• Journal of Microbiology and Biotechnology
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• v.7 no.5
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• pp.360-362
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• 1997

A transposon Tn5 mutant of Rhodobacter sphaeroides 2.4.1 was isolated for its impaired ability of growth on minimal medium containing ${\beta}$-hydroxybutyric acid as a sole carbon source. The mutant, R. sphaeroides S7 showed approximately 6-fold decrease in ${\beta}$-hydroxybutyrate dehydrogenase activity compared with that of wild type. In R. sphaeroides S7 the Tn5 was located in DNA region corresponding to a 4.2-kb EcoRI DNA fragment of R. sphaeroides 2.4.1 chromosome.

• Korean Journal of Environmental Biology
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• v.18 no.2
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• pp.205-213
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• 2000

Laboratory studies have revealed that naturally transformable bacteria develop competence under in situ conditions. Thus, the occurrence of competent bacteria in the environment can be considered as a certainty The persistence of free DNA in natural habitats is influenced by nucleolytic degradation and protection from degradation by adsorption to minerals. Although DNA seeded into natural environment was hydrolysed at substantial rates, but was still detectable at low levels after even several weeks. Compared to the number of laboratory based studies, only a few data have been published dealing with transformation of bacteria in the field. Recently, the potential transfer of recombinant DNA (rDNA) from deliberately or accidentally released bacteria to indigenous microbes has raised biosafety issues, since the persistence of rDNA becomes independent of the survival of its original host and leads to unpredictable, long-term ecological effects. The aim of the present review is to summarise recent literature on horizontal gene transfer (HGT) by transformation among bacteria in both soil and aquatic habitat and special emphasis is placed on recent reports which have addressed HGT among bacteria in the field. [Transformation, Horizontal gene transfer (HGT), recombinant DNA (rDNA), Genetically modified microorganisms (GMMs), Biosafety]

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.4
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• pp.238-244
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• 2007

Nowadays many people are concerned about being healthy, and many dairy products are taken as health supplementary foods. Among dairy products, kefir, also called as Tibet mushroom, is a yogurt fermented by kefir grain, which is a mixture of lactic acid bacteria and yeasts. Although there are many empirical evidences that kefir is very influential for human body, the exact reason is not definitively discovered. Therefore, it would be useful to understand characteristics of a kefir grain and to categorize bacteria in a kefir grain. In this paper, molecular biological apparatus such as PCR, electrophoresis, PCR purification, DNA sequencing were used to identify and classify the species of lactic acid bacteria and yeast in a kefir grain. We used PCR-based identification method using 16S rRNA primer and Internal Transcribed Spacer (ITS) primer. We identified 6 different species which were selected on different medium. In addition, observation with scanning electron microscope (SEM) enabled us to grasp an external shape of the kefir grain. Although we found a limited number of microbial species, more intensive research are needed for extensive identification of microorganism species in Korean kefir grain.

• Molecules and Cells
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• v.27 no.5
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• pp.515-523
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• 2009

To infer the monophyletic origin and phylogenetic relationships of the order Desmoscolecida, a unique and puzzling group of mainly free-living marine nematodes, we newly determined nearly complete 18S rDNA sequences for six marine desmoscolecid nematodes belonging to four genera (Desmoscolex, Greeffiella, Tricoma and Paratricoma). Based on the present data and those of 72 nematode species previously reported, the first molecular phylogenetic analysis focusing on Desmoscolecida was done by using neighbor joining (NJ), maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI) methods. All four resultant trees consistently and strongly supported that the family Desmoscolecidae forms a monophyletic group with very high node confidence values. The monophyletic clade of desmocolecid nematodes was placed as a sister group of the clade including some members of Monhysterida and Araeolaimida, Cyartonema elegans (Cyartonematidae) and Terschellingia Iongicaudata (Linhomoeidae) in all the analyses. However, the present phylogenetic trees do not show any direct attraction between the families Desmoscolecidae and Cyartonematidae. Within the monophyletic clade of the family Desmoscolecidae in all of the present phylogenetic trees, there were consistently observed two distinct subgroups which correspond to the subfamilies Desmoscolecinae [Greeffiella sp. + Desmoscolex sp.] and Tricominae [Paratricoma sp. + Tricoma sp].

• The Korean Journal of Mycology
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• v.44 no.1
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• pp.51-56
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• 2016

Diverse endophytic fungi were isolated from surface-sterilized leaves of three species of conifers inhabiting various sites in Korea: Abies nephrolepis, Pinus koraiensis and Taxus cuspidate. The isolates were identified based on morphological characteristics and sequences analysis of both internal transcribed spacer and large subunit regions of rDNA. In this paper, we report on five previously unreported species of endophytic fungi isolated from conifers: Biscogniauxia maritime, Nemania diffusa, Pezicula carpinea, Phomopsis juglandina and Sydowia polyspora.

