Science.gov

Sample records for rhodococcus rhodochrous s-2

  1. Draft genome sequence of Rhodococcus rhodochrous strain ATCC 17895

    PubMed Central

    Chen, Bi-Shuang; Otten, Linda G.; Resch, Verena; Muyzer, Gerard; Hanefeld, Ulf

    2013-01-01

    Rhodococcus rhodochrous ATCC 17895 possesses an array of mono- and dioxygenases, as well as hydratases, which makes it an interesting organism for biocatalysis. R. rhodochrous is a Gram-positive aerobic bacterium with a rod-like morphology. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 6,869,887 bp long genome contains 6,609 protein-coding genes and 53 RNA genes. Based on small subunit rRNA analysis, the strain is more likely to be a strain of Rhodococcus erythropolis rather than Rhodococcus rhodochrous. PMID:24501654

  2. Draft Genome Sequence of Rhodococcus rhodochrous Strain ATCC 21198

    SciTech Connect

    Shields-Menard, Sara A.; Brown, Steven D; Klingeman, Dawn Marie; Indest, Karl; Hancock, Dawn; Wewalwela, Jayani; French, Todd; Donaldson, Janet

    2014-01-01

    Rhodococcus rhodochrous is a Gram-positive red-pigmented bacterium commonly found in the soil. The draft genome sequence for R. rhodochrous strain ATCC 21198 is presented here to provide genetic data for a better understanding of its lipid-accumulating capabilities.

  3. Molecular biological enhancement of coal biodesulfurization. [Rhodococcus rhodochrous

    SciTech Connect

    Kilbane, J.J.; Bielaga, B.A.

    1990-07-01

    The overall objective of this project is to sue molecular genetics to develop strains of bacteria with enhanced ability to remove sulfur from coal and to obtain data that will allow the performance and economics of a coal biodesulfurization process to be predicted. The work planned for the current quarter (May 1990 to July 1990) includes the following activities: (1) Construct a cloning vector that can be used in Rhodococcus rhodochrous IGTS8 from the small cryptic plasmid found in Rhodococcus rhodochrous ATCC 190607; (2) Develop techniques for the genetic analysis of IGTS8; (3) Continue biochemical experiments, particularly those that may allow the identification of desulfurization-related enzymes; (4) Continue experiments with coal to determine the kinetics of organic sulfur removal.

  4. Draft Genome of Rhodococcus rhodochrous TRN7, Isolated from the Coast of Trindade Island, Brazil.

    PubMed

    Rodrigues, Edmo M; Pylro, Victor S; Dobbler, Priscila T; Victoria, Filipe; Roesch, Luiz F W; Tótola, Marcos R

    2016-01-01

    Here, we present a draft genome and annotation of Rhodococcus rhodochrous TRN7, isolated from Trindade Island, Brazil, which will provide genetic data to benefit the understanding of its metabolism. PMID:26941155

  5. Draft Genome of Rhodococcus rhodochrous TRN7, Isolated from the Coast of Trindade Island, Brazil

    PubMed Central

    Rodrigues, Edmo M.; Pylro, Victor S.; Dobbler, Priscila T.; Victoria, Filipe

    2016-01-01

    Here, we present a draft genome and annotation of Rhodococcus rhodochrous TRN7, isolated from Trindade Island, Brazil, which will provide genetic data to benefit the understanding of its metabolism. PMID:26941155

  6. Microbial strain improvement for organosulfur removal from coal. [Rhodococcus rhodochrous

    SciTech Connect

    Kilbane, J.J. II.

    1991-01-01

    IGT has developed a microbial culture of Rhodococcus rhodochrous, designated as IGTS8, that is capable of specifically cleaving carbon-sulfur bonds in a range of organosulfur model compounds and is capable of removing organic sulfur from coal and petroleum without sacrificing the calorific value of the fuel. Although IGTS8 possesses the ability to specifically remove organic sulfur from coal, a major research need is to develop improved strains of microorganisms that possess higher levels of desulfurization activity and therefore will permit more favorable biodesulfurization process conditions: faster rates, more complete removal, and smaller reactor size. Strain improvement is the single most important aspect to the development of a practical coal desulfurization process. Microbial strain improvement can be accomplished using genetic engineering recombinant DNA techniques as well as by non-recombinant techniques of microbiology and genetics. Both approaches will be employed in the proposed research, with the objective of developing derivatives of IGTS8 with markedly enhanced levels of desulfurization activity and evaluating the ability of improved cultures to remove organic sulfur from coal. During the current quarter, desulfurization-deficient mutants of IGTS8 have been obtained and characterized, improved cloning vectors have been constructed, the construction and screening of geonomic libraries has been initiated, and a derivative of IGTS8 with enhanced desulfurization ability has been obtained.

  7. A 2-Hydroxypyridine Catabolism Pathway in Rhodococcus rhodochrous Strain PY11.

    PubMed

    Vaitekūnas, Justas; Gasparavičiūtė, Renata; Rutkienė, Rasa; Tauraitė, Daiva; Meškys, Rolandas

    2015-12-11

    Rhodococcus rhodochrous PY11 (DSM 101666) is able to use 2-hydroxypyridine as a sole source of carbon and energy. By investigating a gene cluster (hpo) from this bacterium, we were able to reconstruct the catabolic pathway of 2-hydroxypyridine degradation. Here, we report that in Rhodococcus rhodochrous PY11, the initial hydroxylation of 2-hydroxypyridine is catalyzed by a four-component dioxygenase (HpoBCDF). A product of the dioxygenase reaction (3,6-dihydroxy-1,2,3,6-tetrahydropyridin-2-one) is further oxidized by HpoE to 2,3,6-trihydroxypyridine, which spontaneously forms a blue pigment. In addition, we show that the subsequent 2,3,6-trihydroxypyridine ring opening is catalyzed by the hypothetical cyclase HpoH. The final products of 2-hydroxypyridine degradation in Rhodococcus rhodochrous PY11 are ammonium ion and α-ketoglutarate.

  8. A 2-Hydroxypyridine Catabolism Pathway in Rhodococcus rhodochrous Strain PY11

    PubMed Central

    Gasparavičiūtė, Renata; Rutkienė, Rasa; Tauraitė, Daiva; Meškys, Rolandas

    2015-01-01

    Rhodococcus rhodochrous PY11 (DSM 101666) is able to use 2-hydroxypyridine as a sole source of carbon and energy. By investigating a gene cluster (hpo) from this bacterium, we were able to reconstruct the catabolic pathway of 2-hydroxypyridine degradation. Here, we report that in Rhodococcus rhodochrous PY11, the initial hydroxylation of 2-hydroxypyridine is catalyzed by a four-component dioxygenase (HpoBCDF). A product of the dioxygenase reaction (3,6-dihydroxy-1,2,3,6-tetrahydropyridin-2-one) is further oxidized by HpoE to 2,3,6-trihydroxypyridine, which spontaneously forms a blue pigment. In addition, we show that the subsequent 2,3,6-trihydroxypyridine ring opening is catalyzed by the hypothetical cyclase HpoH. The final products of 2-hydroxypyridine degradation in Rhodococcus rhodochrous PY11 are ammonium ion and α-ketoglutarate. PMID:26655765

  9. Nitrile Hydratase and Amidase from Rhodococcus rhodochrous Hydrolyze Acrylic Fibers and Granular Polyacrylonitriles

    PubMed Central

    Tauber, M. M.; Cavaco-Paulo, A.; Robra, K.-H.; Gübitz, G. M.

    2000-01-01

    Rhodococcus rhodochrous NCIMB 11216 produced nitrile hydratase (320 nkat mg of protein−1) and amidase activity (38.4 nkat mg of protein−1) when grown on a medium containing propionitrile. These enzymes were able to hydrolyze nitrile groups of both granular polyacrylonitriles (PAN) and acrylic fibers. Nitrile groups of PAN40 (molecular mass, 40 kDa) and PAN190 (molecular mass, 190 kDa) were converted into the corresponding carbonic acids to 1.8 and 1.0%, respectively. In contrast, surfacial nitrile groups of acrylic fibers were only converted to the corresponding amides. X-ray photoelectron spectroscopy analysis showed that 16% of the surfacial nitrile groups were hydrolyzed by the R. rhodochrous enzymes. Due to the enzymatic modification, the acrylic fibers became more hydrophilic and thus, adsorption of dyes was enhanced. This was indicated by a 15% increase in the staining level (K/S value) for C.I. Basic Blue 9. PMID:10742253

  10. Aliphatic amidase of Rhodococcus rhodochrous PA-34: Purification, characterization and application in synthesis of acrylic acid.

    PubMed

    Thakur, Neerja; Kumar, Vijay; Sharma, Nirmal Kant; Thakur, Shikha; Bhalla, Tek Chand

    2016-01-01

    An intracellular aliphatic amide degrading inducible amidase produced by Rhodococcus rhodochrous PA-34 was characterized and acrylic acid synthesis from acrylamide was carried out using whole cell amidase. A bioprocess was developed at 50 ml fed batch reaction using 400 mM acrylamide feeding at an interval of 30 min resulted in the production of 4 g acrylic acid with volumetric and catalytic productivity of 80 g/l and 19 g/g/h respectively. The amidase of this organism had molecular weight of 40 kDa and was purified to 8.5 fold with 8% yield. This enzyme was active within the temperature range of 30 to 60 °C, with optimum temperature 45 °C and pH 7.5. The Vmax, Km, and kcat of purified amidase were calculated as 250 U/mg protein, 4.5 mM, and 166 sec-1 for acrylamide. The enzyme showed tolerance to metal chelating agent (EDTA) and was strongly inhibited by heavy metal ions Hg2+, Ag2+, Cu2+ and Co2+. R. rhodochrous PA-34 amidase preferentially hydrolyzed small aliphatic toxic amide such as acrylamide. Thus, the amidase of R. rhodochrous PA-34 is promising biocatalyst for the synthesis of industrially important acids and biodegradation of toxic amides. PMID:26667322

  11. Enzymatic degradation of aliphatic nitriles by Rhodococcus rhodochrous BX2, a versatile nitrile-degrading bacterium.

    PubMed

    Fang, Shumei; An, Xuejiao; Liu, Hongyuan; Cheng, Yi; Hou, Ning; Feng, Lu; Huang, Xinning; Li, Chunyan

    2015-06-01

    Nitriles are common environmental pollutants, and their removal has attracted increasing attention. Microbial degradation is considered to be the most acceptable method for removal. In this work, we investigated the biodegradation of three aliphatic nitriles (acetonitrile, acrylonitrile and crotononitrile) by Rhodococcus rhodochrous BX2 and the expression of their corresponding metabolic enzymes. This organism can utilize all three aliphatic nitriles as sole carbon and nitrogen sources, resulting in the complete degradation of these compounds. The degradation kinetics were described using a first-order model. The degradation efficiency was ranked according to t1/2 as follows: acetonitrile>trans-crotononitrile>acrylonitrile>cis-crotononitrile. Only ammonia accumulated following the three nitriles degradation, while amides and carboxylic acids were transient and disappeared by the end of the assay. mRNA expression and enzyme activity indicated that the tested aliphatic nitriles were degraded via both the inducible NHase/amidase and the constitutive nitrilase pathways, with the former most likely preferred.

  12. Characterization of carbon-sulfur bond cleavage by axenic and mixed cultures of Rhodococcus rhodochrous IGTS8

    SciTech Connect

    Kayser, K.J.; Bielaga, B.A.; Jackowski, K.; Oduson, O.; Kilbane, J. II

    1992-12-31

    Growth assays reveal that Rhodococcus rhodochrous IGTS8 can utilize a wide range of organosulfur compounds as the sole source of sulfur. Compounds that are utilized include thiophenes, sulfides, disulfides, mercaptans, sulfoxides, and sulfones. None of the organosulfur compounds tested can serve as a carbon source. A convenient spectrophotometric assay (Gibbs assay) based on the chromogenic reaction of 2,6-dichloroquinone-4-chloroimide with aromatic hydroxyl groups was developed and used in conjunction with GC/MS analysis to examine the kinetics of carbon-sulfur bond cleavage by axenic and mixed cell cultures of Rhodococcus rhodochrous IGTS8. The desulfurization trait is expressed at uniform levels during the mid-exponential phase, reaches a maximum during idiophase, and then declines in stationary-phase cells. Desulfurization rates for dibenzothiophene (DBT) range from 8 to 15 {mu}M of DBT/10{sup 12} cells/hour. Mixtures of genetically marked Rhodococcus rhodochrous IGTS8 and an organisms incapable of cleaning carbon-sulfur bonds in relevant test compounds, Enterobacter cloacae, were prepared in ratios that varied over six orders of magnitude. Growth studies revealed that Enterobacter cloacae was able to gain access to sulfur liberated from organosulfur compounds by IGTS8; however, cell-to-cell contact was required. These data also indicate that the desulfurization activity of IGTS8 cells in mixed cultures may be as much as 200-fold higher than in axenic cultures.

  13. Directed Evolution and Mutant Characterization of Nitrilase from Rhodococcus rhodochrous tg1-A6.

    PubMed

    Luo, Hui; Ma, Jinwei; Chang, Yanhong; Yu, Huimin; Shen, Zhongyao

    2016-04-01

    In this paper, a molecularly directed evolution-based approach was applied to modify the nitrilase from Rhodococcus rhodochrous tg1-A6 for improving properties in catalyzing nitriles. In the process of error-prone polymerase chain reaction (PCR) with the wild-type nitrilase gene acting as the template, a library of the randomly mutated nitrilase gene was constructed. Since the pH value of catalyzing solution decreased when glycolonitrile was used as the substrate of nitrilase, a high-throughput strategy based on the color change of a pH-sensitive indicator was established for rapid screening of the mutated nitrilase. After three rounds of random mutation and screening about 5000 clones, a variant (Mut3) with 5.3-fold activity of the wild-type counterpart was obtained. Five amino acid substitutions (D27E, N97K, L246F, D108E, and S111R) were found in the variant Mut3. The properties of three mutated enzymes obtained in the three-round mutation were investigated. In the conversion of glycolonitrile, the variant (Mut2) accumulated the highest concentration of glycolic acid at 10.6 g l(-1), a much higher value than the wild type (3.2 g l(-1)). PMID:26712248

  14. Draft Genome Sequence of Rhodococcus rhodochrous Strain KG-21, a Soil Isolate from Oil Fields of Krishna-Godavari Basin, India

    PubMed Central

    Dawar, Chhavi

    2015-01-01

    Here, we present the 6.1-Mb draft genome sequence of Rhodococcus rhodochrous strain KG-21, a soil isolate from the oil fields of Krishna-Godavari Basin in Andhra Pradesh, India. This genomic resource may help in the identification of the gene(s) involved in hydrocarbon degradation and their possible deployment for bioremediation. PMID:26472842

  15. Immobilization of Rhodococcus rhodochrous BX2 (an acetonitrile-degrading bacterium) with biofilm-forming bacteria for wastewater treatment.

    PubMed

    Li, Chunyan; Li, Yue; Cheng, Xiaosong; Feng, Liping; Xi, Chuanwu; Zhang, Ying

    2013-03-01

    In this study, a unique biofilm consisting of three bacterial strains with high biofilm-forming capability (Bacillus subtilis E2, E3, and N4) and an acetonitrile-degrading bacterium (Rhodococcus rhodochrous BX2) was established for acetonitrile-containing wastewater treatment. The results indicated that this biofilm exhibited strong resistance to acetonitrile loading shock and displayed a typical spatial and structural heterogeneity and completely depleted the initial concentration of acetonitrile (800mgL(-1)) within 24h in a moving-bed-biofilm reactor (MBBR) after operation for 30days. The immobilization of BX2 cells in the biofilm was confirmed by PCR-DGGE. It has been demonstrated that biofilm-forming bacteria can promote the immobilization of contaminant-degrading bacteria in the biofilms and can subsequently improve the degradation of contaminants in wastewater. This approach offers a novel strategy for enhancing biological oxidation of toxic pollutants in wastewater. PMID:23376196

  16. Rhodococcus rhodochrous ATCC12674 becomes alkane-tolerant upon GroEL2 overexpression and survives in the n-octane phase in two phase culture.

    PubMed

    Takihara, Hayato; Matsuura, Chiaki; Ogihara, Jun; Iwabuchi, Noriyuki; Sunairi, Michio

    2014-01-01

    We recently reported that the overexpression of GroEL2 played an important role in increasing the alkane tolerance of Rhodococcus erythropolis PR4. In the present study, we examined the effects of the introduction of groEL2 on the alkane tolerance of other Rhodococcus strains. The introduction of groEL2 into Rhodococcus strains led to increased alkane tolerance. The translocation of R. rhodochrous ATCC12674 cells to and survival in the n-octane (C8) phase in two phase culture were significantly enhanced by the introduction of groEL2 derived from strain PR4, suggesting that engineering cells to overexpress GroEL2 represents an effective strategy for enhancing organic solvent tolerance in Rhodococcus.

  17. Evaluation of biosurfactants grown in corn oil by Rhodococcus rhodochrous on removing of heavy metal ion from aqueous solution

    NASA Astrophysics Data System (ADS)

    Suryanti, Venty; Hastuti, Sri; Pujiastuti, Dwi

    2016-02-01

    The potential application of biosurfactants to remove heavy metal ion from aqueous solution by batch technique was examined. The glycolipids type biosurfactants were grown in a media containing of 20% v/v corn oil with 7 days of fermentation by Rhodococcus rhodochrous. The biosurfactants reduced the surface tension of water of about 51% from 62 mN/m to 30 mN/m. The biosurfactant increased the E24 of water-palm oil emulsion of about 55% from 43% to 97% and could maintain this E24 value of above 50% for up to 9 days. Heavy metal ion removal, in this case cadmium ion, by crude and patially purified biosurfactants has been investigated from aqueous solution at pH 6. Adsorption capacity of Cd(II) ion by crude biosurfactant with 5 and 10 minutes of contact times were 1.74 and 1.82 mg/g, respectively. Additionally, the adsorption capacity of Cd(II) ion by partially purified biosurfactant with 5 and 10 minutes of contact times were 0.79 and 1.34 mg/g, respectively. The results demonstrated that the adsorption capacity of Cd(II) ion by crude biosurfactant was higher than that of by partially purified biosurfactant. The results suggested that the biosurfactant could be used in the removal of heavy metal ions from aqueous solution.

  18. Optimization of biosurfactant production in soybean oil by rhodococcus rhodochrous and its utilization in remediation of cadmium-contaminated solution

    NASA Astrophysics Data System (ADS)

    Suryanti, Venty; Hastuti, Sri; Andriani, Dewi

    2016-02-01

    Biosurfactant production by Rhodococcus rhodochrous in soybean oil was developed, where the effect of medium composition and fermentation time were evaluated. The optimum condition for biosurfactant production was achieved when a medium containing 30 g/L TSB (tryptic soy broth) and 20% v/v soybean oil was used as media with 7 days of fermentation. Biosurfactant was identified as glycolipids type biosurfactant which had critical micelle concentration (CMC) value of 896 mg/L. The biosurfactant had oil in water emulsion type and was able to reduce the surface tension of palm oil about 52% which could stabilize the emulsion up to 12 days. The batch removal of cadmium metal ion by crude and partially purified biosurfactants have been examined from synthetic aqueous solution at pH 6. The results exhibited that the crude biosurfactant had a much better adsorption ability of Cd(II) than that of partially purified biosurfactant. However, it was found that there was no significant difference in the adsorption of Cd(II) with 5 and 10 minutes of contact time. The results indicated that the biosurfactant could be used in remediation of heavy metals from contaminated aqueous solution.

  19. Multiplicity of 3-Ketosteroid-9α-Hydroxylase Enzymes in Rhodococcus rhodochrous DSM43269 for Specific Degradation of Different Classes of Steroids ▿ †

    PubMed Central

    Petrusma, Mirjan; Hessels, Gerda; Dijkhuizen, Lubbert; van der Geize, Robert

    2011-01-01

    The well-known large catabolic potential of rhodococci is greatly facilitated by an impressive gene multiplicity. This study reports on the multiplicity of kshA, encoding the oxygenase component of 3-ketosteroid 9α-hydroxylase, a key enzyme in steroid catabolism. Five kshA homologues (kshA1 to kshA5) were previously identified in Rhodococcus rhodochrous DSM43269. These KshADSM43269 homologues are distributed over several phylogenetic groups. The involvement of these KshA homologues in the catabolism of different classes of steroids, i.e., sterols, pregnanes, androstenes, and bile acids, was investigated. Enzyme activity assays showed that all KSH enzymes with KshADSM43269 homologues are C-9 α-hydroxylases acting on a wide range of 3-ketosteroids, but not on 3-hydroxysteroids. KshA5 appeared to be the most versatile enzyme, with the broadest substrate range but without a clear substrate preference. In contrast, KshA1 was found to be dedicated to cholic acid catabolism. Transcriptional analysis and functional complementation studies revealed that kshA5 supported growth on any of the different classes of steroids tested, consistent with its broad expression induction pattern. The presence of multiple kshA genes in the R. rhodochrous DSM43269 genome, each displaying unique steroid induction patterns and substrate ranges, appears to facilitate a dynamic and fine-tuned steroid catabolism, with C-9 α-hydroxylation occurring at different levels during microbial steroid degradation. PMID:21642460

  20. Preliminary report on a catalyst derived from induced cells of Rhodococcus rhodochrous strain DAP 96253 that delays the ripening of selected climacteric fruit: bananas, avocados, and peaches.

    PubMed

    Pierce, G E; Drago, G K; Ganguly, S; Tucker, T-A M; Hooker, J W; Jones, S; Crow, S A

    2011-09-01

    Despite the use of refrigeration, improved packaging, adsorbents, and ethylene receptor blockers, on average, nearly 40% of all fruits and vegetables harvested in the US are not consumed. Many plant products, especially fruit, continue to ripen after harvesting, and as they do so, become increasingly susceptible to mechanical injury, resulting in increased rot. Other plant products during transportation and storage are susceptible to chill injury (CI). There is a real need for products that can delay ripening or mitigate the effects of CI, yet still permit full ripeness and quality to be achieved. Preliminary results are discussed where catalyst derived from cells of Rhodococcus rhodochrous DAP 96253, grown under conditions that induced high levels of nitrile hydratase, were able to extend the ripening and thus the shelf-life of selected climacteric fruits (banana, avocado, and peach). A catalyst, when placed in proximity to, but not touching, the test fruit delayed the ripening but did not alter the final ripeness of the fruit tested. Organoleptic evaluations conducted with control peaches and with peaches exposed to, but not in contact with, the catalyst showed that the catalyst-treated peaches achieved full, natural levels of ripeness with respect to aroma, flavor, sweetness, and juice content. Furthermore, the results of delayed ripening were achieved at ambient temperatures (without the need for refrigeration). PMID:21409422

  1. Preliminary report on a catalyst derived from induced cells of Rhodococcus rhodochrous strain DAP 96253 that delays the ripening of selected climacteric fruit: bananas, avocados, and peaches.

