• Food Science and Biotechnology
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• 제15권6호
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• pp.948-953
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• 2006

The D-form of lactic acid is frequently detected in fermented foods, and an excessive dietary intake of D-lactic acid may induce metabolic stress in both infants and patients. This work was carried out to determine the prevailing microorganisms relevant to the accumulation of D-lactic acid in kimchi. Leuconostoc (Leuc.) mesenteroides and Leuc. citreum primarily synthesized D-lactate with a small quantity of L-form. Leuc. gelidum and Leuc. inhae evidenced patterns similar to this. Lactobacillus (Lb.) plantarum and Lb. brevis were shown to convert glucose into a balanced mixture of D-/L-lactic acid, whereas Lb. casei principally synthesized L-lactic acid and a very small quantity of D-lactic acid. When kimchi was incubated at 8 or $22^{\circ}C$, D-lactic acid was over-produced than L-form. Leuconostoc was determined as the primary producer between the initial to mid-phase of fermentation and Lb. plantarum or Lb. brevis seemed to boost D-lactic acid content during later stage of acid accumulation.

• 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.

• KSBB Journal
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• 제30권4호
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• pp.161-165
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• 2015

Lactic acid and its derivatives are widely used in the food, pharmaceutical, and cosmetic industries. It is also a major raw material for the production of poly-lactic acid (PLA), a biodegradable and environmentally friendly polymer and a possible alternative to synthetic plastics derived from petroleum. For PLA production by new strains of lactic acid bacteria (LAB), we screened LAB isolates from shellfish. A total of 51 LAB were isolated from 7 types of shellfishes. Lactic acid production of individual isolates was examined using high-performance liquid chromatography using a Chiralpak MA column and an ultraviolet detector. Lactobacillus plantarum T-3 was selected as the most stress-resistant strain, with minimal inhibition concentrations of 1.2 M NaCl, 15% ethanol, and 0.0020% hydrogen peroxide. In a 1 L fermentation experiment, $\small{D}$-lactic acid production of 19.91 g/L fermentation broth was achieved after 9 h cultivation, whereas the maximum production of total lactic acid was 41.37 g/L at 24 h.

• 대한의생명과학회지
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• 제11권4호
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• pp.539-543
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• 2005

Elevated level of serum cholesterol in humans is a risk factor correlated with the development of coronary heart disease. We have screened lactic acid bacteria from pig and human feces for the development of probiotics which have an anti-cholesterol effect. We have used special media to isolate only lactic acid bacteria and they were subjected to the experiments such as oxgal test, carbohydrate fermentation test. Results from the acid tolerance test and growth test in the presence of oxgal demonstrated that some strains would likely survive in thuman stomach, where acidity is high, and in small intestine, where bile fluid is present. In conclusion, we were able to screen lactic acid bacteria which were tolerant against bile acid and supposed to be prominent to lower the cholesterol level in human serum.

• Journal of Microbiology and Biotechnology
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• 제24권12호
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• pp.1664-1672
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• 2014

In this study, a fibrous bed bioreactor (FBB) was used for $\small{D}$-lactic acid ($\small{D}$-LA) production by Sporolactobacillus inulinus Y2-8. Corn flour hydrolyzed with ${\alpha}$-amylase and saccharifying enzyme was used as a cost-efficient and nutrient-rich substrate for $\small{D}$-LA production. A maximal starch conversion rate of 93.78% was obtained. The optimum pH for $\small{D}$-LA production was determined to be 6.5. Ammonia water was determined to be an ideal neutralizing agent, which improved the $\small{D}$-LA production and purification processes. Batch fermentation and fed-batch fermentation, with both free cells and immobilized cells, were compared to highlight the advantages of FBB fermentation. In batch mode, the $\small{D}$-LA production rate of FBB fermentation was 1.62 g/l/h, which was 37.29% higher than that of free-cell fermentation, and the $\small{D}$-LA optical purities of the two fermentation methods were above 99.00%. In fe$\small{D}$-batch mode, the maximum $\small{D}$-LA concentration attained by FBB fermentation was 218.8 g/l, which was 37.67% higher than that of free-cell fermentation. Repeate$\small{D}$-batch fermentation was performed to determine the long-term performance of the FBB system, and the data indicated that the average $\small{D}$-LA production rate was 1.62 g/l/h and the average yield was 0.98 g/g. Thus, hydrolyzed corn flour fermented by S. inulinus Y2-8 in a FBB may be used for improving $\small{D}$-LA fermentation by using ammonia water as the neutralizing agent.

