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Park, Minjeong,Jeon, Yeji,Jang, Ho Hee,Ro, Hyun-Su,Park, Woojun,Madsen, Eugene L.,Jeon, Che Ok American Society for Microbiology 2007 Applied and environmental microbiology Vol.73 No.16
<B>ABSTRACT</B><P>Prior research revealed that <I>Polaromonas naphthalenivorans</I> CJ2 carries and expresses genes encoding the gentisate metabolic pathway for naphthalene. These metabolic genes are split into two clusters, comprising <I>nagRAaGHAbAcAdBFCQEDJI</I>′-<I>orf1</I>-<I>tnpA</I> and <I>nagR2</I>-<I>orf2I</I>″<I>KL</I> (C. O. Jeon, M. Park, H. Ro, W. Park, and E. L. Madsen, Appl. Environ. Microbiol. 72:1086-1095, 2006). BLAST homology searches of sequences in GenBank indicated that the <I>orf2</I> gene from the small cluster likely encoded a salicylate 5-hydroxylase, presumed to catalyze the conversion of salicylate into gentisate. Here, we report physiological and genetic evidence that <I>orf2</I> does not encode salicylate 5-hydroxylase. Instead, we have found that <I>orf2</I> encodes 3-hydroxybenzoate 6-hydroxylase, the enzyme which catalyzes the NADH-dependent conversion of 3-hydroxybenzoate into gentisate. Accordingly, we have renamed <I>orf2 nagX</I>. After expression in <I>Escherichia coli</I>, the NagX enzyme had an approximate molecular mass of 43 kDa, as estimated by gel filtration, and was probably a monomeric protein. The enzyme was able to convert 3-hydroxybenzoate into gentisate without salicylate 5-hydroxylase activity. Like other 3-hydroxybenzoate 6-hydroxylases, NagX utilized both NADH and NADPH as electron donors and exhibited a yellowish color, indicative of a bound flavin adenine dinucleotide. An engineered mutant of <I>P. naphthalenivorans</I> CJ2 defective in <I>nagX</I> failed to grow on 3-hydroxybenzoate but grew normally on naphthalene. These results indicate that the previously described small catabolic cluster in strain CJ2 may be multifunctional and is essential for the degradation of 3-hydroxybenzoate. Because <I>nagX</I> and an adjacent MarR-type regulatory gene are both closely related to homologues in <I>Azoarcus</I> species, this study raises questions about horizontal gene transfer events that contribute to operon evolution.</P>
Park, Chulwoo,Shin, Bora,Jung, Jaejoon,Lee, Yunho,Park, Woojun BLACKWELL 2017 MICROBIAL BIOTECHNOLOGY -BLACKWELL- Vol.10 No.6
<P><B>Summary</B></P><P><I>Acinetobacter oleivorans </I>DR1 can utilize C<SUB>12</SUB>–C<SUB>30</SUB> alkanes as a sole carbon source but not short‐chain alkanes (C<SUB>6</SUB>, C<SUB>10</SUB>). Two copies of each <I>alkB</I>‐, <I>almA</I>‐ and <I>ladA</I>‐type alkane hydroxylase (AH) are present in the genome of DR1 cells. Expression and mutational analyses of AHs showed that <I>alkB1</I> and <I>alkB2</I> are the major AH‐encoding genes under C<SUB>12</SUB>–C<SUB>30</SUB>, and the roles of other <I>almA</I>‐ and <I>ladA</I> genes are negligible. Our data suggested that AlkB1 is responsible for long‐chain alkane utilization (C<SUB>24</SUB>–C<SUB>26</SUB>), and AlkB2 is important for medium‐chain alkane (C<SUB>12</SUB>–C<SUB>16</SUB>) metabolism. Phylogenetic analyses revealed large incongruities between phylogenies of 16S rRNA and each AH gene, which implies that <I>A. oleivorans </I>DR1 has acquired multiple alkane hydroxylases through horizontal gene transfer. Transcriptomic and qRT‐PCR analyses suggested that genes participating in the synthesis of siderophore, trehalose and poly 3‐hydroxybutyrate (PHB) were expressed at much higher levels when cells used C<SUB>30</SUB> than when used succinate as a carbon source. The following biochemical assays supported our gene expression analyses: (i) quantification of siderophore, (ii) measurement of trehalose and (iii) observation of PHB storage. Interestingly, highly induced both <I>ackA</I> gene encoding an acetate kinase A and <I>pta</I> gene encoding a phosphotransacetylase suggested unusual ATP synthesis during C<SUB>30</SUB> alkane degradation, which was demonstrated by ATP measurement using the <I>ΔackA</I> mutant. Impaired growth of the <I>ΔaceA</I> mutant indicated that the glyoxylate shunt pathway is important when C<SUB>30</SUB> alkane is utilized. Our data provide insight into long‐chain alkane degradation in soil microorganisms.</P>
Luteimonas lutimaris sp. nov., isolated from a tidal flat.
