Woojun Park

Korea University, Sŏul, Seoul, South Korea

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Publications (93)252.59 Total impact

  • Aram Heo, Woojun Park
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    ABSTRACT: This study provides evidence that RecG regulates the expression of the OxyR-independent gene mexA in Pseudomonas aeruginosa PAO1. A reduction in mexA expression was observed in the absence of RecG but not OxyR by northern blot and quantitative real-time PCR analyses. The canonical palindromic RecG binding sequence was present upstream of the mexA promoter, and bound purified RecG and single strand-binding protein. These data reveal a novel mechanism of OxyR-independent gene transcription by RecG.
    Journal of microbiology and biotechnology. 11/2014;
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    ABSTRACT: Nonculture-based procedures were used to investigate plasmids showing ampicillin resistance properties in two different environments: remote mountain soil (Mt. Jeombong) and sludge (Tancheon wastewater treatment plant). Total DNA extracted from the environmental samples was directly transformed into E. coli TOP10, and a single and three different plasmids were obtained from the mountain soil and sludge samples, respectively. Interestingly, the RFLP pattern of the plasmid from the mountain soil sample, designated pEMB1, was identical to the pattern of one of the three plasmids from the sludge sample. Complete DNA sequencing of plasmid pEMB1(8744 bp) showed the presence of six open reading frames (ORFs), including a β-lactamase gene. Using BlastX, the orf5 and orf6 genes were suggested to encode a CopG family transcriptional regulator and a plasmid stabilization system, respectively. Functional characterization of these genes using a knock-out orf5 plasmid (pEMB1r△parD) and the cloning and expression of orf6 (pET21bparE) indicated that these genes were antitoxin (parD) and toxin (parE) genes. Plasmid stability tests using pEMB1 and pEMB1r△parDE in E. coli revealed that the orf5-orf6 genes enhanced plasmid maintenance in the absence of ampicillin. Using a PCR-based survey, pEMB1-like plasmids were additionally detected in samples from other human-impacted sites (sludge samples) and two other remote mountain soil samples, suggesting that plasmids harboring a β-lactamase gene with a ParD-ParE toxin-antitoxin system occurs broadly in the environment. This study extends knowledge about the dissemination and persistence of antibiotic-resistance genes in naturally occurring microbial populations.
    Applied and Environmental Microbiology 10/2014; · 3.95 Impact Factor
  • Jisun Kim, Woojun Park
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    ABSTRACT: Pseudomonas putida is widely distributed in nature and is capable of degrading various organic compounds due to its high metabolic versatility. The survival capacity of P. putida stems from its frequent exposure to various endogenous and exogenous oxidative stresses. Oxidative stress is an unavoidable consequence of interactions with various reactive oxygen species (ROS)-inducing agents existing in various niches. ROS could facilitate the evolution of bacteria by mutating genomes. Aerobic bacteria maintain defense mechanisms against oxidative stress throughout their evolution. To overcome the detrimental effects of oxidative stress, P. putida has developed defensive cellular systems involving induction of stress-sensing proteins and detoxification enzymes as well as regulation of oxidative stress response networks. Genetic responses to oxidative stress in P. putida differ markedly from those observed in Escherichia coli and Salmonella spp. Two major redox-sensing transcriptional regulators, SoxR and OxyR, are present and functional in the genome of P. putida. However, the novel regulators FinR and HexR control many genes belonging to the E. coli SoxR regulon. Oxidative stress can be generated by exposure to antibiotics, and iron homeostasis in P. putida is crucial for bacterial cell survival during treatment with antibiotics. This review highlights and summarizes current knowledge of oxidative stress in P. putida, as a model soil bacterium, together with recent studies from molecular genetics perspectives.
