• Biotechnology and Bioprocess Engineering:BBE
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• 제10권6호
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• pp.522-527
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• 2005

Various processes which produce L-lactic acid using ammonia-tolerant mutant strain, Rhizopus sp. MK-96-1196, in a 3L airlift bioreactor were evaluated. When the fed-batch culture was carried out by keeping the glucose concentration at 30g/L, more than 140 g/L of L-lactic acid was produced with a product yield of 83%. In the case of the batch culture with 200g/L of initial glucose concentration, 121g/L of L-lactic acid was obtained but the low product yield based on the amount of glucose consumed. In the case of a continuous culture, 1.5g/L/h of the volumetric productivity with a product yield of 71% was achieved at dilution rate of $0.024\;h^{-1}$. Basis on these results three processes were evaluated by simple variable cost estimation including carbon source, steam, and waste treatment costs. The total variable costs of the fed-batch and continuous cultures were 88% and 140%, respectively, compared to that of batch culture. The fed-batch culture with high L-lactic acid concentration and high product yield decreased variable costs, and was the best-suited for the industrial production of L-lactic acid.

• 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.

• 대한화학회지
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• 제34권2호
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• pp.203-210
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• 1990

의약 전달체에 사용되는 생체분해성 고분자로서 L-lactic acid 와 L-glutamic acid가 각기 다른 조성비로 이루어진 공중합체를 합성하였다. Poly (L-lactide)는 zink oxide를 이용하여 합성하였으며, Poly (L-lactide) 말단에 3-Amino-l-propanol을 도입시킨 다음 이미 합성된 γ-benzyl-L-glutamate-N-carboxyanhydride (γ-BLG-NCA)를 개환중합시켜서 block copoly (L-lactide-γ-benzyl-L-glutamate)를 합성하였다. NMR로써 L-lactide와 γ-BLG-NCA가 서로 일정한 비율로 이루어진 공중합체가 합성되었음을 확인하였으며, 생성된 공중합체들의 열적성질은 시차주사열량계법 및 열무게 측정법으로 조사하였다.

• 한국미생물·생명공학회지
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• 제30권4호
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• pp.373-379
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• 2002

Nitrile 비대칭 가수분해효소를 지닌 미생물을 이용하여 DL-lactonitrile로부터 D-lactic acid를 생산하기 위하여, DL-acetonitrile을 효소유도제로 이용할 수 있는 균주를 분리하였다. 분리한 균주들 중 WJ-003균주가 D-lactic acid의 생산능력이 가장 우수하였고, Pseudomonas sp.로 부분동정하였다. DL-lactonitrile로부터 D-lactic acid를 생산하기 위한 최적 반응조건을 검토하였으며 결과들을 요약하면 다음과 같다. 반응혼합액은 10mM의 DL-lactonitrile과 20g(wet weight)의 균체를 포함한 11의 20mM 인산완충액(pH7.0)이었으며, 이때 반응온도는 $30^{\circ}C$이었다. 또한, 18시간 반응이 진행되는 동안 0.843 g/l D-lactic acid가 생산되었고, 이때의 전환율은 93.7%,광학순도는 99.8%이었다 한편, 10mM의 DL-lactonitrile을 14시간 후에 다시 첨가했을 때 28시간에 1.64g/l의 D-lactic acid가 생산되었으며 이때의 전환율은 91.1%, 광학순도는 99.8%이었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권4호
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• pp.303-308
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• 2004

We isolated a novel lactic acid bacterium from a Korean traditional fermented food, soybean paste. The newly isolated strain, dubbed RKY2, grew well on glucose, sucrose, galactose, and fructose, but it could not utilize xylose, starch, or glycerol. When the partially amplified 16S rDNA sequence (772 bp) of the strain RKY2 was compared with 10 reference strains, it was found to be most similar to Lactobacillus pentosus JCM $1588^T$, with 99.74% similarity. There-fore, the strain RKY2 was renamed Lactobacillus sp. RKY2, which has been deposited in the Korean Collection for Type Cultures as KCTC 10353BP. Lactobacillus sp. RKY2 was found to be a homofermentative lactic acid bacterium, because its end-product from glucose metabolism was found to be mainly lactic acid. It could produce more than 90 g/L of lactic acid from MRS medium supplemented with 100 g/L of glucose, with 5.2 g $L^-1$ $h^-1$ of productivity and 0.95 g/g of lactic acid yield.

