• KSBB Journal
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• v.21 no.2
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• pp.79-84
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• 2006

In order to minimize the reduction of lysine productivity by accumulation of lysine and byproducts in the end of fed-batch fermentations, a salt-tolerant mutant C14-49-3-15-7-3-20, which could grow at high concentrations of NaCl was isolated through mutagenesis from the Corynebacterium glutamicum mother strain I. In the evaluation of L-lysine productivity by fed-batch fermentations using a 5 L jar fermenter, the salt-tolerant mutant strain C14-49-3-15-7-3-20 produced 130.6 g/L of L-lysine with a 48.6% of yield. The mother strain I produced L-lysine concentration only 104.9 g/L with a yield 41.8%, implying the improvement of L-lysine productivity by introduction of salt-tolerance character.

• Korean Journal of Microbiology
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• v.23 no.3
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• pp.190-196
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• 1985

For frequency improvement of protoplast fusion in Brevibacterium flavum, Brevibacterium lactofermentum lactofermentum and Corynebacterium glutamicum, the effect of plasma expanders on fusion and cell wall regeneration, compatison between direct and two-step selection method, tendency of fusion frequency according to pH of fusion fluid and polyethylene glycol concentration were examined. By addition of 3% polyvinyl pyrrolidone to cell wall regeneration medium, regeneration frequencies were expressed 23 (Brevibacterium lactofermentum), 10.4 (Brevibacterium flavum) and 2.7 (Corynebacterium glutamicum) times higher than those of none polyvinyl pyrrolidone medium respectively.

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.1010-1017
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• 2007

Two alternative pathways for methionine biosynthesis are known in Corynebacterium glutamicum: one involving transsulfuration (mediated by metB and metC) and the other involving direct sulfhydrylation (mediated by metY). In this study, MetB (cystathionine ${\gamma}-synthase$) and MetY (O-acetylhomoserine sulfhydrylase) from C. glutamicum were purified to homogeneity and the biochemical parameters were compared to assess the functional and evolutionary importance of each pathway. The molecular masses of the native MetB and MetY proteins were measured to be approximately 170 and 280 kDa, respectively, showing that MetB was a homotetramer of 40-kDa subunits and MetY was a homohexamer of 45-kDa subunits. The $K_m$ values for the O-acetylhomoserine catalysis effected by MetB and MetY were 3.9 and 6.4 mM, and the maximum catalysis rates were $7.4\;(k_{cat}=21\;S^{-1})\;and\;6.0\;(k_{cat}=28\;S^{-1})\;{\mu}mol\;mg^{-1}\;min^{-1}$, respectively. This suggests that both MetB and MetY can be comparably active in vivo. Nevertheless, the $K_m$ value for sulfide ions by MetY was 8.6mM, which was too high, considering the physiological condition. Moreover, MetB was active at a broad range of temperatures $(30\;and\;65^{\circ}C)$ and pH (6.5 and 10.0), as compared with MetY, which was active in a range from 30 to $45^{\circ}C$ and at pH values from 7.0 to 8.5. In addition, MetY was inhibited by methionine, but MetB was not. These biochemical data may provide insight on the role of the parallel pathways of methionine biosynthesis in C. glutamicum with regard to cell physiology and evolution.

• Microbiology and Biotechnology Letters
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• v.47 no.3
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• pp.337-342
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• 2019

We published that bacterial heme was over-produced in a recombinant Corynebacterium glutamicum expressing 5-aminolevulinic acid synthase ($hemA^+$) under control of a constitutive promoter ($P_{180}$) and the heme-producing C. glutamicum had commercial potentials; as an iron feed additive for swine and as a preservative for lactic acid bacteria. To enhance the heme production, the $hemA^+$ gene was expressed under controls of various promoters in the recombinant C. glutamicum. The $hemA^+$ expression by $P_{gapA}$ (a constitutive glycolytic promoter of glyceraldehyde-3-phosphate dehydrogenase) led 75% increase of heme production while the expression by $P_{H36}$ (a constitutive, very strong synthetic promoter) resulted in 50% decrease compared with the control ($hemA^+$ expression by $P_{180}$ constitutive promoter). The $hemA^+$ expression by a late log-phase activating $P_{sod}$ (an oxidative-stress responding promoter of superoxide dismutase) led 50% greater heme production than the control. The $hemA^+$ expression led by a heat-shock responding chaperone promoter ($P_{dnaK}$) resulted in 121% increase of heme production at the optimized heat-shock conditions. The promoter strength and induction phase are discussed based on the results for the heme production at an industrial scale.

• KSBB Journal
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• v.6 no.1
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• pp.63-68
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• 1991

An auxotrophic regulatory mutant of Corynebacterium glutamicum ATCC 21674 produced 2.1-3.4g/1 of phenylalanine with 2.9-4.4g/l of tyrosine in the batch shake flask fermentations. At higher sugar concentration, the production of both amino acids was lower than that at low sugar concentration. There was a pronounced effect of temperature on the amino acid production. At $30^{\circ}C$, much higher levels of phenylalanine and tyrosine were produced than those at $37^{\circ}C$. The pH decrease in the shake flask fermentation was so fast that it was impossible to maintain a constant pH with calcium carbonate as a buffering agent. Even though the strains we have used are reported as tyrosine auxotrophs, they produced tyrosine and were able to grow on the minimal medium where no tyrosine was present.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.542-547
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• 2005

