• Journal of Microbiology and Biotechnology
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• v.19 no.2
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• pp.167-171
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• 2009

The effects of culture conditions on succinic acid production and its possible scale-up have been studied. Mannheimia succiniciproducens LPK7, engineered for enhanced production of succinic acid and reduced by-product secretion, was used for the experiments. Mannheimia succiniciproducens LPK7 is a knock-out strain of wild type deficient in the ldhA, pflB, and pta-ackA genes, and is derived from Mannheimia succiniciproducens MBEL55E. Process optimization of factors including optimal temperature, pH, carbon source, and nitrogen source was performed to enhance the production of succinic acid in flasks. To observe scale-up effects, batch fermentation was carried out at various working volumes. At a working volume of 7.0 l, the final succinic acid concentration and yield were 15.4g/l and 0.86g/g. This result shows similar amount of succinic acid obtained in lab-scale fermentation, and it is possible to scale up to larger fermentors without major problems.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1147-1151
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• 2007

Biodegradation of endocrine-disrupting bisphenol A was investigated with several white rot fungi (Irpex lacteus, Trametes versicolor, Ganoderma lucidum, Polyporellus brumalis, Pleurotus eryngii, Schizophyllum commune) isolated in Korea and two transformants of T. versicolor (strains MrP 1 and MrP 13). I. lacteus degraded 99.4% of 50 mg/l bisphenol A in 3 h incubation and 100% in 12 h incubation. which was the highest degradation rate among the fungal strains tested. T. versicolor degraded 98.2% of 50 mg/l bisphenol A in 12 h incubation. Unexpectedly, the transformant of the Mn-repressed peroxidase gene of T. versicolor, strain MrP 1, degraded 76.5% of 50 mg/l bisphenol A in 12 h incubation, which was a lower degradation rate than wild-type T. versicolor. The removal of bisphenol A by I. lacteus occurred mainly by biodegradation rather than adsorption. Optimum carbon sources for biodegradation of bisphenol A by I. lacteus were glucose and starch, and optimum nitrogen sources were yeast extract and tryptone in a minimal salts medium; however, bisphenol A degradation was higher in nutrient-rich YMG medium than that in a minimal salts medium. The initial degradation of endocrine disruptors was accompanied by the activities of manganese peroxidase and laccase in the culture of I. lacteus.

• Archives of Pharmacal Research
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• v.12 no.4
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• pp.249-253
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• 1989

High producers or blocked mutants of aminoglycoside antibiotic-producing Streptomyces spp. were selected by application of an agar plug method and by culturing individual colonies in broth. The productivities of aminoglycoside antibiotic producing organisms were increased by selection of a high producer from colonies obtained by spreading spores of wild strain, or survived from treatment of a mutagen or from the colonies regenerated from protoplast-formation and cell-wall regenerations. Some mutagen treated colonies lost the ability to produce antibiotics (5-8%). Some A-factor negative and deostreptamine or streptidine negative mutants were obtained by N-methyl-N'-nitro-N-nitrosomethylguanidine (MNNG) treatment. Many of the survivors from the MNNG treatment lost the ability to produce antibiotics. Major colonies produced less amount of antibiotics ; only few survived colonies produced more antibiotics than the parent. Resistance of Streptomyces spp. against the antibiotics produced by itself was also markedly affected by mutagen treatment.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.164-164
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• 2017

High throughput transcriptome investigations of immunity in plants highlight the complexity of gene networks leading to incompatible interaction. To identify genes crucial to resistance against Xanthomonas oryzae pv oryzae, functional genetic analysis of selected differentially expressed genes from our microarray data set was carried out. A total of 13 overexpression vector constructs were made using 35S CaMV promoter which drive constitutive expression in rice. Most of the genes are developmentally expressed especially during maximum tillering stage and are commonly highly expressed in the leaves. When screened against Xoo strain K2, the transgenic plants displayed shorter lesion length compared with wild type Dongjin which indicates partial resistance. The levels of ROS continuously magnified after inoculation which indicates robust cellular sensing necessary to initiate cell death. Elevated transcripts levels of several defense-related genes at the downstream of defense signal network also corroborate the phenotype reaction of the transgenic plants. Moreover, expression assays revealed regulation of these genes by cross-communicating signal-transductions pathways mediated by salicylic and jasmonic acid. These collective findings revealed the key immune signaling conduits critical to mount full defense against Xoo.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.166-166
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• 2017

OsTAT encodes a twin-arginine translocator (TAT) pathway signal protein. It contains a TRANS membrane domain and a chloroplast transit peptide. mRNA transcription profiling of OsTAT1 revealed that it is highly overexpressed in the leaves corroborating reports on its role in chloroplast. Moreover, its level of expression is more pronounced during earlier stages (germination, 3-leaf stage, and maximum tillering) of growth in rice. A lower disease progress curve of bacterial blight is evident in transgenic lines compared with the wild type, Dongjin indicating its involvement in immunity to Xoo. Expression pattern following infection of Xoo strain K2 depicts highest levels at 4 and 8 hour post-inoculation which implies crucial induction of resistance during early response. This study initially reports a new overview on the biological functions of plant's TAT pathway. Further molecular and genetic analyses are underway to provide detailed involvement of OsTAT in disease resistance.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.496-500
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• 2000