    Applied microbiology and biotechnology. 06/2014;
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    ABSTRACT: A bacterial community analysis of the gut of Tenebrio molitor larvae was performed using pyrosequencing 16S rRNA gene. A predominance of genus Spiroplasma species in phylum Tenericutes was observed in the gut samples, while there was variation found in the community composition between T. molitor individuals. The gut bacteria community structure was not significantly affected by the presence of antibiotics or by the exposure of T. molitor larvae to a highly diverse soil bacteria community. A negative relationship was identified between bacterial diversity and ampicillin concentration; however, no negative relationship was identified with the addition of kanamycin. Ampicillin treatment resulted in a reduction in the bacterial community size estimated using the 16S rRNA gene copy number. A detailed phylogenetic analysis indicated that the Spiroplasma-associated sequences originating from the T. molitor larvae were distinct from previously identified Spiroplasma type species, implying the presence of novel Spiroplasma species. Some Spiroplasma species are known to be insect pathogens; however, the T. molitor larvae did not experience any harmful effects arising from the presence of Spiroplasma species, indicating that Spiroplasma in the gut of T. molitor larvae do not act as a pathogen to the host. A comparison with the bacterial communities found in other insects (Apis and Solenopsis) showed that the Spiroplasma species found in this study were specific to T. molitor.
    Journal of microbiology and biotechnology. 05/2014;
  • Sangwon Han, Jaejoon Jung, Woojun Park
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    ABSTRACT: L-asparaginase from gram-positive bacteria has been poorly explored. We conducted recombinant overexpression and purification of L-asparaginase from Staphylococcus sp. OJ82 (SoAsn) isolated from Korean fermented seafood to evaluate its biotechnological potential as an anti-leukemic agent. SoAsn was expressed in Escherichia coli BL21 (DE3) with an estimated molecular mass of 37.5 kDa determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Consistent with asparaginase in gram-negative bacteria, Size-exclusion chromatography determined SoAsn as a homodimer. Interestingly, optimal temperature of SoAsn was 37°C and over 90% of activity retained between 37°C and 50°C, and its thermal stability range was narrower than that of commercial E. coli L-asparaginase (EcAsn). Both SoAsn and EcAsn were active between pH 9 and pH 10, although their overall pH-dependent enzyme activities were slightly different. The Km value of SoAsn was 2.2 mM, which is higher than that of EcAsn. Among 8 metals tested for enzyme activity, cobalt and magnesium were greatly enhanced the SoAsn and EcAsn activity, respectively. Interestingly, SoAsn retained more than 60% of its activity under 2M NaCl conditions, but the activity of EcAsn was reduced to 48%. Overall, biochemical characteristics of SoAsn was similar to those of EcAsn, but its kinetics, cofactor requirements, and NaCl tolerance differed from those of EcAsn.
    Journal of Microbiology and Biotechnology 05/2014; · 1.40 Impact Factor
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    ABSTRACT: Bacterial community and metabolites were analyzed in a flatfish jeotgal, a Korean fermented seafood. Inverse relationship of pH and 16S rRNA gene copy number was identified during fermentation. Lactobacillus was the predominant bacterial genus. Increase of Firmicutes was a common characteristic shared by other fermented seafood. Fructose, glucose, and maltose were the major metabolites.
    Bioscience Biotechnology and Biochemistry 05/2014; 78(5):908-10. · 1.27 Impact Factor
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    ABSTRACT: Red clay is a type of soil, the red color of which results from the presence of iron oxide. It is considered an eco-friendly material, with many industrial, cosmetic, and architectural uses. A patented method was applied to red clay in order to change its chemical composition and mineral bioavailability. The resulting product was designated processed red clay. This study evaluates the novel use of red clay and processed red clay as biostimulation agents in diesel-contaminated soils. Diesel biodegradation was enhanced in the presence of red clay and processed red clay by 4.9- and 6.7-fold, respectively, and the number of culturable bacterial cells was correlated with the amount of diesel biodegradation. The growth of Acinetobacter oleivorans DR1, Pseudomonas putida KT2440, and Cupriavidus necator was promoted by both types of red clays. Culture-independent community analysis determined via barcoded pyrosequencing indicated that Nocardioidaceae, Xanthomonadaceae, Pseudomonadaceae, and Caulobacteraceae were enriched by diesel contamination. Bacterial strain isolation from naphthalene- and liquid paraffin-amended media was affiliated with enriched taxa based on 16S rRNA gene sequence identity. We suggest that the biostimulating mechanism of red clay and processed red clay is able to support bacterial growth without apparent selection for specific bacterial species.