Park, Youn-Je,Park, Moon Su,Lee, Seung Hyeon,Park, Woojun,Lee, Kangseok,Jeon, Che Ok Society for General Microbiology 2011 International journal of systematic and evolutiona Vol.61 No.11
<P>A Gram-staining-negative, strictly aerobic bacterium, designated strain G3(T), was isolated from a tidal flat of the Taean coast in South Korea. Cells were moderately halotolerant and non-motile rods showing catalase- and oxidase-positive reactions. Growth of strain G3(T) was observed between 15 and 40 C (optimum 30 C) and between pH 5.5 and 9.0 (optimum pH 6.5-7.5). Strain G3(T) contained Q-8 as the predominant lipoquinone and iso-C(15 : 0), iso-C(17 : 1)ω9c, iso-C(16 : 0) and iso-C(11 : 0) as the major fatty acids. The G+C content of the genomic DNA was 69.6 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain G3(T) formed a tight phylogenetic lineage with Luteimonas mephitis B1953/27.1(T) within the genus Luteimonas and was most closely related to L. mephitis B1953/27.1(T) with 98.0 % 16S rRNA gene sequence similarity. The DNA-DNA relatedness between strain G3(T) and L. mephitis B1953/27.1(T) was 35.2 3.3 %. On the basis of chemotaxonomic data and molecular properties, strain G3(T) represents a novel species of the genus Luteimonas, for which the name Luteimonas lutimaris sp. nov. is proposed. The type strain is G3(T) (= KACC 14929(T) = JCM 16916(T)).</P>
Park Yerim,Kim Wonjae,Kim Minkyung,Park Woojun 한국미생물학회 2023 The journal of microbiology Vol.61 No.9
Many freshwater cyanobacteria, including Microcystis aeruginosa, lack several known antibiotic resistance genes; however, both axenic and xenic M. aeruginosa strains exhibited high antibiotic resistance against many antibiotics under our tested concentrations, including colistin, trimethoprim, and kanamycin. Interestingly, axenic PCC7806, although not the xenic NIBR18 and NIBR452 strains, displayed susceptibility to ampicillin and amoxicillin, indicating that the associated bacteria in the phycosphere could confer such antibiotic resistance to xenic strains. Fluorescence and scanning electron microscopic observations revealed their tight association, leading to possible community-level β-lactamase activity. Combinatory treatment of ampicillin with a β-lactamase inhibitor, sulbactam, abolished the ampicillin resistance in the xenic stains. The nitrocefin-based assay confirmed the presence of significant community-level β-lactamase activity. Our tested low ampicillin concentration and high β-lactamase activity could potentially balance the competitive advantage of these dominant species and provide opportunities for the less competitive species, thereby resulting in higher bacterial diversity under ampicillin treatment conditions. Non-PCR-based metagenome data from xenic NIBR18 cultures revealed the dominance of blaOXArelated antibiotic resistance genes followed by other class A β-lactamase genes (AST-1 and FAR-1). Alleviation of ampicillin toxicity could be observed only in axenic PCC7806, which had been cocultured with β-lactamase from other freshwater bacteria. Our study suggested M. aeruginosa develops resistance to old-class β-lactam antibiotics through altruism, where associated bacteria protect axenic M. aeruginosa cells.
Flavobacterium croceum sp. nov., isolated from activated sludge.
Park, Minjeong,Lu, Shipeng,Ryu, Seung Hyun,Chung, Bok Sil,Park, Woojun,Kim, Chang-Jin,Jeon, Che Ok Society for General Microbiology 2006 International journal of systematic and evolutiona Vol.56 No.10
<P>A Gram-negative, non-motile, rod-shaped bacterium, designated strain EMB47(T), was isolated from activated sludge performing enhanced biological phosphorus removal in a sequencing batch reactor. Growth was observed between 10 and 40 degrees C (optimum, 25-35 degrees C) and between pH 5.0 and 8.5 (optimum, pH 7.5-8.0). The predominant fatty acids of strain EMB47(T) were iso-C(16 : 0) 3-OH, iso-C(15 : 1) G, C(15 : 0), iso-C(15 : 0), iso-C(14 : 0) and iso-C(16 : 0) and it contained phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylcholine as polar lipids. The G+C content of the genomic DNA was 40.8 mol% and the major quinone was MK-6. Comparative 16S rRNA gene sequence analyses showed that strain EMB47(T) formed a distinct phyletic line within the genus Flavobacterium. The levels of 16S rRNA gene sequence similarity with respect to Flavobacterium species were below 94.7 %. On the basis of the phenotypic, chemotaxonomic and molecular data, strain EMB47(T) represents a novel species within the genus Flavobacterium, for which the name Flavobacterium croceum sp. nov. is proposed. The type strain is EMB47(T) (=KCTC 12611(T)=DSM 17960(T)).</P>