• 환경위생공학
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• 제19권4호
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• pp.69-75
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• 2004

The inhibitory effect of the food processing agent on growth of Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes was performed with hydrogen peroxide and lactic acid, and combination of hydrogen peroxide and lactic acid. The minimun inhibitory concentration (MIC) of hydrogen peroxide in E coli O157:H7 was 100 ppm at pH 5.0, 6.0, 6.5 and 7.0, while in Listeria monocytogenes 25 ppm at PH 5.5, 6.0 and 50 ppm at PH 6.5, 75ppm at pH 7.0. MIC of lactic acid in E coli O157:H7 was 2500 ppm at pH 5.0, 6.0, 6.5 and 7.0. MIC of lactic acid in S. Enteritidis was 1250 ppm at pH 5.0, 2500 ppm at pH 5.5, 6.0, 5.5 and 7.0, while in L monocytogenes 625 ppm at pH 5.5 and 125 ppm at pH 6.0, 6.5 and 7.0. MIC of combined hydrogen Peroxide and lactic acid in E. coli O157:H7, S. Enteritidis, and L. monocytogenes was 75 ppm of hydrogen peroxide with 2500 ppm of lactic acid at pH 6.5. The correlations between MICs of hydrogen peroxide and lactic acid in E. coli O157:H7, S. Enteritidis and L. monocytogene were obtained through the coefficient of $determination(R^2)$. $R^2$ value were 0.9994, 0.9935 and 0.9283, respectively. The inhibitory effect of hydrogen peroxide and lactic acid in E. coli O157:H7, S. Enteritidis and L. monocytogenes could be confirmed from the result of this experiment. Therefore, it was expected that the food process would increase or maintain by using lactic acid together with hydrogen peroxide.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.124-128
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• 2005

This studies were carried out to investigate optimal conditions for Lactic acid bacteria growth, which was grown in a batch fermenter. The optimal temperature was $30^{\circ}C$, optimal pH was 6.5 and agitation speed was 100rpm and didn't supply the air. Used media compositions were yeast extract 5g/L, peptone 10g/L, sugar 20g/L, beef extract 10g/L, tween 80 1ml/L, ammonium citrate 2g/L, sodium acetate 5g/L, magnesium sulfate 0.1g/L, manganese sulfate 0.05g/L, dipotassium phosphate 2g/L. These results would be useful for enhancing lactic acid bacteria concentration.

• Archives of Pharmacal Research
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• 제20권5호
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• pp.443-447
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• 1997

As the growth factor of lactic acid bacteria, LD (trehalose) was isolated from Lentinus edode5 by using silica gel column chromatography. LD induced the growth of Bifidobacteria breve and Lactobacillus brevis, which were isolated from human feces. LD selectively induced the growth of lactic acid bacteria among total microflora. When total intestinal microflora were cultured in the medium containing LD, it stimulated the growth of lactic acid bacteria and inhibited harmful enzymes, ${\beta}$-glucosidase, ${\beta}$-glucuronidase, and tryptophanase, of intestinal bacteria. LM, which was a monosaccharide from L. edooles, induced the growth of lactic acid bacteria but it seems to be invaluable in vivo. LH isolated from L. edodes by Sephadex G-100 column chromatography was not effective for the growth of lactic acid bacteria.

• 한국미생물·생명공학회지
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• 제22권3호
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• pp.277-282
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• 1994

In batch cultures of Lactobacillus delbrueckii, cell growth and lactic acid production were affected by two main factors, inhibition by lactic acid and limitation by nutritional components. In order to increase th productivity significantly, a continuous stirred tank reactor with cell recycle was employed. A cell desnity of 145g dry weight/l and a volumetric productivity of 73 g/l$\cdot $h were obtained with an effluent concentration of 85 g/l lactic acid. The productivity achieved by this system was 23-fold higher than those obtained by the corresponding batch cultivations. Once the lactic acid concentration reached the steady steady state, lowering the yeast extract concentration caused the reduction of the lactic acid concentration without affection the biomass concentration. Finally, the formation of D-lactate was investgated. During the various cultures, a small amount of D-lactate always formed, even thought a majority of lactate was L-isomer, It was supposed that the relative amount of the D-lactate was affected by glucose limitation, and there seems to exist a certain relationship between the concentration of D-lactate and acetate.

• Journal of Dairy Science and Biotechnology
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• 제40권1호
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• pp.15-22
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• 2022

This study evaluated the levels of D(-)-lactate and L(+)-lactate, and the ratio of D(-)-lactate to total lactate (D(-)-lactate + L(+)-lactate) of 15 lactic acid bacteria (LAB) using an enzymatic method. D(-)-lactate and L(+)-lactate levels in the LAB ranged from 0.31 to 13.9 mM and 0.76 to 39.3 mM, respectively, in Bifidobacterium sp.; 1.08 to 11.7 mM and 0.69-13.0 mM in Lactobacillus sp.; 0.72 to 20.3 mM and 0.98 to 32.3 mM in Leuconostoc sp., and 33.0 mM and 39.2 mM in Pediococcus acidilacti KCCM 11747. The ratio of the range of D(-)-lactic acid to total lactic acid was 28.98%-45.76% in Bifidobacterium sp., 41.18%-61.02% in Lactobacillus sp., 29.85%-42.36% in Leuconostoc sp., and 45.71% in P. acidilacti KCCM 11747. In the future, there is a need to test for D(-)-lactate in various fermented products to which different LAB have been added and study the screening of LAB used as probiotics that produce various concentrations of D(-)-lactate.