    PubMed

    Pierce, G E; Drago, G K; Ganguly, S; Tucker, T-A M; Hooker, J W; Jones, S; Crow, S A

    2011-09-01

    Despite the use of refrigeration, improved packaging, adsorbents, and ethylene receptor blockers, on average, nearly 40% of all fruits and vegetables harvested in the US are not consumed. Many plant products, especially fruit, continue to ripen after harvesting, and as they do so, become increasingly susceptible to mechanical injury, resulting in increased rot. Other plant products during transportation and storage are susceptible to chill injury (CI). There is a real need for products that can delay ripening or mitigate the effects of CI, yet still permit full ripeness and quality to be achieved. Preliminary results are discussed where catalyst derived from cells of Rhodococcus rhodochrous DAP 96253, grown under conditions that induced high levels of nitrile hydratase, were able to extend the ripening and thus the shelf-life of selected climacteric fruits (banana, avocado, and peach). A catalyst, when placed in proximity to, but not touching, the test fruit delayed the ripening but did not alter the final ripeness of the fruit tested. Organoleptic evaluations conducted with control peaches and with peaches exposed to, but not in contact with, the catalyst showed that the catalyst-treated peaches achieved full, natural levels of ripeness with respect to aroma, flavor, sweetness, and juice content. Furthermore, the results of delayed ripening were achieved at ambient temperatures (without the need for refrigeration).

  2. Cloning, Sequencing, and Characterization of the Hexahydro-1,3,5-Trinitro-1,3,5-Triazine Degradation Gene Cluster from Rhodococcus rhodochrous

    PubMed Central

    Seth-Smith, Helena M. B.; Rosser, Susan J.; Basran, Amrik; Travis, Emma R.; Dabbs, Eric R.; Nicklin, Steve; Bruce, Neil C.

    2002-01-01

    Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a high explosive which presents an environmental hazard as a major land and groundwater contaminant. Rhodococcus rhodochrous strain 11Y was isolated from explosive contaminated land and is capable of degrading RDX when provided as the sole source of nitrogen for growth. Products of RDX degradation in resting-cell incubations were analyzed and found to include nitrite, formaldehyde, and formate. No ammonium was excreted into the medium, and no dead-end metabolites were observed. The gene responsible for the degradation of RDX in strain 11Y is a constitutively expressed cytochrome P450-like gene, xplA, which is found in a gene cluster with an adrenodoxin reductase homologue, xplB. The cytochrome P450 also has a flavodoxin domain at the N terminus. This study is the first to present a gene which has been identified as being responsible for RDX biodegradation. The mechanism of action of XplA on RDX is thought to involve initial denitration followed by spontaneous ring cleavage and mineralization. PMID:12324318

  3. Improvement of desulfurization activity in Rhodococcus erythropolis KA2-5-1 by genetic engineering.

    PubMed

    Hirasawa, K; Ishii, Y; Kobayashi, M; Koizumi, K; Maruhashi, K

    2001-02-01

    Rhodococcus erythropolis KA2-5-1 can desulfurize dibenzothiophene (DBT) into 2-hydroxybiphenyl. A cryptic plasmid, pRC4, which was derived from R. rhodochrous IFO3338, was combined with an Escherichia coli vector to construct an E. coli-Rhodococcus shuttle vector. The complete nucleotide sequence of 2582-bp pRC4 was analyzed. Based on the characteristics of its putative replication genes, pRC4 was assigned to the family of pAL5000-related replicons. The desulfurization gene cluster, dszABC, and the related reductase gene, dszD, cloned from KA2-5-1, were reintroduced into KA2-5-1 and efficiently expressed. The DBT desulfurization ability of the transformant carrying two dszABC clusters and one dszD on the vector was about 4-fold higher than that of the parent strain, and the transformant also showed improved desulfurization activity for light gas oil (LGO). Sulfur components in LGO before and after the reaction were analyzed with gas chromatography-atomic emission detection.

  4. Ultrasound assisted biodesulfurization of liquid fuel using free and immobilized cells of Rhodococcus rhodochrous MTCC 3552: A mechanistic investigation.

    PubMed

    Bhasarkar, Jaykumar B; Dikshit, Pritam Kumar; Moholkar, Vijayanand S

    2015-01-01

    This paper attempts to gain mechanistic insight into enhancement effect of sonication on biodesulfurization. The approach has been to fit Haldane kinetics model to dibenzothiophene (DBT) metabolism and analyze trends in model parameters concurrently with simulations of cavitation bubble dynamics. Mechanistic synergy between sonication and biodesulfurization is revealed to be of both physical and chemical nature. Generation of micro-turbulence in medium by sonication leads to fine emulsification and enhancement of DBT transport across organic/aqueous interphase. Microturbulence also enhances transport of substrate and product across cell wall that increases reaction velocity (Vmax). Michaelis constant (Km) and inhibition constant (KI), being intrinsic parameters, remain unaffected by sonication. Radicals produced by transient cavitation oxidize DBT to DBT-sulfoxide and DBT-sulfone (intermediates of metabolism), which contributes enhancement of biodesulfurization. However, high shear generated by ultrasound and cavitation has adverse effect on action of surfactant β-cyclodextrin for enhancement of interphase transport of DBT.

  5. Structural analysis of the 6 kb cryptic plasmid pFAJ2600 from Rhodococcus erythropolis NI86/21 and construction of Escherichia coli-Rhodococcus shuttle vectors.

    PubMed

    De Mot, R; Nagy, I; De Schrijver, A; Pattanapipitpaisal, P; Schoofs, G; Vanderleyden, J

    1997-10-01

    The complete nucleotide sequence of the 5936 bp cryptic plasmid pFAJ2600 from Rhodococcus erythropolis NI86/21 was determined. Based on the characteristics of its putative replication genes, repA and repB, pFAJ2600 was assigned to the family of pAL5000-related small replicons identified in Mycobacterium (pAL5000), Corynebacterium (pXZ10142), Brevibacterium (pRBL1), Bifidobacterium (pMB1) and Neisseria (pJD1). The replication systems of these plasmids show striking similarities to the ones used by the ColE2 family of plasmids from Enterobacteria with respect to both trans-acting factors and ori sequences. Two possible plasmid stabilization systems are encoded on pFAJ2600: a site-specific recombinase (PmrA) related to the Escherichia coli Xer proteins for plasmid multimer resolution and an ATPase (ParA) related to the A-type of proteins in sop/par partitioning systems. The proposed replication termination region of pFAJ2600 has features in common with the Ter loci of Bacillus subtilis. Chimeras composed of a pUC18-Cmr derivative inserted in the parA-repA intergenic region of vector pFAJ2600 produced vectors that could be shuttled between Escherichia coli and several Rhodococcus species (R. erythropolis, R. fascians, R. rhodochrous, R. ruber). The pFAJ2600-based shuttle vector pFAJ2574 was stably maintained in R. erythropolis and R. fascians growing under non-selective conditions.

  6. Identification and environmental detection of Rhodococcus species by 16S rDNA-targeted PCR.

    PubMed

    Bell, K S; Kuyukina, M S; Heidbrink, S; Philp, J C; Aw, D W; Ivshina, I B; Christofi, N

    1999-10-01

    Bacteria of the genus Rhodococcus can degrade a wide range of organic pollutants and catalyse many useful biotransformations. There is a need for improved tests to identify Rhodococcus species. PCR-based methods for species identification offer advantages in terms of speed and accuracy over traditional methods and can allow direct detection of microbes in environmental samples., PCR tests, using primers targeted at species-specific sequences in the 16S rRNA gene, were successfully developed for R. globerulus, R. erythropolis, R. opacus and R. ruber. These tests gave positive results with all or most strains of target species but did not generally cross-react with other species. Cases of apparent cross-reaction were shown to be due to prior misclassification of strains of R. opacus as R. erythropolis and of strains of R. ruber as R. rhodochrous. A simple and rapid method for the extraction and purification of DNA from soil was developed and successfully applied to the PCR detection of indigenous R. erythropolis in an environmental sample. Cell lysis in the samples was achieved by lysozyme and sarkosyl treatment, aided by freeze-thaw cycles. Removal of humic compounds inhibitory to PCR was accomplished by CTAB treatment with solvent extraction and, if necessary, passage of extracts through Sepharose CL-6B in a spun-column format. Extracts prepared using a tris-EDTA buffer were much clearer than those prepared using a sodium phosphate buffer, indicating lower levels of humic compounds. A detection limit of 104 cfu g-1 of soil was achieved and the use of a secondary PCR allowed detection of 1 cfu g-1.

  7. Cloning systems for Rhodococcus and related bacteria

    DOEpatents

    Finnerty, William R.; Singer, Mary E.

    1990-01-01

    A plasmid transformation system for Rhodococcus was developed using an Escherichia coli-Rhodococcus shuttle plasmid. Rhodococcus sp. H13-A contains three cryptic indigenous plasmids, designated pMVS100, pMVS200 and pMVS300, of 75, 19.5 and 13.4 kilobases (Kb), respectively. A 3.8 Kb restriction fragment of pMVS300 was cloned into pIJ30, a 6.3 Kb pBR322 derivative, containing the E. coli origin of replication (ori) and ampicillin resistance determinant (bla) as well as a Streptomyces gene for thiostrepton resistance, tsr. The resulting 10.1 Kb recombinant plasmid, designated pMVS301, was isolated from E. coli DH1 (pMVS301) and transformed into Rhodococcus sp. AS-50, a derivative of strain H13-A, by polyethylene glycol-assisted transformation of Rhodococcus protoplasts and selection for thiostrepton-resistant transformants. This strain was deposited with the ATCC on Feb. 1, 1988 and assigned ATCC 53719. The plasmid contains the Rhodococcus origin of replication. The plasmid and derivatives thereof can therefore be used to introduce nucleic acid sequences to and from Rhodococcus for subsequent expression and translation into protein. The isolated origin of replication can also be used in the construction of new vectors.

  8. Cloning systems for Rhodococcus and related bacteria

    DOEpatents

    Finnerty, W.R.; Singer, M.E.

    1990-08-28

    A plasmid transformation system for Rhodococcus was developed using an Escherichia coli-Rhodococcus shuttle plasmid. Rhodococcus sp. H13-A contains three cryptic indigenous plasmids, designated pMVS100, pMVS200 and pMVS300, of 75, 19.5 and 13.4 kilobases (Kb), respectively. A 3.8 Kb restriction fragment of pMVS300 was cloned into pIJ30, a 6.3 Kb pBR322 derivative, containing the E. coli origin of replication (ori) and ampicillin resistance determinant (bla) as well as a Streptomyces gene for thiostrepton resistance, tsr. The resulting 10.1 Kb recombinant plasmid, designated pMVS301, was isolated from E. coli DH1 (pMVS301) and transformed into Rhodococcus sp. AS-50, a derivative of strain H13-A, by polyethylene glycol-assisted transformation of Rhodococcus protoplasts and selection for thiostrepton-resistant transformants. This strain was deposited with the ATCC on Feb. 1, 1988 and assigned ATCC 53719. The plasmid contains the Rhodococcus origin of replication. The plasmid and derivatives thereof can therefore be used to introduce nucleic acid sequences to and from Rhodococcus for subsequent expression and translation into protein. The isolated origin of replication can also be used in the construction of new vectors. 2 figs.

  9. Rhodococcus empyema in a heart transplant patient

    PubMed Central

    Rose, Richard; Nord, John; Lanspa, Michael

    2014-01-01

    Rhodococcus equi is a rare cause of pneumonia and empyema almost exclusively occurring in immunocompromised patients. Most people who become infected have direct exposure to livestock. We present a case where the exposure was presumed to be through a family member in close contact with horses. Our case describes an infection in a heart transplant patient that was initially identified as a probable intra-abdominal infection and later reidentified as Rhodococcus equi empyema, and was treated with surgery and prolonged antibiotics. PMID:25473561

  10. Vanillin catabolism in Rhodococcus jostii RHA1.

    PubMed

    Chen, Hao-Ping; Chow, Mindy; Liu, Chi-Chun; Lau, Alice; Liu, Jie; Eltis, Lindsay D

    2012-01-01

    Genes encoding vanillin dehydrogenase (vdh) and vanillate O-demethylase (vanAB) were identified in Rhodococcus jostii RHA1 using gene disruption and enzyme activities. During growth on vanillin or vanillate, vanA was highly upregulated while vdh was not. This study contributes to our understanding of lignin degradation by RHA1 and other actinomycetes.

  11. Alteration of Acrylonitrile-Methylacrylate-Butadiene Terpolymer by Nocardia rhodochrous and Penicillium notatum†

    PubMed Central

    Antoine, A. D.; Dean, A. V.; Gilbert, S. G.

    1980-01-01

    [14C]Barex-210, a terpolymer of acrylonitrile, methylacrylate, and butadiene, was tested for bioconversion. Powdered samples of polymer, each specifically 14C labeled at different carbon atoms of the polymer, were incubated with either Nocardia rhodochrous or Penicillium notatum in an enriched growth medium for various periods of time. After 6 months of incubation, the 14C-labeled polymer was transformed from a high-molecular-weight material completely soluble in dimethyl formamide (DMF) into both a lower-molecular-weight form still soluble in DMF and a second form that was no longer soluble in DMF. The amount of 14C-labeled carbon atoms converted into DMF-insoluble material was 8% of the backbone carbon-carbon atoms and 12% of the side-chain nitrile and acrylate atoms from the acrylonitrile-methylacrylate copolymer and 60% of the elastomer (acrylonitrile-butadiene copolymer) atoms. Metabolism of the polymer was not established from measurements of metabolic 14CO2. Evolution of 14CO2 amounted to only 0.3, 0.6, 1.8, and 3.3% of these four fractions, respectively. Although the transformation of high-molecular-weight polymer into DMF-insoluble material was rapid in the early stages of microbial growth, the accompanying CO2 evolution was much slower. Further evidence of polymer alteration was indicated by the infrared spectrum of the insoluble material, which showed a disappearance of the nitrile and methylacrylate peaks. PMID:16345541

  12. Trehalolipid biosurfactants from nonpathogenic Rhodococcus actinobacteria with diverse immunomodulatory activities.

    PubMed

    Kuyukina, Maria S; Ivshina, Irena B; Baeva, Tatiana A; Kochina, Olesia A; Gein, Sergey V; Chereshnev, Valery A

    2015-12-25

    Actinobacteria of the genus Rhodococcus produce trehalolipid biosurfactants with versatile biochemical properties and low toxicity. In recent years, these biosurfactants are increasingly studied as possible biomedical agents with expressed immunological activities. Applications of trehalolipids from Rhodococcus, predominantly cell-bound, in biomedicine are also attractive because their cost drawback could be less significant for high-value products. The review summarizes recent findings in immunomodulatory activities of trehalolipid biosurfactants from nonpathogenic Rhodococcus and related actinobacteria and compares their biomedical potential with well-known immunomodifying properties of trehalose dimycolates from Mycobacterium tuberculosis. Molecular mechanisms of trehalolipid interactions with immunocompetent cells are also discussed.

  13. Use of whole genome sequences to develop a molecular phylogenetic framework for Rhodococcus fascians and the Rhodococcus genus

    PubMed Central

    Creason, Allison L.; Davis, Edward W.; Putnam, Melodie L.; Vandeputte, Olivier M.; Chang, Jeff H.

    2014-01-01

    The accurate diagnosis of diseases caused by pathogenic bacteria requires a stable species classification. Rhodococcus fascians is the only documented member of its ill-defined genus that is capable of causing disease on a wide range of agriculturally important plants. Comparisons of genome sequences generated from isolates of Rhodococcus associated with diseased plants revealed a level of genetic diversity consistent with them representing multiple species. To test this, we generated a tree based on more than 1700 homologous sequences from plant-associated isolates of Rhodococcus, and obtained support from additional approaches that measure and cluster based on genome similarities. Results were consistent in supporting the definition of new Rhodococcus species within clades containing phytopathogenic members. We also used the genome sequences, along with other rhodococcal genome sequences to construct a molecular phylogenetic tree as a framework for resolving the Rhodococcus genus. Results indicated that Rhodococcus has the potential for having 20 species and also confirmed a need to revisit the taxonomic groupings within Rhodococcus. PMID:25237311

  14. Alkylated benzothiophene desulfurization by Rhodococcus sp. strain T09.

    PubMed

    Matsui, T; Onaka, T; Tanaka, Y; Tezuka, T; Suzuki, M; Kurane, R

    2000-03-01

    A benzothiophene desulfurizing bacterium was isolated and identified as Rhodococcus sp. strain T09. Growth assays revealed that this strain assimilated, as the sole sulfur source, various organosulfur compounds that cannot be assimilated by the well-studied dibenzothiophene-desulfurizing Rhodococcus sp. IGTS8. The cellular growth rate of strain T09 for the alkylated benzothiophenes depended on the alkylated position and the length of the alkyl moiety.

  15. Epidemiology of Rhodococcus equi infection in horses.

    PubMed

    Prescott, J F

    1987-08-01

    Current understanding of the epidemiology of Rhodococcus equi infection on horse farms is reviewed. Infection is widespread in herbivores and their environment, because herbivore manure supplies the simple organic acid substrates on which the organism thrives. There is a progressive development of infection in the soil on horse farms with prolonged use, because: (1) there is a continual supply of nutrients; (2) the organism multiplies progressively as temperatures rise; (3) the bacterium has a robust nature. While this aerobic organism fails to multiply in the largely anaerobic intestine of the adult horse, multiplication to very large numbers may occur in the intestine of a foal in its first 8-12 weeks of life. Farms used for foal breeding over many years may thus become particularly dangerous for foals. Areas for future study include the effectiveness of decontamination, manure-removal programs and dust reduction in reducing challenge to susceptible foals.

  16. Rhodococcus aerolatus sp. nov., isolated from subarctic rainwater.

    PubMed

    Hwang, C Y; Lee, I; Cho, Y; Lee, Y M; Baek, K; Jung, Y-J; Yang, Y Y; Lee, T; Rhee, T S; Lee, H K

    2015-02-01

    A Gram-stain-positive, rod-shaped and non-motile strain, designated PAMC 27367(T), was isolated from rainwater collected on the Bering Sea. Analysis of the 16S rRNA gene sequence of the strain showed an affiliation with the genus Rhodococcus. Phylogenetic analyses revealed that strain PAMC 27367(T) formed a robust clade with the type strains of Rhodococcus rhodnii, Rhodococcus aetherivorans and Rhodococcus ruber with 16S rRNA gene sequence similarities of 96.3 %, 95.8 % and 95.5 %, respectively. Cells of the strain grew optimally at 25 °C and at pH 6.5-7.0 in the presence of 0-2 % (w/v) sea salts. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside and three unknown phospholipids. The major cellular fatty acids (>10 %) were iso-C16 : 0, C17 : 1ω8c and 10-methyl C17 : 0. Cell wall analysis showed that strain PAMC 27367(T) contained meso-diaminopimelic acid. The genomic DNA G+C content was 77.1 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic data presented here, we propose a novel species with the name Rhodococcus aerolatus sp. nov., with PAMC 27367(T) ( = KCTC 29240(T) = JCM 19485(T)) as the type strain.

  17. Rhodococcus equi: an animal and human pathogen.

    PubMed Central

    Prescott, J F

    1991-01-01

    Recent isolations of Rhodococcus equi from cavitatory pulmonary disease in patients with AIDS have aroused interest among medical microbiologists in this unusual organism. Earlier isolations from humans had also been in immunosuppressed patients following hemolymphatic tumors or renal transplantation. This organism has been recognized for many years as a cause of a serious pyogranulomatous pneumonia of young foals and is occasionally isolated from granulomatous lesions in several other species, in some cases following immunosuppression. The last decade has seen many advances in understanding of the epidemiology, pathogenesis, diagnosis, treatment, and immunity to infection in foals. The particular susceptibility of the foal is not understood but can be explained in part by a combination of heavy challenge through the respiratory route coinciding with declining maternally derived antibody in the absence of fully competent foal cellular immune mechanisms. R. equi is largely a soil organism but is widespread in the feces of herbivores. Its growth in soil is considerably improved by simple nutrients it obtains from herbivore manure. About one-third of human patients who have developed R. equi infections had contact in some way with herbivores or their manure. Others may have acquired infection from contact with soil or wild bird manure. R. equi is an intracellular parasite, which explains the typical pyogranulomatous nature of R. equi infections, the predisposition to infection in human patients with defective cell-mediated immune mechanisms, and the efficacy of antimicrobial drugs that penetrate phagocytic cells. Images PMID:2004346

  18. Spheroplast formation and plasmid isolation from Rhodococcus spp.

    PubMed

    Assaf, N A; Dick, W A

    1993-12-01

    The genus Rhodococcus comprises aerobic gram-positive actinomycetes that show considerable morphological and metabolic diversity and are known to be involved in the development of plant diseases and degradation of environmental pollutants. We describe a method for cell lysis and large plasmid DNA isolation from Rhodococcus by creating lysozyme susceptible cells by predigestion with the enzyme mutanolysin. Mutanolysin action resulted in the liberation of reducing sugars and free amino acids from the peptidoglycan layers of the cell wall. A 1-h predigestion with mutanolysin followed by a 0.5-h incubation with lysozyme resulted in spheroplast formation. Complete lysis of cells and efficient isolation of intact large plasmid DNA (108 kb) from wild-type Rhodococcus strains was confirmed.

  19. Detection of genes for alkane and naphthalene catabolism in Rhodococcus sp. strain 1BN.

    PubMed

    Andreoni, V; Bernasconi, S; Colombo, M; van Beilen, J B; Cavalca, L

    2000-10-01

    Rhodococcus sp. 1BN was isolated from a contaminated site and showed various biodegradative capabilities. Besides naphthalene, strain 1BN degraded medium- (C6) and long-chain alkanes (C16-C28), benzene and toluene, alone or when the hydrocarbons were mixed in equal proportions. The nucleotide sequence of an alk polymerase chain reaction (PCR) fragment revealed a 59% nucleotide homology to the Pseudomonas oleovorans alkB gene. The nar fragments were highly homologous to genes coding for large and small subunits of cis-naphthalene 1,2-dioxygenase (narAa and narAb) and to cis-naphthalene dihydrodiol dehydrogenase (narB) from other rhodococci. The oxidation of indene to cis-(1S,2R)-1,2-dihydroxyindan by toluene-induced cells allows to hypothesize that strain 1BN also carries a toluene dioxygenase-like system. PMID:11233165

  20. Can whole genome analysis refine the taxonomy of the genus Rhodococcus?

    PubMed

    Gürtler, Volker; Mayall, Barrie C; Seviour, Robert

    2004-06-01

    The current systematics of the genus Rhodococcus is unclear, partly because many members were originally included before the application of a polyphasic taxonomic approach, central to which is the acquisition of 16S rRNA sequence data. This has resulted in the reclassification and description of many new species. Hence, the literature is replete with new species names that have not been brought together in an organized and easily interpreted form. This taxonomic confusion has been compounded by assigning many xenobiotic degrading isolates with phylogenetic positions but without formal taxonomic descriptions. In order to provide a framework for a taxonomic approach based on multiple genetic loci, a survey was undertaken of the known genome characteristics of members of the genus Rhodococcus including: (i) genetics of cell envelope biosynthesis; (ii) virulence genes; (iii) gene clusters involved in metabolic degradation and industrially relevant pathways; (iv) genetic analysis tools; (v) rapid identification of bacteria including rhodococci with specific gene RFLPs; (vi) genomic organization of rrn operons. Genes encoding virulence factors have been characterized for Rhodococcus equi and Rhodococcus fascians. Based on peptide signature comparisons deduced from gene sequences for cytochrome P-450, mono- and dioxygenases, alkane degradation, nitrile metabolism, proteasomes and desulfurization, phylogenetic relationships can be deduced for Rhodococcus erythropolis, Rhodococcus globerulus, Rhodococcus ruber and a number of undesignated Rhodococcus spp. that may distinguish the genus Rhodococcus into two further genera. The linear genome topologies that exist in some Rhodococcus species may alter a previously proposed model for the analysis of genomic fingerprinting techniques used in bacterial systematics.

