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Choi, Mi-Hwa,Sun, Hui-Yu,Park, Ra-Young,Kim, Choon-Mee,Bai, Young-Hoon,Kim, Young-Ran,Rhee, Joon-Haeng,Shin, Sung-Heui Published by Elsevier/North Holland on behalf of t 2006 FEMS microbiology letters Vol.257 No.2
<P>Cyclic AMP-cAMP receptor protein (CRP) complex plays an essential role in the global regulation of Vibrio vulnificus virulence. We found that growth retardation of V. vulnificus caused by mutation of the crp gene encoding CRP was exacerbated under iron-limited conditions. Accordingly, we investigated the effect of crp mutation on the expression of the vulnibactin-mediated iron-uptake system and the ability of V. vulnificus to utilize transferrin-bound iron, and thus to grow in cirrhotic ascites, a human ex vivo system. The production of vulnibactin was suppressed, and the transcription of the vis and vuuA genes, which encode an enzyme required for vulnibactin synthesis and vulnibactin receptor protein, was also suppressed in the crp mutant. Moreover, the crp mutant could not utilize transferrin-bound iron, and its growth was severely suppressed both on transferrin-bound iron and in cirrhotic ascites. All the defects in the crp mutant were recovered by the in trans complementation of the wild-type crp gene. Putative CRP-binding sequences were found in the regulatory regions of the fur, vis and vuuA genes. These results indicate that crp mutation attenuates the ability to grow on transferrin-bound iron and in a human body fluid by down-regulating the vulnibactin-mediated iron-uptake system.</P>
Lee, Kil-Soo,Dubey, Vinod S.,Kolattukudy, Pappachan E.,Song, Chang-Hwa,Shin, A-Rum,Jung, Saet-Byel,Yang, Chul-Su,Kim, Su-Young,Jo, Eun-Kyeong,Park, Jeong-Kyu,Kim, Hwa-Jung Published by Elsevier/North Holland on behalf of t 2007 FEMS microbiology letters Vol.267 No.1
<P>The lipids located in the outer layer of Mycobacterium tuberculosis, which include sulfolipid, phthiocerol dimycocerosate (PDIM), diacyltrehalose, and polyacyltrehalose, may play a role in host-pathogen interactions. These lipids were purified using thin-layer chromatography, and their ability to induce proinflammatory cytokines in human monocytes and in a human acute monocytic leukemia cell line (THP-1) was examined. None of the lipids tested induced significant interleukin (IL)-12p40 or tumor necrosis factor (TNF)-alpha production in monocytic cells. Diacyltrehalose significantly inhibited lipopolysaccharide- and M. tuberculosis-induced IL-12p40, TNF-alpha, and IL-6 productions in human monocytes, whereas other lipids had no effect. However, diacyltrehalose was unable to inhibit peptidoglycan-induced IL-12p40 production. These results suggest that diacyltrehalose is a mycobacterial factor capable of modulating host immune responses.</P>
Lee, Jay J.,Yoon, Jung-Hoon,Yang, Sang-Yong,Lee, Sung-Taik Published by Elsevier/North Holland on behalf of t 2006 FEMS microbiology letters Vol.254 No.1
<P>A filamentous bacterium capable of utilizing 4-methylpyridine and 4-ethylpyridine as the sole source of carbon, nitrogen and energy was isolated from sludge. The organism, designated as strain M43, clustered most closely with members of the genus Pseudonocardia by 16S rRNA gene sequence analysis. During the degradation of 4-methylpyridine and 4-ethylpyridine, c. 60% of nitrogen in the pyridine ring was released as ammonia. Metabolite analyses showed that 2-hydroxy-4-methylpyridine and 2-hydroxy-4-ethylpyridine were transiently accumulated during the degradation of 4-methylpyridine and 4-ethylpyridine, respectively. Strain M43 was also able to degrade pyridine, 3,4-dimethylpyridine, 4-carboxypyridine and 2-hydroxy-4-methylpyridine. The results indicate that degradation of 4-methylpyridine and 4-ethylpyridine by strain M43 proceeded via initial hydroxylation.</P>
Hong, Gyeong-Eun,Kim, Dong-Gyun,Bae, Ju-Yoon,Ahn, Sun-Hee,Bai, Sungchul C.,Kong, In-Soo Published by Elsevier/North Holland on behalf of t 2007 FEMS microbiology letters Vol.269 No.2
<P>Vibrio anguillarum is the causative agent of the fish disease vibriosis and is the most intensely studied species of Vibrio. In the present study, specific primers and a PCR assay were designed to detect V. anguillarum. The primers were designed to amplify a 429-bp internal region of the V. anguillarum amiB gene, which encodes the peptidoglycan hydrolase N-acetylmuramoyl-L-alanine amidase. PCR specificity was demonstrated by successful amplification of DNA from V. anguillarum and by the absence of a PCR product from 25 other Vibrio strains and various enteric bacteria. The PCR produced a 429-bp amplified fragment from as little as 1 pg of V. anguillarum DNA. The limit of detection for this PCR technique was c. 20 bacterial colonies in 25 mg of infected flounder tissue. These results suggest that this PCR system is a sensitive and species-specific detection method, and is possible to use as a diagnostic tool to detect V. anguillarum.</P>
Quorum sensing in metal tolerance of Acinetobacter junii BB1A is associated with biofilm production.
