• Microbiology and Biotechnology Letters
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• v.31 no.3
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• pp.250-256
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• 2003

Lactic acid bacteria with amylolytic and acid producing activities can ferment starch directly to lactic acid thereby producing a monomer for the production of biodegradable poly lactic acid (PLA). In this study, the strain producing L-lactic acid from soluble starch was isolated from Nuruk. The isolated strain was identified as Enterococcus sp. through its morphological, cultural, biochemical characteristics as well as the 16S rDNA sequence analysis, and named Enterococcus sp. JA-27. Enterococcus sp. JA-27 produced exclusively L-lactic acid from soluble starch as a carbon source. The optimal conditions for the maximum production of L-lactic acid from Enterococcus sp. JA-27 were 30 C, pH 8, 1.5 % soluble starch as a substrate and 3.5 % tryptone as a nitrogen source, 0.1 % $K_2$$HPO_4$, 0.04 % $MgSO_4$. $7H_2$O, 0.014 % $MnSO_4$$.$4$H_2O$, 0.004% $FeSO_4$$.$$7H_2$O. Batch and fed batch culture were carried out and the former was more effective. L-Lactic acid production in the optimum medium was significantly increased in a 7 L jar fermenter, where the maximum L-lactic acid concentration was 3 g/L. For the purification of lactic acid in fermented broth, two stage ionexchange column chromatographies were employed and finally identified by HPLC.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.2
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• pp.234-239
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• 2012

The objective of this study was to evaluate the effects of forage level and oil supplement on selected strains of rumen bacteria believed to be involved in biohydrogenation (BH). A continuous culture system consisting of four fermenters was used in a $4{\times}4$ Latin square design with a factorial arrangement of treatments, with four 10 d consecutive periods. Treatment diets were: i) high forage diet (70:30 forage to concentrate (dry matter basis); HFC), ii) high forage plus oil supplement (HFO), iii) low forage diet (30:70 forage to concentrate; LFC), and iv) low forage plus oil supplement (LFO). The oil supplement was a blend of fish oil and soybean oil added at 1 and 2 g/100 g dry matter, respectively. Treatment diets were fed for 10 days and samples were collected from each fermenter on the last day of each period 3 h post morning feeding. The concentrations of vaccenic acid (t11C18:1; VA) and c9t11 conjugated linoleic acid (CLA) were greater with the high forage diet while the concentrations of t10 C18:1 and t10c12 CLA were greater with the low forage diet and addition of oil supplement increased their concentrations at both forage levels. The DNA abundance of Anaerovibrio lipolytica, and Butyrivibrio fibrisolvens vaccenic acid subgroup (Butyrivibrio VA) were lower with the low forage diets but not affected by oil supplement. The DNA abundance of Butyrivibrio fibrisolvens stearic acid producer subgroup (Butyrivibrio SA) was not affected by forage level or oil supplement. In conclusion, oil supplement had no effects on the tested rumen bacteria and forage level affected Anaerovibrio lipolytica and Butyrivibrio VA.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.53-56
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• 2000

Two-stage fed-batch culture was peformed to improve the volumetric productivity of erythritol. In the growth phase dissolved oxygen was maintained to 20% and the feed medium was automatically supplied to the fermenter by pH-stat mode. The cell yield was 0.76 g-cell/g-glucose. In two-stage fed-batch culture, 41% of total erythritol conversion yield with 187 g/L of erythritol concentration and 2.79 g/L-h of maximum erythritol Productivity were obtained when 400 g/L of glucose was directly added in the form of non-sterile powder at production phase. The erythritol productivity increased in parallel with cell mass. The metabolic shift in the biosynthetic pathway of erythritol was caused by dissolved oxygen concentration. The production of gluconic acid was observed when the dissolved oxygen in the medium was maintained over 40% during the production phase, whereas the dissolved oxygen concentration lower than 40% caused the production of citric acid. But the butyric acid was produced independently with dissolved oxygen concentration in the medium. The production of organic acids such as gluconic acid, citric acid, and butyric acid was decreased by addition of mineral salts.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1136-1140
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• 2008

