• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.101-110
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• 2021

Interactions between microalgae and heterotrophic bacteria are common in natural environments. This study investigated the effect of heterotrophic bacteria on the activity of the photosynthetic eukaryotic alga Chlorella sp. MF1907 when cocultured. A total of 31 heterotrophic bacterial isolates belonging to different genera were cocultured with MF1907. Interactions of the alga with Agromyces, Rhodococcus, Sphingomonas, Hyphomicrobium, Rhizobium, and Pseudomonas were positive, while those with Burkholderia, Paraburkholderia, Micrococcus, Arthrobacter, Mycobacterium, Streptomyces, Pedobacter, Mucilaginibacter, Fictibacillus, Tumebacillus, Sphingopyxis, and Erythrobacter were negative (p < 0.05). A turnover experiment demonstrating a switch from heterotrophic to autotrophic activity of MF1907 was performed using 16 isolates exhibiting apparent effects (positive, negative, or neutral). Compared with the results of the coculture experiment, eight isolates exhibited the same outcomes, while the others did not. Consistently, Pseudomonas and Agromyces showed a remarkable positive effect on MF1907 activity, and Burkholderia, Streptomyces, and Erythrobacter had a marked negative effect. Our results suggest that it may be possible to use the isolates for controlling populations of microalgae in natural and engineered environments.

• Korean Journal of Environmental Biology
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• v.29 no.1
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• pp.52-60
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• 2011

Today, the weather is changing continually, due to the progress of global warming. As the weather changes, the habitats of different organisms will change as well. It cannot be predicted whether or not the weather will change with each passing day. In particular, the biological distribution of the areas climate change affects constitutes a major factor in determining the natural state of indigenous plants; additionally, plants are constantly exposed to rhizospheric microorganisms, which are bound to be sensitive to these changes. Interest has grown in the relationship between plants and rhizopheric microorganisms. As a result of this interest we elected to research and experiment further. We researched the dominant changes that occur between plants and rhizospheric organisms due to global warming. First, we used temperature as a variable. We employed four different temperatures and four different sites: room temperature ($27^{\circ}C$), $+2^{\circ}C$, $+4^{\circ}C$, and $+6^{\circ}C$. The four different sites we used were populated by the following species: Pinus deniflora, Pinus koraiensis, Quercus acutissima, and Alnus japonica. We counted colonies of these plants and divided them. Then, using 16S rRNA analysis we identified the microorganisms. In conclusion, we identified the following genera, which were as follows: 10 species of Bacillus, 2 Enterobacter species, 4 Pseudomonas species, 1 Arthrobacter species, 1 Chryseobacterium species, and 1 Rhodococcus species. Among these genera, the dominant species in Pinus deniflora was discovered in the same genus, but a different species dominated at $33^{\circ}C$. Additionally, that of Pinus koraiensis changed in both genus and species which changed into the Chryseobacrterium genus from the Bacilus genus at $33^{\circ}C$.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.495-501
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• 2011

Bacterial strains were isolated from forest soils of Halla mountain, Jeju island in Korea. The soil samples were collected at each altitude of 100m from 1,000 m above sea level. Total 398 strains were isolated and tested for their physiological characteristics of antagonistic and proteolytic activities, and auxin production. Among the isolates, 172 strains were selected as antifungal strains showing antagonistic activity against at least one of 8 plant fungal pathogens (Alternaria alternata, Botrytis cinerea, Collectotrichum acutatum, Fusarium oxysporum, Phytophthora capsici, Pythium ultimum and Sclerotinia sclerotiorum). In addition 203 strains for proteolytic activity and 26 strains for auxin production were characterized for further study. Je28-4 (Rhodococcus sp.) were showed 80% of control value against tomato gray mold in vivo. Thus, it is suggested that soil bacteria isolated from forest soils of Halla mountain can be important sources of bioactive compounds for improving plant growth or promising biocontrol agents.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.668-676
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• 2001

Pseudomonas sp. strain SY5 is a PCB-degrading bacterium [24] that includes two different enzymes (BphC1 and BphC2) encoding 2,3-dihdroxybiphenyl 1,2-dioxygenase and BphD encoding 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase. The bphC1 and bphC2 genes were found to consist of 897 based encoding 299 amino acids and 882 bases encoding 294 amino acids, respectively, whereas the bphD gene consisted of 861 bases encoding 287 amino acids. According to a homology search, a 50% and 39% similarity between the bphC1 and bphC2 genes at the nucleotide and amino acid level was shown, respectively. The bphC1 gene showed a 38% and 45% similarity at the amino acid level to Alcaligenes eutrophus A5 and Rhodococcus rhodochrous, respectively, whereas, bphC2 showed a 95% and 43% similarity, respectively. A comparison of the deduced amino acid sequence of the bphD product of Pseudomonas sp. SY5 with that of A. eutrophus A5, Pseudomons sp. KKS102, and LB400 showed a sequence identity of 92, 92, and 79%, respectively. Strain SY5 was originally isolated from municipal sewage containing recalcitrant organic compounds an found to have a high degradability of various aromatic compounds [23]. The current study found that strain SY5 had two extradiol-type dioxygenases, which did not hybridize with each other as they had a low similarity, yet a similar structure of evolutionarily conserved amino acids residues for catalytic activity between BphC1 and BphC2 was observed.