    Microbial Ecology 04/2014; · 3.28 Impact Factor
  • Hyerim Hong, Woojun Park
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    ABSTRACT: Tetracycline (TC)-sensing bioreporters using green fluorescent protein (GFP) were generated in Escherichia coli and solvent-tolerant Acinetobacter oleivorans. A TC-inducible promoter, tetH promoter, and a TetR repressor of the pAST2 plasmid recovered from sludge were used to construct plasmid-based and chromosome-based bioreporters. Two host plasmids with a broad range, pRK415 and pBBR1MCS2, and three randomly chosen chromosomal sites were used to create the reporter strains. Although the copy numbers of the two plasmids in A. oleivorans were greater than those in E. coli, GFP expression from the tetH promoter and growth under TC were significantly higher in E. coli. Thus, the E. coli bioreporter had higher GFP expression driven by TC, and the two plasmids differed in terms of their sensitivity. Our data reflected mosaic evolution of the constructed plasmids, suggesting that the plasmid replication efficiency and the tetH promoter strength differed in the two different hosts. Among the tested TC compounds, doxycycline (DC) was the most effective in promoting GFP expression. qRT-PCR data confirmed that the expression of the tetH promoter in the original pAST2 plasmid produced the most rapid response to DC. E. coli- and A. oleivorans-based plasmid reporters could detect 5 and 30 nM DC, respectively. Insertion of the GFP reporter into different positions of the A. oleivorans chromosome resulted in variations of GFP expression. Our stable A. oleivorans chromosomal bioreporter was functional in the presence of toxic organic solvents. Furthermore, the field test showed that strain A. oleivorans DR1-Tet1 could act as a sensitive bioreporter in activated sludge for DC detection.
    Applied Microbiology and Biotechnology 02/2014; · 3.81 Impact Factor
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    ABSTRACT: The effects of antibiotics on environment-originated nonpathogenic Acinetobacter species have been poorly explored. To understand the antibiotic-resistance mechanisms that function in nonpathogenic Acinetobacter species, we used an RNA-sequencing (RNA-seq) technique to perform global gene-expression profiling of soil-borne Acinetobacter oleivorans DR1 after exposing the bacteria to 4 classes of antibiotics (ampicillin, Amp; kanamycin, Km; tetracycline, Tc; norfloxacin, Nor). Interestingly, the well-known two global regulators, the soxR and the rpoE genes are present among 41 commonly upregulated genes under all 4 antibiotic-treatment conditions. We speculate that these common genes are essential for antibiotic resistance in DR1. Treatment with the 4 antibiotics produced diverse physiological and phenotypic changes. Km treatment induced the most dramatic phenotypic changes. Examination of mutation frequency and DNA-repair capability demonstrated the induction of the SOS response in Acinetobacter especially under Nor treatment. Based on the RNA-seq analysis, the glyoxylate-bypass genes of the citrate cycle were specifically upregulated under Amp treatment. We also identified newly recognized non-coding small RNAs of the DR1 strain, which were also confirmed by Northern blot analysis. These results reveal that treatment with antibiotics of distinct classes differentially affected the gene expression and physiology of DR1 cells. This study expands our understanding of the molecular mechanisms of antibiotic-stress response of environment-originated bacteria and provides a basis for future investigations.
    PLoS ONE 01/2014; 9(10):e110215. · 3.53 Impact Factor
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    Hyerim Hong, Jaejoon Jung, Woojun Park
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    ABSTRACT: Acquisition of the extracellular tetracycline (TC) resistance plasmid pAST2 affected host gene expression and phenotype in the oil-degrading soil bacterium, Acinetobacter oleivorans DR1. Whole-transcriptome profiling of DR1 cells harboring pAST2 revealed that all the plasmid genes were highly expressed under TC conditions, and the expression levels of many host chromosomal genes were modulated by the presence of pAST2. The host energy burden imposed by replication of pAST2 led to (i) lowered ATP concentrations, (ii) downregulated expression of many genes involved in cellular growth, and (iii) reduced growth rate. Interestingly, some phenotypes were restored by deleting the plasmid-encoded efflux pump gene tetH, suggesting that the membrane integrity changes resulting from the incorporation of efflux pump proteins also resulted in altered host response under the tested conditions. Alteration of membrane integrity by tetH deletion was shown by measuring permeability of fluorescent probe and membrane hydrophobicity. The presence of the plasmid conferred peroxide and superoxide resistance to cells, but only peroxide resistance was diminished by tetH gene deletion, suggesting that the plasmid-encoded membrane-bound efflux pump protein provided peroxide resistance. The downregulation of fimbriae-related genes presumably led to reduced swimming motility, but this phenotype was recovered by tetH gene deletion. Our data suggest that not only the plasmid replication burden, but also its encoded efflux pump protein altered host chromosomal gene expression and phenotype, which also alters the ecological fitness of the host in the environment.
