• 한국축산식품학회지
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• 제30권1호
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• pp.154-162
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• 2010

This study was carried out to compare the efficacy and selectivity of TOS and BS media for enumeration of bifidobacteria in commercial fermented milk products. First, bifidobacteria was isolated from 20 fermented milk products, and all isolated bifidobacteria were identified by genomic technology as Bifidobacterium lactis. The two media significantly differed from each other with regard to the recovery of B. lactis, that is, the recovery of this organism was as much as 6 logs lower on BS medium than on TOS. When the concentration of BS solution (mixture of paromomycin sulfate, neomycin, sodium propionate, and lithium chloride) used in BS medium was reduced to 50% (BS50), a relatively high percentage recovery of bifidobacteria from pure cultures was achieved. Susceptibility tests to antibiotics and tests for selective agents for the isolated bifidobacteria and lactic acid bacteria were conducted. The BS solution inhibited some lactic acid bacteria and Bifidobacterium species, while mupirocin (MU) suppressed the growth of all tested lactic acid bacteria but not Bifidobacterium. As compared with BS50 medium, TOS with or without MU showed good bifidobacteria recovery and readily distinguishable colonies; in particular, TOS supplemented with MU had a high selectivity for bifidobacteria. In conclusion, all results suggested that TOS medium with or without MU was found to be suitable for selective enumeration of bifidobacteria from mixed cultures in fermented milk, and better in that capacity than BS medium.

• 한국식품과학회지
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• 제26권5호
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• pp.526-531
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• 1994

한국인의 장내 균총 조사를 하던 중 Bifidobacterium 선택배지로 개발된 Mitsuoka의 BS배지에서 상당수의 Bifidobacterium이 사멸되는 것으로 나타났다. 이에 보다 개량된 Bifidobacterium의 선택배지를 조제하기 위하여 한국인들로부터 Bifidobacterium들을 비선택 배지및 기존의 선택배지에서 분리한 뒤 동정하였다. 분리 동정된 균주들에 대하여 항생제와 대사저해제에 대한 감수성 조사 및 특이 기질검사를 하여 선택배지 조제의 기초 자료로 활용하여 Bifidobacterium이 선택적으로 자랄 수 있는 배지로 TP배지를 고안하였다 TP배지는 상용되는 Mitsuoka의 BS배지보다 Bifidobacterium 선택성이 우수하였고 colony 성장속도도 빨랐다.

• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.81-88
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• 2015

This study describes a novel strategy to regulate the metabolic flux for lactic acid production in Lactobacillus casei. The ldhL gene encoding _L-lactate dehydrogenase (L-LDH) was overexpressed in L. casei, and a two-stage oxygen supply strategy (TOS) that maintained a medium oxygen supply level during the early fermentation phase, and a low oxygen supply level in the later phase was carried out. As a consequence, a maximum L-LDH activity of 95.6 U/ml was obtained in the recombinant strain, which was over 4-fold higher than that of the initial strain. Under the TOS for L. casei (pMG-ldhL), the maximum lactic acid concentration of 159.6 g/l was obtained in 36 h, corresponding to a 62.8% increase. The results presented here provide a novel way to regulate the metabolic flux of L. casei for lactic acid production in different fermentation stages, which is available to enhance organic acid production in other strains.

• Plant Resources
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• 제8권1호
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• pp.60-66
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• 2005

Lysine is the first essential amino acid for optimal nutrient quality in rice grain. For the narrow genetic diversities of lysine contents in rice, somaclonal variation was the source of mutation in our breeding program. Biochemical selection was conducted using 1 mM S-(2-aminoethyl) cysteine followed by two passages of 5 mM lysine plus threonine in the callus subculture medium. The lysine contents in endosperm of all progenies recovered from the biochemical selection were higher than those of their donor cultivar 'Hwayeongbyeo'. These elevated lysine levels of mutants were successfully transmitted to $M_4$ generation. The lysine contents in endosperm varied 3.85 to $4.80\%$ compare to their donor cultivar 'Hwayeongbyeo' was $3.85\%$. Three of high-lysine germplasms, Lys-l, Lys-2 and Lys-7 were selected by biochemical selection and rapid screening methods. DNA analysis showed that a new insertion of Tos 17 which mapped to rice chromosome 11 on the high-lysine mutant, Lys-2.