• Korean Journal of Microbiology
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• v.36 no.2
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• pp.109-111
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• 2000

A 3.5 kb plasmid from Lactobacillus. casei ssp. cosei NCIB 4114 was isolated and E. cali-L. casei shuttle vectors were constructed containing this plasmid. Transformation by electroporation was successful with all the plasmids constructed. Optimized condition for the electroporation was established with efficiency level of $2{\times}10^5$ transformants per $\mu$g of vector DNA. Successful introduction of those shuttle vectors enable to these vectors as food grade vector for lactic acid bacteria.

• Microbiology and Biotechnology Letters
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• v.20 no.1
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• pp.6-13
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• 1992

- Protoplast fusion between lincomycin resistant Lactobacillus casei KCTC 1121 and rifarnpicin resistant Lactobacillus delbrueckii JK-414 was attempted to obtain the improved strains. Protoplasts of L. casei and L. delbrueckii were produced by mutanolysin digestion at $42^{\circ}C$ for 15 min. L. casei cells were converted to protoplasts by treating with 5 $\mu g$ / m l of mutanolysin in 20 mM HEPES buffer (pH 7.0) containing 0.75 M sucrose at the middle logarithmic growth phase. In case of L. delbrueckii 1.0 M sucrose was used osmotic stabilizer. Regeneration of protoplast in both strains was efficiently accomplished on the regeneration medium containing 10% sucrose, 6 mM $MgC1_2, 6 mM CaC1_2$, and 2.5% gelatin. Protoplast fusion between L. casei and L. delbrueckii was carried out in the presence of 40% of PEG 4,000. The frequency of protoplast fusion was found to be about $3.2\times 10^4$. Acid production of L. casei was better than that of L. delbrueckii. Among fusants, F23 and F35 exhibited excellent lactic acid production. F23 and F24 exhibited the improved proteolysis compared to that of the parent strains and they had twice as much as DNA content of the parents.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.577-583
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• 1994

To classify Lactobacillus casei strains on the basis of difference in their chromosomal DNA sequence, we have performed polymerase chain reactions on their chromosomal DNA by using random primers, and followed by analyzing randomly amplified polymorphic DNA fragments. We also developed a mini-preparative method to isolate PCR-grade chromosomal DNA from Lacto- bacillus casei strains within 3 hours. Based on RAPD pattems by polymerase chain reactions with degenerated random primers, 4 Lactobacillus casei strains and 2 mutant strains were successfully discriminated. Results were very sensitive, strain-specific and reproducible. It was also reliable. These results suggest that RAPD may be applied efficiently for the identification of several Lactoba- cillus casei strains.

• Journal of Microbiology and Biotechnology
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• v.5 no.5
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• pp.257-263
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• 1995

As a first step for developing Lactobacillus strains capable of fermenting starch directly, the $\alpha$-amylase gene (amyL) from Bacillus licheniformis (Kim et al., 1988. Kor. J. Appl. Microbiol. Bioeng. 16: 369-373) was introduced into Lactobacillus casei strains and the level of $\alpha$-amylase expression in transformants was examined. 3 kb EcoRI fragments encompassing amyL were subcloned into the suitable lactococcal cloning vectors (pSA3, pMG36e, and p1L2530) and then recombinant plasmids were introduced into E. coli and L. casei strains by electroporation. Only one recombinant plasmid, $pIL2530\alpha$ was able to transform few L. casei strains tested at low efficiencies. The transformation efficiencies with the plasmid into L. casei YIT 9018 and L. casei A Tee 4646 were less than $10^2/\mu$ g pIL2530\alpha$. The level of amylase activities in L. casei was five to ten-fold lower than that in E. coli cells. $p1L2530\alpha$ was stably maintained in Lactobacillus strains in the presence of Em (5 $\mu $g/ml) but without antibiotic selection, it was unstable so more than 95$%$ of cells lost plasmids after a week of daily subculturing.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.8
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• pp.1352-1359
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• 2020

Objective: Lactobacilli in rabbit intestine is rare and its function in rabbit gut health is not fully understood. The present study aimed to evaluate in vivo the probiotic potential of Lactobacillus casei for suckling rabbits. Methods: Two healthy 5-day-old suckling rabbits with similar weights from each of 12 New Zealand White litters were selected and disturbed to control group and treatment group. All rabbits were artificially fed. The treatment group had been supplemented with live Lactobacillus casei in the milk from the beginning of the trial to 13 days of age. At 15 days of age, healthy paired rabbits were slaughtered to collect intestinal samples. Results: i) Oral administration of Lactobacillus casei significantly increased the proportion of Lactobacilli in the total intestinal bacteria (p<0.01) and obviously reduced that of Escherichia-Shigella (p<0.01); ii) treatment increased the length of vermiform appendix (p<0.05); iii) a higher percentage of degranulated paneth cells was observed in the duodenum and jejunum when rabbits administered with Lactobacillus casei (p<0.01); and iv) the expression of toll-like receptor 9, lysozyme (LYZ), and defensin-7-like (DEFEN) in the duodenum and jejunum was stimulated by supplemented Lactobacillus casei (p<0.05). Conclusion: Orally administered Lactobacillus casei could increase the abundance of intestinal Lactobacilli, decrease the relative abundance of intestinal Escherichia-Shigella, promote the growth of appendix vermiform, stimulate the degranulation of paneth cells and induce the expression of DEFEN and LYS. The results of the present study implied that Lactobacillus casei exhibited probiotic potential for suckling rabbits.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.467-476
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• 1994