  1. Complete Genome and Plasmid Sequences for Rhodococcus fascians D188 and Draft Sequences for Rhodococcus Isolates PBTS 1 and PBTS 2

    PubMed Central

    Stamler, Rio A.; Vereecke, Danny; Zhang, Yucheng; Schilkey, Faye; Devitt, Nico

    2016-01-01

    Rhodococcus fascians, a phytopathogen that alters plant development, inflicts significant losses in plant production around the world. We report here the complete genome sequence of R. fascians D188, a well-characterized model isolate, and Rhodococcus species PBTS (pistachio bushy top syndrome) 1 and 2, which were shown to be responsible for a disease outbreak in pistachios. PMID:27284129

  2. Complete Genome and Plasmid Sequences for Rhodococcus fascians D188 and Draft Sequences for Rhodococcus Isolates PBTS 1 and PBTS 2.

    PubMed

    Stamler, Rio A; Vereecke, Danny; Zhang, Yucheng; Schilkey, Faye; Devitt, Nico; Randall, Jennifer J

    2016-01-01

    Rhodococcus fascians, a phytopathogen that alters plant development, inflicts significant losses in plant production around the world. We report here the complete genome sequence of R. fascians D188, a well-characterized model isolate, and Rhodococcus species PBTS (pistachio bushy top syndrome) 1 and 2, which were shown to be responsible for a disease outbreak in pistachios. PMID:27284129

  3. Rhodococcus equi (Prescottella equi) vaccines; the future of vaccine development.

    PubMed

    Giles, C; Vanniasinkam, T; Ndi, S; Barton, M D

    2015-09-01

    For decades researchers have been targeting prevention of Rhodococcus equi (Rhodococcus hoagui/Prescottella equi) by vaccination and the horse breeding industry has supported the ongoing efforts by researchers to develop a safe and cost effective vaccine to prevent disease in foals. Traditional vaccines including live, killed and attenuated (physical and chemical) vaccines have proved to be ineffective and more modern molecular-based vaccines including the DNA plasmid, genetically attenuated and subunit vaccines have provided inadequate protection of foals. Newer, bacterial vector vaccines have recently shown promise for R. equi in the mouse model. This article describes the findings of key research in R. equi vaccine development and looks at alternative methods that may potentially be utilised.

  4. Rhodococcus nanhaiensis sp. nov., an actinobacterium isolated from marine sediment.

    PubMed

    Li, Jie; Zhao, Guo-Zhen; Long, Li-Juan; Wang, Fa-Zuo; Tian, Xin-Peng; Zhang, Si; Li, Wen-Jun

    2012-10-01

    In this study, two strains (SCSIO 10187(T) and SCSIO 10197) were isolated from a sediment sample collected from the South China Sea and characterized by using a polyphasic approach. Growth was observed at 15-35 °C (optimum 28 °C) and pH 5.0-8.0 (optimum pH 6.0). Based on 16S rRNA gene sequence analysis, the strains were identified as members of the genus Rhodococcus. Phylogenetic analysis showed that the two strains clustered together and the 16S rRNA gene sequence similarities between them and other members of the genus Rhodococcus were 93.2-97.7 %. The menaquinone type was MK-8(H(2)). Major cellular fatty acids were C(16 : 0), C(18 : 1)ω9c, C(17 : 0), 10-methyl C(18 : 0), C(18 : 0), C(19 : 0) and C(17 : 1)ω8c. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The DNA G+C contents of strains SCSIO 10187(T) and SCSIO 10197 were 63.7 and 63.2 mol%, respectively. The combined genotypic and phenotypic data showed that the two strains represent a novel species of the genus Rhodococcus, for which the name Rhodococcus nanhaiensis is proposed; the type strain is SCSIO 10187(T) ( = DSM 45608(T) = CCTCC AB 2011024(T)), with SCSIO 10197 ( = DSM 45609 = CCTCC AB 2011025) as a reference strain.

  5. Complete Genome Sequence of a Rhodococcus Species Isolated from the Winter Skate Leucoraja ocellata

    PubMed Central

    Wiens, Julia; Ho, Ryan; Fernando, Dinesh; Kumar, Ayush; Loewen, Peter C.; Anderson, W. Gary

    2016-01-01

    We report here a genome sequence for Rhodococcus sp. isolate UM008 isolated from the renal/interrenal tissue of the winter skate Leucoraja ocellata. Genome sequence analysis suggests that Rhodococcus bacteria may act in a novel mutualistic relationship with their elasmobranch host, serving as biocatalysts in the steroidogenic pathway of 1α-hydroxycorticosterone. PMID:27587827

  6. Rhodococcus equi Infection after Alemtuzumab Therapy for T-cell Prolymphocytic Leukemia

    PubMed Central

    Sprenger, Herman G.; van Assen, Sander; Leduc, Dominique; Daenen, Simon M.G.J.; Arends, Jan P.; van der Werf, Tjip S.

    2007-01-01

    Rhodococcus equi, mainly known from veterinary medicine as a pathogen in domestic animals, can also cause infections in immunocompromised humans, especially in those with defects in cellular immunity. Alemtuzumab, an anti-CD52 monoclonal antibody, causes lymphocytopenia by eliminating CD52-positive cells. We report a patient in whom Rhodococcus equi infection developed after alemtuzumab therapy. PMID:18258054

  7. Complete Genome Sequence of a Rhodococcus Species Isolated from the Winter Skate Leucoraja ocellata.

    PubMed

    Wiens, Julia; Ho, Ryan; Fernando, Dinesh; Kumar, Ayush; Loewen, Peter C; Brassinga, Ann Karen C; Anderson, W Gary

    2016-01-01

    We report here a genome sequence for Rhodococcus sp. isolate UM008 isolated from the renal/interrenal tissue of the winter skate Leucoraja ocellata Genome sequence analysis suggests that Rhodococcus bacteria may act in a novel mutualistic relationship with their elasmobranch host, serving as biocatalysts in the steroidogenic pathway of 1α-hydroxycorticosterone. PMID:27587827

  8. Rhodococcus soli sp. nov., an actinobacterium isolated from soil using a resuscitative technique.

    PubMed

    Li, Shan-Hui; Yu, Xiao-Yun; Park, Dong-Jin; Hozzein, Wael N; Kim, Chang-Jin; Shu, Wen-Sheng; Wadaan, Mohammed A M; Ding, Lin-Xian; Li, Wen-Jun

    2015-02-01

    A Gram-positive, aerobic, non-motile, non-spore forming strain, designated DSD51W(T), was isolated using a resuscitative technique from a soil sample collected from Kyoto park, Japan, and characterized by using a polyphasic approach. The morphological and chemotaxonomic properties of the isolate were typical of those of members of the genus Rhodococcus. Strain DSD51W(T) was found to form a coherent cluster with Rhodococcus hoagii ATCC 7005(T), Rhodococcus equi NBRC 101255(T), Rhodococcus defluvii Call(T) and Rhodococcus kunmingensis YIM 45607(T) as its closest phylogenetic neighbours in 16S rRNA gene sequence analysis. However, the DNA-DNA hybridization values with the above strains were 58.2 ± 2.2, 58.4 ± 1.9, 45.1 ± 1.4 and 40.3 ± 4.7 %, respectively. In combination with differences in physiological and biochemical properties, strain DSD51W(T) can be concluded to represent a novel species of the genus Rhodococcus, for which the name Rhodococcus soli sp. nov. is proposed, with the type strain DSD51W(T) (=KCTC 29259(T) = JCM 19627(T) = DSM 46662(T) = KACC 17838(T)).

  9. Survival and replication of Rhodococcus equi in macrophages.

    PubMed Central

    Hondalus, M K; Mosser, D M

    1994-01-01

    Rhodococcus equi is a facultative intracellular bacterium of macrophages that can cause serious pneumonia in both young horses and immunocompromised people. Essential to understanding rhodococcus pathogenesis is a quantitative documentation of the intracellular events that follow macrophage phagocytosis of the organism. By using a bacterial immunofluorescence staining assay, we verified the intracellular survival and replicative potential of R. equi in both murine peritoneal macrophages and equine alveolar macrophages in vitro. Following an initial lag period of 6 to 12 h, the intracellular numbers of R. equi begin to rise, often reaching macrophage-compromising levels by 48 h. A quantitative determination of bacterial growth by a novel image analysis cytometry technique confirmed our fluorescence microscopic results. By 48 h postinfection, bacterial numbers had increased by more than fivefold, and the majority of infected macrophages in the monolayer contained 10 or more bacteria per cell. The intracellular organisms were viable, as evidenced by the ability to incorporate radiolabeled uracil. The use of these techniques has identified differences in the in vitro replicative capacities of a virulent strain and an avirulent strain of R. equi. A clinical isolate of R. equi expressing a 17-kDa virulence-associated plasmid-encoded antigen was able to survive and replicate within macrophages, whereas an avirulent, non-plasmid-containing strain replicated poorly. These results suggest that plasmid-encoded bacterial virulence factors may contribute to the ability of R. equi to replicate within its host cell, the macrophage. Images PMID:7927672

  10. Rhodococcus baikonurensis BTM4c, a boron-tolerant actinobacterial strain isolated from soil.

    PubMed

    Yoon, Jaewoo; Miwa, Hiroki; Ahmed, Iftikhar; Yokota, Akira; Fujiwara, Toru

    2010-01-01

    By screening a bacterial population from the soil in Tokyo, Japan, we isolated a boron-tolerant bacterium, strain BTM4c. Strain BTM4c grew under the boron excess conditions with 100 mM boric acid, which is generally toxic to bacteria. Molecular phylogenetic, chemotaxonomic, and physiological data showed that the strain belongs to the genus Rhodococcus, and is to be identified as Rhodococcus baikonurensis. PMID:20057133

  11. Genome Sequence of Rhodococcus sp. Strain BCP1, a Biodegrader of Alkanes and Chlorinated Compounds

    PubMed Central

    Cappelletti, M.; Di Gennaro, P.; D’Ursi, P.; Orro, A.; Mezzelani, A.; Landini, M.; Fedi, S.; Frascari, D.; Presentato, A.; Milanesi, L.

    2013-01-01

    Rhodococcus sp. strain BCP1 cometabolizes chlorinated compounds and mineralizes a broad range of alkanes, as it is highly tolerant to them. The high-quality draft genome sequence of Rhodococcus sp. strain BCP1, consisting of 6,231,823 bp, with a G+C content of 70.4%, 5,902 protein-coding genes, and 58 RNA genes, is presented here. PMID:24158549

  12. An Adenoviral Vector Based Vaccine for Rhodococcus equi.

    PubMed

    Giles, Carla; Ndi, Olasumbo; Barton, Mary D; Vanniasinkam, Thiru

    2016-01-01

    Rhodococcus equi is a respiratory pathogen which primarily infects foals and is endemic on farms around the world with 50% mortality and 80% morbidity in affected foals. Unless detected early and treated appropriately the disease can be fatal. Currently, there is no vaccine available to prevent this disease. For decades researchers have endeavoured to develop an effective vaccine to no avail. In this study a novel human adenoviral vector vaccine for R. equi was developed and tested in the mouse model. This vaccine generated a strong antibody and cytokine response and clearance of R. equi was demonstrated following challenge. These results show that this vaccine could potentially be developed further for use as a vaccine to prevent R. equi disease in foals. PMID:27008624

  13. Radiological findings in nine AIDS patients with Rhodococcus equi pneumonia.

    PubMed

    Wicky, S; Cartei, F; Mayor, B; Frija, J; Gevenois, P A; Giron, J; Laurent, F; Perri, G; Schnyder, P

    1996-01-01

    Rhodococcus equi (R. equi) infections have been incidentally reported as a cause of pulmonary infection in severely immunocompromised hosts, including AIDS patients. Our purpose is to describe the radiological findings in nine AIDS patients with R. equi pneumonia assessed by bronchoalveolar lavage (BAL), biopsies, cultures of sputum, and hemocultures. All patients were examined by chest radiographs and contrast-medium-enhanced chest CT. Dense pulmonary consolidations with or without cavitations accounted for the most striking radiological patterns. Chest CT also revealed six mediastinal involvements, strongly mimicking a lymphoma. Two of them had multiple bilateral pulmonary nodular opacities. Pleural effusion was not identified. Although intensive therapies were administered, seven among nine patients died within few months. In an AIDS patient living in a rural area or exposed to horses and presenting these radiological patterns, the possibility of R. equi pneumonia should be considered in the differential diagnosis along with other infectious diseases or lymphomas. PMID:8972317

  14. Investigation of the biotransformation of TNT by a Rhodococcus sp.

    SciTech Connect

    Tharakan, J.P.; Welsh, G.; Johnson, J.H. Jr.

    1995-12-31

    Tri-nitro-toluene (TNT) has contaminated waterways and soils as a result of its widespread military and non-military uses. Several researches have isolated or constructed strains of microorganisms that are able to utilize TNT as sole carbon, nitrogen or energy sources. Researchers have also reported high TNT concentrations (> 50 mg/l) as inhibitory to bacteria, yeast and fungi. This study examines the degradation of TNT and pyrene using a Rhodococcus sp. isolated based on its ability to survive on pyrene as the sole carbon source. The experiments were designed to study both the direct and cometabolic transformation of TNT by the microbes in both batch and continuous modes, and to determine the optimum conditions under which TNT would be degradable.

  15. An Adenoviral Vector Based Vaccine for Rhodococcus equi

    PubMed Central

    Giles, Carla; Ndi, Olasumbo; Barton, Mary D.; Vanniasinkam, Thiru

    2016-01-01

    Rhodococcus equi is a respiratory pathogen which primarily infects foals and is endemic on farms around the world with 50% mortality and 80% morbidity in affected foals. Unless detected early and treated appropriately the disease can be fatal. Currently, there is no vaccine available to prevent this disease. For decades researchers have endeavoured to develop an effective vaccine to no avail. In this study a novel human adenoviral vector vaccine for R. equi was developed and tested in the mouse model. This vaccine generated a strong antibody and cytokine response and clearance of R. equi was demonstrated following challenge. These results show that this vaccine could potentially be developed further for use as a vaccine to prevent R. equi disease in foals. PMID:27008624

  16. Biofilm development of the polyethylene-degrading bacterium Rhodococcus ruber.

    PubMed

    Sivan, A; Szanto, M; Pavlov, V

    2006-09-01

    We have recently isolated a biofilm-producing strain (C208) of Rhodococcus ruber that degraded polyethylene at a rate of 0.86% per week (r2=0.98). Strain C208 adheres to polyethylene immediately upon exposure to the polyolefin. This initial biofilm differentiates (in a stepwise process that lasts about 20 h) into cell-aggregation-forming microcolonies. Further organization yields "mushroom-like" three-dimensional structures on the mature biofilm. The ratio between the population densities of the biofilm and the planktonic C208 cells after 10 days of incubation was about 60:1, indicating a high preference for the biofilm mode of growth. Analysis of extracellular polymeric substances (EPS) in the biofilm of C208 revealed that the polysaccharides level was up to 2.5 folds higher than that of the protein. The biofilm showed a high viability even after 60 days of incubation, apparently due to polyethylene biodegradation. PMID:16534612

  17. Genome and Phenotype Microarray Analyses of Rhodococcus sp. BCP1 and Rhodococcus opacus R7: Genetic Determinants and Metabolic Abilities with Environmental Relevance

    PubMed Central

    D’Ursi, Pasqualina; Milanesi, Luciano; Di Canito, Alessandra; Zampolli, Jessica; Collina, Elena; Decorosi, Francesca; Viti, Carlo; Fedi, Stefano; Presentato, Alessandro; Zannoni, Davide; Di Gennaro, Patrizia

    2015-01-01

    In this paper comparative genome and phenotype microarray analyses of Rhodococcus sp. BCP1 and Rhodococcus opacus R7 were performed. Rhodococcus sp. BCP1 was selected for its ability to grow on short-chain n-alkanes and R. opacus R7 was isolated for its ability to grow on naphthalene and on o-xylene. Results of genome comparison, including BCP1, R7, along with other Rhodococcus reference strains, showed that at least 30% of the genome of each strain presented unique sequences and only 50% of the predicted proteome was shared. To associate genomic features with metabolic capabilities of BCP1 and R7 strains, hundreds of different growth conditions were tested through Phenotype Microarray, by using Biolog plates and plates manually prepared with additional xenobiotic compounds. Around one-third of the surveyed carbon sources was utilized by both strains although R7 generally showed higher metabolic activity values compared to BCP1. Moreover, R7 showed broader range of nitrogen and sulphur sources. Phenotype Microarray data were combined with genomic analysis to genetically support the metabolic features of the two strains. The genome analysis allowed to identify some gene clusters involved in the metabolism of the main tested xenobiotic compounds. Results show that R7 contains multiple genes for the degradation of a large set of aromatic and PAHs compounds, while a lower variability in terms of genes predicted to be involved in aromatic degradation was found in BCP1. This genetic feature can be related to the strong genetic pressure exerted by the two different environment from which the two strains were isolated. According to this, in the BCP1 genome the smo gene cluster involved in the short-chain n-alkanes degradation, is included in one of the unique regions and it is not conserved in the Rhodococcus strains compared in this work. Data obtained underline the great potential of these two Rhodococcus spp. strains for biodegradation and environmental decontamination

  18. Degradation of a Mixture of Hydrocarbons, Gasoline, and Diesel Oil Additives by Rhodococcus aetherivorans and Rhodococcus wratislaviensis▿

    PubMed Central

    Auffret, Marc; Labbé, Diane; Thouand, Gérald; Greer, Charles W.; Fayolle-Guichard, Françoise

    2009-01-01

    Two strains, identified as Rhodococcus wratislaviensis IFP 2016 and Rhodococcus aetherivorans IFP 2017, were isolated from a microbial consortium that degraded 15 petroleum compounds or additives when provided in a mixture containing 16 compounds (benzene, toluene, ethylbenzene, m-xylene, p-xylene, o-xylene, octane, hexadecane, 2,2,4-trimethylpentane [isooctane], cyclohexane, cyclohexanol, naphthalene, methyl tert-butyl ether [MTBE], ethyl tert-butyl ether [ETBE], tert-butyl alcohol [TBA], and 2-ethylhexyl nitrate [2-EHN]). The strains had broad degradation capacities toward the compounds, including the more recalcitrant ones, MTBE, ETBE, isooctane, cyclohexane, and 2-EHN. R. wratislaviensis IFP 2016 degraded and mineralized to different extents 11 of the compounds when provided individually, sometimes requiring 2,2,4,4,6,8,8-heptamethylnonane (HMN) as a cosolvent. R. aetherivorans IFP 2017 degraded a reduced spectrum of substrates. The coculture of the two strains degraded completely 13 compounds, isooctane and 2-EHN were partially degraded (30% and 73%, respectively), and only TBA was not degraded. Significant MTBE and ETBE degradation rates, 14.3 and 116.1 μmol of ether degraded h−1 g−1 (dry weight), respectively, were measured for R. aetherivorans IFP 2017. The presence of benzene, toluene, ethylbenzene, and xylenes (BTEXs) had a detrimental effect on ETBE and MTBE biodegradation, whereas octane had a positive effect on the MTBE biodegradation by R. wratislaviensis IFP 2016. BTEXs had either beneficial or detrimental effects on their own degradation by R. wratislaviensis IFP 2016. Potential genes involved in hydrocarbon degradation in the two strains were identified and partially sequenced. PMID:19837842

  19. Rhodococcus agglutinans sp. nov., an actinobacterium isolated from a soil sample.

    PubMed

    Guo, Qian-Qian; Ming, Hong; Meng, Xiao-Ling; Duan, Yan-Yan; Gao, Rui; Zhang, Jian-Xin; Huang, Jian-Rong; Li, Wen-Jun; Nie, Guo-Xing

    2015-05-01

    A Gram-positive, aerobic, non-motile and non-spore forming strain, designated CFH S0262(T), was isolated from a soil sample collected from Catba island in Halong Bay, Vietnam. A polyphasic approach was used to study the taxonomic position of this new isolate. Phylogenetic analyses based on 16S rRNA gene sequence showed that strain CFH S0262(T) belongs to the genus Rhodococcus and clustered with Rhodococcus soli DSD51W(T), Rhodococcus hoagii NBRC 103062(T), Rhodococcus defluvii Call(T) and Rhodococcus kunmingensis YIM 45607(T) (98.7, 98.5, 97.9 and 97.6% similarities, respectively). Strain CFH S0262(T) could grow in the presence of NaCl (0-4%, optimum 0-3%), at pH 6.0-8.0 (optimum, pH 7.0) and at 10-40 °C (optimum, 28 °C). The predominant menaquinones of strain CFH S0262(T) were identified as MK-8 (H2) and MK-8 (H4). The major fatty acids (≥10%) were found to be C(16:0) and C(18:1)ω9c. The polar lipids detected were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, a glycolipid and two unidentified phospholipids. The DNA G+C content was determined to be 71.4 mol%. Based on a comparative analysis of phenotypic and genotypic characteristics, in combination with low values of DNA-DNA hybridization between strain CFH S0262(T) and its closest neighbours, it is proposed that strain CFH S0262(T) represents a novel species of the genus Rhodococcus, for which the name Rhodococcus agglutinans sp. nov., is proposed, with the type strain CFH S0262(T) (=CCTCC AB2014297(T)=KCTC 39118(T)).

  20. Cloning and Characterization of a Novel Esterase from Rhodococcus sp. for Highly Enantioselective Synthesis of a Chiral Cilastatin Precursor

    PubMed Central

    Zhang, Yan; Pan, Jiang; Luan, Zheng-Jiao; Park, Sunghoon

    2014-01-01

    A novel nonheme chloroperoxidase (RhEst1), with promiscuous esterase activity for enantioselective hydrolysis of ethyl (S)-2,2-dimethylcyclopropanecarboxylate, was identified from a shotgun library of Rhodococcus sp. strain ECU1013. RhEst1 was overexpressed in Escherichia coli BL21(DE3), purified to homogeneity, and functionally characterized. Fingerprinting analysis revealed that RhEst1 prefers para-nitrophenyl (pNP) esters of short-chain acyl groups. pNP esters with a cyclic acyl moiety, especially that with a cyclobutanyl group, were also substrates for RhEst1. The Km values for methyl 2,2-dimethylcyclopropanecarboxylate (DmCpCm) and ethyl 2,2-dimethylcyclopropane carboxylate (DmCpCe) were 0.25 and 0.43 mM, respectively. RhEst1 could serve as an efficient hydrolase for the bioproduction of optically pure (S)-2,2-dimethyl cyclopropane carboxylic acid (DmCpCa), which is an important chiral building block for cilastatin. As much as 0.5 M DmCpCe was enantioselectively hydrolyzed into (S)-DmCpCa, with a molar yield of 47.8% and an enantiomeric excess (ee) of 97.5%, indicating an extremely high enantioselectivity (E = 240) of this novel and unique biocatalyst for green manufacturing of highly valuable chiral chemicals. PMID:25239898

  1. Bubbling geometries for AdS2× S2

    NASA Astrophysics Data System (ADS)

    Lunin, Oleg

    2015-10-01

    We construct BPS geometries describing normalizable excitations of AdS2×S2. All regular horizon-free solutions are parameterized by two harmonic functions in R 3 with sources along closed curves. This local structure is reminiscent of the "bubbling solutions" for the other AdS p ×S q cases, however, due to peculiar asymptotic properties of AdS2, one copy of R 3 does not cover the entire space, and we discuss the procedure for analytic continuation, which leads to a nontrivial topological structure of the new geometries. We also study supersymmetric brane probes on the new geometries, which represent the AdS2×S2 counterparts of the giant gravitons.