    PLoS ONE 01/2014; 9(9):e107716. · 3.53 Impact Factor
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    ABSTRACT: Bacteria belonging to the Staphylococcus genus reside in various natural environments; however, only disease-associated Staphylococcus strains have received attention while ecological function and physiologies of non-pathogenic strains were often neglected. Because high level of tolerance against NaCl is a common trait of Staphylococcus, we investigated the characteristics of halotolerance in Staphylococcus sp. OJ82 isolated from fermented seafood containing a high concentration of NaCl. Among the 292 isolates screened, OJ82 showed the highest β-galactosidase and extracellular protease activities under high-salt conditions. Comparative genomic analysis with other Staphylococcus strains showed that (a) replication origins are highly conserved, (b) the OJ82 strain has a high number of amino acid transport- and metabolism-related genes, and (c) OJ82 has many unique proteins (15 %) and 12 prophage-related genomic islands. RNA-seq analysis under high-salt conditions showed that genes involved in cell membranes, transport, osmotic stress, ATP synthesis, and translation are highly expressed. OJ82 may use the ribulose monophosphate pathway to detoxify some toxic intermediates under high-salt conditions. Six new and three known non-coding small RNAs of the OJ82 strain were also found in the RNA-seq analysis. Genomic and transcriptomic analyses identified target β-galactosidase and extracellular protease. Interestingly, the OJ82 strain became resistant to bacteriocin produced by the Bacillus strain only under high-salt conditions. Our data showed that the OJ82 strain adapted to high-salt conditions by expressing core cellular processes (translation, ATP production) and defense genes (membrane synthesis, compatible solute transports, ribulose monophosphate pathway) could survive bacteriocin exposure under high-salt conditions.
    Applied Microbiology and Biotechnology 12/2013; · 3.81 Impact Factor
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    ABSTRACT: We used culture-dependent and culture-independent methods to extract previously undescribed plasmids harboring tetracycline (TC) resistance genes from activated sludge. The extracted plasmids were transformed into naturally competent Acinetobacter oleivorans DR1 to recover a non-Escherichia coli-based plasmid. The transformed cells showed 80-100-fold higher TC resistance than the wild-type strain. Restriction length polymorphism performed using 30 transformed cells showed four different types of plasmids. Illumina-based whole sequencing of the four plasmids identified three previously unreported plasmids and one previously reported plasmid. All plasmids carried TC resistance-related genes (tetL, tetH), tetracycline transcriptional regulators (tetR), and mobilization-related genes. As per expression analysis, TC resistance genes were functional in the presence of TC. The recovered plasmids showed mosaic gene acquisition through horizontal gene transfer. Membrane fluidity, hydrophobicity, biofilm formation, motility, growth rate, sensitivity to stresses, and quorum sensing signals of the transformed cells were different from those of the wild-type cells. Plasmid-bearing cells seemed to have an energy burden for maintaining and expressing plasmid genes. Our data showed that acquisition of TC resistance through plasmid uptake is related to loss of biological fitness. Thus, cells acquiring antibiotic resistance plasmids can survive in the presence of antibiotics, but must pay ecological costs.