Sarkar, Suchitra,Chakraborty, Ranadhir Published by Elsevier/North Holland on behalf of t 2008 FEMS microbiology letters Vol.282 No.2
<P>Acinetobacter junii strain BB1A, a novel metal-tolerant bacterium, produced biofilm in the presence of added ions such as Ni(2+), AsO(2)(-), Cd(2+) and Hg(2+) on surfaces such as glass and polystyrene. Generation of a metal-sensitive and adhesion-deficient mutant by transposition of Tn5-mob in the A. junii genome has putatively confirmed the association of metal tolerance with the production of biofilm. The requirement of a critical cell density for biofilm formation and presence of acyl-homoserine lactone-like autoinducer molecules in the cell-free supernatant indicated the phenomenon of quorum sensing. Addition of a natural quorum-sensing inhibitor (garlic extract) or synthetic quorum-sensing inhibitor (4-nitro-pyridine oxide) significantly inhibited cell growth and biofilm formation in the presence of metal/metalloid ions.</P>
Veeranagouda, Yaligara,Lee, Kyoung,Cho, Ah Ra,Cho, Kyungyun,Anderson, Erin M,Lam, Joseph S Published by Elsevier/North Holland on behalf of t 2011 FEMS microbiology letters Vol.315 No.1
<P>In the presence of vaporized p-cresol, Pseudomonas alkylphenolia KL28 forms specialized aerial structures (SAS). A transposon mutant of strain KL28 (C23) incapable of forming mature SAS was isolated. Genetic analysis of the C23 mutant revealed the transposon insertion in a gene (ssg) encoding a putative glycosyltransferase, which is homologous to the Pseudomonas aeruginosa PAO1 PA5001 gene. Deletion of ssg in KL28 caused the loss of lipopolysaccharide O antigen and altered the composition of the exopolysaccharide. Wild-type KL28 produced a fucose-, glucose- and mannose-rich exopolysaccharide, while the mutant exopolysaccharide completely lacked fucose and mannose, resulting in an exopolysaccharide with glucose as the major component. The mutant strain showed reduced surface spreading, pellicle and biofilm formation, probably due to the cumulative effect of lipopolysaccharide truncation and altered exopolysaccharide composition. Our results show that the ssg gene of KL28 is involved in both lipopolysaccharide and exopolysaccharide biosynthesis and thus plays an important role in cell surface properties and cell-cell interactions of P. alkylphenolia.</P>
Nam, Hyo Song,Anderson, Anne J.,Yang, Kwang Yeol,Cho, Baik Ho,Kim, Young Cheol Published by Elsevier/North Holland on behalf of t 2006 FEMS microbiology letters Vol.256 No.1
<P>Transcription from the dctA gene, which encodes an organic acid transporter in the root-colonizing bacterium Pseudomonas chlororaphis O6, is under complex regulatory control. Promoter sequence analysis revealed an RpoN binding site. The regulation of transcript accumulation by the level of ammonium ions in the growth medium confirmed RpoN regulation, even in the presence of glucose. A dctA mutant colonized tobacco roots to a lesser extent than the wild-type mutant during early seedling development. Colonization by the dctA mutant, as compared to the wild type, also reduced the level of systemically induced resistance against the soft rot pathogen Erwinia carotovora SCC1. We ascribe this reduced colonization to the inability of the mutant to utilize certain organic acid components in the root exudates. The dctA mutant failed to grow on succinate and fumarate, and showed reduced growth on malate. All altered properties of the mutant were complemented by the full-length dctA gene. We propose that organic acids in root exudates may provide important nutrient sources for the beneficial root-colonizing pseudomonad.</P>
Toxicity of phenanthrene dissolved in nonionic surfactant solutions to<i>Pseudomonas putida</i>P2
Jang, Soon A.,Lee, Dae S.,Lee, Min W.,Woo, Seung H. Published by Elsevier/North Holland on behalf of t 2007 FEMS microbiology letters Vol.267 No.2
<P>The fraction in which direct contact occurs between micellar-phase phenanthrene and the bacterial cell surface was estimated by measuring the toxicity of nonionic surfactant (Tween 80 and Triton X-100) solutions to the phenanthrene-degrading bacterium, Pseudomonas putida P2. Cell viability of completely dissolved phenanthrene decreased by 30% at concentrations greater than 0.3 mg L(-1), which is equal to approximately one third of its solubility. Both nonionic surfactants had no effect on cell viability up to 5 g L(-1). Cell viability increased with increasing surfactant concentration at a fixed phenanthrene concentration, due to the decreased concentration of aqueous-pseudophase phenanthrene and the reduced fraction of direct contact. The fraction of direct contact was c. 20% or more below 3 g L(-1) of Triton X-100. The fraction of direct contact for Tween 80 was estimated to be lower than Triton X-100.</P>