• Asian-Australasian Journal of Animal Sciences
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• 제17권3호
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• pp.394-400
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• 2004

To investigate the efficacy of alternatives to antibiotics, the present study was conducted to compare the effects of antibiotic, lactic acid, a blend of commercial essential oils (EOs) and EOs in combination with lactic acid on growth performance and the functional activity of the gut in broiler chickens. A total of 168 broiler chickens were given the basal diet supplemented with 10 ppm colistin (T1), 0.1% lactic acid (T2), 25 ppm EOs (T3), 25 ppm EOs+0.1% lactic acid (T4), 50 ppm EOs (T5) or 50 ppm EOs+0.1% lactic acid (T6) in the period 3 to 35 days of age. As a result, the broiler chickens assigned to T4 group throughout the experimental period had apparently (p<0.05) greater body weight and total gain than these assigned to T1, T2, T3 and T5 groups. However, there was no difference in growth performance among the birds fed the diets supplemented with antibiotic (T1), lactic acid (T2) and EOs (T3 and T5) alone. The weights of digestive organs and the number of lactobacilli and E. coli in the lower ileum were not affected by dietary treatments. Total trypsin activity was significantly (p<0.05) greater in T4 than T1, T2, T3 and T5 groups. Total and specific pancreatic $\alpha$-amylase activities were significantly (p<0.05) enhanced in the broiler chickens fed T4 diet compared with these fed T1, T2 and T3 diets. However, there were no differences in growth performance and digestive enzyme activities including pancreatic trypsin and $\alpha$-amylase between T4 and T6 groups fed the diets supplemented with either low or high EOs levels in combination of lactic acid. In conclusion, a blend of commercial EOs combined with lactic acid showed significant increases in digestive enzyme activities of the pancreas and intestinal mucosa, leading to increase in growth performance.

• Preventive Nutrition and Food Science
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• 제12권1호
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• pp.58-63
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• 2007

Bifidobacteria are probiotic organisms that provide both flavor and health benefits when incorporated as live cultures into commercial dairy products. Because bifidobacteria are very sensitive to environmental conditions (acids, temperature, oxygen, bile salts, the presence of other cultures, etc.), their viability in human gastrointestinal tract is limited. The microencapsulation of bifidobacteria is a process to protect them against harsh environmental conditions, thereby increasing their viability while passing through human gastrointestinal tract. To confirm the survival rate of microencapsulated Bifidobacterium breve CBG-C2 in milk, their survival rate was compared with several kinds of free bifidobacteria and lactic acid bacteria in commercial yogurt products under simulated gastric and small intestinal conditions. Double-microencapsulation of the bacteria was employed to increase the survival rate during digestion. The outer layer was covered with starch and gelatin to endure gastric conditions, and the inner layer was composed of a hard oil for the upper small intestinal regions. Almost all microencapsulted bifidobacteria in the milk survived longer than the free bifidobacteria and lactic acid bacteria in the commericial yogurt products under the simulated gastric conditions. Numbers of surviving free bifidobacteria and lactic acid bacteria in the commercial products were significantly reduced, however, the viability of the microencapsulated bificobacteria in the milk remained quite stable under gastric and small intestine conditions over 3$\sim$6 hrs. Thus double-microencapsualtion of bifidobacteria in milk is a promising method for improving the survival of bifidobacteria during the digestive process.

