• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.791-807
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• 2017

The type II secretion system (T2SS), which transports selected periplasmic proteins across the outer membrane, has rarely been studied in nonpathogens or in organisms classified as Betaproteobacteria. Therefore, we studied Cupriavidus metallidurans (Cme), a facultative chemilithoautotroph. Gel analysis of extracellular proteins revealed no remarkable differences between the wild type and the T2SS mutants. However, enzyme assays revealed that native extracellular alkaline phosphatase is a T2SS substrate, because activity was 10-fold greater for the wild type than a T2SS mutant. In Cme engineered to produce three Ralstonia solanacearum (Rso) exoenzymes, at least 95% of their total activities were extracellular, but unexpectedly high percentages of these exoenzymes remained extracellular in T2SS mutants cultured in rich broth. These conditions appear to permit an alternative secretion process, because neither cell lysis nor periplasmic leakage was observed when Cme produced a Pectobacterium carotovorum exoenzyme, and wild-type Cme cultured in minimal medium secreted 98% of Rso polygalacturonase, but 92% of this exoenzyme remained intracellular in T2SS mutants. We concluded that Cme has a functional T2SS despite lacking any abundant native T2SS substrates. The efficient secretion of three foreign exoenzymes by Cme is remarkable, but so too is the indication of an alternative secretion process in rich culture conditions. When not transiting the T2SS, we suggest that Rso exoenzymes are probably selectively packaged into outer membrane vesicles. Phylogenetic analysis of T2SS proteins supports the existence of at least three T2SS subfamilies, and we propose that Cme, as a representative of the Betaproteobacteria, could become a new useful model system for studying T2SS substrate specificity.

• Korean Journal of Medicinal Crop Science
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• v.10 no.3
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• pp.217-221
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• 2002

Callus induction and embryogenesis were studied in three different genotypes of Acanthopanax senticosus, to develop a protocol for somatic embryogenesis and acclimatization. Young leaf, stem, node, petiole, peduncle, flower and root explants were collected from 3-year old trees of A. senticosus accessions (Korea, Russia and Japan). Callus was obtained from all cultured explants but showed the higher rate of callus formation in flower cultured. For the three A. senticosus accessions, callus was well formd on MS media containing 2mg/ l of 2,4-D and 2mg/ l of TDZ, 4mg/ l of 2,4-D and 1mg/ l of TDZ than other treatments. For three A. senticosus accessions, when callus transferred to MS medium with 2,4-D, embryogenic cell formed. For A. senticosus accessions Korea, embryogenic cells were obtained on callus induced from petiole, stem, node and root explants, and induction rate was lower than 3%. 200mg of embryogenic callus was transferred to MS free liquid medium and somatic embryos of heart stage were obtained after 45days of culture. When somatic embryo of germination stage were transferred to solid medium, most of the embryos were regenerated into plantlets on 1/4 MS medium. Normal plants with both shoots and roots were transferred to greenhouse soil and were successfully acclimatized.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1001-1010
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• 2005

Bacillus megaterium KL39, an antibiotic-producing plant growth promoting rhizobacterium (PGPR), was selected from soil. The antifungal antibiotic, denoted KL39, was purified from culture filtrate by column chromatography using Dion HP-20, Silica gel, Sephadex LH-20, and prep-HPLC. Thin layer chromatography, employing the solvent system of ethanol:ammonia:water=8:1:1, showed the $R_{f}$. value of 0.32. The antibiotic KL39 showed a negative reaction with ninhydrin solution, positive with iodine vapor, and also positive with Ehrlich reagent. It was soluble in methanol, ethanol, butanol, and acetonitrile, but insoluble in chloroform, toluene, hexane, ethyl ether, or acetone. Its UV spectrum had the maximum absorption at 208 nm. Amino acid composition, FAB-mass, $^{1}H-NMR,\;^{13}C-NMR$, and atomic analyses showed that the antibiotic KL39 (MW=1,071) has a structure very similar to iturin E. The antibiotic KL39 has a broad antifungal spectrum against a variety of plant pathogenic fungi including Rhizoctonia solani, Pyricularia oryzae, Monilinia froeticola, Botrytis cinenea, Altenaria kikuchiana, Fusarium oxysporum, and F. solani. An MIC value of $10\;{\mu}g/ml$ was determined for Phytophthora capsici. Macromolecular incorporation studies with P. capsici using radioactive [$^{3}H-adenine$] as the precursor, indicated that the antibiotic KL39 strongly inhibits the DNA biosynthesis of the fungal cell. Microscopic observation of the antifungal action showed abnormal hyphal swelling of P. capsici. The purified antibiotic KL39 was very effective for the biocontrol of in vivo Phytophthora-blight disease of pepper.