Biosorption is considered to be a promising alternative to replace or supplement the present methods for the treatment of dye-containing wastewater. In this study, the protonated biomass of Corynebacterium glutamicum was evaluated for its potential to remove two types of reactive dyes (Reactive Red 4, Reactive Blue 4) from aqueous solution. The uptakes of dyes were enhanced with decrease in the solution pH, which was likely because the biomass functional groups increased at acidic pH and the positively charged sites could bind the negatively charged sulfonate group ($dye-SO_3^-$) of dye molecules. An equilibrium state was practically achieved in 10 hr. The Langmuir sorption model was used for the mathematical description of the sorption equilibrium. The maximum sorption capacities of C. glutamicum biomass for Reactive Red 4 and Reactive Blue 4 were estimated to 112.36 mg/g and 263.16 mg/g at pH 1, and 71.94 mg/g and 155.88 mg/g at pH 3.

• Microbiology and Biotechnology Letters
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• v.15 no.2
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• pp.104-111
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• 1987

As a trial method of breeding L-lysine producing strains, the intraspecific protoplast fusion bet-ween Brevibacterium flavum ATCC 21528R and Brevibacterium flavum ATCC 21529S and the intergeneric protoplast fusion between Brevibacterium flavum ATCC 21528R and Corynebacterium glutamicum ATCC 13058S were performed. The optimum conditions for protoplast formation of these strains were examined and the effect of plasma expander on regeneration and/or fusion was also observed. Both fusants No. CH23 and No. CH4l showed higher productivity of L-lysine than those of parental cells under the optimum cultural conditions at a rate of 21％ and 8.9％, respectively. And, activity of several enzymes in L-lysine biosynthetic pathway including aspartokinase, a rate-limiting enzyme, was determined. Besides, metabolic control mechanism of L-lysine biosynthesis in fusant No. CH23 and in No. CH41 was investigated to compare with that of parental strains.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.2
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• pp.322-327
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• 1994

For the improvement of L-lysine productivity, development of the continuous fermentation system by a bioreactor assembly was attempted. Primarily, optimal conditions on the whole cell immobilization of Corynebacterium glutamicum ATCC21514 were studied and 76.2% of immobilization ratio was obtained when the cells were entrapped with 4% k-carrageenan showing 4.0kg gel strength. A bioreactor system was set up using the immobilized cells was applied for the continuous production of L-lysine. The results obtained under the optimum conditions were compared with those of the batchwise fermentation. Experimental results obtained from 14 day continuous fermentation showed 36.7% of sugar conversion to L-lysine while the productivity of L-lysine was disclosed as 4.96mg/ml mg-dry cell weight /hr which is 2.5times and 4.1 times higher than those of the batchwise fermentation by the intact cells and by the immobilized cells, respectively.

• Korean Journal of Food Science and Technology
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• v.23 no.5
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• pp.561-567
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• 1991

This study was designed to investigate the productivity of L-methionine by the method of protoplast fusion between Brevibacterium flavum ATCC 14067 and Corynebacterium glutamicm ATCC 13032, and then L-methionine production was performed to continuous fermentation using the immobilized fusant cells. Mutants B. flavum K 104($thr\;met\;Km^{r}\;Et^{r}\;Sm^{r}\;Tm^{r}\;as\;genetic\;marker$) and C. glutamicum B 70($thr\;Hos\;Km^{r}\;Et^{r}\;Sm^{r}\;Tm^{r}as\;genetic\;marker$) were isolated by MNNG treatment. On the other hand, protoplast of mutants were formed to treat with lysis solution containing $500{\mu}g/ml$ of lysozyme. The ratios of protoplast formation and regeneration were 99% and $64{\sim}66%$ respectively. Fusion frequency between B. flavum K 104 and C. glutamicum B 70 showed the $3.5{\times}10^{5}$ in the 35% polyethylene glycol(PEG6000) containing 3% PVP solution. The productivity of L-methionine by fusant BFCG 37 immobilized with sodium alginate was 0.89 g/l the batch fermentation and was $18.75mg/^{1}hr\;^{1}$ on the continuous fermentation at $30^{\circ}C$ for 72 hr.

• Korean Journal of Microbiology
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• v.48 no.3
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• pp.207-211
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• 2012

Autoinduction is mediated by signaling molecules known as autoinducers (AIs) that are produced, released and detected by bacterium itself. We recently reported that Corynebacterium glutamicum possesses an autoinduction system which secretes autoinducers during the stationary-phase of growth, triggering the expression of acyltransferase gene. However, it is still not clear what may act as autoinducers for the autoinduction in C. glutamicum. In this study, we compared the inducing effects of cell-free culture fluids obtained from a number of microbes including Agrobacterium tumefaciens, Vibrio harveyi, and Escherichia coli. Fluids from A. tumefaciens did not increase the expression of acyltransferase, whereas fluids from V. harveyi BB120 ($AI-1^+$, $AI-2^+$) did. Interestingly, the expression was increased by the fluids obtained from the early exponential-phase culture of BB120. Furthermore, this induction was not observed by the fluids from autoinducer mutants of V. harveyi MM77 ($AI-1^-$, $AI-2^-$) and BB152 ($AI-1^-$, $AI-2^+$). Unlike the effect shown by BB152, fluids from E. coli ($AI-1^-$, $AI-2^+$) still induced the acyltransferase expression. Taken together, these results suggest that C. glutamicum autoinducers seem to be unidentified molecules which do not belong to AI-1 or AI-2.