• The Korean Journal of Mycology
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• v.40 no.3
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• pp.174-176
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• 2012

We report morphological and physiological characteristics of newly isolated six kinds of yeasts which are new in Korean mycoflora. The yeasts were isolated from wild flowers in Daejeon city, Korea and identified by molecular analysis of the amplified internal transcribed space rDNA sequence or partial 18S rDNA sequence. Species of isolates were identified as Kuraishia capsulate, Lodderomyces elongisporus, Pseudozyma antarctica, Starmerella bombicola.

• The Korean Journal of Mycology
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• v.28 no.2
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• pp.112-117
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• 2000

A similarity coefficient were analyzed by RFLP of fourteen species of entomopathogenic fungi, isolated from inhabiting pupa and adult insect at forest. Each rDNA ITS I and ITS II with primers of ITS 1 and ITS 4 was amplified by PCR. The amplified products were conserved to 500 bp were not demarcated between genus and species. Four Paeciliomyces tenuipes, two Beauveria bassiana and six Cordyceps militaris were treated by seven restriction enzymes and confirmed in species except JB3 by electrophoresis band. However, the band of C. scarabaeicola showed the identity with B. bassiana. The result of this experiment indicated that the teleomorph of C. scarabaeicola was the same as that of B. bassiana. CfoI and HpaII of seven restricted enzymes were easily discriminating in the genus between Paecilomyees and Cordyceps. Especially, CfoI was more effective to classify the genera of Paecilomyees, Cordyceps and Beauveria than other restriction enzymes. The band patterns of RFLP of P. tenuipes, C. militaris, C. scarabaeicola and B. bassiana were also analyzed by UPGMA program of NTSYS-pc and showed 100% significance. Thus, the similarity coefficient tended to be lower between genera by RFLP analysis, but was higher between species.

• ALGAE
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• v.37 no.4
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• pp.281-291
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• 2022

Quantifying the abundance of Chattonella species is necessary to effectively manage the threats from ichthyotoxic raphidophytes, which can cause large-scale mortality of aquacultured fish in temperate waters. The identification and cell counting of Chattonella species have been conducted primarily on living cells without fixation by light microscopy because routine fixatives do not retain their morphological features. Species belonging to the Chattonella marina complex, including C. marina and C. marina var. ovata, had high genetic similarities and the lack of clear morphological delimitations between the species. To estimate the abundance of C. marina complex in marine plankton samples, we developed a protocol based on the droplet digital polymerase chain reaction (ddPCR) assay, with C. marina complex-specific primers targeting the internal transcribed spacer (ITS) region of the rDNA. Cell abundance of the C. marina complex can be determined using the ITS copy number per cell, ranging from 25 ± 1 for C. marina to 112 ± 7 for C. marina var. ovata. There were no significant differences in ITS copies estimated by the ddPCR assay between environmental DNA samples from various localities spiked with the same number of cells of culture strains. This approach can be employed to improve the monitoring efficiency of various marine protists and to support the implementation of management for harmful algal blooms, which are difficult to analyze using microscopy alone.

• Molecules and Cells
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• v.38 no.8
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• pp.697-704
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• 2015

Deleted in breast cancer-1 (DBC1) contributes to the regulation of cell survival and apoptosis. Recent studies demonstrated that DBC is phosphorylated at Thr454 by ATM/ATR kinases in response to DNA damage, which is a critical event for p53 activation and apoptosis. However, how DBC1 phosphorylation is regulated has not been studied. Here we show that protein phosphatase 4 (PP4) dephosphorylates DBC1, regulating its role in DNA damage response. PP4R2, a regulatory subunit of PP4, mediates the interaction between DBC1 and PP4C, a catalytic subunit. PP4C efficiently dephosphorylates pThr454 on DBC1 in vitro, and the depletion of PP4C/PP4R2 in cells alters the kinetics of DBC1 phosphorylation and p53 activation, and increases apoptosis in response to DNA damage, which are compatible with the expression of the phosphomimetic DBC-1 mutant (T454E). These suggest that the PP4-mediated dephosphorylation of DBC1 is necessary for efficient damage responses in cells.

• The Korean Journal of Mycology
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• v.49 no.1
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• pp.81-86
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• 2021

We isolated endophytic fungi from Smilax china and Cryptomeria japonica. These fungal strains were identified based on their morphological characteristics and phylogenetic analyses of their internal transcribed spacer, large subunit rDNA, and translation elongation factor 1-α DNA. Among them, we discovered two fungi belonging to the genus Phyllosticta, which have not been previously recorded in Korea. We have described these two fungal strains, Phyllosticta ericarum 19E458 and Phyllosticta philoprina 19E012 in this study.