  2. Saccharification of Cellulose by Recombinant Rhodococcus opacus PD630 Strains

    PubMed Central

    Hetzler, Stephan; Bröker, Daniel

    2013-01-01

    The noncellulolytic actinomycete Rhodococcus opacus strain PD630 is the model oleaginous prokaryote with regard to the accumulation and biosynthesis of lipids, which serve as carbon and energy storage compounds and can account for as much as 87% of the dry mass of the cell in this strain. In order to establish cellulose degradation in R. opacus PD630, we engineered strains that episomally expressed six different cellulase genes from Cellulomonas fimi ATCC 484 (cenABC, cex, cbhA) and Thermobifida fusca DSM43792 (cel6A), thereby enabling R. opacus PD630 to degrade cellulosic substrates to cellobiose. Of all the enzymes tested, five exhibited a cellulase activity toward carboxymethyl cellulose (CMC) and/or microcrystalline cellulose (MCC) as high as 0.313 ± 0.01 U · ml−1, but recombinant strains also hydrolyzed cotton, birch cellulose, copy paper, and wheat straw. Cocultivations of recombinant strains expressing different cellulase genes with MCC as the substrate were carried out to identify an appropriate set of cellulases for efficient hydrolysis of cellulose by R. opacus. Based on these experiments, the multicellulase gene expression plasmid pCellulose was constructed, which enabled R. opacus PD630 to hydrolyze as much as 9.3% ± 0.6% (wt/vol) of the cellulose provided. For the direct production of lipids from birch cellulose, a two-step cocultivation experiment was carried out. In the first step, 20% (wt/vol) of the substrate was hydrolyzed by recombinant strains expressing the whole set of cellulase genes. The second step was performed by a recombinant cellobiose-utilizing strain of R. opacus PD630, which accumulated 15.1% (wt/wt) fatty acids from the cellobiose formed in the first step. PMID:23793636

  3. Deep Desulfurization of Extensively Hydrodesulfurized Middle Distillate Oil by Rhodococcus sp. Strain ECRD-1

    PubMed Central

    Grossman, M. J.; Lee, M. K.; Prince, R. C.; Minak-Bernero, V.; George, G. N.; Pickering, I. J.

    2001-01-01

    Dibenzothiophene (DBT), and in particular substituted DBTs, are resistant to hydrodesulfurization (HDS) and can persist in fuels even after aggressive HDS treatment. Treatment by Rhodococcus sp. strain ECRD-1 of a middle distillate oil whose sulfur content was virtually all substituted DBTs produced extensive desulfurization and a sulfur level of 56 ppm. PMID:11282654

  4. Establishment of Cellobiose Utilization for Lipid Production in Rhodococcus opacus PD630

    PubMed Central

    Hetzler, Stephan

    2013-01-01

    Rhodococcus opacus PD630, which is known for its ability to accumulate large amounts of triacylglycerols (TAG), was metabolically engineered, and a cellobiose utilization pathway was introduced. Activities of β-glucosidases were determined, and recombinant strains accumulated fatty acids up to 39.5 ± 5.7% (wt/wt) of cell dry mass from cellobiose. PMID:23435878

  5. Rhodococcus equi hyperimmune plasma decreases pneumonia severity after a randomised experimental challenge of neonatal foals.

    PubMed

    Sanz, M G; Loynachan, A; Horohov, D W

    2016-03-12

    Since a vaccine is not available against Rhodococcus equi, R equi-specific hyperimmune plasma (HIP) is commonly used, although its efficacy remains controversial. The objective of this study was to evaluate the ability of a commercially available HIP to prevent clinical rhodococcal pneumonia in neonatal foals after experimental challenge. PMID:26932206

  6. Cesium accumulation of Rhodococcus erythropolis CS98 strain immobilized in hydrogel matrices.

    PubMed

    Takei, Takayuki; Yamasaki, Mika; Yoshida, Masahiro

    2014-04-01

    Agarose gels were superior to calcium-alginate gels for immobilizing Rhodococcus erythropolis CS98 strain to remove cesium from water. Suitable incubation time of the immobilized cells in cesium solutions, cell number in the gels and volume ratio of the cesium solution to the gels for efficient cesium removal were identified.

  7. Conversion of the Pseudomonas aeruginosa Quinolone Signal and Related Alkylhydroxyquinolines by Rhodococcus sp. Strain BG43

    PubMed Central

    Müller, Christine; Birmes, Franziska S.; Niewerth, Heiko

    2014-01-01

    A bacterial strain, which based on the sequences of its 16S rRNA, gyrB, catA, and qsdA genes, was identified as a Rhodococcus sp. closely related to Rhodococcus erythropolis, was isolated from soil by enrichment on the Pseudomonas quinolone signal [PQS; 2-heptyl-3-hydroxy-4(1H)-quinolone], a quorum sensing signal employed by the opportunistic pathogen Pseudomonas aeruginosa. The isolate, termed Rhodococcus sp. strain BG43, cometabolically degraded PQS and its biosynthetic precursor 2-heptyl-4(1H)-quinolone (HHQ) to anthranilic acid. HHQ degradation was accompanied by transient formation of PQS, and HHQ hydroxylation by cell extracts required NADH, indicating that strain BG43 has a HHQ monooxygenase isofunctional to the biosynthetic enzyme PqsH of P. aeruginosa. The enzymes catalyzing HHQ hydroxylation and PQS degradation were inducible by PQS, suggesting a specific pathway. Remarkably, Rhodococcus sp. BG43 is also capable of transforming 2-heptyl-4-hydroxyquinoline-N-oxide to PQS. It thus converts an antibacterial secondary metabolite of P. aeruginosa to a quorum sensing signal molecule. PMID:25239889

  8. Pyogenic Liver Abscess Due to Rhodococcus equi in an Immunocompetent Host

    PubMed Central

    Napoleão, Fátima; Vieira Damasco, Paulo; Ferreira Camello, Thereza Cristina; Damasceno do Vale, Márcio; Braga de Andrade, Arnaldo Feitosa; Hirata, Raphael; de Mattos-Guaraldi, Ana Luíza

    2005-01-01

    A case of pyogenic liver abscess (PLA) due to Rhodococcus equi in an immunocompetent individual was successfully treated by combining surgery and antibiotics. The R. equi-targeted antimicrobial agents erythromycin and rifampin were used only after surgical resection of the lesion and identification of the infective organism. PMID:15695730

  9. Comparison of three techniques for isolation of Rhodococcus (Corynebacterium) equi from contaminated sources.

    PubMed

    Barton, M D; Hughes, K L

    1981-01-01

    Inoculation of a liquid medium comprised of Trypticase soy broth (BBL Microbiology Systems), cycloheximide, nalidixic acid, penicillin, and potassium tellurite and subcultured onto M3 medium plus potassium tellurite was highly successful for the isolation of Rhodococcus (Corynebacterium) equi from soil. PMID:7007424

  10. Complete Genome Sequence of the Polychlorinated Biphenyl Degrader Rhodococcus sp. WB1

    PubMed Central

    Yu, Man; Shen, Alin

    2016-01-01

    Rhodococcus sp. WB1 is a polychlorinated biphenyl degrader which was isolated from contaminated soil in Zhejiang, China. Here, we present the complete genome sequence. The analysis of this genome indicated that a biphenyl-degrading gene cluster and several xenobiotic metabolism pathways are harbored. PMID:27738025

  11. Genome Sequence of Rhodococcus opacus Strain R7, a Biodegrader of Mono- and Polycyclic Aromatic Hydrocarbons

    PubMed Central

    Zampolli, J.; Presti, I.; Cappelletti, M.; D’Ursi, P.; Orro, A.; Mezzelani, A.; Milanesi, L.

    2014-01-01

    Rhodococcus opacus strain R7 (CIP107348) degrades several mono- and polycyclic aromatic hydrocarbons. Here, we present the high-quality draft genome sequence of strain R7, consisting of 10,118,052 bp, with a G+C content of 67.0%, 9,602 protein-coding genes, and 62 RNAs genes. PMID:25146139

  12. Intracellular accumulation of trehalose and glycogen in an extreme oligotroph, Rhodococcus erythropolis N9T-4.

    PubMed

    Yano, Takanori; Funamizu, Yuhei; Yoshida, Nobuyuki

    2016-01-01

    An extreme oligotroph, Rhodococcus erythropolis N9T-4, showed intracellular accumulation of trehalose and glycogen under oligotrophic conditions. No trehalose accumulation was observed in cells grown on the rich medium. Deletion of the polyphosphate kinase genes enhanced the trehalose accumulation and decreases the intracellular glycogen contents, suggesting an oligotrophic relationship between among the metabolic pathways of trehalose, glycogen, and inorganic polyphosphate biosyntheses.

  13. Comparative and Functional Genomics of Rhodococcus opacus PD630 for Biofuels Development

    PubMed Central

    Holder, Jason W.; Ulrich, Jil C.; DeBono, Anthony C.; Godfrey, Paul A.; Desjardins, Christopher A.; Zucker, Jeremy; Zeng, Qiandong; Leach, Alex L. B.; Ghiviriga, Ion; Dancel, Christine; Abeel, Thomas; Gevers, Dirk; Kodira, Chinnappa D.; Desany, Brian; Affourtit, Jason P.; Birren, Bruce W.; Sinskey, Anthony J.

    2011-01-01

    The Actinomycetales bacteria Rhodococcus opacus PD630 and Rhodococcus jostii RHA1 bioconvert a diverse range of organic substrates through lipid biosynthesis into large quantities of energy-rich triacylglycerols (TAGs). To describe the genetic basis of the Rhodococcus oleaginous metabolism, we sequenced and performed comparative analysis of the 9.27 Mb R. opacus PD630 genome. Metabolic-reconstruction assigned 2017 enzymatic reactions to the 8632 R. opacus PD630 genes we identified. Of these, 261 genes were implicated in the R. opacus PD630 TAGs cycle by metabolic reconstruction and gene family analysis. Rhodococcus synthesizes uncommon straight-chain odd-carbon fatty acids in high abundance and stores them as TAGs. We have identified these to be pentadecanoic, heptadecanoic, and cis-heptadecenoic acids. To identify bioconversion pathways, we screened R. opacus PD630, R. jostii RHA1, Ralstonia eutropha H16, and C. glutamicum 13032 for growth on 190 compounds. The results of the catabolic screen, phylogenetic analysis of the TAGs cycle enzymes, and metabolic product characterizations were integrated into a working model of prokaryotic oleaginy. PMID:21931557

  14. Isolation and characterization of RDX-degrading Rhodococcus species from a contaminated aquifer.

    PubMed

    Bernstein, Anat; Adar, Eilon; Nejidat, Ali; Ronen, Zeev

    2011-09-01

    Groundwater contamination by the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a global problem. Israel's coastal aquifer was contaminated with RDX. This aquifer is mostly aerobic and we therefore sought aerobic bacteria that might be involved in natural attenuation of the compound in the aquifer. RDX-degrading bacteria were captured by passively sampling the indigenous bacteria onto sterile sediments placed within sampling boreholes. Aerobic RDX biodegradation potential was detected in the sediments sampled from different locations along the plume. RDX degradation with the native sampled consortium was accompanied by 4-nitro-2,4-diazabutanal formation. Two bacterial strains of the genus Rhodococcus were isolated from the sediments and identified as aerobic RDX degraders. The xplA gene encoding the cytochrome P450 enzyme was partially (~500 bp) sequenced from both isolates. The obtained DNA sequences had 99% identity with corresponding gene fragments of previously isolated RDX-degrading Rhodococcus strains. RDX degradation by both strains was prevented by 200 μM of the cytochrome P450 inhibitor metyrapone, suggesting that cytochrome P450 indeed mediates the initial step in RDX degradation. RDX biodegradation activity by the T7 isolate was inhibited in the presence of nitrate or ammonium concentrations above 1.6 and 5.5 mM, respectively (100 mg l(-1)) while the T9N isolate's activity was retarded only by ammonium concentrations above 5.5 mM. This study shows that bacteria from the genus Rhodococcus, potentially degrade RDX in the saturated zone as well, following the same aerobic degradation pathway defined for other Rhodococcus species. RDX-degrading activity by the Rhodococcus species isolate T9N may have important implications for the bioremediation of nitrate-rich RDX-contaminated aquifers.

  15. Molecular biological enhancement of coal desulfurization: Cloning and expression of the sulfoxide/sulfone/sulfonate/sulfate genes in Pseudomonads and Thiobacillae. [Rhodococcus erythropolis, Thiobacillus acidophilus, Thiobacillus novellus

    SciTech Connect

    Krawiec, S.

    1992-01-01

    Research continues on desulfurization of coal using microorganisms. Topics reported on this quarter include: desulfurization with N1-36 (presumptively identified as Rhodochrous erythropolis), pulsed-field gel electrophoresis of chromosomal DNA's of Thiobacillus spp., and fresh isolates with the presumptive capacity to desulfurize dibenzothiophenes.

  16. Rhodococcus erythropolis DCL14 Contains a Novel Degradation Pathway for Limonene

    PubMed Central

    van der Werf, Mariët J.; Swarts, Henk J.; de Bont, Jan A. M.

    1999-01-01

    Strain DCL14, which is able to grow on limonene as a sole source of carbon and energy, was isolated from a freshwater sediment sample. This organism was identified as a strain of Rhodococcus erythropolis by chemotaxonomic and genetic studies. R. erythropolis DCL14 also assimilated the terpenes limonene-1,2-epoxide, limonene-1,2-diol, carveol, carvone, and (−)-menthol, while perillyl alcohol was not utilized as a carbon and energy source. Induction tests with cells grown on limonene revealed that the oxygen consumption rates with limonene-1,2-epoxide, limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and carveol were high. Limonene-induced cells of R. erythropolis DCL14 contained the following four novel enzymatic activities involved in the limonene degradation pathway of this microorganism: a flavin adenine dinucleotide- and NADH-dependent limonene 1,2-monooxygenase activity, a cofactor-independent limonene-1,2-epoxide hydrolase activity, a dichlorophenolindophenol-dependent limonene-1,2-diol dehydrogenase activity, and an NADPH-dependent 1-hydroxy-2-oxolimonene 1,2-monooxygenase activity. Product accumulation studies showed that (1S,2S,4R)-limonene-1,2-diol, (1S,4R)-1-hydroxy-2-oxolimonene, and (3R)-3-isopropenyl-6-oxoheptanoate were intermediates in the (4R)-limonene degradation pathway. The opposite enantiomers [(1R,2R,4S)-limonene-1,2-diol, (1R,4S)-1-hydroxy-2-oxolimonene, and (3S)-3-isopropenyl-6-oxoheptanoate] were found in the (4S)-limonene degradation pathway, while accumulation of (1R,2S,4S)-limonene-1,2-diol from (4S)-limonene was also observed. These results show that R. erythropolis DCL14 metabolizes both enantiomers of limonene via a novel degradation pathway that starts with epoxidation at the 1,2 double bond forming limonene-1,2-epoxide. This epoxide is subsequently converted to limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and 7-hydroxy-4-isopropenyl-7-methyl-2-oxo-oxepanone. This lactone spontaneously rearranges to form 3-isopropenyl-6-oxoheptanoate. In

  17. Draft Genome Sequence of Rhodococcus erythropolis NSX2, an Actinobacterium Isolated from a Cadmium-Contaminated Environment

    PubMed Central

    Egidi, Eleonora; Wood, Jennifer L.; Fox, Edward M.; Liu, Wuxing

    2016-01-01

    Rhodococcus erythropolis NSX2 is a rhizobacterium isolated from a heavy metal–contaminated environment. The 6.2-Mb annotated genome sequence shows that this strain harbors genes associated with heavy-metal resistance and xenobiotics degradation. PMID:27795276

  18. Rhodococcus jostii porin A (RjpA) functions in cholate uptake.

    PubMed

    Somalinga, Vijayakumar; Mohn, William W

    2013-10-01

    RjpA in Rhodococcus jostii is the ortholog of a channel-forming porin, MspA. Deletion of rjpA delayed growth of R. jostii on cholate but not on cholesterol. Eventual growth on cholate involved increased expression of other porins, namely, RjpB, RjpC, and RjpD. Porins appear essential for the uptake of bile acids by mycolic acid bacteria.

  19. Metabolism of naphthalene, 1-naphthol, indene, and indole by Rhodococcus sp. strain NCIMB 12038

    SciTech Connect

    Allen, C.C.R.; Boyd, D.R.; Larkin, M.J.

    1997-01-01

    Naphthalene and its 1-hydroxy derivative, 1-naphthol, are examples of common bicyclic aromatics often released into the environment. Bacteria which degrade these compounds under aerobic conditions are widely distributed; however, the metabolism of naphthalene in gram-positive nocardioform bacteria has not been well investigated. This study described the independent regulation of 1-naphthol and naphthalene metabolism in Rhodococcus strain 12038. 45 refs., 2 figs., 1 tab.

  20. MoS2 spaser

    NASA Astrophysics Data System (ADS)

    Jayasekara, Charith; Premaratne, Malin; Gunapala, Sarath D.; Stockman, Mark I.

    2016-04-01

    We present a comprehensive analysis of a spaser made of a circular shaped highly doped molybdenum disulfide (MoS2) resonator. "Spaser" is an acronym for "surface plasmon amplification by stimulated emission of radiation"-a nanoscale source of surface plasmons generated by stimulated emission in a plasmonic resonator which receives energy nonradiatively. By considering localized surface plasmon modes, operation characteristics of the model are analysed, and tunability of the design is demonstrated. We find the optimum geometric and material parameters of the spaser that provides efficient outputs and carryout a comparative analysis with a similar circular spaser made of graphene. Owing to physical and chemical properties of MoS2 and the active medium, the proposed design delivers efficient outputs in terms of spaser mode energy, operating thresholds, Q-factor, and electric field amplitude. Lower operating thresholds and higher mode energies are notable advantages of the design. Owing to having many superior features to existing similar designs, this MoS2 spaser may be much suited for applications in nanoplasmonic devices.

  1. Rhodococcus sp. F92 immobilized on polyurethane foam shows ability to degrade various petroleum products.

    PubMed

    Quek, Eugene; Ting, Yen-Peng; Tan, Hai Meng

    2006-01-01

    This work reports on the immobilization and performance of a hydrocarbon-degrading microorganism on polyurethane foam (PUF) in the bioremediation of petroleum hydrocarbons. The ability of four different microorganisms to immobilize on PUF and to degrade various petroleum products (Arabian light crude (ALC), Al-Shaheen crude (ASC), diesel and oil slops) was assessed by measuring the n-alkane fraction remaining in the petroleum products over time. A Rhodococcus sp. (designated as F92) had the highest number of immobilized viable cells (10(9) cells per cm3 PUF) and a maximum attachment efficiency of 90% on PUF of a density of 14 kg/m3. Scanning electron microscopy showed the presence of extracellular structures that could play an important role in the immobilization of F92 on PUF. Analysis by GC-MS revealed that both free and immobilized F92 cells were able to degrade approximately 90% of the total n-alkanes in the petroleum products tested within 1 week at 30 degrees C. Rhodococcus sp. F92 was efficiently immobilized onto PUF and the immobilized cells were able to degrade a variety of petroleum products such as ALC, ASC, diesel and oil slops. The results suggest the potential of using PUF-immobilized Rhodococcus sp. F92 to bioremediate petroleum hydrocarbons in an open marine environment.

  2. A new cellulose-producing bacterium, Rhodococcus sp. MI 2: screening and optimization of culture conditions.

    PubMed

    Tanskul, Somporn; Amornthatree, Korntip; Jaturonlak, Nathakan

    2013-01-30

    A total of 59 bacterial strains were isolated from ripe fruits and vegetables and tested for their ability to produce cellulose. Only one identified as Rhodococcus sp. MI 2 based on its taxonomic characteristics and 16S rDNA sequence analysis. The glucose was the only product of digestion by cellulase confirmed by TLC and reversed phase HPLC. Rhodococcus sp. MI 2 produced significantly more cellulose with the SH medium containing glucose than with the coconut juice medium. Rhodococcus sp. MI 2 initially produced 3.91 ± 0.091, 2.20 ± 0.090 and 0.19 ± 0.051 g/L/6 days cellulose under static, agitated and stirred conditions, respectively, whereas A. xylinum 998 produced 1.17 ± 0.065, 1.34 ± 0.115 and 0.12 ± 0.046 g/L/6 days cellulose under the same conditions, respectively. The optimum culture conditions for cellulose production in SH medium were room temperature (25 °C), a 5% (v/v) inoculum, peptone 0.7%, yeast extract 0.9%, and sucrose 1.5%, at a pH of 3.5. The cellulose yield was increased by adding 0.5% CaCO(3) to the SH medium with sucrose but added agar had no effect. The cellulose yield under optimum and static conditions was increased about twice, from 3.7 to 7.4 g/L/14 days.

  3. Membrane transport systems and the biodegradation potential and pathogenicity of genus Rhodococcus

    PubMed Central

    de Carvalho, Carla C. C. R.; Costa, Sofia S.; Fernandes, Pedro; Couto, Isabel; Viveiros, Miguel

    2014-01-01

    The Rhodococcus genus contains species with remarkable ability to tolerate toxic compounds and to degrade a myriad of substrates. These substrates have to cross a distinctive cell envelope dominated by mycolic acids anchored in a scaffold of arabinogalactan covalently attached to the cell wall peptidoglycan, and a cellular membrane with phospholipids, whose composition in fatty acids can be rapidly altered in response to environmental conditions. The hydrophobic nature of the cell envelope facilitates the entrance of hydrophobic molecules but some substrates require active transport systems. Additionally, toxic compounds may also be extruded by energy spending efflux systems. In this review, physiological evidences of the use of transport systems by Rhodococcus strains and genomic studies that corroborate their existence are presented and discussed. The recently released complete genomes of several Rhodococcus strains will be the basis for an in silico correlation analysis between the efflux pumps present in the genome and their role on active transport of substrates. These transport systems will be placed on an integrative perspective of the impact of this important genus on biotechnology and health, ranging from bioremediation to antibiotic and biocide resistance. PMID:24772091

  4. Microbial cleavage of organic C-S bonds

    DOEpatents

    Kilbane, II, John J.

    1994-01-01

    A microbial process for selective cleavage of organic C--S bonds which may be used for reducing the sulfur content of sulfur-containing organic carbonaceous materials, Microorganisms of Rhodococcus rhodochrous and Bacillus sphaericus have been found which have the ability of selective cleavage of organic C--S bonds. Particularly preferred microorganisms are Rhodococcus rhodochrous strain ATCC 53968 and Bacillus sphaericus strain ATCC 53969 and their derivatives.

  5. Microbial cleavage of organic C-S bonds

    DOEpatents

    Kilbane, J.J. II.

    1994-10-25

    A microbial process is described for selective cleavage of organic C-S bonds which may be used for reducing the sulfur content of sulfur-containing organic carbonaceous materials. Microorganisms of Rhodococcus rhodochrous and Bacillus sphaericus have been found which have the ability of selective cleavage of organic C-S bonds. Particularly preferred microorganisms are Rhodococcus rhodochrous strain ATCC 53968 and Bacillus sphaericus strain ATCC 53969 and their derivatives.