• Journal of Microbiology and Biotechnology
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• v.32 no.11
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• pp.1416-1426
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• 2022

The need to discover new types of antimicrobial agents has grown since the emergence of antibiotic-resistant pathogens that threaten human health. The world's oceans, comprising complex niches of biodiversity, are a promising environment from which to extract new antibiotics-like compounds. In this study, we newly isolated Pseudomonas sp. NIBR-H-19 from the gut of the sea roach Ligia exotica and present both phenotypes and genomic information consisting of 6,184,379 bp in a single chromosome possessing a total of 5,644 protein-coding genes. Genomic analysis of the isolated species revealed that numerous genes involved in antimicrobial secondary metabolites are predicted throughout the whole genome. Moreover, our analysis showed that among twenty-five pathogenic bacteria, the growth of three pathogens, including Staphylococcus aureus, Streptococcus hominis and Rhodococcus equi, was significantly inhibited by the culture of Pseudomonas sp. NIBR-H-19. The characterization of marine microorganisms with biochemical assays and genomics tools will help uncover the biosynthesis and action mechanism of antimicrobial metabolites for development as antagonistic probiotics against fish pathogens in an aquatic culture system.

• Proceedings of the Microbiological Society of Korea Conference
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• 2001.11a
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• pp.157-163
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• 2001

Mycolic acid-containing gram-positive bacteria, so called nocardioform actinomycetes, have become a great interest to environmental microbiologists due to their metabolic versatility, multidegradative capacity and potential for bioremediation of priority pollutants. For example, Rhodococcus rhodochrous N75 was able to metabolize 4-methy1catechol via a modified $\beta$-ketoadipate pathway whereby 4-methylmuconolactone methyl isomerase catalyzes the conversion of 4-methylmuconolactone to 3-methylmuconolactone in order to circumvent the accumulation of the 'dead-end' metabolite, 4-methylmuconolactone. R. rhodochrous N75 has also shown the ability to transform a range of alkyl-substituted catechols to the corresponding muconolactones. A novel 3-methylmuconolactone-CoAsynthetase was found to be involved in the degradation of 3-methylmuconolactone, which is not mediated in a manner analogous to the classical $\beta$-ketoadipate pathway but activated by the addition of CoA prior to hydrolysis of lactone ring, suggesting that the degradative pathway for methylaromatic compounds by gram-positive bacteria diverges from that of proteobacteria. Mycobacterium sp. Strain PYR-l isolated from oil-contaminated soil was capable of mineralizing various polyaromatic hydrocarbons (PAHs), such as naphthalene, phenanthrene, pyrene, fluoranthrene, 1-nitropyrene, and 6-nitrochrysene. The pathways for degradation of PAHs by this organism have been elucidated through the isolation and characterization of chemical intermediates. 2-D gel electrophoresis of PAH-induced proteins enabled the cloning of the dioxygenase system containing a dehydrogenase, the dioxygenase small ($\beta$)-subunit, and the dioxygenase large ($\alpha$)-subunit. Phylogenetic analysis showed that the large a subunit did not cluster with most of the known sequences except for three newly described a subunits of dioxygenases from Rhodococcus spp. and Nocardioides spp. 2-D gel analysis also showed that catalase-peroxidase, which was induced with pyrene, plays a role in the PAH metabolism. The survival and performance of these bacteria raised the possibility that they can be excellent candidates for bioremediation purposes.

• Proceedings of the Microbiological Society of Korea Conference
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• 2004.05a
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• pp.35-38
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• 2004

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.105-110
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• 2002

The sequence of 3,221 nucleotides immediately adjacent to rpsA gene encoding 30S ribosomal protein S1 of Brevibacterium ammoniagenes was determined. A putative open reading frame (ORF) of 2,670 nucleotides for a polypeptide of 889 amino acid residues and a TAG stop codon was found, which is located at a distance of 723 nucleotides upstream from rpsA gene with same translational direction. The deduced amino acid sequence of the ORF was found to be highly homologous to the DNA polymerase I of Streptomyces griseus (75.48％), Rhodococcus sp. ATCC 15963 (56.69％), Mycobacterium tuberculosis (55.46％) and Mycobacterium leprae (53.99％). It was suggested that the predicted product of the ORF is a DNA polymerase I with three functional domains. Two domains of 5 → 3 exonuclease and DNA polymerase are highly conserved with other DNA polymerase I, but 3 → 5 exonuclease domain is less conserved.

• Journal of Life Science
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• v.15 no.5 s.72
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• pp.743-748
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• 2005

Histamine can be produced at early spoilage stage through decarboxylation of histidine in red-flesh fish by Proteus morganii, Hafnia alvei or Klebsiella pneumoniae. Allergic food poisoning is resulted from the histamine produced when the freshness of Mackerel degrades. Conversely it has been reported that there are bacteria which decompose histamine at the later stage. We isolated histamine decomposers from salted mackerel and studied the characteristics to help establish hygienic measure to prevent outbreak of salted mackerel food poisoning. All the samples were purchased through local supermarket. Histamine decomposers were isolated using restriction medium using histamine 10 species were selected. Identification of these isolates were carried out by the comparison of 16S rDNA partial sequence; as a result, we identified Pseudomonas putida strain RA2 and Halomonas marina, Uncultured Arctic sea ice bacterium clone ARKXV1/2-136, Halomonas venusta, Psychrobacter sp. HS5323, Pseudomonas putida KT2440, Rhodococcus erythropolis, Klebsiella terrigena (Raoultella terrigena), Alteromonadaceae bacterium T1, Shewanella massilia with homology of $100\%,{\;}100\%,{\;}99\%,{\;}99\%,{\;}99\%,{\;}99\%,{\;}100\%,{\;}95\%,{\;}99\%,{\;}and{\;}100\%$respectively. Turbidometry determination method and enzymic method were employed to determine the ability of histamine decomposition. Among those species Shewanella massilia showed the highest in ability of histamine decomposition. From these results we confirmed various histamine decomposer were present in salted mackerel product in the market.