• Journal of Plant Biotechnology
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• v.30 no.2
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• pp.135-141
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• 2003

Peroxiredoxin(Pix) are large family of peroxidases that reduce alkyl hydroperoxides and hydrogen peroxide. A cDNA clone (referred to as swPrxl) encoding Pix was from a sweetpotato cDNA library constructed from suspension-sultured cells, and its expression was investigated in terms of stress. The swPrxl contained an open reading frame (ORF) encoding mature protein of 193 amino acids with calculated molecular mass of 20.8kDa. The predicted amino acid sequence of swPrxl has two conserved cysteines that are essential resicues for the reduction of peroxides. It showed high amino acid sequence homology ot PixIIF of Arabidopsis (77%) and putative Prx of rice(72%). RNA gel-blot analysis showed that swPrxl gene was expressed dominantly in leave among intact tissues, and also highly detect in suspension-cultured cells. Interestingly, the level of swPrxl transcripts was almost the same regardless of the growth stage in suspension culture. Furthermore, the transcription level of swPrxl gene was not significantly changed in response to various stress treatments such as wounding, extreme temperature and stress-related chemicals RT-PCR analyses.

• Korean Journal of Plant Tissue Culture
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• v.22 no.6
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• pp.323-327
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• 1995

This experiment was carried out to observe the origin and developmental pattern of somatic embryos of Oenanthe javanica ($B^{L}.$) DC. The experiment included observation of embryogenic cells and their development stages by light microscope, transmission electron microscope and scanning electron microscope. The embryogenic cells, which were smaller than non-embryogenic cells in size with expanded nucleus and dense cytoplasm. When stained with hematoxylin, the embryogenic cells were readily distinguished from the non-embryogenic cells of which cell walls were stained with safranin. It was observed at somatic embryos developed from single cells on the epidermis of developing embryos or in the surface or inside of embryogenic clumps by segmentation pattern. Observation with a transmission electron microscope revealed that the embryogenic cells had dense cytoplasm expanded nucleus, small vacuoles, large amyloplasts containing starch grains, and abundant organelles including lipid bodies. Under a scanning electron microscope, embryogenic callus was shown to consist of very smaller cells than non-embryogenic cells in an orderly arrangement and covered with a net-like structure, while the non-embryogenic callus consisted of large cells, irregular in size and arrangement, and covered with a gelatin-like material.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.1
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• pp.107-113
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• 2015

This study was conducted to find out the effective induction method of tetraploid plants to obtain potential data for cultivating superior varieties by colchicine treatment. The seed germination were decreased by the higher concentration of colchicine treatment and longer soaking time. A total of 907 individuals were germinated in 16 treated plots except control (untreated plot) and 28 tetraploids were induced which was about 3.1% of the number of seed germinated. The plant regeneration rate by colchicine treatment on explant of Prunella vulgaris for. albiflora Nakai under in vitro culture was decreased with the higher concentration of colchicine. While a total of 312 individuals were regenerated in all treatments, the explant was soaked in more than 0.05% for over 1 hour, tetraploid could be obtained. In particular, for the soaking treatment in 0.05% for 6 hours and 12 hours, 37 tetraploids were induced, which was about 57.8% of the number of plant regenerated. In accordance with the observation on doubling of DNA contents in leaf in order to identify polyploid, the peak DNA content of G1 phase was 101.3 for diploid and 197.2 for tetraploid. The result confirmed the doubling of DNA content. Furthermore, the number of chloroplasts per guard cell depending on polyploid was around 10 in diploid and 19.3 in tetraploid, which was around 1.9 times as much as diploid.

• Journal of Plant Biotechnology
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• v.31 no.2
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• pp.145-149
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• 2004

We investigated the anatomical aspects of vitrification in peace poplar. Comparisons were made with regard to characteristics occurring between hyperhydric and normal shoots in shoot proliferation cultures on MS medium containing 0.2 mg/L BA. Compared with normal plants, hyperhydric plants had thick, curled, and dark green leaves. Hyperhydric stems were thicker and shorter than those of normal stems. When examined under the microscopes, the mesophyll palisade cells of hyperhydric leaves were vacuolated, whereas those of normal leaves contained normal and enriched vacuole with cytoplasm. Generally, the hyperhydric leaves showed poorly developed palisade parenchyma, and revealed irregular and bigger sized intercellular structures in both palisade and spongy parenchyma as well as epidermis cells compare to those of normal leaves. In addition, the hyperhydric leaves had lower stomatal density and bigger sized cell. Vascular tissues of hyperhydic stems were less differentiated because of poorly lignified xylem tissue. The greatly expanded cortical cells and pith appeared to be the main cause of thick stems as compared with normal stems.