The Rhodopseudomonas palustris KUGB306 hemA gene codes for 5-aminolevulinic acid (ALA) synthase. This enzyme catalyzes the condensation of glycine and succinyl-CoA to yield ALA in the presence of the cofactor pyridoxal 5'-phosphate. The R. palustris KUGB306 hemA gene in the pGEX-KG vector system was transformed into Escherichia coli BL21. The effects of physiological factors on the extracellular production of ALA by the recombinant E. coli were studied. Terrific Broth (TB) medium resulted in significantly higher cell growth and ALA production than did Luria-Bertani (LB) medium. ALA production was significantly enhanced by the addition of succinate together with glycine in the medium. Maximal ALA production (2.5 g/l) was observed upon the addition of D-glucose as an ALA dehydratase inhibitor in the late-log culture phase. Based on the results obtained from the shake-flask cultures, fermentation was carried out using the recombinant E. coli in TB medium, with the initial addition of 90 mM glycine and 120 mM succinate, and the addition of 45 mM D-glucose in the late-log phase. The extracellular production of ALA was also influenced by the pH of the culture broth. We maintained a pH of 6.5 in the fermenter throughout the culture process, achieving the maximal levels of extracellular ALA production (5.15 g/l, 39.3 mM).

• Journal of Korean Society of Water and Wastewater
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• v.20 no.3
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• pp.397-402
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• 2006

The treatment characteristics of leachate produced from pretreatment facilities like composting and feeding were investigated in a mesophilic anaerobic treatment. Experiments were performed in two phase which were acidification and methane fermentation. The acidification step was optimized for OLR from 1 to $4.5kg\;COD/kg\;VS{\cdot}day$ without adding NaOH. As experiment dates became longer, the solubilization ratio of particles increased up to 30% over 70 days. TVA was generated up to maximum 9,970mg HAc/L at OLR of $2kg\;COD/kg\;VS{\cdot}day$. But TVA was generated to minimum 6,519mg HAc/L at OLR of $4.5kg\;COD/kg\;VS{\cdot}day$. The acidification ratio was analyzed from 10.9% to 3.8% at OLR of $2kg\;COD/kg\;VS{\cdot}day$ and $4.5kg\;COD/kg\;VS{\cdot}day$ respectively. After 55 days, salt contents in the acid fermenter were accumulated and stabilized at the concentration of 3,150mg/L. Sodium ion($Na^+$) concentration was stabilized at 1,300mg/L. At methane fermentation step, biogas was generated up to 750ml and 937.5ml at the feeding volume of 20ml and 25ml respectively for acid fermented liquid during 25 days. About 80% of total biogas was generated during early 15 days and 95% were generated during 18 days respectively. After 25 days of the BMP test, acetic acid was removed approximately 97% and 98%, in case of those two experimental conditions.

• Journal of Microbiology
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• v.44 no.4
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• pp.439-446
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• 2006

In this study, the growth kinetics of Lactobacillus rhamnosus and lactic acid production in continuous culture were assessed at a range of dilution rates $(0.05 h^{-1}\;to\;0.40h^{-1})$ using a 2L stirred tank fermenter with a working volume of 600ml. Unstructured models, predicated on the Monod and Luedeking-Piret equations, were employed to simulate the growth of the bacterium, glucose consumption, and lactic acid production at different dilution rates in continuous cultures. The maximum specific growth rate of L. rhamnosus, ${\mu}_{max}$, was estimated at $0.40h^{-1}$I, and the Monod cell growth saturation constant, Ks, at approximately 0.25g/L. Maximum cell viability $(1.3{\times}10^{10}CFU/ml)$ was achieved in the dilution rate range of $D=0.28h^{-1}\;to\;0.35h^{-1}$. Both maximum viable cell yield and productivity were achieved at $D=0.35h^{-1}$. The continuous cultivation of L. rhamnosus at $D=0.35h^{-1}$ resulted in substantial improvements in cell productivity, of 267% (viable cell count) that achieved via batch cultivation.