  6. Analysis of Genes for Succinoyl Trehalose Lipid Production and Increasing Production in Rhodococcus sp. Strain SD-74

    PubMed Central

    Inaba, Tomohiro; Tokumoto, Yuta; Miyazaki, Yusuke; Inoue, Naoyuki; Maseda, Hideaki; Nakajima-Kambe, Toshiaki; Uchiyama, Hiroo

    2013-01-01

    Succinoyl trehalose lipids (STLs) are promising glycolipid biosurfactants produced from n-alkanes that are secreted by Rhodococcus species bacteria. These compounds not only exhibit unique interfacial properties but also demonstrate versatile biochemical actions. In this study, three novel types of genes involved in the biosynthesis of STLs, including a putative acyl coenzyme A (acyl-CoA) transferase (tlsA), fructose-bisphosphate aldolase (fda), and alkane monooxygenase (alkB), were identified. The predicted functions of these genes indicate that alkane metabolism, sugar synthesis, and the addition of acyl groups are important for the biosynthesis of STLs. Based on these results, we propose a biosynthesis pathway for STLs from alkanes in Rhodococcus sp. strain SD-74. By overexpressing tlsA, we achieved a 2-fold increase in the production of STLs. This study advances our understanding of bacterial glycolipid production in Rhodococcus species. PMID:24038682

  7. ChoG is the main inducible extracellular cholesterol oxidase of Rhodococcus sp. strain CECT3014.

    PubMed

    Fernández de Las Heras, Laura; Mascaraque, Victoria; García Fernández, Esther; Navarro-Llorens, Juana María; Perera, Julián; Drzyzga, Oliver

    2011-07-20

    Cholesterol catabolism has been reported in different bacteria and particularly in several Rhodococcus species, but the genetic of this complex pathway is not yet very well defined. In this work we report the isolation and sequencing of a 9.8 kb DNA fragment of Rhodococcus sp. strain CECT3014, a bacterial strain that we here identify as a Rhodococcus erythropolis strain. In this DNA fragment we found several ORF that are probably involved in steroid catabolism, and choG, a gene encoding a putative cholesterol oxidase whose functional characterization we here report. ChoG protein is a class II cholesterol oxidase with all the structural features of the enzymes of this group. The disruption of the choG gene does not alter the ability of strain CECT3014 cells to grow on cholesterol, but it abolishes the production of extracellular cholesterol oxidase. This later effect is reverted when the mutant cells are transformed with a plasmid expressing choG. We conclude that choG is the gene responsible for the inducible extracellular cholesterol oxidase activity of strain CECT3014. This activity distributes between the cellular membrane and the culture supernatant in a way that suggests it is produced by the same ChoG protein that occurs in two different locations. RT-PCR transcript analysis showed a dual scheme of choG expression: a low constitutive independent transcription, plus a cholesterol induced transcription of choG into a polycistronic kstD-hsd4B-choG mRNA. PMID:20630728

  8. Rhodococcus equi Sepsis in a Renal Transplant Recipient: A Case Study

    PubMed Central

    Macken, Eline; de Jonge, Hylke; Van Caesbroeck, Daniël; Verhaegen, Jan; Van Kerkhoven, Dana; Van Wijngaerden, Eric; Kuypers, Dirk

    2015-01-01

    Abstract Rhodococcus equi is an unusual cause of infection in humans, but has emerged as an opportunistic pathogen among immunocompromised patients. Primary pulmonary involvement is the most common clinical presentation, although the spectrum of disease is broad. Diagnosing R. equi infections remains challenging, both from clinical and microbiological view, and no standard treatment has been established. In this report, we present a detailed case of a 57-year-old male renal transplant recipient who developed R. equi bacteremia with a concomitant Pneumocystis jirovecii pneumonia. We describe the clinical features of R. equi infections, highlight the importance of an early diagnosis, and briefly review treatment options for this rare infection. PMID:27500216

  9. Catabolism of 1,3-dinitrobenzene by Rhodococcus sp. QT-1.

    PubMed

    Dickel, O; Knackmuss, H J

    1991-01-01

    The 1,3-dinitrobenzene-degrading Rhodococcus strain QT-1 was isolated under nitrogen limiting conditions from contaminated soil samples. Experimental data indicate tha 1,3-dinitrobenzene is metabolized via 4-nitrocatechol. Both compounds were oxidized by resting cells and nitro groups were completely eliminated as nitrite. Strain QT-1 utilizes both 1,3-dinitrobenzene and 4-nitrocatechol as source of nitrogen in the absence as well as in the presence of high amounts of ammonia. Growth on 4-nitrocatechol does not induce the enzyme(s) for the initial oxidation of 1,3-dinitrobenzene.

  10. Rhodococcus equi Sepsis in a Renal Transplant Recipient: A Case Study.

    PubMed

    Macken, Eline; de Jonge, Hylke; Van Caesbroeck, Daniël; Verhaegen, Jan; Van Kerkhoven, Dana; Van Wijngaerden, Eric; Kuypers, Dirk

    2015-04-01

    Rhodococcus equi is an unusual cause of infection in humans, but has emerged as an opportunistic pathogen among immunocompromised patients. Primary pulmonary involvement is the most common clinical presentation, although the spectrum of disease is broad. Diagnosing R. equi infections remains challenging, both from clinical and microbiological view, and no standard treatment has been established. In this report, we present a detailed case of a 57-year-old male renal transplant recipient who developed R. equi bacteremia with a concomitant Pneumocystis jirovecii pneumonia. We describe the clinical features of R. equi infections, highlight the importance of an early diagnosis, and briefly review treatment options for this rare infection. PMID:27500216

  11. [Biodegradation of di-n-butyl phthalate by mangrove microorganism Rhodococcus ruber 1K].

    PubMed

    Li, Kuixiao; Gu, Jidong

    2005-08-01

    A di-n-butyl phthalate (DBP)degrading bacterium Rhodococcus ruber was isolated from mangrove soil, and its degrading characteristics were studied. The results showed that the bacterium could grow well on the substrate with DBP as the sole source of carbon and energy, and the DBP of 50 mg x L(-1) could be completely degraded after 48 h. Under aerobic condition, the tentative pathway proposed for DBP degradation was through monoester initially, then phthalic acid, and finally CO2 and H2O.

  12. Combination of degradation pathways for naphthalene utilization in Rhodococcus sp. strain TFB

    PubMed Central

    Tomás-Gallardo, Laura; Gómez-Álvarez, Helena; Santero, Eduardo; Floriano, Belén

    2014-01-01

    Rhodococcus sp. strain TFB is a metabolic versatile bacterium able to grow on naphthalene as the only carbon and energy source. Applying proteomic, genetic and biochemical approaches, we propose in this paper that, at least, three coordinated but independently regulated set of genes are combined to degrade naphthalene in TFB. First, proteins involved in tetralin degradation are also induced by naphthalene and may carry out its conversion to salicylaldehyde. This is the only part of the naphthalene degradation pathway showing glucose catabolite repression. Second, a salicylaldehyde dehydrogenase activity that converts salicylaldehyde to salicylate is detected in naphthalene-grown cells but not in tetralin-or salicylate-grown cells. Finally, we describe the chromosomally located nag genes, encoding the gentisate pathway for salicylate conversion into fumarate and pyruvate, which are only induced by salicylate and not by naphthalene. This work shows how biodegradation pathways in Rhodococcus sp. strain TFB could be assembled using elements from different pathways mainly because of the laxity of the regulatory systems and the broad specificity of the catabolic enzymes. PMID:24325207

  13. Trans-membrane transport of fluoranthene by Rhodococcus sp. BAP-1 and optimization of uptake process.

    PubMed

    Li, Yi; Wang, Hongqi; Hua, Fei; Su, Mengyuan; Zhao, Yicun

    2014-03-01

    The mechanism of transport of (14)C-fluoranthene by Rhodococcus sp. BAP-1, a Gram-positive bacterium isolated from crude oil-polluted soil, was examined. Our finding demonstrated that the mechanism for fluoranthene travel across the cell membrane in Rhodococcus sp. BAP-1 requires energy. Meanwhile, the transport of fluoranthene involves concurrent catabolism of (14)C, that leading to the generation of significant amount of (14)CO2. Combined with trans-membrane transport dynamic and response surface methodology, a significant influence of temperature, pH and salinity on cellular uptake rate was screened by Plackett-Burman design. Then, Box-Behnken design was employed to optimize and enhanced the trans-membrane transport process. The results predicted by Box-Behnken design indicated that the maximum cellular uptake rate of fluoranthene could be achieve to 0.308μmolmin(-1)mg(-1)·protein (observed) and 0.304μmolmin(-1)mg(-1)·protein (predicted) when the initial temperature, pH and salinity were set at 20°C, 9% and 1%, respectively.

  14. Combination of degradation pathways for naphthalene utilization in Rhodococcus sp. strain TFB.

    PubMed

    Tomás-Gallardo, Laura; Gómez-Álvarez, Helena; Santero, Eduardo; Floriano, Belén

    2014-03-01

    Rhodococcus sp. strain TFB is a metabolic versatile bacterium able to grow on naphthalene as the only carbon and energy source. Applying proteomic, genetic and biochemical approaches, we propose in this paper that, at least, three coordinated but independently regulated set of genes are combined to degrade naphthalene in TFB. First, proteins involved in tetralin degradation are also induced by naphthalene and may carry out its conversion to salicylaldehyde. This is the only part of the naphthalene degradation pathway showing glucose catabolite repression. Second, a salicylaldehyde dehydrogenase activity that converts salicylaldehyde to salicylate is detected in naphthalene-grown cells but not in tetralin- or salicylate-grown cells. Finally, we describe the chromosomally located nag genes, encoding the gentisate pathway for salicylate conversion into fumarate and pyruvate, which are only induced by salicylate and not by naphthalene. This work shows how biodegradation pathways in Rhodococcus sp. strain TFB could be assembled using elements from different pathways mainly because of the laxity of the regulatory systems and the broad specificity of the catabolic enzymes.

  15. Influence of Rhodococcus equi on the respiratory burst of resident alveolar macrophages from horses

    SciTech Connect

    Brumbaugh, G.W.

    1986-01-01

    Rhodococcus equi is the etiologic agent of a devastating pneumonia of sporadic incidence in foals. The purpose of this study was to evaluate the influence of R. equi on the superoxide anion production, measured spectrophotometrically as the reduction of cytochrome C, and hexose monophosphate shunt activity, measured by /sup 14/CO/sub 2/ liberation from /sup 14/C-1-D-glucose, of alveolar macrophages from horses. Alveolar macrophages were harvested from 6 anesthetized, healthy, light-breed, adult horses by bronchoalveolar lavage. Following a randomized complete block design, the suspension of cells was divided into aliquots of 10/sup 6/ viable alveolar macrophages which were exposed to 1, 10 or 100 g. of opsonized R. equi or opsonized zymosan A at 37 C for 2 hours. In this study the respiratory burst of equine alveolar macrophages was only evidenced by the hexose monophosphate shunt activity and superoxide anion was not coincidentally produced. Rhodococcus equi did not adversely affect that response. The insignificant superoxide anion production by the alveolar macrophages suggests that this may not be a significant oxygen metabolite in those cells.

  16. Characterization of the desulfurization genes from Rhodococcus sp. strain IGTS8.

    PubMed Central

    Denome, S A; Oldfield, C; Nash, L J; Young, K D

    1994-01-01

    Rhodococcus sp. strain IGTS8 possesses an enzymatic pathway that can remove covalently bound sulfur from dibenzothiophene (DBT) without breaking carbon-carbon bonds. The DNA sequence of a 4.0-kb BstBI-BsiWI fragment that carries the genes for this pathway was determined. Frameshift and deletion mutations established that three open reading frames were required for DBT desulfurization, and the genes were designated soxABC (for sulfur oxidation). Each sox gene was subcloned independently and expressed in Escherichia coli MZ1 under control of the inducible lambda pL promoter with a lambda cII ribosomal binding site. SoxC is an approximately 45-kDa protein that oxidizes DBT to DBT-5,5'-dioxide. SoxA is an approximately 50-kDa protein responsible for metabolizing DBT-5,5'-dioxide to an unidentified intermediate. SoxB is an approximately 40-kDa protein that, together with the SoxA protein, completes the desulfurization of DBT-5,5'-dioxide to 2-hydroxybiphenyl. Protein sequence comparisons revealed that the predicted SoxC protein is similar to members of the acyl coenzyme A dehydrogenase family but that the SoxA and SoxB proteins have no significant identities to other known proteins. The sox genes are plasmidborne and appear to be expressed as an operon in Rhodococcus sp. strain IGTS8 and in E. coli. Images PMID:7961424

  17. [Degradation of p-nitrophenol by a mangrove bacterial Rhodococcus sp. Ns].

    PubMed

    Wan, Nian-Sheng; Gu, Ji-Dong; Hao, Fu-Qin; Xiao, Xiang-Qun

    2007-02-01

    A bacterium capable of utilizing p-nitrophenol (PNP) as the sole nitrogen, carbon, and energy source was isolated from mangrove sediment. This bacterium was confirmed based on 16S rDNA sequence analysis and taxonomic analysis as being a member of the genus Rhodococcus and was designated strain Ns. The strain Ns could tolerate high concentrations of PNP up to 1.5 mmol/L and complete degradation was achieved in four days at 30 degrees C in the dark under aerobic conditions. Biodegradation of PNP quickly occurred at optimal pH above 5.0, and at least 5 per thousand salinity. Bacterial growth on PNP was observed with the simultaneous production of 4-nitrocatechol, which was also degraded by the same bacterium, as a degradation intermediate, Moreover, Rhodococcus sp. Ns was able to also deplete 2-nitrophenol(ONP) as the sole source of carbon, nitrogen and energy, but not 3-nitrophenol. The experimental results show that bacteria indigenous to the natural wetland sediment are capable of complete degradation of PNP and ONP.

  18. In Vitro Activities of Polycationic Peptides Alone and in Combination with Clinically Used Antimicrobial Agents against Rhodococcus equi

    PubMed Central

    Giacometti, A.; Cirioni, O.; Ancarani, F.; Del Prete, M. S.; Fortuna, M.; Scalise, G.

    1999-01-01

    The in vitro activities of magainin II, nisin, and ranalexin alone and in combination with other antimicrobial agents against six clinical isolates of Rhodococcus equi were investigated by MIC and time-kill studies. All isolates were more susceptible to nisin. A positive interaction was observed when the peptides were combined with ampicillin, ceftriaxone, rifabutin, rifampin, azithromycin, clarithromycin, and vancomycin. PMID:10428947

  19. In vitro activities of polycationic peptides alone and in combination with clinically used antimicrobial agents against Rhodococcus equi.

    PubMed

    Giacometti, A; Cirioni, O; Ancarani, F; Del Prete, M S; Fortuna, M; Scalise, G

    1999-08-01

    The in vitro activities of magainin II, nisin, and ranalexin alone and in combination with other antimicrobial agents against six clinical isolates of Rhodococcus equi were investigated by MIC and time-kill studies. All isolates were more susceptible to nisin. A positive interaction was observed when the peptides were combined with ampicillin, ceftriaxone, rifabutin, rifampin, azithromycin, clarithromycin, and vancomycin. PMID:10428947

  20. Gene Cloning and Nucleotide Sequencing and Properties of a Cocaine Esterase from Rhodococcus sp. Strain MB1

    PubMed Central

    Bresler, Matthew M.; Rosser, Susan J.; Basran, Amrik; Bruce, Neil C.

    2000-01-01

    A strain of Rhodococcus designated MB1, which was capable of utilizing cocaine as a sole source of carbon and nitrogen for growth, was isolated from rhizosphere soil of the tropane alkaloid-producing plant Erythroxylum coca. A cocaine esterase was found to initiate degradation of cocaine, which was hydrolyzed to ecgonine methyl ester and benzoate; both of these esterolytic products were further metabolized by Rhodococcus sp. strain MB1. The structural gene encoding a cocaine esterase, designated cocE, was cloned from Rhodococcus sp. strain MB1 genomic libraries by screening recombinant strains of Rhodococcus erythropolis CW25 for growth on cocaine. The nucleotide sequence of cocE corresponded to an open reading frame of 1,724 bp that codes for a protein of 574 amino acids. The amino acid sequence of cocaine esterase has a region of similarity with the active serine consensus of X-prolyl dipeptidyl aminopeptidases, suggesting that the cocaine esterase is a serine esterase. The cocE coding sequence was subcloned into the pCFX1 expression plasmid and expressed in Escherichia coli. The recombinant cocaine esterase was purified to apparent homogeneity and was found to be monomeric, with an Mr of approximately 65,000. The apparent Km of the enzyme (mean ± standard deviation) for cocaine was measured as 1.33 ± 0.085 mM. These findings are of potential use in the development of a linked assay for the detection of illicit cocaine. PMID:10698749

  1. Sequence and molecular characterization of a DNA region encoding the dibenzothiophene desulfurization operon of Rhodococcus sp. strain IGTS8.

    PubMed

    Piddington, C S; Kovacevich, B R; Rambosek, J

    1995-02-01

    Dibenzothiophene (DBT), a model compound for sulfur-containing organic molecules found in fossil fuels, can be desulfurized to 2-hydroxybiphenyl (2-HBP) by Rhodococcus sp. strain IGTS8. Complementation of a desulfurization (dsz) mutant provided the genes from Rhodococcus sp. strain IGTS8 responsible for desulfurization. A 6.7-kb TaqI fragment cloned in Escherichia coli-Rhodococcus shuttle vector pRR-6 was found to both complement this mutation and confer desulfurization to Rhodococcus fascians, which normally is not able to desulfurize DBT. Expression of this fragment in E. coli also conferred the ability to desulfurize DBT. A molecular analysis of the cloned fragment revealed a single operon containing three open reading frames involved in the conversion of DBT to 2-HBP. The three genes were designated dszA, dszB, and dszC. Neither the nucleotide sequences nor the deduced amino acid sequences of the enzymes exhibited significant similarity to sequences obtained from the GenBank, EMBL, and Swiss-Prot databases, indicating that these enzymes are novel enzymes. Subclone analyses revealed that the gene product of dszC converts DBT directly to DBT-sulfone and that the gene products of dszA and dszB act in concert to convert DBT-sulfone to 2-HBP.

  2. Structural insights into substrate specificity and solvent tolerance in alcohol dehydrogenase ADH-'A' from Rhodococcus ruber DSM 44541.

    PubMed

    Karabec, Martin; Łyskowski, Andrzej; Tauber, Katharina C; Steinkellner, Georg; Kroutil, Wolfgang; Grogan, Gideon; Gruber, Karl

    2010-09-14

    The structure of the alcohol dehydrogenase ADH-'A' from Rhodococcus ruber reveals possible reasons for its remarkable tolerance to organic co-solvents and suggests new directions for structure-informed mutagenesis to produce enzymes of altered substrate specificity or improved selectivity.

  3. Physiological and genetic differences amongst Rhodococcus species for using glycerol as a source for growth and triacylglycerol production.

    PubMed

    Herrero, O Marisa; Moncalián, Gabriel; Alvarez, Héctor M

    2016-02-01

    We analysed the ability of five different rhodococcal species to grow and produce triacylglycerols (TAGs) from glycerol, the main byproduct of biodiesel production. Rhodococcus fascians and Rhodococcus erythropolis grew fast on glycerol, whereas Rhodococcus opacus and Rhodococcus jostii exhibited a prolonged lag phase of several days before growing. Rhodococcus equi only exhibited poor growth on glycerol. R. erythropolis DSMZ 43060 and R. fascians F7 produced 3.9-4.3 g cell biomass l(-1) and 28.4-44.6% cellular dry weight (CDW) of TAGs after 6 days of incubation; whereas R. opacus PD630 and R. jostii RHA1 produced 2.5-3.8 g cell biomass l(-1) and 28.3-38.4% CDW of TAGs after 17 days of growth on glycerol. Genomic analyses revealed two different sets of genes for glycerol uptake and degradation (here named clusters 1 and 2) amongst rhodococci. Those species that possessed cluster 1 (glpFK1D1) (R. fascians and R. erythropolis) exhibited fast growth and lipid accumulation, whereas those that possessed cluster 2 (glpK2D2) (R. opacus, R. jostii and R. equi) exhibited delayed growth and lipid accumulation during cultivation on glycerol. Three glycerol-negative strains were complemented for their ability to grow and produce TAGs by heterologous expression of glpK2 from R. opacus PD630. In addition, we significantly reduced the extension of the lag phase and improved glycerol assimilation and oil production of R. opacus PD630 when expressing glpK1D1 from R. fascians. The results demonstrated that rhodococci are a flexible and amenable biological system for further biotechnological applications based on the reutilization of glycerol.

  4. Cold adaptive traits revealed by comparative genomic analysis of the eurypsychrophile Rhodococcus sp. JG3 isolated from high elevation McMurdo Dry Valley permafrost, Antarctica.

    PubMed

    Goordial, Jacqueline; Raymond-Bouchard, Isabelle; Zolotarov, Yevgen; de Bethencourt, Luis; Ronholm, Jennifer; Shapiro, Nicole; Woyke, Tanja; Stromvik, Martina; Greer, Charles W; Bakermans, Corien; Whyte, Lyle

    2016-02-01

    The permafrost soils of the high elevation McMurdo Dry Valleys are the most cold, desiccating and oligotrophic on Earth. Rhodococcus sp. JG3 is one of very few bacterial isolates from Antarctic Dry Valley permafrost, and displays subzero growth down to -5°C. To understand how Rhodococcus sp. JG3 is able to survive extreme permafrost conditions and be metabolically active at subzero temperatures, we sequenced its genome and compared it to the genomes of 14 mesophilic rhodococci. Rhodococcus sp. JG3 possessed a higher copy number of genes for general stress response, UV protection and protection from cold shock, osmotic stress and oxidative stress. We characterized genome wide molecular adaptations to cold, and identified genes that had amino acid compositions favourable for increased flexibility and functionality at low temperatures. Rhodococcus sp. JG3 possesses multiple complimentary strategies which may enable its survival in some of the harshest permafrost on Earth.

  5. Cold adaptive traits revealed by comparative genomic analysis of the eurypsychrophile Rhodococcus sp. JG3 isolated from high elevation McMurdo Dry Valley permafrost, Antarctica.

    PubMed

    Goordial, Jacqueline; Raymond-Bouchard, Isabelle; Zolotarov, Yevgen; de Bethencourt, Luis; Ronholm, Jennifer; Shapiro, Nicole; Woyke, Tanja; Stromvik, Martina; Greer, Charles W; Bakermans, Corien; Whyte, Lyle

    2016-02-01

    The permafrost soils of the high elevation McMurdo Dry Valleys are the most cold, desiccating and oligotrophic on Earth. Rhodococcus sp. JG3 is one of very few bacterial isolates from Antarctic Dry Valley permafrost, and displays subzero growth down to -5°C. To understand how Rhodococcus sp. JG3 is able to survive extreme permafrost conditions and be metabolically active at subzero temperatures, we sequenced its genome and compared it to the genomes of 14 mesophilic rhodococci. Rhodococcus sp. JG3 possessed a higher copy number of genes for general stress response, UV protection and protection from cold shock, osmotic stress and oxidative stress. We characterized genome wide molecular adaptations to cold, and identified genes that had amino acid compositions favourable for increased flexibility and functionality at low temperatures. Rhodococcus sp. JG3 possesses multiple complimentary strategies which may enable its survival in some of the harshest permafrost on Earth. PMID:26637477

  6. Simultaneous species-specific PCR detection and viability testing of poly(vinyl alcohol) cryogel-entrapped Rhodococcus spp. after their exposure to petroleum hydrocarbons.