• Plant Biotechnology Reports
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• v.4 no.1
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• pp.53-59
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• 2010

A specific deleted version of ARABIDOPSIS RESPONSE REGULATOR1 (ARR1) lacking the signal receiver domain (1.152 amino acids)-coding sequence, referred to as $ARR1{\Delta}DDK$, was amplified using Arabidopsis thaliana cDNA prepared from adult leaves and transferred into the genome of Nicotiana tabacum cv. Samsun under the transcriptional control of a ${\beta}$-estradiol-inducible expression system. The ectopic expression of $ARR1{\Delta}DDK$ affected the morphology of transgenic seedlings and their segments in vitro. In the presence of an inducer, ${\beta}$-estradiol, ectopic expression of $ARR1{\Delta}DDK$ induced only the formation of soft, pseudo-bulbous tissue in the root tip region of intact seedlings, which appeared similar to callus generated on a hypocotyl segment in the presence of 2,4-D and 6-benzyladenine (BA), both at $1\;{\mu}M$. Those callus tissues on the root tip region could not generate shoots unless $1\;{\mu}M$ BA was supplied. In segment culture, ectopic expression of $ARR1{\Delta}DDK$ induced calluslike tissue around the cut-end of cotyledon and hypocotyl segments with occasional shoot formation, suggesting that the expression of $ARR1{\Delta}DDK$ could substitute for the effects of cytokinin on these segments. Additionally, treatment with only ${\beta}$-estradiol induced NtWUS, a WUS ortholog in tobacco, which was detected during the process of callus tissue formation in the root tip region and also in cotyledon or hypocotyl segments. These findings suggest that the NtWUS might be associated in the transdifferentiation process caused by the functional regulation of $ARR1{\Delta}DDK$ in transgenic tobacco seedlings.

• Journal of Environmental Science International
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• v.16 no.11
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• pp.1219-1223
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• 2007

The removal of nitrogen compounds from a wastewater is essential and it is often accomplished by bio-logical process. An aerobic nitrate-removing bacterium was isolated from a municipal sewage treatment plant and soil. On the basis of its morphological, cultural and physiological characteristics and 16S rRNA sequencing data, this strain was identified as Pseudomonas fluorescens, and named as P. fluorescens K4. The optimal conditions of the initial pH and temperature of media for its growth were $7.0{\sim}8.0$ and $30^{\circ}C$, respectively. P. fluorescens K4 was able to remove 99.9% of nitrate after 24 h in a culture. The strain could grow with a nitrate concentration up to 800 mg/l and was able to remove 99.9% of nitrate after 104 h of incubation. The optimal electron donor was sodium citrate for a nitrate removal. The strain K4 showed a capability of a complete nitrate removal when the initial C/N ratio was 1.0. An effect of the initial seed concentration was observed for a cell of 10% (v/v) for a nitrate removal. Especially P. fluorescens K4 could completely remove 200 mg/l ammonium for 3 days.

• Food Science of Animal Resources
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• v.28 no.4
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• pp.512-516
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• 2008

To search for anit-H5N1 influenza virus agent, the anti-viral activity of methanol and aqueous extracts from thirty medicinal plants were examined in this study. The plant material (30 g) was extracted with methanol (300 mL) for 24 hr at room temperature. Methanol extracts were filtered and evaporated, then freeze-dried. Aqueous extracts were prepared with dried plant material (30 g) and hot distilled water (300 mL). After 3 hr, the aqueous extracts were filtered and evaporated, then lyophilized. Extracts prepared from different plants were tested the antiviral activity against influenza viruses [A/vietnam/1194/04 (H5N1)-NIBRG-14] using the hemagglutination (HA) assay. Among the test plants, Asarum sieboldii was found to be a potent inhibitor of H5N1 influenza virus in MDCK cell culture. Virus titers were 7 log, whereas with methanol extract of Asarum sieboldii for 48 hr titers were 3 log, indicating that methanol extract of Asarum sieboldii inhibited the H5N1 influenza viruses from the infected cells.