• Journal of Microbiology
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• v.40 no.4
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• pp.260-266
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• 2002

Bacterial strains were isolated from biofilms formed on glass slides submerged in seawater in Dae-Ho Dike. Eight strains showing fast attaching ability were selected and identified. Their exopolysaccharide (EPS)-producing ability and EPS properties were characterized. Based on Microlog System, 4 among the 8 strains were identified as Micrococcus luteus and the rest were Bacillus thuringiensis, Bacillus megaterium,, Staphylococcus saprophyticus and Agrobacterium vitis. A, vitis was reidentified as Sulfitobacter pontiacus based on 16S rDNA sequence data. The amount of water-soluble EPS produced by the 8 strains ranged from 0.114 to 1.329 g$.$l$\^$-1/ and the productivity was negatively correlated with the cell biomass. The molecular weight of the produced EPS ranged from 0.38 to 25.19$\times$10$\^$4/ Da. Glucose and galactose were ubiquitous sugar components. Mannose, ribose, and xylose were also major sugar components. The molecular weight and composition of the EPS showed strain-specific variation.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.762-766
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• 2001

The nar promoter of Escherichia coli was known to induce maximally under anaerobic or microaerobic conditions in the presence of nitrate. In this study, the nar promoter was tested to see whether the expression level of a reporter gene which fused lacZ gene at nar promoter's downstream, in the some gram negative host strains(Agrobacterium, Pseudomonas and Rhizobium). A nar promoter system(Combination of nar promoter and gram negative strain) was grown under aerobic conditions to absorbance at 600 nm of nearly 2.0 and then, the nar promoter was induced by lowering DO to 1-2% with alternating microaerobic and aerobic condition in the fermentor cultures, using different gram negative hosts. For a wild type nar promoter (pNW61), it was possible to maintain production of ${\beta}-galactosidase$ activity per cell(specific ${\beta}-galactosidase$ activity) at 14,000, 9600, 45 Miller units in the presence of 1% nitrate. and for a nitrate - independent nar promoter (pNW618) at 12,000, 10,400 and 58 Miller units in the absence of nitrate ion, respectively.

• Mycobiology
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• v.49 no.2
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• pp.95-104
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• 2021

Species of the genus Aspergillus have a variety of effects on humans and have been considered industrial cell factories due to their prominent ability for manufacturing several products such as heterologous proteins, secondary metabolites, and organic acids. Scientists are trying to improve fungal strains and re-design metabolic processes through advanced genetic manipulation techniques and gene delivery systems to enhance their industrial efficiency and utility. In this review, we describe the current status of the genetic manipulation techniques and transformation methods for species of the genus Aspergillus. The host strains, selective markers, and experimental materials required for the genetic manipulation and fungal transformation are described in detail. Furthermore, the advantages and disadvantages of these techniques are described.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.310-315
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• 1989

Tabtoxin produced in Pseudomonas syringae pv. tabace irreversibly inhibits its known physiological target, glutamine synthetase so that causes wildfire disease on leaves of host plant. In this study, we examined a rapid and sensitive microbiological method for tabtoxin assay in several media. In minimal A agar medium nd minimal glucose agar medium, growth inhibition zone of Agrobacterium tumefaciens was larger than that of other indicator strain. However, mostly, growth inhibition zone of indicator strains on the minimal glucose agar medium was smaller than that of on the miniaml A agar medium. In complex agar medium, growth inhibithiton zone was not observed in all the tested indicator strains. Pseudomonas syringae pv. tabaci produced more tabtoxin according to the incubation time. When glutamine was added to the minimal glucose agar medium, growth inhkbition zone of Agrobacterium tumefaciens was reduced.

• The Plant Pathology Journal
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• v.39 no.3
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• pp.255-264
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• 2023

Sweet potato symptomless virus 1 (SPSMV-1) is a single-stranded circular DNA virus, belonging to the genus Mastrevirus (family Geminiviridae) that was first identified on sweet potato plants in South Korea in 2012. Although SPSMV-1 does not induce distinct symptoms in sweet potato plants, its co-infection with different sweet potato viruses is highly prevalent, and thus threatens sweet potato production in South Korea. In this study, the complete genome sequence of a Korean isolate of SPSMV-1 was obtained by Sanger sequencing of polymerase chain reaction (PCR) amplicons from sweet potato plants collected in the field (Suwon). An infectious clone of SPSMV-1 (1.1-mer) was constructed, cloned into the plant expression vector pCAMBIA1303, and agro-inoculated into Nicotiana benthamiana using three Agrobacterium tumefaciens strains (GV3101, LBA4404, and EHA105). Although no visual differences were observed between the mock and infected groups, SPSMV-1 accumulation was detected in the roots, stems, and newly produced leaves through PCR. The A. tumefaciens strain LBA4404 was the most effective at transferring the SPSMV-1 genome to N. benthamiana. We confirmed the viral replication in N. benthamiana samples through strand-specific amplification using virion-sense- and complementary-sense-specific primer sets.

• Journal of Microbiology and Biotechnology
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• v.17 no.2
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• pp.226-233
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• 2007

Members of Methylobacterium, referred as pink-pigmented facultative methylotrophic bacteria, are frequently associated with terrestrial and aquatic plants, tending to form aggregates on the phyllosphere. We report here that the production of autoinducer molecules involved in the cell-to-cell signaling process, which is known as quorum sensing, is common among Methylobacterium species. Several strains of Methylobacterium were tested for their ability to produce N-acyl-homoserine lactone (AHL) signal molecules using different indicators. Most strains of Methylobacterium tested could elicit a positive response in Agrobacterium tumefaciens harboring lacZ fused to a gene that is regulated by autoinduction. The synthesis of these compounds was cell-density dependent, and the maximal activity was reached during the late exponential to stationary phases. The bacterial extracts were separated by thin-layer chromatography and bioassayed with A. tumefaciens NTI (traR, tra::lacZ749). They revealed the production of various patterns of the signal molecules, which are strain dependent. At least two signal molecules could be detected in most of the strains tested, and comparison of their relative mobilities suggested that they are homologs of N-octanoyl-$_{DL}$-homoserine lactone ($C_8-HSL$) and N-decanoyl-$_{DL}$-homoserine lactone ($C_{10}-HSL$).