• 한국초지조사료학회지
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• 제15권4호
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• pp.285-290
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• 1995

This experiment was conducted to investigate the effects of wheat bran addition on the fermentative quality and dry matter digestibility(Dh4D) of rye silage. This hexbage was ensiled by the conventional methods in small glass silo of 0.82 liter with addition of wheat bran of 0%, 5%. 01%, and 15%. mpectivery.The samples of rye silage were determined the pH, lactic acid, acetic acid and butyric acid. The DMD was evaluated by pepsin-cellulase technique method. The energy values (total digestible nutrients. TDN : digestible energy, DE : metabolizable energy, ME) were calculated by DMD. The results obtained were as follows : 1. The pH and butyric acid of rye silage were reduced with increasing of wheat bran addition, but the contents of lactic acid and total acid were increased. 2. TDN, DE and ME were increased with high rate of wheat bran addition. 3. Regression equation and correlation coefficients between Flieg's score(X) and DMD(Y) of silage were Y =48.7+0.157X(r=0.917, p<0.01). 4. Regression equation and correlation coefficients between level of wheat bran(X) and Flieg's score(Y) of silage were Y= 18.3+5.56X(r=0.929, p<0.01).

• Asian-Australasian Journal of Animal Sciences
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• 제18권9호
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• pp.1273-1278
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• 2005

This study is to evaluate the effect of different levels of ensiling density on the fermentation quality of guineagrass silages during the early stage of ensiling. Guineagrass at the milky ripe stage was chopped and ensiled into a small-scale laboratory silo at two ensiling density levels (high density at 95 g/silo and low density at 75 g/silo). Three silos per level were opened after six ensiling periods (0.5, 1, 1.5, 2, 3 and 7 days of ensiling) and the fermentation qualities were analyzed. Within the initial 1.5 days of ensiling there were not significant (p>0.05) differences in the fermentation qualities between two density levels silages, and an almost constant pH and no or only small amounts of lactic acid, acetic acid and total volatile fatty acids were detected. However, the high density silage significantly (p<0.05) increased the rate and extent of fermentation after 1.5 days of ensiling, which was well reflected in significantly (p<0.05) faster and larger pH decline and lactic acid production at each elapsed time as compared with the low density silage. This resulted in significantly (p<0.05) lower finial pH and significantly (p<0.05) higher lactic acid content at the end of the experiment. Moreover, there was higher AA content relative to LA in both the H-D and L-D silages during the full fermentation course, and resulted in the AA-type silage. There were generally somewhat or significantly (p<0.05) higher acetic acid, volatile fatty acids and ammonia-N/total nitrogen in the high density silage than in the low density silage during the initial 3 days of ensiling. However, there were higher (p>0.05) ammonia-N/total nitrogen and significantly (p<0.05) higher butyric acid content in the low density silage at day 7 of ensiling. The silages of two density levels showed an initial increase in glucose between 0.5 and 1 day for the high density silage and between 1 and 1.5 days for the low density silage, respectively, thereafter showed a large decrease until the end of the experiment. There were not large differences (p>0.05) in ethanol content between the low density and high density silages that showed small amounts within initial 3 days of ensiling. However, the low density silage had a significantly (p<0.05) higher ethanol content than the high density silage at the end of experiment. From the above results it was suggested that the increase in ensiling density was an effective method to improve the fermentation quality, especially for tropical grasses.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.183-184
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• 2003

Poly(lactic acid) (PLA) is a highly versatile, biodegradable, aliphatic polyester derived from 100% renewable resources, such as corn and sugar beets. Because of the degradation mechanism, PLA is ideally suited for many applications in the environment where recovery of the product is not practical, such as agricultural mulch films and bags. Composting of post consumer PLA items is also a viable solution for many PLA products. (omitted)