Lactobacillus casei HY 2782, prophage cured strain was characterized to be stable as much as L casei YIT 9018, parent strain. By southern hybridization, it was confirmed that the temperate phage was incorporated in chromosomal DNA of L. casei YIT 9018 as a prophage. It was also proved that the prophage was cured from chromosomal DNA of L casei HY 2782. The growth rate, lactic acid producing ability, carbohydrates fermentation, and enzymatic activity of L. casei HY 2782 were found to be similar to those of L. casei YIT 9018. When L casei HY 2782 was used as a host, the multiplicity of infection (M.O.I.) of the temperate phage for L. casei HY 2782 was 1.0~5.0. Restriction enzyme analysis of pLC90 plasmid from L. casei HY 2782 was shown that the size was an approximately 68.22 kb. The plasmid profiles, genomic DNA patterns, and cellular fatty acids composition of L. casei HY 2782 were similar to those of L casei YIT 9018. And the major fatty acids composition of these strains were C$_{14;0}$,C$_{16;1}$, C$_{16;0}$, C$_{18;1}$ and C$_{19;cyclo-}$ 10 sets of arbitrary primer in the PCR were screened to find differentiation against two strains of L. casei. Among them, b$_{5}-1/17-1 primer was produced an approximately 1.3 kb DNA band of only L casei YIT 9018. And b$_{5}-2/17-2 primer was produced an approximately 1.0 kb DNA band of only L casei HY 2782.

• Biomedical Science Letters
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• v.7 no.1
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• pp.27-30
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• 2001

We have examined if lactic acid bacteria could suppress the toxic effect of bisphenol A. Lactobacillus casei YA-70 was chosen as representative. Thirty rats were divided into two groups (immature and mature) according to the weight. Each group was divided again into the control group (only alcohol treatment), bisphenol A treated group, and bisphenol A plus Lactobacillus casei YA-70 treated group. When 500 ppm of bisphenol A was fed everyday, 83% of immature group and 50% of mature group died within 3 weeks. Their internal organs, mainly livers and lungs, were changed in color and severely damaged. In the intestine of 5 ppm-fed group tumor-like nodules were observed. However, their number and size were markedly decreased when Lactobacillus casei YA-70 was supplemented in diet. This study strongly indicates that Lactobacillus casei YA-70 might play an important role to suppress the toxic effect of endocrine disruptor.

• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1953-1957
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• 2008

Recombinant Lactobacillus strains have been constructed using gene splicing by overlap extension (SOE). Primers were designed of which one end of an amplified product contained complementary sequences for an end of other amplified fragment. For efficient matching, we used an asymmetric PCR step that was effective at generating an excess of strands that would anneal in the final PCR. CP12, a recombinant fragment consisting of the integrase gene and attachment site of the bacteriophage A2, was constructed and inserted into the genome of Lactobacillus casei ATCC 393, yielding Lb. casei ATCC 393::XCP12. Another recombinant Lb. casei strain was constructed, where the egfp gene was a part of the construction. The EGFP produced from Lb. casei ATCC 393::XCEGFP14 was detected by Western blot hybridization. This simple and widely applicable approach has significant advantages over standard recombinant DNA techniques for Lactobacillus species.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.188-193
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• 1989

Gene for lactose catabolism in Lactobacillus casei SW-M1 was encoded by a 60Kb metabolic plasmid. A derivative of only 10kb, pPlac 15 of recombinant plasmid, was constructed by introducing into pBR322 and was cloned into E. coli using restriction endonuclease Pst I. A 10kb insery DNA in plasmid pBR322 was identified as a gene encoded phospho-$\beta$-galactosidase by the determination of enzyme activity. Phospho-$\beta$-galactosidase was apparently expressed in E. coli. The enzyme activities of cell-free extract from transformant E. coli HB101 carrying pPLac 15 DNA were not different from that of L. casei as a donor strain on the basis of enzyme properites. However, specific activity of phospho-$\beta$-galactosidase in the cloned strain with Lac $Y^{-}$ phenotype of E. coli HB101 was lower than that in L. casei strain.

• International Journal of Oral Biology
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• v.39 no.1
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• pp.35-40
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• 2014

Halitosis is caused by consumption of certain foods or drinks and production of volatile sulfur compounds (VSCs) by periodontopathogens. VSCs-related halitosis is not easily removed using mechanical or chemical therapies such as dental floss, plaque control and mouth rinse. Lactobacillus are known to be probiotics and stimulate immune systems of human. Furthermore, L. casei ATCC 334 and L. rhamnosus GG have an effect on protection of dental caries in vitro studies. The aim of this study was to investigate effect of Lactobacillus on halitosis by Fusobacterium nucleatum- and Porphyromonas gingivalis-producing VSCs and to analyze inhibitory mechanism. The periodontopathogens were cultivated in the presence or the absence Lactobacillus, and the level of VSCs was measured by gas chromatograph. For analysis of inhibitory mechanisms, the susceptibility assay of the spent culture medium of Lactobacillus against F. nucleatum and P. gingivalis was investigated. Also, the spent culture medium of Lactobacillus and periodontopathogens were mixed, and the emission of VSCs from the spent culture medium was measured by gas chromatograph. L. casei and L. rhamnosus significantly reduced production of VSCs. L. casei and L. rhamnosus exhibited strong antibacterial activity against F. nucleatum and P. gingivalis. The spent culture medium of L. casei inhibited to emit gaseous hydrogen sulfide, methyl mercaptan and dimethyl sulfide from the spent culture medium of periodontopathogens. However, the spent medium of L. rhamnosus repressed only dimethyl sulfide. L. casei ATCC 334 may improve halitosis by growth inhibition of periodontopathogens and reduction of VSCs emission.