• 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.

• 한국식품저장유통학회지
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• 제19권6호
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• pp.933-938
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• 2012

막걸리 양조시 품질변화 방지를 목적으로 젖산 첨가량에 따른 주모의 pH, 총산, ethanol 및 미생물 균수를 측정하고, 젖산 농도에 따른 주모별 막걸리를 제조하여 이화학적 및 관능평가 등 품질특성을 확인한 결과는 다음과 같다. 젖산 농도에 따른 주모의 pH는 젖산 0.5% 이상 첨가 시료구가 pH 3.31~3.33으로 젖산 무첨가구와 0.3% 첨가 시료구의 pH 3.52, 3.56에 비해 낮았다. 총산 함량은 젖산 무첨가구와 젖산 0.3%첨가 주모가 0.56%와 0.54%로 높게 나타났고, 0.5%첨가 주모는 0.51%로 가장 낮은 함량을 보였다. Ethanol 함량은 젖산을 첨가하지 않은 주모와 젖산을 첨가한 주모 모두 유의적 차이를 보이지 않았다. 주모의 미생물의 균수를 측정한 결과는 세균 및 젖산균은 젖산 첨가량이 증가할수록 감소하였고, 효모는 젖산을 첨가하지 않은 대조구와 비교해 0.3~0.5% 첨가구는 증가하였으나 0.7~1.0% 첨가구는 감소하였다. 젖산 첨가량에 따른 주모로 담금한 막걸리의 pH 및 총산은 0.5% 이상 첨가구에서 발효기간 동안 안정된 값을 보여 주모의 안전 제조에 적합한 조건을 보였다. 유기산은 lactic acid의 함량이 가장 높았고, succinic acid, tartaric acid, citric acid 및 acetic acid가 검출되었다. acetic acid는 젖산을 첨가하지 않은 시료구의 경우 390.88 mg%로 함량이 가장 높았고 젖산 첨가량이 증가할수록 낮았으며, 1.0% 첨가 시료구의 경우 검출되지 않았다. Ethanol 함량은 시료구별 차이를 보이지 않았고, 관능평가 결과 젖산 0.5%이상 첨가구부터 향, 맛 및 종합기호도에서 선호도가 좋은 결과를 보였다. 이러한 결과를 볼 때 젖산을 첨가하지 않은 주모에 비해 젖산을 첨가하여 주모를 제조할 경우 막걸리의 품질이 더 향상될 것으로 판단되며, 젖산량은 주모 중량대비 0.5%첨가가 적당할 것으로 사료된다.

• KSBB Journal
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• 제14권5호
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• pp.566-571
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• 1999

최근 들어 카르복실산 중에서 lactic acid는 생분해성 고분자의 원료물질로서 주목받고 있다. 본 연구에서는 혼합 3차 amine 추출제를 이용한 반응추출을 통해 lactic acid를 정제하였다. 다양한 TPA/TOA 혼합비에 따라 lactic acid의 분배계수를 얻었으며 그 결과 8:2의 혼합비에서 최대의 분배계수를 얻을 수 있었다. 또한 발효조에서 생산되는 lactic acid를 대상으로 하였을 때 혼합 3차 amine을 사용할 경우 추출효율이 90% 이상이 되는 것을 볼 때 본 연구에서 사용된 혼합 3차 amine이 발효 lactic acid의 정제에 적합한 추출제임을 알 수 있었다.

• KSBB Journal
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• 제19권5호
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• pp.410-414
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• 2004

Fed-batch cultures of Enterococcus faecalis RKY1 were performed to maximize the L(+)-Iactic acid concentration in the bioreactor. The highest lactic acid concentration was obtained at around 225 g/L by intermittent feeding the concentrated glucose media containing 500 g/L of glucose and 15 g/L (or 75 g/L) of yeast extract. However, in all fed-batch cultures, volumetric productivities of lactic acid gradually decreased due to the inhibitory effect of lactic acid produced during the fermentation. The highest value of lactic acid concentration obtained in this work corresponded to around 1.5-fold increase compared with conventional batch fermentation.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.181-185
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• 2005

We investigated the fermentative production of lactic acid from cheese whey and corn steep liquor as cheap raw materials using Lactobacillus sp. RKY2 to reduce the manufacturing cost of lactic acid. Lactic acid yields were obtained at more than 0.98 g/g from medium containing whey lactose. Lactic aid productivities and yields obtained from whey lactose were slightly higher than those obtained from pure lactose. The final concentration of lactic acid increased with increase, in whey lactose concentration, whereas the lactic acid productivity decreased probably due to substrate inhibition. The fermentation efficiencies were improved by addition of more corn steep liquor to the medium.

• Journal of Chest Surgery
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• 제12권4호
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• pp.395-402
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• 1979

Intracellular pH was determined by distribution of 5.5-dimethyl-2,4-oxazolidlnedione [DMO]in the skeletal muscle of dogs before and after lactic acidosis induced by intravenous infusion of lactic acid solution. After infusion of lactic acid solution arterial pH decreased from 7.40 to around 7.12 [P<0.001]and metabolic acidosis was induced. However, dose-pH change response was not proportional as in the case of hydrochloric acid infusion. During lactic acidosis, intracellular pH changed very little except when venous blood $pCO_2$ increased significantly. The decrease of intracellular pH in lactic acidosis might be due primarily to the increase of intracellular $pCO_2$. And during lactic acidosis, change of extracellular pH was larger than that of intracellular pH, and this was also the case of change In hydrogen Ion concentration in extracellular and intracellular fluid. The fact was estimated that exogenous lactic acid transported into the cell does not contribute to pH change by the participation in the metabolism. Change in plasma potassium Ion concentration was not eminent as metabolic acid-base disturbances by other origin, and changing pattern of Hi/He ratio was not same as Ki/Ke ratio. In spite of no changes in extracellular potassium ion concentration after exogenous lactic acidosis total amount of potassium ion in extracellular fluid increased from 12.62mEg to 18.26mEg [P< 0.05].

