• KSBB Journal
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• v.31 no.1
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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.

• KSBB Journal
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• v.26 no.6
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• pp.477-482
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• 2011

There has been a growing attention on PDLA (poly D-lactic acid) since stereocomplex PLA, a kind of polymer alloy between PLLA and PDLA was known much thermally stable compared PLLA. Superior characteristics of stereocomplex PLA result in the elevated demand for D-lactic acid. Although many research works have been reported for L-lactic acid production especially food industry, however there are relatively few research works for D-lactic acid production since D-lactic acid cannot find any applications in food industry. Most imminent issue for D-lactic acid is the economic production process that requires low cost medium, efficient lactic acid producing microorganism and finally large scale-up design. In this review, current status of D-lactic acid production process will be summarized and discussed for the further improvement of D-lactic acid production process.

• KSBB Journal
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• v.30 no.4
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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.

• Korean Journal of Pharmacognosy
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• v.18 no.1
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• pp.34-40
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• 1987

Onion extracts were tested for effects on the growth and lactic acid production of Lactobacillus bulgaricus in the medium containing mercury. The media containing mercury were added with onion extracts and inoculated with the bacterium and then incubated at $39^{\circ}$ for four days. All of the onion extracts examined increased the growth and lactic acid production of the bacterium in the medium containing mercury. At the addition of the edible portion extract of onion to the medium containing 5 ppm, 10 ppm and 20 ppm mercury, the higher the concentration of the onion extract was added, the greater the increasing effect on the growth and lactic acid production. The brown peel extract of onion increased the growth and lactic acid production of the bacterium in the medium containing mercury at all concentrations. The higher the concentration of the extract added, the more effective the increasing effect. The onion solutions of edible portion and brown peel extracted at $90^{\circ}\;to\;100^{\circ}$ showed more desirable effects than those extracted at the room temperature. Among four kinds of the onion extracts, the brown peel solution extracted at $90^{\circ}\;to\;100^{\circ}$ was the most effective in increase of the growth and lactic acid production in the medium containing mercury.

• Microbiology and Biotechnology Letters
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• v.24 no.3
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• pp.357-363
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• 1996

For the production of D-lactic acid from DL-2-chloropropionic acid, about 80 strains of bacteria capable of assimilating DL-2-chloropropionic acid as a sole carbon and energy source were isolated from the soil. JH-007 strain that showed the higest productivity of D-lactic acid and didn't produce L-lactic acid from DL-2-chloropropionic acid was selected from them and identified as Pseudomonas sp. The optimal conditions for the production of D-lactic acid from DL-2-chloropropionic acid were examined. The resting cells of JH-007 cultured in LB medium containing 3 g/l of DL-2-chloropropionic acid were used as an enzyme source. The reaction mixtures for the maximal production of D-lactic acid were consist of 10 g/l of resting cells and 3 g/l of DL-2-chloropropionic acid in 125 mM sodium carbonate buffer. The optimal pH for the reaction was 10.0 and the optimal temperature was 30$\circ$C. When 1 g/l of DL-2-chloropropionic acid was added intermittently to the reaction mixture under the above condition, 5.72 g/l of D-lactic acid was produced after incubation of 5 hrs. This amount of D-lactic acid corresponded to a 98.4% yields and the optical purity was 99.8%.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.6-11
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• 1995

In order to screen microorganism producing lactic acid with high productivity from nature, we used a medium containing 100 g/l glucose and selected several microorganisms producing more than 80 g/l L-lactic acid. We investigated their physiological characteristics and compared them. The best microorganism was identified as Lactobacillus casei subsp. rhamnosus. The optimum pH for growth and production of lactic acid was 6.0 and this strain showed the highest growth rate at around 30$\circ$C , but the optimum temperature for lactic acid production was 45$\circ$C . The growth was inhibited proportionally from 50 g/l to 300 g/l of glucose and the maximal cell mass increased according to increasing the concentration of corn steep liquor (CSL) protein up to 30 g/l. In batch fermentation for lactic acid production, we produced 128 g/l L-lactic acid with 20 g/l CSL protein and 150 g/l glucose in 35 hours. In pH-stat fed-batch fermentation, we were able to produce 183 g/l L-lactic acid.