    Microbial Ecology 12/2013; · 3.28 Impact Factor
  • Jisun Kim, Woojun Park
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    ABSTRACT: Quorum sensing (QS)-dependent biofilm formation and motility were controlled by AqsR in Acinetobacter oleivorans DR1. QS-controlled phenotypes appeared to be inhibited by indole, and the aqsR mutant had the same phenotypes. We demonstrated that the turnover rate of AqsR became more rapid without the AHL signal and that indole could increase the expression of many protease and chaperone proteins. The addition of exogenous indole decreased the expression of two AqsR-targeted genes, which were AOLE_03905 (putative surface adhesion protein) and AOLE_11355 (L-asparaginase). The overexpression of AqsR in Escherichia coli was impossible with the indole treatment. Surprisingly, our [35S]-methionine pulse labeling data demonstrated that the stability and folding of the AqsR protein decreased in the presence of indole without changing the aqsR mRNA expression in E. coli. Interestingly, indole resulted in a loss of TraR-dependent traG expression in an Agrobacterium tumefaciens indicator strain. However, when indole was added after incubation with exogenous AHL, indole could not inhibit the TraR-dependent expression of the traG promoter. This indicated that AHL-bound TraR could be protective against indole, but TraR without AHL could not be active in the presence of indole. Here, we provided evidence for the first time showing that the indole effect on QS-controlled bacterial phenotypes is due to inhibited QS regulator folding and not a reduced QS signal.
    Microbiology 09/2013; · 3.06 Impact Factor
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    Jaejoon Jung, Woojun Park
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    ABSTRACT: Alishewanella species are expected to have high adaptability to diverse environments because they are isolated from different natural habitats. To investigate how the evolutionary history of Alishewanella species is reflected in their genomes, we performed comparative genomic and transcriptomic analyses of A. jeotgali, A. aestuarii, and A. agri, which were isolated from fermented seafood, tidal flat sediment, and soil, respectively. Genomic islands with variable GC content indicated that invasion of prophage and transposition events occurred in A. jeotgali and A. agri, but not in A. aestuarii. Habitat differentiation of A. agri from a marine environment to a terrestrial environment was proposed because the species-specific genes of A. agri were similar to those of soil bacteria, whereas those of A. jeotgali and A. aestuarii were more closely related to marine bacteria. Comparative transcriptomic analysis with pectin as a sole carbon source revealed different transcriptional responses in Alishewanella species, especially in oxidative stress-, methylglyoxal detoxification-, membrane maintenance-, and protease/chaperone activity-related genes. Transcriptomic and experimental data demonstrated that A. agri had a higher pectin degradation rate and more resistance to oxidative stress under pectin-amended conditions than the other 2 Alishewanella species. However, expression patterns of genes in the pectin metabolic pathway and of glyoxylate bypass genes were similar among all 3 Alishewanella species. Our comparative genomic and transcriptomic data revealed that Alishewanella species have evolved through horizontal gene transfer and habitat differentiation and that pectin degradation pathways in Alishewanella species are highly conserved, although stress responses of each Alishewanella species differed under pectin culture conditions.
    Applied and Environmental Microbiology 08/2013; · 3.95 Impact Factor
  • Jisun Kim, Jaemin Noh, Woojun Park
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    ABSTRACT: Antibiotic resistance of soil-borne Acinetobacter species has been poorly explored. In this study, norfloxacin resistance of a soil bacterium, Acinetobacter oleivorans DR1 was investigated. Frequencies of mutant appearance of all tested non-pathogenic Acinetobacter strains were lower than those of pathogenic strains under minimum inhibitory concentration (MIC). When the quinolone-resistance-determining region (QRDR) of the gyrA gene were examined, only one mutant (His78Asn) out of 10 resistant variants had a mutation. Whole transcriptome analysis using a RNA-seq demonstrated that genes involved in SOS response and DNA repair were significantly up-regulated by norfloxacin. Determining the MICs of survival cells after norfloxacin treatment confirmed some of those cells were indeed persister cells. Ten colonies, randomly selected from amongst those that survived in the presence of norfloxacin, did not exhibit increased MIC. Thus, both low mutation frequency of the target gene and SOS reponse under norfloxacin suggested that persister formation might contribute to resistance of DR1 against norfloxacin. Persister frequency increased without a change in MIC when stationary phase cells, low growth rates conditions, and growth deficient dnaJ mutant were used. Taken together, our comprehensive approach, which included mutational analysis of target gene, persister formation assays, and RNA sequencing, indicated that DR1 survival when exposed to norfloxacin is related not only to target gene mutation but also to persister formation possibly through upregulation of SOS response and DNA repair genes.