• 한국버섯학회지
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• 제11권4호
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• pp.187-193
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• 2013

A galactose fermentation bacterium producing lactose from red seaweed, which was known well to compromise the galactose as main reducing sugar, was isolated from button mushroom bed in Buyeo-Gun, Chungchugnamdo province. The lactic acid bacteria MONGB-2 was identified as Lactobacillus paracasei subsp. tolerans by analysis of 16S rRNA gene sequence. When the production of lactic acid and acetic acid by L. paracasei MONGB-2 was investigated by HPLC analysis with various carbohydrates, the strain MONGB-2 efficiently convert the glucose and galactose to lactic acid with the yield of 18.86 g/L and 18.23 g/L, respectively and the ratio of lactic acid to total organic acids was 1.0 and 0.91 g/g for both substrates. However, in the case of acetic acid fermentation, other carbohydrates besides galactose and red seaweed hydrolysate could not be totally utilized as carbon sources for acetic acid production by the strain. The lactic acid production from glucose and galactose in the fermentation time courses was gradually enhanced upto 60 h fermentation and the maximal concentration reached to be 16-18 g/L from both substrates after 48 h of fermentation. The initial concentration of glucose and galactose were completely consumed within 36 h of fermentation, of which the growth of cell also was maximum level. In addition, the bioconversion of lactic acid from the red seaweed hydrolysate by L. paracasei MONGB-2 appeared to be about 20% levels of the initial substrates concentration and this results were entirely lower than those of galactose and glucose showed about 60% of conversion. The apparent results showed that L. paracasei MONGB-2 could produce the lactic acid with glucose as well as galactose by the homofermentation through EMP pathway.

• Preventive Nutrition and Food Science
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• 제4권4호
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• pp.236-240
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• 1999

The characteristics of natural lactic acid fermentation of radish juice were investigated at different salt concentrations (0~2%) and temperatures (10~3$0^{\circ}C$). Major lactic acid bacteria isolated from the radish juice fermented at 2% slat concentration were Leuconostoc mesenteroides, Lactobacillus plantarum, and Lactobacillus brevis. The percentage of lactic acid bacteria against total microbe in the fermented radish juice was over 80% at 0~1% salt concentrations, suggesting the possibility of fermentation even at low salt concentration, but was still active even at 1$0^{\circ}C$. The time to reach pH 4.0 during fermentation of juice of 1% salt concentration was 281~301 hrs at 1$0^{\circ}C$ and 50-73 hrs at 3$0^{\circ}C$. The concentrations of sucrose and glucose in the fermented juice were low at high temperatures and were the lowest at a 1.0% salt concentration. However, the content of mannitol showed the opposite trend. Although sour taste, ripened taste, and acidic odor of the fermented juice showed no significant differences among various temperatures and salt concentrations, sensory values of ripened taste and sour acidic were high at high temperatures. The overall quality was the best at 1.0% salt concentration, irrespective of the temperature.

• Journal of Microbiology and Biotechnology
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• 제26권7호
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• pp.1182-1189
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• 2016

Lactobacillus brevis ATCC 14869 exhibited a carbon catabolite derepressed phenotype that has ability to consume fermentable sugars simultaneously with glucose. To evaluate this unusual phenotype under harsh conditions during fermentation, the effects of lactic acid and hydrogen ion concentrations on L. brevis ATCC 14869 were examined. Kinetic equations describing the relationship between specific cell growth rate and lactic acid or hydrogen ion concentration were deduced empirically. The change of substrate utilization and product formation according to lactic acid and hydrogen ion concentration in the media were quantitatively described. Although the simultaneous utilization has been observed regardless of hydrogen ion or lactic acid concentration, the preference of substrates and the formation of two-carbon products were changed significantly. In particular, acetic acid present in the medium as sodium acetate was consumed by L. brevis ATCC 14869 under extreme pH of both acid and alkaline conditions.

• KSBB Journal
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• 제31권1호
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• pp.85-89
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• 2016

Lactic acid fermentations were conducted using water hyacinth. It is known that the pretreatment and enzyme hydrolysis process optimize the potential of water hyacinth. Lactic acid produced by using lactic acid bacteria. All cells were grown at $37^{\circ}C$ and initial pH 5.5. Lactic acid production was measured by HPLC. All Lactobacillus strains could produce lactic acid from pretreated water hyacinth. The highest lactic acid was achieved when lactic acid fermentation was carried out by L. delbrueckii for D-form and L. helveticus for L-form lactic acid production. The lactic acid concentration was 10.70 g/L by L. delbrueckii and it converted glucose in the medium to lactic acid, almost perfectly. Lactic acid production became higher when fermentation was carried out at a controlled pH 5.5. Lactic acid yield and productivity were 0.52 g/g and 0.19 g/L/h for L. helveticus, while L. delbrueckii was 0.64 g/g and 0.27 g/L/h. This study showed that water hyacinth medium could be alternative medium which can replace the complex and expensive medium for growing Lactobacillus strains in production of lactic acid.