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.150-156
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• 2000

Oligotrophic bacteria isolated from forest soil showed a specific community consisting of various taxonomic groups compared with those in other soil or aquatic habitats. Based on the cell shape, the isolates were divided into four groups: regular rod, curved/spiral rod, irregular rod, and prosthecate bacteria. The cellular fatty acids 60 oligotrophic isolates were analyzed. The 30 fatty acids which were identified or characterized are classified. At the dendrogram based on cellular fatty acid composition, four clusters(I-IV) were separated at a euclidian distance of about 50. Cluster 3 and 4-a strains were containing Q-8, these strains are accommodated in the Proteobacteria gamma and beta subdivision. The chemotaxonomic profiles of the cluster 4-a strains showed good agreement with those of the genus Burkholderia. Cluster 3 was characterized by the presence of branched-chain fatty acids, iso-C15:0, iso-C17:1, and iso-C17:0 as the major components. These chemotaxonomy suggested the close relationship of the isolates with Xathomonas/Sterotrophomonas group. Based on the 16S rDNA sequence analysis, the two representative strains(MH256 and MA828) of cluster 3 showed the close relation to genera, Xathomonas/Sterotrophomonas, but were not included in these genera. These strains were even further away from core Xanthomonas, and clearly were seen to branch outside the cluster formed by the Sterotrophomonas maltophilia. MH256 and MA828 16S rDNA sequence was different enough to put new genus on a separate branch. The isolates with Q-10 were also studied. They are corresponded to the two large groups in Proteobacteria alpha subdivision. One was incorporated in the genus Bradyrhizobium cluster, which also includes Agromonas, a genus for oligotrophic bacteria. The strains of the other group showed high similarity to the genus Agrobacterium.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.126-126
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• 2003

Incidence of crown gall on lower stem of chrysanthemum, Chrysanthemum morifolium Ramat., was first observed at Hwasung, Gyeonggi, Korea in 2001, Tumors on the stem were 1.5-2 cm in size and semi-round with rough surface texture of dark brown color. Four strains of bacteria isolated from the tumor tissues were characterized. Their colonies were convex, glistening, circular with an entire edge, and white to tannish-cream in color on PDA plus CaCO$_3$. They were gram negative, oxidase positive, and growing on DIM agar. The bacterial isolates inducing gall formation in chrysanthemum were identified as Agrobacterium tumefaciens based on biochemical and physiological characteristics, fatty acid profile using Sherlock Microbial Identification System, and substrate utilization patterns using Biolog Identification System. Young chrysanthemum plants inoculated with the bacteria developed typical galls within two to three weeks. Seedlings of tomato and slices of carrot roots also produced typical galls two to three weeks after inoculation. This is the first report on crown gall of chrysanthemum in Korea.

• The Plant Pathology Journal
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• v.22 no.4
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• pp.318-322
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• 2006

One hundred and nine Agrobacterium isolates were recovered from 68 samples(51 plant tumor and 17 soil) that were collected from different habitats in Northern Jordan. The isolated cultures were grouped into 3 biovars based on their biochemical characteristics and biovar I, II, and III comprised a total number of 46, 41, and 22 isolates, respectively. Isolates of biovar I were obtained primarily from the diseased peach, oak and rose plants, whereas isolates of biovar II and ill were obtained mostly from apple and grape plants, respectively. Twenty-nine isolates were found to be virulent to at least one of the tested hosts such as carrots, chickpeas, garden peas and tomato plants with a response of tumor formation or tumor with roots induction. Our result suggested that A. tumefaciens strains from tumor of various plants and soil of Jordan were diverse and they have a variation in their virulence.

• Journal of Plant Biotechnology
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• v.4 no.3
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• pp.129-134
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• 2002

We report the development of a new selection system for the transformation of pepper plants by mannose. In order to achieve this, we first tested several factors related to regeneration conditions. Among the 30 inbred lines examined, line P9l5 was able to generate shoots at the highest rate from both cotyledons and hyporotyls in MS media. A dosage curve for optimizing the selection conditions was established by mixing mannose (range 0-50 g/L) and sucrose (range 0-30 g/L). The least selection pressure on shoot formation was created by a mixture of sucrose and mannose at 20 g/L and 15 g/L, respectively, and the threshold for ultimate tissue death was 50 g/L of mannose irrespective of the sucrose concentration. However, we found that mannose itself was not the sole inhibitor of pepper shoot development. High concentrations of sucrose (30 g/L) contributed additively to the inhibition of shoot formation at higher mannose concentrations. Genotype preference is a major factor that enhances regeneration ability in mannose media, as was observed in MS media. P9l5 and P410 line had high regeneration rates under mannose selection conditions in the presence of Agrobacterium infection. Different virulence levels of Agrobacterium strains did change the regeneration rates, probably due to interaction with the specificities of the inbred lines. Taken together, P9l5 offers the best pepper inbred line for transformation and we recommend a selection condition of 20 g/L of sucrose and 15 g/L or more of mannose up to 50 g/L in media.