    PubMed

    Kuyukina, Maria S; Ivshina, Irena B; Serebrennikova, Marina K; Rubtsova, Ekaterina V; Krivoruchko, Anastasiya V

    2013-08-01

    A method of simultaneous species-specific PCR detection and viability testing of poly(vinyl alcohol) cryogel-entrapped Rhodococcus spp. was developed that allowed the estimation of immobilized Rhodococcus opacus and Rhodococcus ruber survival after their exposure to petroleum hydrocarbon mixture. Spectrophotometric INT assay revealed high tolerance of gel-immobilized rhodococci to petroleum hydrocarbons, while among two Rhodococcus strains studied, R. ruber tolerated better to hydrocarbons compared to R. opacus. These findings were confirmed by respirometry results that showed increased respiratory activity of gel-immobilized Rhodococcus strains after 10-day incubation with 3% (v/v) petroleum hydrocarbon mixture. Moreover, jointly incubated rhodococcal strains demonstrated higher oxidative activities toward petroleum hydrocarbons than individual strains. Both Rhodococcus species were recovered successfully in cryogel granules using 16S rDNA-targeted PCR, even though the granules were previously stained with INT and extracted with ethanol. The method developed can be used for rapid detection and monitoring of gel-immobilized bacterial inocula in bioreactors or contaminated soil systems.

  7. The fas operon of Rhodococcus fascians encodes new genes required for efficient fasciation of host plants.

    PubMed Central

    Crespi, M; Vereecke, D; Temmerman, W; Van Montagu, M; Desomer, J

    1994-01-01

    Three virulence loci (fas, att, and hyp) of Rhodococcus fascians D188 have been identified on a 200-kb conjugative linear plasmid (pFiD188). The fas locus was delimited to a 6.5-kb DNA fragment by insertion mutagenesis, single homologous disruptive recombination, and in trans complementation of different avirulent insertion mutants. The locus is arranged as a large operon containing six open reading frames whose expression is specifically induced during the interaction with host plants. One predicted protein is homologous to P-450 cytochromes from actinomycetes. The putative ferredoxin component is of a novel type containing additional domains homologous to transketolases from chemoautotrophic, photosynthetic, and methylotrophic microorganisms. Genetic analysis revealed that fas encodes, in addition to the previously identified ipt, at least two new genes that are involved in fasciation development, one of which is only required on older tobacco plants. PMID:8169198

  8. Formaldehyde removal in synthetic and industrial wastewater by Rhodococcus erythropolis UPV-1.

    PubMed

    Hidalgo, A; Lopategi, A; Prieto, M; Serra, J L; Llama, M J

    2002-02-01

    Rhodococcus erythropolis strain UPV-1 is able to grow on phenol as the only carbon and energy source and to remove formaldehyde completely from both synthetic and industrial wastewater. The rate of formaldehyde removal is independent of either initial biomass or formaldehyde concentration. The presence of viable, intact cells is strictly necessary for this removal to take place. Discontinuous and continuous formaldehyde-feed systems were successfully tested with synthetic wastewater in shaken flasks. Once biodegradation was well established in model synthetic wastewater, a real wastewater sample was obtained from a local phenolic and melamine resin-manufacturing company. Incubation of biomass with this wastewater at subtoxic concentrations of formaldehyde resulted in the complete removal of the pollutant. Parameters, such as chemical oxygen demand and toxicity, were assessed as indicators of wastewater cleanup progress.

  9. Specificity of catechol ortho-cleavage during para-toluate degradation by Rhodococcus opacus 1cp.

    PubMed

    Suvorova, M M; Solianikova, I P; Golovleva, L A

    2006-12-01

    Degradation of para-toluate by Rhodococcus opacus 1cp was investigated. Activities of the key enzymes of this process, catechol 1,2-dioxygenase and muconate cycloisomerase, are detected in this microorganism. Growth on p-toluate was accompanied by induction of two catechol 1,2-dioxygenases. The substrate specificity and physicochemical properties of one enzyme are identical to those of chlorocatechol 1,2-dioxygenase; induction of the latter enzyme was observed during R. opacus 1cp growth on 4-chlorophenol. The other enzyme isolated from the biomass grown on p-toluate exhibited lower rate of chlorinated substrate cleavage compared to the catechol substrate. However, this enzyme is not identical to the catechol 1,2-dioxygenase cloned in this strain within the benzoate catabolism operon. This supports the hypothesis on the existence of multiple forms of dioxygenases as adaptive reactions of microorganisms in response to environmental stress.

  10. Characterization of Rhodococcus wratislaviensis strain J3 that degrades 4-nitrocatechol and other nitroaromatic compounds.

    PubMed

    Navrátilová, Jitka; Tvrzová, Ludmila; Durnová, Eva; Spröer, Cathrin; Sedlácek, Ivo; Neca, Jirí; Nemec, Miroslav

    2005-02-01

    The bacterial strain J3 was isolated from soil by selective enrichment on mineral medium containing 4-nitrocatechol as the sole carbon and energy source. This strain was identified as Rhodococcus wratislaviensis on the basis of morphology, biochemical, physiological and chemotaxonomic characterization and complete sequencing of the 16S rDNA gene. The isolated bacterium could utilize 4-nitrocatechol, 3-nitrophenol and 5-nitroguaiacol as sole carbon and energy sources. Stoichiometric release of nitrites was measured during degradation of 4-nitrocatechol both in growing cultures and for stationary phase cells. The J3 strain was unable to degrade 4-nitroguaiacol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrobenzoic acid, 4,5-dimethoxy-2-nitrobenzoic acid and 2,3-difluoro-6-nitrophenol. The J3 strain is deposited in the Czech Collection of Microorganisms as CCM 4930.

  11. Requirement of duplicated operons for maximal metabolism of phthalate by Rhodococcus sp. strain DK17.

    PubMed

    Choi, Ki Young; Kim, Dockyu; Chae, Jong-Chan; Zylstra, Gerben J; Kim, Eungbin

    2007-06-01

    The operons encoding the transformation of phthalate to protocatechuate are duplicated and present on two different megaplasmids [pDK2 (330 kb) and pDK3 (750 kb)] in Rhodococcus sp. strain DK17. RT-PCR experiments using gene-specific primers showed that both the pDK2- and the pDK3-encoded dihydroxyphthalate decarboxylase genes are simultaneously expressed during growth on phthalate. The doubling time of the pDK2-cured mutant strain DK176 in minimal liquid medium with 5mM phthalate is 52.5% of that of the wild-type strain DK17. The data indicate that both copies of the phthalate operon are equally functional in DK17, and gene dosage is the main reason for slower growth of DK176 on phthalate. PMID:17449009

  12. [Genetics and biochemistry of surfactant synthesis in Rhodococcus sp. H13-A]. Final report

    SciTech Connect

    Not Available

    1989-12-31

    The rationale for these studies resides is that biosurfactant synthesis occurs only when cells are grown with alkanes as sole source of carbon and energy. It is reasoned that biosurfactant synthesis is linked genetically to alkane oxidation and that the identification and characterization of the alk genes would provide information about the structural and regulator genes involved, in biosurfactant synthesis. Rhodococcus H13-A chromosomal DNA was isolated and digested with the restriction endonuclease Sau3A. The shuttle vector, pMVS301, was single site cleaved with Bgl II, phosphorylated, and the chromosomal DNA fragments agated into linearized pMVS301. The ligation mixture was used to transform competent E. coli HB101. The chromosomal DNA fragment has been cloned into pMVS301 which appears to contain genes encoding the initial oxidation of alkane. Electrophoration of Rhodococaus indicates transformation by this technique. Further studies are required to optimize conditions.

  13. (Genetics and biochemistry of surfactant synthesis in Rhodococcus sp. H13-A)

    SciTech Connect

    Not Available

    1989-01-01

    The rationale for these studies resides is that biosurfactant synthesis occurs only when cells are grown with alkanes as sole source of carbon and energy. It is reasoned that biosurfactant synthesis is linked genetically to alkane oxidation and that the identification and characterization of the alk genes would provide information about the structural and regulator genes involved, in biosurfactant synthesis. Rhodococcus H13-A chromosomal DNA was isolated and digested with the restriction endonuclease Sau3A. The shuttle vector, pMVS301, was single site cleaved with Bgl II, phosphorylated, and the chromosomal DNA fragments agated into linearized pMVS301. The ligation mixture was used to transform competent E. coli HB101. The chromosomal DNA fragment has been cloned into pMVS301 which appears to contain genes encoding the initial oxidation of alkane. Electrophoration of Rhodococaus indicates transformation by this technique. Further studies are required to optimize conditions.

  14. Equid herpesvirus 1 and rhodococcus equi coinfection in a foal with bronchointerstitial pneumonia

    PubMed Central

    PEREZ-ECIJA, Alejandro; MENDOZA, Francisco Javier; ESTEPA, José Carlos; BAUTISTA, María José; PÉREZ, José

    2016-01-01

    A 2-month-old foal with septic shock and severe respiratory distress was referred to the Veterinary Teaching Hospital. Due to poor prognosis, the foal was euthanized. Histopathology showed lesions suggestive of Rhodococcus equi infection associated with a diffuse interstitial infiltrate of foamy macrophages and syncytial cells presenting large acidophilic intranuclear inclusion bodies, fibrin exudates and hyaline membranes. Bacteriological examination from lung and respiratory exudates confirmed R. equi infection, whilst immunohistochemistry and PCR yielded a positive result for Equid herpesvirus type 1 (EHV-1). Several etiologies have been proposed for bronchointerstitial pneumonia in foals, although a multifactorial origin for this lesional pattern could be possible. This work is the first one describing a combined EHV-1 and R. equi infection in a foal affected with bronchointerstitial pneumonia. PMID:27264610

  15. Biosynthesis of polyhydroxyalkanoates from low-rank coal liquefaction products by Pseudomonas oleovorans and Rhodococcus ruber

    PubMed

    Fuchtenbusch; Steinbuchel

    1999-07-01

    A screening identified several bacteria that were able to use chemically heterogeneous low-rank coal liquefaction products as complex carbon sources for growth. Pseudomonas oleovorans and Rhodococcus ruber accumulated polyhydroxyalkanoic acids (PHA) amounting to 2%-8% of the cell dry weight when the cells were cultivated on these liquefaction products in the absence of any other carbon source. R. ruber accumulated, in addition to PHA, small amounts of triacylglycerols. The accumulated PHA consisted of 3-hydroxyhexanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate (P. oleovorans) or 3-hydroxybutyric acid and 3-hydroxyvaleric acid (R. ruber). Low-rank coal liquefaction products obtained from Trichoderma atroviride were better substrates for P. oleovorans than chemically produced fulvic acids.

  16. Enhanced desulfurization in a transposon-mutant strain of Rhodococcus erythropolis.

    PubMed

    Watanabe, Kimiko; Noda, Ken-ichi; Maruhashi, Kenji

    2003-08-01

    The dsz desulfurization gene cluster from Rhodococcus erythropolis strain KA2-5-1 was transferred into R. erythropolis strain MC1109, unable to desulfurize light gas oil (LGO), using a transposon-transposase complex. As a result, two recombinant strains, named MC0203 and MC0122, were isolated. Resting cells of strain MC0203 decreased the sulfur concentration of LGO from 120 mg l(-1) to 70 mg l(-1) in 2 h. The LGO-desulfurization activity of strain MC0203 was about twice that of strain MC0122 and KA2-5-1. The 10-methyl fatty acids of strain MC0203 were about 28%-41% that of strain MC1109. It is likely that strain MC0203 had a mutation involving alkylenation or methylation of delta9-unsaturated fatty acids caused by the transposon inserted in the chromosome, which increased the fluidity of cell membranes and enhanced the desulfurization activity.

  17. Rhodococcus equi peritonitis in continuous ambulatory peritoneal dialysis: a first in Australia.

    PubMed

    Azzam, Omar; Crowe, Amy; Sajiv, Cherian; Pawar, Basant

    2015-01-01

    A 33-year-old Caucasian man with end-stage renal disease secondary to biopsy-proven IgA nephropathy, managed with continuous ambulatory peritoneal dialysis (PD), presented with PD-related peritonitis, the causal organism being a non-branching Gram-positive bacillus, Rhodococcus equi. Initial empirical Gram positive and negative coverage with cefazolin and ceftazidime was unsuccessful, but following isolation of the organism, and conversion to intraperitoneal vancomycin and oral ciprofloxacin, the peritonitis episode resolved. At day 10, vancomycin was switched to azithromycin for a total of 6 weeks of antimicrobial therapy. The PD catheter was preserved, and the patient remained peritonitis-free at 6 months of follow-up.

  18. Optimization of nutrient component for diesel oil degradation by Rhodococcus erythropolis.

    PubMed

    Huang, Lei; Ma, Ting; Li, Dan; Liang, Feng-lai; Liu, Ru-Lin; Li, Guo-qiang

    2008-10-01

    A novel bacterium T7-2 was isolated from the oil-polluted sea-bed mud of Bohai Sea, northern China, which can degrade diesel oil at 15 degrees C. This bacterium was identified as a strain of Rhodococcus erythropolis according to its 16S rDNA gene. In order to enhance degradation efficiency, a five-level, three-factor central composite design was employed to optimize the nutrition supplied to artificial seawater. The results indicate that a supplement of 2.53 g (NH(4))(2)SO(4)L(-1), 2.75 g Na(2)HPO(4)L(-1) and 0.01 g yeast extract L(-1) to artificial seawater increases the degradation rate from 12.61% to 75% within 7d.

  19. Rhodococcus percolatus sp. nov., a bacterium degrading 2,4,6-trichlorophenol.

    PubMed

    Briglia, M; Rainey, F A; Stackebrandt, E; Schraa, G; Salkinoja-Salonen, M S

    1996-01-01

    A bacterial strain that was able to mineralize 2,4,6-trichlorophenol was isolated from a chlorophenol-fed percolator and was identified as a member of the genus Rhodococcus on the basis of chemotaxonomic characteristics and 16S RNA phylogenetic inference data. This organism (strain MBS1T [T = type strain]) exhibited a typical irregular rod-coccus cycle, and the cells had fimbria-like structures on their surfaces. The diagnostic cell wall amino acid was meso-diaminopimelic acid, and the sugars were arabinose and galactose; the mycolic acids contained 46 to 54 carbon atoms. The main menaquinone was MK-8(H2), and MK-9(H2) was a minor component. The cellular phospholipids were phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositolmannoside, phosphatidylglycerol, and diphosphatidylglycerol. Tuberculostearic acid was present. The whole-cell fatty acids were straight-chain acids with 14 to 18 C atoms. The G+C content of the DNA was 67.4 mol%. This organism grew on sucrose, pyruvate, and 2,4,6-trichlorophenol, and it oxidized a large number of carbon compounds, including catechol, 3-hydroxyphenylacetic acid, and phenol. It also exhibited beta-galactosidase, urease, and 2-acetyl-lactate decarboxylase activities. On a phylogenetic tree that was based on 16S ribosomal DNA gene sequences strain MBS1T was found among the rhodococci on an independent branch. On the basis of the chemotaxonomic and phenotypic characteristics of strain MBS1T and its phylogenetic position we suggest that this bacterium should be placed in a new species, Rhodococcus percolatus; the specific epithet was chosen because the organism was isolated by using an enriched percolator. The type strain is strain MBS1. PMID:8573500

  20. Biodegradation of the Organic Disulfide 4,4′-Dithiodibutyric Acid by Rhodococcus spp.

    PubMed Central

    Khairy, Heba; Wübbeler, Jan Hendrik

    2015-01-01

    Four Rhodococcus spp. exhibited the ability to use 4,4′-dithiodibutyric acid (DTDB) as a sole carbon source for growth. The most important step for the production of a novel polythioester (PTE) using DTDB as a precursor substrate is the initial cleavage of DTDB. Thus, identification of the enzyme responsible for this step was mandatory. Because Rhodococcus erythropolis strain MI2 serves as a model organism for elucidation of the biodegradation of DTDB, it was used to identify the genes encoding the enzymes involved in DTDB utilization. To identify these genes, transposon mutagenesis of R. erythropolis MI2 was carried out using transposon pTNR-TA. Among 3,261 mutants screened, 8 showed no growth with DTDB as the sole carbon source. In five mutants, the insertion locus was mapped either within a gene coding for a polysaccharide deacetyltransferase, a putative ATPase, or an acetyl coenzyme A transferase, 1 bp upstream of a gene coding for a putative methylase, or 176 bp downstream of a gene coding for a putative kinase. In another mutant, the insertion was localized between genes encoding a putative transcriptional regulator of the TetR family (noxR) and an NADH:flavin oxidoreductase (nox). Moreover, in two other mutants, the insertion loci were mapped within a gene encoding a hypothetical protein in the vicinity of noxR and nox. The interruption mutant generated, R. erythropolis MI2 noxΩtsr, was unable to grow with DTDB as the sole carbon source. Subsequently, nox was overexpressed and purified, and its activity with DTDB was measured. The specific enzyme activity of Nox amounted to 1.2 ± 0.15 U/mg. Therefore, we propose that Nox is responsible for the initial cleavage of DTDB into 2 molecules of 4-mercaptobutyric acid (4MB). PMID:26407888

  1. Enzymatic cyanide degradation by cell-free extract of Rhodococcus UKMP-5M.

    PubMed

    Nallapan Maniyam, Maegala; Sjahrir, Fridelina; Latif Ibrahim, Abdul; Cass, Anthony E G

    2015-01-01

    The cell-free extract of locally isolated Rhodococcus UKMP-5M strain was used as an alternative to develop greener and cost effective cyanide removal technology. The present study aims to assess the viability of the cell-free extract to detoxify high concentrations of cyanide which is measured through the monitoring of protein concentration and specific cyanide-degrading activity. When cyanide-grown cells were subjected to grinding in liquid nitrogen which is relatively an inexpressive and fast cell disruption method, highest cyanide-degrading activity of 0.63 mM min(-1) mg(-1) protein was obtained in comparison to enzymatic lysis and agitation with fine glass beads. The cell-free extracts managed to degrade 80% of 20 mM KCN within 80 min and the rate of cyanide consumption increased linearly as the concentration of protein was raised. In both cases, the addition of co-factor was not required which proved to be advantageous economically. The successful formation of ammonia and formate as endproducts indicated that the degradation of cyanide by Rhodococcus UKMP-5M proceeded via the activity of cyanidase and the resulting non-toxic products are safe for disposal into the environment. Further verification with SDS-PAGE revealed that the molecular weight of the active enzyme was estimated to be 38 kDa, which is consistent with previously reported cyanidases. Thus, the utilization of cell-free extracts as an alternative to live microbial in cyanide degradation offers numerous advantageous such as the potential to tolerate and degrade higher concentration of cyanide and total reduction in the overall cost of operation since the requirement for nutrient support is irrelevant. PMID:25723061

  2. The Genome of a Pathogenic Rhodococcus: Cooptive Virulence Underpinned by Key Gene Acquisitions

    PubMed Central

    Letek, Michal; González, Patricia; MacArthur, Iain; Rodríguez, Héctor; Freeman, Tom C.; Valero-Rello, Ana; Blanco, Mónica; Buckley, Tom; Cherevach, Inna; Fahey, Ruth; Hapeshi, Alexia; Holdstock, Jolyon; Leadon, Desmond; Navas, Jesús; Ocampo, Alain; Quail, Michael A.; Sanders, Mandy; Scortti, Mariela M.; Prescott, John F.; Fogarty, Ursula; Meijer, Wim G.; Parkhill, Julian; Bentley, Stephen D.; Vázquez-Boland, José A.

    2010-01-01

    We report the genome of the facultative intracellular parasite Rhodococcus equi, the only animal pathogen within the biotechnologically important actinobacterial genus Rhodococcus. The 5.0-Mb R. equi 103S genome is significantly smaller than those of environmental rhodococci. This is due to genome expansion in nonpathogenic species, via a linear gain of paralogous genes and an accelerated genetic flux, rather than reductive evolution in R. equi. The 103S genome lacks the extensive catabolic and secondary metabolic complement of environmental rhodococci, and it displays unique adaptations for host colonization and competition in the short-chain fatty acid–rich intestine and manure of herbivores—two main R. equi reservoirs. Except for a few horizontally acquired (HGT) pathogenicity loci, including a cytoadhesive pilus determinant (rpl) and the virulence plasmid vap pathogenicity island (PAI) required for intramacrophage survival, most of the potential virulence-associated genes identified in R. equi are conserved in environmental rhodococci or have homologs in nonpathogenic Actinobacteria. This suggests a mechanism of virulence evolution based on the cooption of existing core actinobacterial traits, triggered by key host niche–adaptive HGT events. We tested this hypothesis by investigating R. equi virulence plasmid-chromosome crosstalk, by global transcription profiling and expression network analysis. Two chromosomal genes conserved in environmental rhodococci, encoding putative chorismate mutase and anthranilate synthase enzymes involved in aromatic amino acid biosynthesis, were strongly coregulated with vap PAI virulence genes and required for optimal proliferation in macrophages. The regulatory integration of chromosomal metabolic genes under the control of the HGT–acquired plasmid PAI is thus an important element in the cooptive virulence of R. equi. PMID:20941392

  3. Enzymatic cyanide degradation by cell-free extract of Rhodococcus UKMP-5M.

    PubMed

    Nallapan Maniyam, Maegala; Sjahrir, Fridelina; Latif Ibrahim, Abdul; Cass, Anthony E G

    2015-01-01

    The cell-free extract of locally isolated Rhodococcus UKMP-5M strain was used as an alternative to develop greener and cost effective cyanide removal technology. The present study aims to assess the viability of the cell-free extract to detoxify high concentrations of cyanide which is measured through the monitoring of protein concentration and specific cyanide-degrading activity. When cyanide-grown cells were subjected to grinding in liquid nitrogen which is relatively an inexpressive and fast cell disruption method, highest cyanide-degrading activity of 0.63 mM min(-1) mg(-1) protein was obtained in comparison to enzymatic lysis and agitation with fine glass beads. The cell-free extracts managed to degrade 80% of 20 mM KCN within 80 min and the rate of cyanide consumption increased linearly as the concentration of protein was raised. In both cases, the addition of co-factor was not required which proved to be advantageous economically. The successful formation of ammonia and formate as endproducts indicated that the degradation of cyanide by Rhodococcus UKMP-5M proceeded via the activity of cyanidase and the resulting non-toxic products are safe for disposal into the environment. Further verification with SDS-PAGE revealed that the molecular weight of the active enzyme was estimated to be 38 kDa, which is consistent with previously reported cyanidases. Thus, the utilization of cell-free extracts as an alternative to live microbial in cyanide degradation offers numerous advantageous such as the potential to tolerate and degrade higher concentration of cyanide and total reduction in the overall cost of operation since the requirement for nutrient support is irrelevant.

  4. Structure of the virulence-associated protein VapD from the intracellular pathogen Rhodococcus equi

    SciTech Connect

    Whittingham, Jean L.; Blagova, Elena V.; Finn, Ciaran E.; Luo, Haixia; Miranda-CasoLuengo, Raúl; Turkenburg, Johan P.; Leech, Andrew P.; Walton, Paul H.; Murzin, Alexey G.; Meijer, Wim G.; Wilkinson, Anthony J.

    2014-08-01

    VapD is one of a set of highly homologous virulence-associated proteins from the multi-host pathogen Rhodococcus equi. The crystal structure reveals an eight-stranded β-barrel with a novel fold and a glycine rich ‘bald’ surface. Rhodococcus equi is a multi-host pathogen that infects a range of animals as well as immune-compromised humans. Equine and porcine isolates harbour a virulence plasmid encoding a homologous family of virulence-associated proteins associated with the capacity of R. equi to divert the normal processes of endosomal maturation, enabling bacterial survival and proliferation in alveolar macrophages. To provide a basis for probing the function of the Vap proteins in virulence, the crystal structure of VapD was determined. VapD is a monomer as determined by multi-angle laser light scattering. The structure reveals an elliptical, compact eight-stranded β-barrel with a novel strand topology and pseudo-twofold symmetry, suggesting evolution from an ancestral dimer. Surface-associated octyl-β-d-glucoside molecules may provide clues to function. Circular-dichroism spectroscopic analysis suggests that the β-barrel structure is preceded by a natively disordered region at the N-terminus. Sequence comparisons indicate that the core folds of the other plasmid-encoded virulence-associated proteins from R. equi strains are similar to that of VapD. It is further shown that sequences encoding putative R. equi Vap-like proteins occur in diverse bacterial species. Finally, the functional implications of the structure are discussed in the light of the unique structural features of VapD and its partial structural similarity to other β-barrel proteins.