    Journal of Microbiology and Biotechnology 08/2013; · 1.40 Impact Factor
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    ABSTRACT: Jeotgal fermentation is dependent upon a diverse microbial community, although a detailed understanding of its microbial composition is limited to a relatively small number of jeotgal. Pyrosequencing-based bacterial community analysis was performed in fermented squid, ojingeo jeotgal. Leuconostoc was identified as the predominant bacterial genus, with Bacillus and Staphylococcus also accounting for a large proportion of the bacterial community. Phylogenetic analysis with 16S rRNA genes of Leuconostoc type species indicated that L. citreum- and L. holzapfelii-like strains could be the major Leuconostoc strains in jeotgal. High concentrations of NaCl were thought to be an important factor determining the makeup of the bacterial community in fermented squid; however, a genomic survey with osmotic stress-related genes suggests the existence of more complex factors selecting the dominant bacterial species in fermented squid.
    Journal of Microbiology and Biotechnology 07/2013; · 1.40 Impact Factor
  • Jisun Kim, Woojun Park
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    ABSTRACT: The complete genome of Acinetobacter oleivorans DR1 contains AqsR and AqsI genes, which are LuxR and LuxI homolog, respectively. In a previous study, we demonstrated that quorum sensing (QS) signals play an important role in biofilm formation and hexadecane biodegradation. However, the regulation of genes controlled by the QS system in DR1 remains unexplored. We constructed an aqsR mutant and performed RNA sequencing analysis to understand the QS system. A total of 353 genes were differentially expressed during the stationary phase of wild-type cells compared to that of the aqsR mutant. AqsR appears to be an exceptionally important regulator because knockout of aqsR affected global gene expression. Genes involved in posttranslational modification, chaperones, cell wall structure, secondary metabolites biosynthesis, and stress defense were highly upregulated only in the wild type. Among upregulated genes, both the AOLE_03905 (putative surface adhesion protein) and the AOLE_11355 (L-asparaginase) genes have putative LuxR binding sites at their promoter regions. Soluble AqsR proteins were successfully purified in Escherichia coli harboring both aqsR and aqsI. Comparison of QS signals in an AqsI-AqsR co-overexpression strain with N-acyl homoserine lactone standards showed that the cognate N-acyl homoserine lactone binding to AqsR might be 3OH C12HSL. Our electrophoretic mobility shift assays with purified AqsR revealed direct binding of AqsR to those promoter regions. Our data showed that AqsR functions as an important regulator and is associated with several phenotypes, such as hexadecane utilization, biofilm formation, and sensitivity to cumene hydroperoxide.
    Applied Microbiology and Biotechnology 06/2013; · 3.81 Impact Factor
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    ABSTRACT: Global warming will have far-reaching effects on our ecosystem. However, its effects on Antarctic soils have been poorly explored. To assess the effects of warming on microbial abundance and community composition, we sampled Antarctic soils from the King George Island in the Antarctic Peninsula and incubated these soils at elevated temperatures of 5°C and 8°C for 14 days. Reduction in total organic carbon and increased soil respiration were attributed to increased proliferation of bacteria, fungi, and archaea. Interestingly, bacterial ammonia monooxygenase (amoA) genes were predominant over archaeal amoA, unlike in many other environments reported previously. Phylogenetic analyses of bacterial and archaeal amoA communities via a clone libraries revealed that the diversity of amoA genes in Antarctic ammonia-oxidizing prokaryotic (AOP) communities were temperature-insensitive. Interestingly, our data also showed that the amoA of Antarctic AOB communities differed from previously described amoA sequences of cultured isolates and clone library sequences, suggesting the presence of novel Antarctic-specific AOB communities. Denitrification-related genes were significantly reduced under warming conditions, whereas the abundance of amoA and nifH increased. Barcoded pyrosequencing of bacterial 16S rRNA gene revealed that Proteobacteria, Acidobacteria, and Actinobacteria were the major phyla in Antarctic soils and the effect of short-term warming on the bacterial community was not apparent.