• Journal of Korean Society of Water and Wastewater
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• v.17 no.4
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• pp.550-558
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• 2003

Digestion of primary sludge was conducted to evaluate the effects of reactor configuration using UAD, CUAD, TPAD, and semi-continuos CSTR. Highest VSS reduction and gas production were obtained in CUAD at all HRT. More efficient digestion was accomplished in upflow digesters compared to TPAD and CSTR. Higher thickening of solids in reactor and longer solids retention were main reasons for the enhanced digestion in CUAD and UAD. Performance based on the SRT of CUAD was nearly identical to that of UAD. However, those of TPAD and CSTR were lower than that of CUAD. Particulate and soluble organics in upflow reactors were well adsorbed due to secreted extracellular polymeric substances from the sludge granules. These might result in close proximity of microorganisms and substrates and enhanced hydrolysis. Additionally, diverse anaerobic microorganisms and neutral pH in upflow reactor could induce more activity of hydrolytic enzymes and sludge granules might offer lower thermodynamic energy state. While, excessive mixing in CSTR could break conglomerates of enzymes and substrates into fine particles, which resulted in lowered hydrolysis. Low pH level in acid fermenter of TPAD lowered hydrolysis of the particulate substrates.

• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.968-971
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• 2011

Leuconostoc genus, which comprise heterofermentative lactic acid bacteria, reduces fructose to mannitol by recycling intracellular NADH. To evaluate the mannitol productivities of different Leuconostoc species, 5 stock cultures and 4 newly isolated strains were cultivated in MRS and simplified media containing glucose and fructose (1:2 ratio). Among them, L. citreum KACC 91348P, which was isolated from kimchi, showed superior result in cell growth rate, mannitol production rate, and yield in both media. The optimal condition for mannitol production of this strain was pH 6.5 and $30^{\circ}C$. When L. citreum KACC was cultured in simplified medium in a 2 l batch fermenter under optimal conditions, the maximum volumetric productivity was 14.83 $g{\cdot}l^{-1}h^{-1}$ and overall yield was 86.6%. This strain is a novel and efficient mannitol producer originated from foods to be used for fermentation of fructose-containing foods.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.613-618
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• 1999

L-Proline-producing mutant strains were developed by exposing L-glutamic acid-producing bacteria to N-metyl-N-nitro-nitrosoguanidine and UV irradiation. A L-histidine auxotroph of Corynebacterium acetoacidophilum RYU3161(KCTC 0616BP), which was resistant to sulfaguanidine and proline analogs (DHP, AZC, TAC), was isolated. The activity of the mutant strain's $\gamma$-glutamyl kinase was 45% higher than that of the parent strain. The optimum level of L-histidine for production of L-proline was 0.16 g/l. In a 5-1 jar fermenter, the mutant strain produced L-proline at a high concentration (35 g/l) level within 48 h of cultivation.

• Microbiology and Biotechnology Letters
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• v.49 no.4
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• pp.559-565
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• 2021

This study aimed to optimize gamma-aminobutyric acid (GABA) production by employing five strains of lactic acid bacteria (LAB) that were capable of high cell growth and GABA production using a modified synthetic medium. GABA production in the strains was qualitatively confirmed via detection of colored spots using thin layer chromatography. Lactobacillus plantarum SGL058 and Lactococcus lactis SGL027 were selected as the suitable strains for GABA production. The conditions of the carbon and nitrogen sources were determined as 5 g/l glucose (L. plantarum SGL058), 5 g/l lactose (L. lactis SGL027), 10 g/l yeast extract (L. plantarum SGL058), and 20 g/l yeast extract (L. lactis SGL027) for GABA production. The cell growth, monitored by optical density at 600 nm, was 5.93 for L. plantarum SGL058. This value was higher than the 3.04 produced by L. lactis SGL027 at 36 h using a 5-L fermenter. The highest concentration of GABA produced was 546.7 ㎍/ml by L. plantarum SGL058 and 404.6 ㎍/ml by L. lactis SGL027, representing a GABA conversion efficiency of (%, w/w) of 4.0% and 3.4%, respectively. The fermentation profiles of L. plantarum SGL058 and L. lactis SGL027 provide a basis for the utilization of LAB in GABA production using a basal synthetic medium.