  5. Web-type evolution of rhodococcus gene clusters associated with utilization of naphthalene.

    PubMed

    Kulakov, Leonid A; Chen, Shenchang; Allen, Christopher C R; Larkin, Michael J

    2005-04-01

    Clusters of genes which include determinants for the catalytic subunits of naphthalene dioxygenase (narAa and narAb) were analyzed in naphthalene-degrading Rhodococcus strains. We demonstrated (i) that in the region analyzed homologous gene clusters are separated from each other by nonhomologous DNA, (ii) that there are various degrees of homology between related genes, and (iii) that nar genes are located on plasmids in strains NCIMB12038 and P400 and on a chromosome in P200. These observations suggest that genetic exchange and reshuffling of genetic modules, as well as vertical descent of the genetic information, were the main routes in the evolution of naphthalene degradation in Rhodococcus. These conclusions were supported by studies of transcription patterns in the region analyzed. It was found that the nar region is not organized into a single operon but there are several transcription units which differ in the strains investigated. The narA and narB genes were found to be transcribed as a single unit in all strains analyzed, and their transcription was induced by naphthalene. The putative aldolase gene (narC) was found on the same transcript only in strains P200 and P400. In NCIMB12038 transcription of two more gene clusters was induced by growth on naphthalene. Transcription start sites for narA and narB were found to be different in all of the strains studied. Putative regulatory genes (narR1 and narR2) were transcribed as a single mRNA in naphthalene-induced cells. At the same time, a number of the genes known to be essential for naphthalene catabolism in gram-negative bacteria were not found in the region analyzed.

  6. The Hydroxamate Siderophore Rhequichelin Is Required for Virulence of the Pathogenic Actinomycete Rhodococcus equi

    PubMed Central

    Coulson, Garry B.; Miranda-CasoLuengo, Aleksandra; Vázquez-Boland, José A.; Hondalus, Mary K.

    2012-01-01

    We previously showed that the facultative intracellular pathogen Rhodococcus equi produces a nondiffusible and catecholate-containing siderophore (rhequibactin) involved in iron acquisition during saprophytic growth. Here, we provide evidence that the rhbABCDE cluster directs the biosynthesis of a hydroxamate siderophore, rhequichelin, that plays a key role in virulence. The rhbC gene encodes a nonribosomal peptide synthetase that is predicted to produce a tetrapeptide consisting of N5-formyl-N5-hydroxyornithine, serine, N5-hydroxyornithine, and N5-acyl-N5-hydroxyornithine. The other rhb genes encode putative tailoring enzymes mediating modification of ornithine residues incorporated into the hydroxamate product of RhbC. Transcription of rhbC was upregulated during growth in iron-depleted medium, suggesting that it plays a role in iron acquisition. This was confirmed by deletion of rhbCD, rendering the resulting strain R. equi SID2 unable to grow in the presence of the iron chelator 2,2-dipyridyl. Supernatant of the wild-type strain rescued the phenotype of R. equi SID2. The importance of rhequichelin in virulence was highlighted by the rapid increase in transcription levels of rhbC following infection and the inability of R. equi SID2 to grow within macrophages. Unlike the wild-type strain, R. equi SID2 was unable to replicate in vivo and was rapidly cleared from the lungs of infected mice. Rhequichelin is thus a key virulence-associated factor, although nonpathogenic Rhodococcus species also appear to produce rhequichelin or a structurally closely related compound. Rhequichelin biosynthesis may therefore be considered an example of cooption of a core actinobacterial trait in the evolution of R. equi virulence. PMID:22966042

  7. Clinical application of a polymerase chain reaction assay in the diagnosis of pneumonia caused by Rhodococcus equi in a horse.

    PubMed

    Vivrette, S L; Sellon, D C; Gibbons, D S

    2000-11-01

    Diagnosis of pneumonia caused by Rhodococcus equi can be made more rapidly by use of a polymerase chain reaction (PCR) assay than by use of conventional bacteriologic culture techniques. Use of a PCR assay aids in the differentiation between virulent and avirulent strains of R equi, and the assay may be used to identify R equi in feces and soil of breeding farms. PMID:11061388

  8. Overexpression of a phosphatidic acid phosphatase type 2 leads to an increase in triacylglycerol production in oleaginous Rhodococcus strains.

    PubMed

    Hernández, Martín A; Comba, Santiago; Arabolaza, Ana; Gramajo, Hugo; Alvarez, Héctor M

    2015-03-01

    Oleaginous Rhodococcus strains are able to accumulate large amounts of triacylglycerol (TAG). Phosphatidic acid phosphatase (PAP) enzyme catalyzes the dephosphorylation of phosphatidic acid (PA) to yield diacylglycerol (DAG), a key precursor for TAG biosynthesis. Studies to establish its role in lipid metabolism have been mainly focused in eukaryotes but not in bacteria. In this work, we identified and characterized a putative PAP type 2 (PAP2) encoded by the ro00075 gene in Rhodococcus jostii RHA1. Heterologous expression of ro00075 in Escherichia coli resulted in a fourfold increase in PAP activity and twofold in DAG content. The conditional deletion of ro00075 in RHA1 led to a decrease in the content of DAG and TAG, whereas its overexpression in both RHA1 and Rhodococcus opacus PD630 promoted an increase up to 10 to 15 % by cellular dry weight in TAG content. On the other hand, expression of ro00075 in the non-oleaginous strain Rhodococcus fascians F7 promoted an increase in total fatty acid content up to 7 % at the expense of free fatty acid (FFA), DAG, and TAG fractions. Moreover, co-expression of ro00075/atf2 genes resulted in a fourfold increase in total fatty acid content by a further increase of the FFA and TAG fractions. The results of this study suggest that ro00075 encodes for a PAP2 enzyme actively involved in TAG biosynthesis. Overexpression of this gene, as single one or with an atf gene, provides an alternative approach to increase the biosynthesis and accumulation of bacterial oils as a potential source of raw material for biofuel production.

  9. Analysis and optimization of triacylglycerol synthesis in novel oleaginous Rhodococcus and Streptomyces strains isolated from desert soil.

    PubMed

    Röttig, Annika; Hauschild, Philippa; Madkour, Mohamed H; Al-Ansari, Ahmed M; Almakishah, Naief H; Steinbüchel, Alexander

    2016-05-10

    As oleaginous microorganisms represent an upcoming novel feedstock for the biotechnological production of lipids or lipid-derived biofuels, we searched for novel, lipid-producing strains in desert soil. This was encouraged by the hypothesis that neutral lipids represent an ideal storage compound, especially under arid conditions, as several animals are known to outlast long periods in absence of drinking water by metabolizing their body fat. Ten lipid-accumulating bacterial strains, affiliated to the genera Bacillus, Cupriavidus, Nocardia, Rhodococcus and Streptomyces, were isolated from arid desert soil due to their ability to synthesize poly(β-hydroxybutyrate), triacylglycerols or wax esters. Particularly two Streptomyces sp. strains and one Rhodococcus sp. strain accumulate significant amounts of TAG under storage conditions under optimized cultivation conditions. Rhodococcus sp. A27 and Streptomyces sp. G49 synthesized approx. 30% (w/w) fatty acids from fructose or cellobiose, respectively, while Streptomyces isolate G25 reached a cellular fatty acid content of nearly 50% (w/w) when cultivated with cellobiose. The stored triacylglycerols were composed of 30-40% branched fatty acids, such as anteiso-pentadecanoic or iso-hexadecanoic acid. To date, this represents by far the highest lipid content described for streptomycetes. A biotechnological production of such lipids using (hemi)cellulose-derived raw material could be used to obtain sustainable biodiesel with a high proportion of branched-chain fatty acids to improve its cold-flow properties and oxidative stability. PMID:27034020

  10. Triacylglycerol accumulation and oxidative stress in Rhodococcus species: differential effects of pro-oxidants on lipid metabolism.

    PubMed

    Urbano, Susana Bequer; Di Capua, Cecilia; Cortez, Néstor; Farías, María E; Alvarez, Héctor M

    2014-03-01

    In general, members of Rhodococcus genus are highly resistant to desiccation. Desiccation is a complex process which includes the formation of reactive oxygen species that results in significant damage to cells. In this study, we demonstrate that extremophile actinobacterial strains isolated from diverse environments, mainly belonging to Rhodococcus genus, exhibited high tolerance to the pro-oxidants hydrogen peroxide (H2O2) and methyl viologen (MV). In addition, we investigated the possible interconnections between the responses of the oleaginous Rhodococcus opacus PD630 to oxidative stress and lipid metabolism, since both processes demand a metabolic reorganization of cells. Experiments with metabolic inhibitors showed differential effects of both pro-oxidants on lipid metabolism in PD630 cells. The inhibition of carotenoid biosynthesis by the addition of diphenylamine to the media negatively affected the tolerance of cells to H2O2, but not to MV. The inhibition of triacylglycerol (TAG) biosynthesis and accumulation in PD630 did not affect the tolerance of cells to H2O2 and MV; whereas, the blockage of lipolysis decreased the tolerance of cells to H2O2 (but not MV) under carbon-starvation conditions. Interestingly, the addition of MV to the media (but not H2O2) induced a reduction of TAG accumulation by cells. Resuming, results of this study revealed metabolic connections between lipid metabolism and oxidative stress responses in R. opacus PD630, and probably in other extremophile TAG-accumulating rhodococci.

  11. Analysis and optimization of triacylglycerol synthesis in novel oleaginous Rhodococcus and Streptomyces strains isolated from desert soil.

    PubMed

    Röttig, Annika; Hauschild, Philippa; Madkour, Mohamed H; Al-Ansari, Ahmed M; Almakishah, Naief H; Steinbüchel, Alexander

    2016-05-10

    As oleaginous microorganisms represent an upcoming novel feedstock for the biotechnological production of lipids or lipid-derived biofuels, we searched for novel, lipid-producing strains in desert soil. This was encouraged by the hypothesis that neutral lipids represent an ideal storage compound, especially under arid conditions, as several animals are known to outlast long periods in absence of drinking water by metabolizing their body fat. Ten lipid-accumulating bacterial strains, affiliated to the genera Bacillus, Cupriavidus, Nocardia, Rhodococcus and Streptomyces, were isolated from arid desert soil due to their ability to synthesize poly(β-hydroxybutyrate), triacylglycerols or wax esters. Particularly two Streptomyces sp. strains and one Rhodococcus sp. strain accumulate significant amounts of TAG under storage conditions under optimized cultivation conditions. Rhodococcus sp. A27 and Streptomyces sp. G49 synthesized approx. 30% (w/w) fatty acids from fructose or cellobiose, respectively, while Streptomyces isolate G25 reached a cellular fatty acid content of nearly 50% (w/w) when cultivated with cellobiose. The stored triacylglycerols were composed of 30-40% branched fatty acids, such as anteiso-pentadecanoic or iso-hexadecanoic acid. To date, this represents by far the highest lipid content described for streptomycetes. A biotechnological production of such lipids using (hemi)cellulose-derived raw material could be used to obtain sustainable biodiesel with a high proportion of branched-chain fatty acids to improve its cold-flow properties and oxidative stability.

  12. Influence of Plasmid Type on the Replication of Rhodococcus equi in Host Macrophages

    PubMed Central

    Willingham-Lane, Jennifer M.; Berghaus, Londa J.; Giguère, Steeve

    2016-01-01

    ABSTRACT The soil-dwelling, saprophytic actinomycete Rhodococcus equi is a multihost, facultative intracellular pathogen of macrophages. When inhaled by susceptible foals, it causes severe bronchopneumonia. It is also a pathogen of pigs, which may develop submaxillary lymphadenitis upon exposure. R. equi isolates obtained from foals and pigs possess conjugative plasmids housing a pathogenicity island (PAI) containing a novel family of genes of unknown function called the virulence-associated protein or vap family. The PAI regions of the equine and swine plasmids differ in vap gene composition, with equine isolates possessing six vap genes, including the major virulence determinant vapA, while the PAIs of swine isolates house vapB and five other unique vap genes. Possession of the pVAPA-type virulence plasmid by equine isolates bestows the capacity for intramacrophage replication essential for disease development in vivo. Swine isolates of R. equi are largely unstudied. Here, we show that R. equi isolates from pigs, carrying pVAPB-type plasmids, are able to replicate in a plasmid-dependent manner in macrophages obtained from a variety of species (murine, swine, and equine) and anatomical locations. Similarly, equine isolates carrying pVAPA-type plasmids are capable of replication in swine macrophages. Plasmid swapping between equine and swine strains through conjugation did not alter the intracellular replication capacity of the parental strain, indicating that coevolution of the plasmid and chromosome is not crucial for this attribute. These results demonstrate that while distinct plasmid types exist among R. equi isolates obtained from equine and swine sources, this tropism is not determined by host species-specific intramacrophage replication capabilities. IMPORTANCE This work greatly advances our understanding of the opportunistic pathogen Rhodococcus equi, a disease agent of animals and immunocompromised people. Clinical isolates from diseased foals carry a

  13. SiS2 in circumstellar shells

    NASA Astrophysics Data System (ADS)

    Goebel, J. H.

    1993-10-01

    Solid state SiS2 is proposed as the material responsible for the recently discovered 21 micrometer emission feature that is observed in the carbon-rich circumstellar shells of certain protoplanetary nebulae. Sulfurized SiC, or SiS2 mantles on grains of either SiC or a:C-H are discussed as possible forms for which no spectroscopic laboratory observations yet exist. The identification with a relatively minor species and required special abundance ratios are consistent with the low incidence rate that the 21 micrometer feature presents in the population of carbon rich objects. It is also consistent with the lack of a good correlation between the 21 micrometer feature and the other solid-state spectroscopic features that have been observed in protoplanetaries that would be expected if the feature arose from molecules composed of H, C, N, and O. SiS2 condensate is consistent with the circumstellar shell temperature range, TCS approximately equal to or less than 150 K, at which the feature appears, and the available mass of SiS2, MSiS2 approx. = 5 x 10-6 solar mass, that is possible in the circumstellar shell.

  14. Prevalence and Antibiogram study of Rhodococcus equi in equines of Jammu and Kashmir, India.

    PubMed

    Mir, Irfan Ahmad; Kumar, Bablu; Taku, Anil; Bhardwaj, Rajinder Kumar; Bhat, Mohd Altaf; Badroo, Gulzar Ahmad

    2015-01-01

    The present study was conducted to determine the prevalence of Rhodococcus equi infection in equines of Jammu and Kashmir, India, and evaluate the zoonotic threat posed by this organism to equine owners and tourists. One hundred and forty-one samples (98 samples from adult animals ≥5 years old and 43 samples from foals less than 6 months old) were collected in duplicate from nasopharyngeal tract of equines for isolation and direct PCR. A total of 12 isolates of R. equi were recovered, of which 9 were from foals and 3 from adult animals. Therefore, the present study recorded prevalence rates of 20.93% and 3.06% among foals and adult equines respectively. The prevalence rates were found to be 25.58% and 4.08% by 16S rRNA species-specific PCR among foals and adult animals respectively. Thus, the PCR-based assay was found to be more sensitive and helped in quick detection of R. equi than the culture based method which is time consuming and laborious. However, the culture-based method is still preferred due to some limitations of PCR. The antibiogram of the isolates revealed that erythromycin and rifampicin were the most effective antimicrobials with 100% sensitivity, followed by amoxicillin (66.67%), lincomycin (58.3%) and kanamycin (58.3%). The results also revealed that resistance was highest for penicillin G (50%), followed by kanamycin (25%) and streptomycin (25%).

  15. High cell density cultivation of Rhodococcus opacus for lipid production at a pilot-plant scale.

    PubMed

    Voss, I; Steinbüchel, A

    2001-05-01

    The triacylglycerol (TAG)-accumulating bacterium Rhodococcus opacus strain PD630 was investigated with respect to the fermentative production of TAGs consisting of an unusually high fraction of fatty acids with an odd-number of carbon atoms and unsaturated monoenic fatty acids from sugar beet molasses and sucrose. Fed-batch fermentations were optimized at the 30-1 scale in a stirred tank bioreactor at 30 degrees C using a mineral salts medium, which contained sugar beet molasses and sucrose as sole carbon sources. Approximately 37.5 g cell dry matter (CDM) per liter was the highest cell density that was obtained at that scale with a TAG content in the cells of 52%. This fermentative process was also applied to a 500-1 pilot-plant scale. Cell densities as high as 18.4 g CDM per liter were obtained, and 42% of the sucrose present in the medium was converted into cell mass which consisted of 38.4% TAGs. PMID:11414319

  16. Growth rate and nutrient limitation affect the transport of Rhodococcus sp. strain DN22 through sand.

    PubMed

    Priestley, James T; Coleman, Nicholas V; Duxbury, Trevor

    2006-12-01

    Rhodococcus strain DN22 grows on the nitramine explosive RDX as a sole nitrogen source, and is potentially useful for bioremediation of explosives-contaminated soil. In order for strain DN22 to be effectively applied in situ, inoculum cells must reach zones of RDX contamination via passive transport, a process that is difficult to predict at field-scale. We examined the effect of growth conditions on the transport of DN22 cells through sand columns, using chemostat-grown cultures. Strain DN22 formed smaller coccoid cells at low dilution rate (0.02 h(-1)) and larger rods at high dilution rate (0.1 h(-1)). Under all nutrient limitation conditions studied, smaller cells grown at low dilution rate were retained more strongly by sand columns than larger cells grown at high dilution rate. At a dilution rate of 0.05, cells from nitrate-limited cultures were retained more strongly than cells from RDX-limited or succinate-limited cultures. Breakthrough concentrations (C/C (0)) from sand columns ranged from 0.04 (nitrate-limited, D=0.02 h(-1)) to 0.98 (succinate-limited, D=0.1 h(-1)). The observed strong effect of culture conditions on transport of DN22 cells emphasizes the importance of physiology studies in guiding the development of bioremediation technologies.

  17. Crystallization and preliminary characterization of chloromuconolactone dehalogenase from Rhodococcus opacus 1CP

    PubMed Central

    Roth, Christian; Kaschabek, Stefan R.; Gröning, Janosch A. D.; Handrek, Thomas; Schlömann, Michael; Sträter, Norbert

    2012-01-01

    Chloroaromatic compounds are often very persistent environmental pollutants. Nevertheless, numerous bacteria are able to metabolize these compounds and to utilize them as sole energy and carbon sources. Rhodococcus opacus 1CP is able to degrade several chloroaromatic compounds, some of them via a variation of the 3-chlorocatechol branch of the modified ortho-cleavage pathway. This branch in R. opacus differs from that in Proteobacteria in the inability of the chloromuconate cycloisomerase to dehalogenate. Instead, a unique enzyme designated as chloromuconolactone dehalogenase (ClcF) is recruited. ClcF dehalogenates 5-chloromuconolactone to cis-dienelactone and shows a high similarity to muconolactone isomerases (EC 5.3.3.4). However, unlike the latter enzymes, it is unable to catalyse the isomerization of muconolactone to 3-­oxoadipate enollactone. In order to characterize the catalytic mechanism of this unusual dehalogenase, the enzyme was crystallized and subjected to X-ray structural analysis. Data sets to up to 1.65 Å resolution were collected from two different crystal forms using synchrotron radiation. Crystal form I (space group P21) contained 40 subunits in the asymmetric unit, whereas ten subunits were present in crystal form II (space group P212121). The self-rotation function revealed the orientations of the molecular symmetry axes of the homodecamer of 52 symmetry. PMID:22691795

  18. Response of Rhodococcus erythropolis strain IBBPo1 to toxic organic solvents.

    PubMed

    Stancu, Mihaela Marilena

    2015-01-01

    Recently, there has been a lot of interest in the utilization of rhodococci in the bioremediation of petroleum contaminated environments. This study investigates the response of Rhodococcus erythropolis IBBPo1 cells to 1% organic solvents (alkanes, aromatics). A combination of microbiology, biochemical, and molecular approaches were used to examine cell adaptation mechanisms likely to be pursued by this strain after 1% organic solvent exposure. R. erythropolis IBBPo1 was found to utilize 1% alkanes (cyclohexane, n-hexane, n-decane) and aromatics (toluene, styrene, ethylbenzene) as the sole carbon source. Modifications in cell viability, cell morphology, membrane permeability, lipid profile, carotenoid pigments profile and 16S rRNA gene were revealed in R. erythropolis IBBPo1 cells grown 1 and 24 h on minimal medium in the presence of 1% alkanes (cyclohexane, n-hexane, n-decane) and aromatics (toluene, styrene, ethylbenzene). Due to its environmental origin and its metabolic potential, R. erythropolis IBBPo1 is an excellent candidate for the bioremediation of soils contaminated with crude oils and other toxic compounds. Moreover, the carotenoid pigments produced by this nonpathogenic Gram-positive bacterium have a variety of other potential applications. PMID:26691458

  19. Response of Rhodococcus erythropolis strain IBBPo1 to toxic organic solvents

    PubMed Central

    Stancu, Mihaela Marilena

    2015-01-01

    Abstract Recently, there has been a lot of interest in the utilization of rhodococci in the bioremediation of petroleum contaminated environments. This study investigates the response of Rhodococcus erythropolis IBBPo1 cells to 1% organic solvents (alkanes, aromatics). A combination of microbiology, biochemical, and molecular approaches were used to examine cell adaptation mechanisms likely to be pursued by this strain after 1% organic solvent exposure. R. erythropolis IBBPo1 was found to utilize 1% alkanes (cyclohexane, n-hexane, n-decane) and aromatics (toluene, styrene, ethylbenzene) as the sole carbon source. Modifications in cell viability, cell morphology, membrane permeability, lipid profile, carotenoid pigments profile and 16S rRNA gene were revealed in R. erythropolis IBBPo1 cells grown 1 and 24 h on minimal medium in the presence of 1% alkanes (cyclohexane, n-hexane, n-decane) and aromatics (toluene, styrene, ethylbenzene). Due to its environmental origin and its metabolic potential, R. erythropolis IBBPo1 is an excellent candidate for the bioremediation of soils contaminated with crude oils and other toxic compounds. Moreover, the carotenoid pigments produced by this nonpathogenic Gram-positive bacterium have a variety of other potential applications. PMID:26691458

  20. Development of a genetic transformation system for benzene-tolerant Rhodococcus opacus strains.

    PubMed

    Na, Kyung-Su; Nagayasu, Kan; Kuroda, Akio; Takiguchi, Noboru; Ikeda, Tsukasa; Ohtake, Hisao; Kato, Junichi

    2005-04-01

    Rhodococcus opacus B-4 and B-9 are tolerant to various organic solvents including benzene, toluene, ethylbenzene, xylenes and styrene, and are suitable bacterial hosts for the production of chemical products from hydrophobic substrates. A 4.4-kb endogenous plasmid (pKNR 01) was isolated from R. opacus B-4 and sequenced completely. Plasmid pKNR 01 encodes proteins that share similarity to replication proteins from the enteric bacterial and actinomycete theta-replication plasmids. A 7.4-kb chimeric plasmid, designated pKNR 01.1, was constructed by fusing XhoI-digested pKNR 01 and Escherichia coli vector pSTV 28. Plasmid pKNR 01.1 had the ability to replicate in B-4 and B-9. A protocol for transformation of B-9 by electroporation was optimized employing pKNR 01.1. Frequencies of 4.1 x 10(5) transformants per mug of plasmid DNA were obtained for B-9 cells, whereas B-4 harboring naturally occurring pKNR 01 was transformed at lower frequencies (approximately 1 x 10(4) transformants per mug of plasmid DNA). Deletion analysis of pKNR 01.1 showed that the 1.9-kb SphI-XhoI region containing the repA and rep B genes and the 0.6-kb region upstream of repA was essential for plasmid maintenance in R. opacus strains.