    Journal of Microbiology and Biotechnology 06/2013; · 1.40 Impact Factor
  • Jisun Kim, Hyerim Hong, Aram Heo, Woojun Park
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    ABSTRACT: High concentrations of indole are known to be toxic to cells due to perturbations in membrane potential. Here, we report for the first time a transcriptome analysis of a soil model bacterium, Pseudomonas putida KT2440, under indole treatment. We demonstrated that 47 genes are differentially expressed, including 11 genes involved in the tricarboxylic acid cycle (TCA cycle) and 12 genes involved in chaperone and protease functions (hslV, hslU, htpG, grpE, dnaK, ibpA, groEL, groES, clpB, lon-1, lon-2, and hflk). Mutant analysis supported the observation that protease genes including hslU are essential for the indole resistance of Pseudomonas strains. Subsequent biochemical analyses have shown that indole increases the NADH/NAD(+) ratio and decreases the adenosine triphosphate (ATP) concentration inside cells, due to membrane perturbation and higher expression of TCA cycle genes in the presence of indole. This energy reduction leads to a reduction in cell size and an enhancement of biofilm formation in P. putida. The observed upregulation in many chaperones and proteases led us to speculate that protein folding might be inhibited by indole treatment. Interestingly, our in vitro protein-refolding assay using malate dehydrogenase with purified GroEL/GroES demonstrated that indole interferes with protein folding. Taken together, our data provides new evidence that indole causes toxicity to Pseudomonas putida by inhibiting cellular energy production and protein folding. © 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
    FEMS Microbiology Letters 03/2013; · 2.05 Impact Factor
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    ABSTRACT: The effects of malachite green (MG) on the bacterial community in Antarctic soil were assessed. Culture-independent community analysis using 16S rRNA gene pyrosequencing showed that, in the presence of MG, the relative abundance of Pseudomonas dramatically increased from 2.2 % to 36.6 % (16.6-fold), and Pseudomonas became the predominant genus. The reduction in bacterial biodiversity was demonstrated by diversity indices and rarefaction curves. MG-degrading Pseudomonas sp. MGO was isolated from Antarctic soil. MG tolerance and decolorization activity were confirmed by growth, spectrophotometric, high-performance liquid chromatography, and thin-layer chromatography analyses in high MG concentrations. Our data showed that the decolorization process occurred via biodegradation, while biosorption also occurred after some time during the fed-batch decolorization process. Significant inductions in laccase, nicotinamide adenine dinucleotide-2,6 dichlorophenol indophenol reductase, and MG reductase activities suggested their involvement in the decolorization process. We also showed that the high tolerance of strain MGO to toxic MG might be mediated by upregulation of oxidative stress defense systems such as superoxide dismutase and protease. Collectively, these results demonstrated the response of the Antarctic soil bacterial community to MG and provided insight into the molecular mechanism of MG-tolerant Pseudomonas strains isolated from Antarctic soil.
    Applied Microbiology and Biotechnology 01/2013; · 3.81 Impact Factor

Publication Stats

781 Citations
252.59 Total Impact Points

Institutions

  • 2006–2014
    • Korea University
      • Department of Environmental Science and Ecological Engineering
      Sŏul, Seoul, South Korea
  • 2012
    • Dongguk University
      • Department of Life Science
      Seoul, Seoul, South Korea
    • Seoul National University
      • Department of Biological Sciences
      Sŏul, Seoul, South Korea
  • 2009–2012
    • Chung-Ang University
      • School of Biological Sciences
      Seoul, Seoul, South Korea
    • Ewha Womans University
      • Department of Chemistry Nano Science
      Seoul, Seoul, South Korea
    • Sunchon National University
      • Department of Environmental Education
      South Korea
  • 2002–2011
    • Cornell University
      • • Department of Microbiology
      • • Department of Microbiology and Immunology
      Ithaca, New York, United States
  • 2010
    • CHA University
      • Department of Applied Bioscience
      Seoul, Seoul, South Korea
    • Korea Atomic Energy Research Institute (KAERI)
      • Advanced Radiation Technology Institute
      Taiden, Daejeon, South Korea
  • 2006–2008
    • Gyeongsang National University
      • Division of Applied Life Science
      Chinju, South Gyeongsang, South Korea