize the EPS production. Our study showed that incubation temperature played an important role in EPS production. When incubation temperature was changed from $37^{\circ}C$ to $25^{\circ}C$, the increase of EPS production (28.1 mg/ml) was the highest in our experiment. The type of carbon source in the medium also affected EPS production. Galactose was the most effective for EPS production among the carbon sources examined. Using galactose, glucose, lactose and sucrose, the amount of released EPS was 38.9 mg/ml, 35.6 mg/ml, 21.76 mg/ml and 16.9 mg/ml, respectively. However, acidity in growth medium inhibited EPS productivity due to the low growth yield. When grown at pH 4, L. paracasei KLB58 could only produce EPS of 14.6 mg/ml. When the initial amounts of nitrogen and carbon sources were examined, EPS production was not significantly affected by nitrogen source while carbon source affected considerably.

• KSBB Journal
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• v.18 no.1
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• pp.14-18
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• 2003

In this study of the simultaneous saccharification and fermentation (SSF) of paper sludge, fed-batch cultivation of Lactobacillus paracasei subsp. paracasei KLB58 was attempted to produce viable KLB58 cells and lactic acid. Optimal culture conditions, including the temperature and concentration of the supplemented enzyme, were examined in terms of lactic acid production and viable cell count. When the effects of culture temperature and $\beta$-glucosidase concentration were examined in fed-batch SSF, the highest viable cell counts and lactic acid production (i.e. 5$\times$$10^9$ CFU/ml and 45 g/L, respectively) were obtained at 37$^{\circ}C$ and 2 unit/ml of $\beta$-glucosidase.

• KSBB Journal
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• v.24 no.2
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• pp.182-188
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• 2009

Lactobacillus spp., primary members of probiotics, have significant benefits for health and well-being of human. In this study Lactobacillus strains representing six species (L. paracasei KLB58, L. fermentum MS79 and KLB282, L. plantarum KLB213, L. gasseri KLB238, and L. reuteri KLB270) isolated from Korean adults were electrotransformed with plasmid pNCKH104. To determine optimal electrotransformation conditions, various conditions including cell wall weakening agent, electroporation buffer, electric field strength and time constant were tested for each strain. Overall, high transformation efficiency of approximately 2.5 ${\times}$ $10^3$ ${\sim}$ 5.5 ${\times}$ $10^4$ CFU/${\mu}g$ DNA was obtained where conditions of 0.5 M sucrose electroporation buffer, 1.8 kV pulse voltage and 5 ms time constant were applied. The common conditions developed in this study will make transformation of various Lactobacillus spp. easier than previous procedures.