• KSBB Journal
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• v.15 no.4
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• pp.359-365
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• 2000

Three lactic acid bacteria (C-1 K-3 and T-1 strain) were isolated from Nuruk and characterized subsequently. They were useful strains for production of lactic acid and their growth was inhibited at 10% ethanol pH 4 These strains were identified as lactococcus lactis subsp. lactis NR C-1 Leuconostoc mesenteroides subsp. mesenterides NR K-3 and pediococcus pentosaceus NR T-1 respectively by morphological physiological and biochemical characterization Lac lactis subsp lactis NR C-1 showed the highest lactic acid productivity. Leu measenteroides subsp mesenteroides NR K-3 showed stable lactic acid productivity and its growth was inhibited at pH 4. P pentosaceus NR T-1 had lower lactic acid productivity than the other two bacteria but it could not grow at 10% ethanol pH 4 The lactic acid productivity of these three strains in MRS broth were higher than that in Skim milk media the optimum pH and temperature for the lactic acid production of the three strains were 30-32$^{\circ}C$ and pH 6.0∼6.8 Glucose was the optimal carbon souorce for the lactic acid production. In terms of antagonism lac lactis subsp lactis NR c-1 showed somewhat inhibitory efects against some Gram positive rod and cocci such as Lactobacillus brevis and Streptococcus mitis. And Leu mesenteroides subsp mesenteroides NR K-3 showed the inhibitory effects against Streptococcus mitis but P. pentosaceus NR T-1 didn't show any inhibitory effects against tested strains.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.1-5
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• 2015

Lactic acid, the most widely occurring hydroxy-carboxylic acid, has traditionally been used as food, cosmetic, pharmaceutical, and chemical industries. Even though it has tremendous potential for large scale production and use in a wide variety of applications, high cost lactic acid materials are primarily problems. Lactic acid can be obtained on either by fermentation or chemical synthesis. In recent years, the fermentation approach has become more successful because of the increasing market demand for naturally produced lactic acid. Generally, lactic acid was produced from pure starch or from glucose. As an alternative, biomass which is the most abundant renewable resources on earth have been considered for conversion to readily utilizable hydrolysate. In this study, we conducted the fermentation method to produce L(+)-lactic acid production from pretreated hydrolysate was investigated by Lactobacillus rhamnosus ATCC 10863. The hydrolysate was obtained from pretreatment process of biomass using Ammonia percolation process (AP) followed by enzymatic hydrolysis. In order to effectively enhance lactic acid conversion and product yield, controlled medium, temperature, glucose concentration was conducted under pure glucose conditions. The optimum conditions of lactic acid production was investigated and compared with those of hydrolysate.

• Journal of Microbiology and Biotechnology
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• v.25 no.1
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• pp.26-32
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• 2015

Four types of straw, namely, soybean, wheat, corn, and rice, were investigated for use in lactic acid production. These straws were mainly composed of cellulose, hemicellulose, and lignin. After pretreatment with ammonia, the cellulose content increased, whereas the hemicellulose and lignin contents decreased. Analytical results also showed that the liquid enzymatic hydrolysates were primarily composed of glucose, xylose, and cellobiose. Preliminary experiments showed that a higher lactic acid concentration could be obtained from the wheat and soybean straw. However, soybean straw was chosen as the substrate for lactic acid production owing to its high protein content. The maximum lactic acid yield (0.8 g/g) and lactic acid productivity (0.61 g/(l/h)) were obtained with an initial reducing sugar concentration of 35 g/l at 30℃ when using Lactobacillus casei (10% inoculum) for a 42 h fermentation period. Thus, the experimental results demonstrated the feasibility of using a soybean straw enzymatic hydrolysate as a substrate for lactic acid production.

• KSBB Journal
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• v.16 no.2
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• pp.207-211
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• 2001

Statistical experimental design methods were employed to select the cultivation factors influencing latic acid production during the fermentation of kitchen refuses. Working volume and pH swings were identified as the main factors affecting lactic acid production. Optimum pH swing was pH 7.8 and working volume was 125 mL in a 250 mL flask. Under optimum condition, lactic acid was produced at 21.8 g/L, which was 6.2 times higher than produced during uncontrolled fermentation.