Partial fragments of nuclear 185 rDNAs from morphologically wide and narrow thalli of the seaweed Porphyra pseudolineazis were amplified and sequenced to compare their DNA homology. Both sequences of 311 base pairs showed $100{\%}$ identical each other. They showed $97.7{\%}$ similarity with a wild strain collected at Sodol in Kangwondo, and $99.4{\%}$ similarity with the GenBank accession number AB013185 of the Japanese P. pseudolinearis. Thus the morphological difference of wide and narrow blades might not be a classification criterion for the sub-species level of P. pseudolinearis.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1533-1537
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• 2007

In this study, in order to develop a continuous production process of lactosucrose in a packed-bed reactor, Sterigmatomyces elviae ATCC 18894 was selected and mutated. The mutant strain of S. elviae showed 54.3% higher lactosucrose production than the wild type. Reaction conditions such as temperature, pH, substrate concentration and flow rate were also optimized. Under optimized reaction conditions ($50^{\circ}C$, pH 6.0, 25% sucrose and 25% lactose as substrate, flow rate 1.2 ml/min), the maximum concentration of lactosucrose (192 g/l) was obtained. In a packed-bed reactor, continuous production of lactosucrose was performed using S. elviae mutant immobilized in calcium alginate, and about 180 g/l of lactosucrose production was achieved for 48 days.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2001.06a
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• pp.62-72
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• 2001

The N-carbamoyl-D-amino acid amidohydrolase (D-carbamoylase) gene (dcb) from Agrobacterium tumefaciens AM 10 has been successfully cloned and expressed in Escherichia coli. Expression of D-carbamoylase gene under the 17 promoter in different host strains showed that the optimal expression was achieved in E. coli JM109 (DE3) with a 9-fold increase in enzyme production compared to the wild-type strain. The co-expression of the GroEL/ES protein with D-carbamoylase protein caused an in vivo solubilization of D-carbamoylase in an active form. The synergistic effect of GroEL/ES at 28$^{\circ}C$ led to 60 ％ solubilization of the total expressed target protein with a 6.2-fold increase in enzyme activity in comparison to that expressed without GroEL/ES and 43-fold increase in enzyme activity compared to A. tumefaciens AM 10. Attempts to express D-carbamoylase in an altered redox cytoplasmic milieu did not improve the enzyme production in an active form. The Histidyl-tagged D-carbamoylase was purified in a single step by Nickel-affinity chromatography and was found to have a specific activity of 9.5 U/mg protein.

• The Plant Pathology Journal
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• v.29 no.1
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• pp.59-66
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• 2013

Colonization studies previously performed with a green-fluorescent-protein, GFP, labeled derivative of Bacillus amyloliquefaciens FZB42 revealed that the bacterium behaved different in colonizing surfaces of plant roots of different species (Fan et al., 2012). In order to extend these studies and to elucidate which genes are crucial for root colonization, we applied targeted mutant strains to Arabidopsis seedlings. The fates of root colonization in mutant strains impaired in synthesis of alternative sigma factors, non-ribosomal synthesis of lipopeptides and polyketides, biofilm formation, swarming motility, and plant growth promoting activity were analyzed by confocal laser scanning microscopy. Whilst the wild-type strain heavily colonized surfaces of root tips and lateral roots, the mutant strains were impaired in their ability to colonize root tips and most of them were unable to colonize lateral roots. Ability to colonize plant roots is not only dependent on the ability to form biofilms or swarming motility. Six mutants, deficient in abrB-, sigH-, sigD-, nrfA-, yusV and RBAM017410, but not affected in biofilm formation, displayed significantly reduced root colonization. The nrfA- and yusV-mutant strains colonized border cells and, partly, root surfaces but did not colonize root tips or lateral roots.

• Biomolecules & Therapeutics
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• v.15 no.3
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• pp.192-198
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• 2007

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is a major constituent of rhubarb. Although it has been claimed to have a wild spectrum of therapeutic value, its side effects, especially in human kidney cells have not been well characterized. In this study, we have carried out in vitro genetic toxicity test of emodin and microarray analysis of differentially expressed genes in response to emodin. The result of Ames test showed mutations with emodin treatment in base substitution strain TA1535 both with and without exogenous metabolic activation. Likewise, emodin showed mutations in frame shift TA98 both with and without exogenous metabolic activation. The result of COMET assay in L5178Y cells with emodin treatment showed DNA damage both with and without exogenous metabolic activation. Emodin did not increase micronuclei in CHO cells both with and without exogenous metabolic activation. 150 Genes were selected as differentially expressed genes in response to emodin by microarray analysis and these genes would be candidate biomarkers of genetic toxic action of emodin.