  1. Three new serotypes of Rhodococcus equi in Prescott's serotyping system - Short communication.

    PubMed

    Makrai, László; Fodor, László; Hajtós, István; Varga, János; Dénes, Béla

    2015-09-01

    Three new serotypes were found among Rhodococcus equi strains, which could not be assigned into any of the seven serotypes of Prescott's system. Fortythree R. equi strains out of 44 previously nontypable ones isolated in Hungary could be allocated into one of the three new serotypes using the agar gel immunodiffusion (AGID) test. The three new suggested serotypes are serotype 8 (proposed reference strain: HNCMB-138003), serotype 9 (proposed reference strain: HNCMB-138004) and serotype 10 (proposed reference strain: HNCMB-138005). Hyperimmune sera produced in rabbits against the new serotypes and reference strains gave precipitation only with their homologous antigens, and no crossreactions were observed. All of the previously nontypable isolates from clinical samples of horses (lung abscesses, intestinal lymph nodes, mediastinal lymph nodes) proved to be serotype 8, while strains of serotypes 8, 9 and 10 could be isolated from nasal and rectal swabs of horses and from the soil. Serotype 9 dominated among the previously nontypable strains of swine origin. One of the previously nontypable human strains was serotype 10. This serotype was also isolated from pigs, horses and the soil. The description of the three new serotypes can help us reveal new correlations between the host species, geographical origin and serotype of R. equi isolates.

  2. Septic pleuritis and abdominal abscess formation caused by Rhodococcus equi in a foal.

    PubMed

    Valdes, Alejandro; Johnson, Jill R

    2005-09-15

    A 3-month-old female Arabian horse was evaluated because of fever, respiratory distress, lethargy, and decreased appetite of 5 days' duration. Pleural effusion was diagnosed on the basis of ultrasonographic and radiographic examinations. Cytologic examination of pleural fluid collected via thoracocentesis revealed septic inflammation; bacteriologic culture of a sample of that fluid yielded Rhodococcus equi. A large intra-abdominal mass adjacent to the body wall was identified ultrasonographically. A specimen of the mass was collected via aspiration; the specimen was identified cytologically as purulent exudate that contained large numbers of rod-shaped bacteria, which confirmed abdominal abscess formation. Bacteriologic culture of a sample of the exudate also yielded R. equi. The foal was treated with azithromycin (10 mg/kg [4.5 mg/lb], PO, q 24 h for 5 days then q 48 h) and rifampin (5 mg/kg [2.3 mg/lb], PO, q 12 h) for 8 weeks and metronidazole (15 mg/kg [6.8 mg/lb], PO, q 8 h) for 3 weeks. Clinically, the foal responded to antimicrobial treatment within 2 weeks. At 8 weeks after the initial evaluation, ultrasonographic examination of the foal revealed resolution of the pleural effusion and abdominal abscess. In foals, R. equi infection typically results in pyogranulomatous pneumonia, and pleural effusion is an uncommon clinical sign. The combination of azithromycin and rifampin appears to be an effective treatment for R. equi infection in foals. PMID:16190597

  3. Benzoate degradation by Rhodococcus opacus 1CP after dormancy: Characterization of dioxygenases involved in the process.

    PubMed

    Solyanikova, Inna P; Emelyanova, Elena V; Borzova, Oksana V; Golovleva, Ludmila A

    2016-01-01

    The process of benzoate degradation by strain Rhodococcus opacus 1CP after a five-year dormancy was investigated and its peculiarities were revealed. The strain was shown to be capable of growth on benzoate at a concentration of up to 10 g L(-1). The substrate specificity of benzoate dioxygenase (BDO) during the culture growth on a medium with a low (200-250 mg L(-1)) and high (4 g L(-1)) concentration of benzoate was assessed. BDO of R. opacus 1CP was shown to be an extremely narrow specificity enzyme. Out of 31 substituted benzoates, only with one, 3-chlorobenzoate, its activity was higher than 9% of that of benzoate. Two dioxygenases, catechol 1,2-dioxygenase (Cat 1,2-DO) and protocatechuate 3,4-dioxygenase (PCA 3,4-DO), were identified in a cell-free extract, purified and characterized. The substrate specificity of Cat 1,2-DO isolated from cells of strain 1CP after the dormancy was found to differ significantly from that of Cat 1,2-DO isolated earlier from cells of this strain grown on benzoate. By its substrate specificity, the described Cat 1,2-DO was close to the Cat 1,2-DO from strain 1CP grown on 4-methylbenzoate. Neither activity nor inhibition by protocatechuate was observed during the reaction of Cat 1,2-DO with catechol, and catechol had no inhibitory effect on the reaction of PCA 3,4-DO with protocatechuate. PMID:26669259

  4. Aerobic Biodegradation of N-Nitrosodimethylamine by the Propanotroph Rhodococcus ruber ENV425▿

    PubMed Central

    Fournier, Diane; Hawari, Jalal; Halasz, Annamaria; Streger, Sheryl H.; McClay, Kevin R.; Masuda, Hisako; Hatzinger, Paul B.

    2009-01-01

    The propanotroph Rhodococcus ruber ENV425 was observed to rapidly biodegrade N-nitrosodimethylamine (NDMA) after growth on propane, tryptic soy broth, or glucose. The key degradation intermediates were methylamine, nitric oxide, nitrite, nitrate, and formate. Small quantities of formaldehyde and dimethylamine were also detected. A denitrosation reaction, initiated by hydrogen atom abstraction from one of the two methyl groups, is hypothesized to result in the formation of n-methylformaldimine and nitric oxide, the former of which decomposes in water to methylamine and formaldehyde and the latter of which is then oxidized further to nitrite and then nitrate. Although the strain mineralized more than 60% of the carbon in [14C]NDMA to 14CO2, growth of strain ENV425 on NDMA as a sole carbon and energy source could not be confirmed. The bacterium was capable of utilizing NDMA, as well as the degradation intermediates methylamine and nitrate, as sources of nitrogen during growth on propane. In addition, ENV425 reduced environmentally relevant microgram/liter concentrations of NDMA to <2 ng/liter in batch cultures, suggesting that the bacterium may have applications for groundwater remediation. PMID:19542346

  5. Differential Degradation of Bicyclics with Aromatic and Alicyclic Rings by Rhodococcus sp. Strain DK17 ▿

    PubMed Central

    Kim, Dockyu; Yoo, Miyoun; Choi, Ki Young; Kang, Beom Sik; Kim, Tai Kyoung; Hong, Soon Gyu; Zylstra, Gerben J.; Kim, Eungbin

    2011-01-01

    The metabolically versatile Rhodococcus sp. strain DK17 is able to grow on tetralin and indan but cannot use their respective desaturated counterparts, 1,2-dihydronaphthalene and indene, as sole carbon and energy sources. Metabolite analyses by gas chromatography-mass spectrometry and nuclear magnetic resonance spectrometry clearly show that (i) the meta-cleavage dioxygenase mutant strain DK180 accumulates 5,6,7,8-tetrahydro-1,2-naphthalene diol, 1,2-indene diol, and 3,4-dihydro-naphthalene-1,2-diol from tetralin, indene, and 1,2-dihydronaphthalene, respectively, and (ii) when expressed in Escherichia coli, the DK17 o-xylene dioxygenase transforms tetralin, indene, and 1,2-dihydronaphthalene into tetralin cis-dihydrodiol, indan-1,2-diol, and cis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene, respectively. Tetralin, which is activated by aromatic hydroxylation, is degraded successfully via the ring cleavage pathway to support growth of DK17. Indene and 1,2-dihydronaphthalene do not serve as growth substrates because DK17 hydroxylates them on the alicyclic ring and further metabolism results in a dead-end metabolite. This study reveals that aromatic hydroxylation is a prerequisite for proper degradation of bicyclics with aromatic and alicyclic rings by DK17 and confirms the unique ability of the DK17 o-xylene dioxygenase to perform distinct regioselective hydroxylations. PMID:21965391

  6. Purification and characterization of an amidase from an acrylamide-degrading Rhodococcus sp.

    PubMed Central

    Nawaz, M S; Khan, A A; Seng, J E; Leakey, J E; Siitonen, P H; Cerniglia, C E

    1994-01-01

    A constitutively expressed aliphatic amidase from a Rhodococcus sp. catalyzing acrylamide deamination was purified to electrophoretic homogeneity. The molecular weight of the native enzyme was estimated to be 360,000. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified preparation yielded a homogeneous protein band having an apparent molecular weight of about 44,500. The amidase had pH and temperature optima of 8.5 and 40 degrees C, respectively, and its isoelectric point was pH 4.0. The amidase had apparent K(m) values of 1.2, 2.6, 3.0, 2.7, and 5.0 mM for acrylamide, acetamide, butyramide, propionamide, and isobutyramide, respectively. Inductively coupled plasma-atomic emission spectometry analysis indicated that the enzyme contains 8 mol of iron per mol of the native enzyme. No labile sulfide was detected. The amidase activity was enhanced by, but not dependent on Fe(2+), Ba(2+), and Cr(2+). However, the enzyme activity was partially inhibited by Mg(2+) and totally inhibited in the presence of Ni(2+), Hg(2+), Cu(2+), Co(2+), specific iron chelators, and thiol blocking reagents. The NH2-terminal sequence of the first 18 amino acids displayed 88% homology to the aliphatic amidase of Brevibacterium sp. strain R312. Images PMID:7944367

  7. Calcium carbonate formation on mica supported extracellular polymeric substance produced by Rhodococcus opacus

    NASA Astrophysics Data System (ADS)

    Szcześ, Aleksandra; Czemierska, Magdalena; Jarosz-Wilkołazka, Anna

    2016-10-01

    Extracellular polymeric substance (EPS) extracted from Rhodococcus opacus bacterial strain was used as a matrix for calcium carbonate precipitation using the vapour diffusion method. The total exopolymer and water-soluble exopolymer fraction of different concentrations were spread on the mica surface by the spin-coating method. The obtained layers were characterized using the atomic force microscopy measurement and XPS analysis. The effects of polymer concentration, initial pH of calcium chloride solution and precipitation time on the obtained crystals properties were investigated. Raman spectroscopy and scanning electron microscopy were used to characterize the precipitated minerals. It was found that the type of precipitated CaCO3 polymorph and the crystal size depend on the kind of EPS fraction. The obtained results indicates that the water soluble fraction favours vaterite dissolution and calcite growth, whereas the total EPS stabilizes vaterite and this effect is stronger at basic pH. It seems to be due to different contents of the functional group of EPS fractions.

  8. An Evaluation of Kinetic Models in the Biodesulfurization of Synthetic Oil by Rhodococcus erythropolis ATCC 4277.

    PubMed

    Maass, D; Mayer, D A; Moritz, D E; Oliveira, D; de Souza, A A Ulson; Souza, S M A Guelli

    2015-10-01

    Biodesulfurization is an eco-friendly technology applied in the removal of sulfur from fossil fuels. This technology is based on the use of microorganisms as biocatalysts to convert the recalcitrant sulfur compounds into others easily treatable, as sulfides. Despite it has been studied during the last decades, there are some unsolved questions, as per example the kinetic model which appropriately describes the biodesulfurization globally. In this work, different kinetic models were tested to a batch desulfurization process using dibenzothiophene (DBT) as a model compound, n-dodecane as organic solvent, and Rhodococcus erythropolis ATCC 4277 as biocatalyst. The models were solved by ODE45 function in the MATLAB. Monod model was capable to describe the biodesulfurization process predicting all experimental data with a very good fitting. The coefficients of determination achieved to organic phase concentrations of 20, 80, and 100 % (v/v) were 0.988, 0.995, and 0.990, respectively. R. erythropolis ATCC 4277 presented a good affinity with the substrate (DBT) since the coefficients of saturation obtained to reaction medium containing 20, 80, and 100 % (v/v) were 0.034, 0.07, and 0.116, respectively. This kinetic evaluation provides an improvement in the development of biodesulfurization technology because it showed that a simple model is capable to describe the throughout process. PMID:26201481

  9. Catabolic pathway of gamma-caprolactone in the biocontrol agent Rhodococcus erythropolis.

    PubMed

    Barbey, Corinne; Crépin, Alexandre; Cirou, Amélie; Budin-Verneuil, Aurélie; Orange, Nicole; Feuilloley, Marc; Faure, Denis; Dessaux, Yves; Burini, Jean-François; Latour, Xavier

    2012-01-01

    Gamma-caprolactone (GCL) is well-known as a food flavor and has been recently described as a biostimulant molecule promoting the growth of bacteria with biocontrol activity against soft-rot pathogens. Among these biocontrol agents, Rhodococcus erythropolis, characterized by a remarkable metabolic versatility, assimilates various γ-butyrolactone molecules with a branched-aliphatic chain, such as GCL. The assimilative pathway of GCL in R. erythropolis was investigated by two-dimensional gel electrophoresis coupled to matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) analysis. This analysis suggests the involvement of the lactonase QsdA in ring-opening, a feature confirmed by heterologous expression in Escherichia coli. According to proteome analysis, the open-chain form of GCL was degraded by β- and ω-oxidation coupled to the Krebs cycle and β-ketoadipate pathway. Ubiquity of qsdA gene among environmental R. erythropolis isolates was verified by PCR. In addition to a previous N-acyl homoserine lactone catabolic function, QsdA may therefore be involved in an intermediate degradative step of cyclic recalcitrant molecules or in synthesis of flavoring lactones. PMID:22085026

  10. Engineering L-arabinose metabolism in triacylglycerol-producing Rhodococcus opacus for lignocellulosic fuel production.

    PubMed

    Kurosawa, Kazuhiko; Plassmeier, Jens; Kalinowski, Jörn; Rückert, Christian; Sinskey, Anthony J

    2015-07-01

    Advanced biofuels from lignocellulosic biomass have been considered as a potential solution for the issues of energy sustainability and environmental protection. Triacylglycerols (TAGs) are potential precursors for the production of lipid-based liquid biofuels. Rhodococcus opacus PD630 can accumulate large amounts of TAGs when grown under physiological conditions of high carbon and low nitrogen. However, R. opacus PD630 does not utilize the sugar L-arabinose present in lignocellulosic hydrolysates. Here, we report the engineering of R. opacus to produce TAGs on L-arabinose. We constructed a plasmid (pASC8057) harboring araB, araD and araA genes derived from a Streptomyces bacterium, and introduced the genes into R. opacus PD630. One of the engineered strains, MITAE-348, was capable of growing on high concentrations (up to 100 g/L) of L-arabinose. MITAE-348 was grown in a defined medium containing 16 g/L L-arabinose or a mixture of 8 g/L L-arabinose and 8 g/L D-glucose. In a stationary phase occurring 3 days post-inoculation, the strain was able to completely utilize the sugar, and yielded 2.0 g/L for L-arabinose and 2.2 g/L for L-arabinose/D-glucose of TAGs, corresponding to 39.7% or 42.0%, respectively, of the cell dry weight. PMID:25936337

  11. Induction of Viable but Nonculturable State in Rhodococcus and Transcriptome Analysis Using RNA-seq.

    PubMed

    Su, Xiaomei; Guo, Li; Ding, Linxian; Qu, Kun; Shen, Chaofeng

    2016-01-01

    Viable but nonculturable (VBNC) bacteria, which maintain the viability with loss of culturability, universally exist in contaminated and non-contaminated environments. In this study, two strains, Rhodococcus sp. TG13 and TN3, which were isolated from PCB-contaminated sediment and non-contaminated sediment respectively, were investigated under low temperature and oligotrophic conditions. The results indicated that the two strains TG13 and TN3 could enter into the VBNC state with different incubation times, and could recover culturability by reversal of unfavourable factors and addition of resuscitation-promoting factor (Rpf), respectively. Furthermore, the gene expression variations in the VBNC response were clarified by Illumina high throughput RNA-sequencing. Genome-wide transcriptional analysis demonstrated that up-regulated genes in the VBNC cells of the strain TG13 related to protein modification, ATP accumulation and RNA polymerase, while all differentially expressed genes (DEGs) in the VBNC cells of the strain TN3 were down-regulated. However, the down-regulated genes in both the two strains mainly encoded NADH dehydrogenase subunit, catalase, oxidoreductase, which further verified that cold-induced loss of ability to defend oxidative stress may play an important role in induction of the VBNC state. This study further verified that the molecular mechanisms underlying the VBNC state varied with various bacterial species. Study on the VBNC state of non-pathogenic bacteria will provide new insights into the limitation of environmental micro-bioremediation and the cultivation of unculturable species. PMID:26808070

  12. Degradation of chloronitrobenzenes by a coculture of Pseudomonas putida and a Rhodococcus sp.

    SciTech Connect

    Park, H.S.; Lim, S.J.; Chang, Y.K.; Kim, H.S.; Livingston, A.G.

    1999-03-01

    A single microorganism able to mineralize chloronitrobenzenes (CNBs) has not been reported, and degradation of CNBs of coculture of two microbial strains was attempted. Pseudomonas putida HS12 was first isolated by analogue enrichment culture using nitrobenzene (NB) as the substrate, and this strain was observed to possess a partial reductive pathway for the degradation of NB. From high-performance liquid chromatography-mass spectrometry and {sup 1}H nuclear magnetic resonance analyses, NB-grown cells of P. putida HS12 were found to convert 3- and 4-CNBs to the corresponding 5- and 4-chloro-2-hydroxyacetanilides, respectively, by partial reduction and subsequent acetylation. For the degradation of CNBs, Rhodococcus sp. strain HS51, which degrades 4- and 5-chloro-2-hydroxyacetanilides, was isolated and combined with P. putida HS12 to give a coculture. This coculture was confirmed to mineralize 3- and 4-CNBs in the presence of an additional carbon source. A degradation pathway for 3- and 4-CNBs by the two isolated strains was also proposed.

  13. Trehalose promotes Rhodococcus sp. strain YYL colonization in activated sludge under tetrahydrofuran (THF) stress

    PubMed Central

    He, Zhixing; Zhang, Kai; Wang, Haixia; Lv, Zhenmei

    2015-01-01

    Few studies have focused on the role of compatible solutes in changing the microbial community structure in bioaugmentation systems. In this study, we investigated the influence of trehalose as a biostimulant on the microbial community in tetrahydrofuran (THF)-treated wastewater bioaugmentation systems with Rhodococcus sp. YYL. Functional gene profile changes were used to study the variation in the microbial community. Soluble di-iron monooxygenases (SDIMO), particularly group-5 SDIMOs (i.e., tetrahydrofuran and propane monooxygenases), play a significant role in the initiation of the ring cleavage of tetrahydrofuran. Group-5 SDIMOs genes are enriched upon trehalose addition, and exogenous tetrahydrofuran monooxygenase (thmA) genes can successfully colonize bioaugmentation systems. Cytochrome P450 monooxygenases (P450s) have a significant role in catalyzing the region- and stereospecific oxidation of non-activated hydrocarbons, and THF was reported to inhibit P450s in the environment. The CYP153 family was chosen as a representative P450 to study the inhibitory effects of THF. The results demonstrated that CYP153 family genes exhibited significant changes upon THF treatment and that trehalose helped maintain a rich diversity and high abundance of CYP153 family genes. Biostimulation with trehalose could alleviate the negative effects of THF stress on microbial diversity in bioaugmentation systems. Our results indicated that trehalose as a compatible solute plays a significant role for environmental strains under extreme conditions. PMID:26029182

  14. Identification, characterization and molecular analysis of the viable but nonculturable Rhodococcus biphenylivorans

    PubMed Central

    Su, Xiaomei; Sun, Faqian; Wang, Yalin; Hashmi, Muhammad Zaffar; Guo, Li; Ding, Linxian; Shen, Chaofeng

    2015-01-01

    Numerous bacteria, including pollutant-degrading bacteria can enter the viable but nonculturable state (VBNC) when they encounter harsh environmental conditions. VBNC bacteria, as a vast majority of potent microbial resource can be of great significance in environmental rehabilitation. It is necessary to study the VBNC state of pollutant-degrading bacteria under various stress conditions. The aim of this study was to determine whether Rhodococcus biphenylivorans could enter the VBNC state under oligotrophic and low temperature conditions, and to examine the changes of morphology, enzymatic activity and gene expressions that might underline such state. The obtained results indicated that R. biphenylivorans TG9T could enter into the VBNC state and recover culturability under favorable environmental conditions. Results from Illumina high throughput RNA-sequencing revealed that the up-regulated genes related to ATP accumulation, protein modification, peptidoglycan biosynthesis and RNA polymerase were found in the VBNC cells, and the down-regulated genes mainly encoded hypothetical protein, membrane protein and NADH dehydrogenase subunit, which render VBNC cells more tolerant to survive under inhospitable conditions. This study provides new insights into prevention and control of the VBNC state of pollutant-degrading bacteria for their better capabilities in environmental rehabilitation. PMID:26687808

  15. Effect of extracellular polymeric substances on the mechanical properties of Rhodococcus.

    PubMed

    Pen, Yu; Zhang, Zhenyu J; Morales-García, Ana L; Mears, Matthew; Tarmey, Drew S; Edyvean, Robert G; Banwart, Steven A; Geoghegan, Mark

    2015-02-01

    The mechanical properties of Rhodococcus RC291 were measured using force spectroscopy equipped with a bacterial cell probe. Rhodococcal cells in the late growth stage of development were found to have greater adhesion to a silicon oxide surface than those in the early growth stage. This is because there are more extracellular polymeric substances (EPS) that contain nonspecific binding sites available on the cells of late growth stage. It is found that EPS in the late exponential phase are less densely bound but consist of chains able to extend further into their local environment, while the denser EPS at the late stationary phase act more to sheath the cell. Contraction and extension of the EPS could change the density of the binding sites, and therefore affect the magnitude of the adhesion force between the EPS and the silicon oxide surface. By treating rhodococcal EPS as a surface-grafted polyelectrolyte layer and using scaling theory, the interaction between EPS and a solid substrate was modelled for the cell approaching the surface which revealed that EPS possess a large capacity to store charge. Changing the pH of the surrounding medium acts to change the conformation of EPS chains.

  16. Comparative transcriptomics elucidates adaptive phenol tolerance and utilization in lipid-accumulating Rhodococcus opacus PD630

    DOE PAGESBeta

    Yoneda, Aki; Henson, William R.; Goldner, Nicholas K.; Park, Kun Joo; Forsberg, Kevin J.; Kim, Soo Ji; Pesesky, Mitchell W.; Foston, Marcus; Dantas, Gautam; Moon, Tae Seok

    2016-02-02

    Lignin-derived (e.g. phenolic) compounds can compromise the bioconversion of lignocellulosic biomass to fuels and chemicals due to their toxicity and recalcitrance. The lipid-accumulating bacterium Rhodococcus opacus PD630 has recently emerged as a promising microbial host for lignocellulose conversion to value-added products due to its natural ability to tolerate and utilize phenolics. To gain a better understanding of its phenolic tolerance and utilization mechanisms, we adaptively evolved R. opacus over 40 passages using phenol as its sole carbon source (up to 373% growth improvement over wild-type), and extensively characterized two strains from passages 33 and 40. The two adapted strains showedmore » higher phenol consumption rates (~20 mg/l/h) and ~2-fold higher lipid production from phenol than the wild-type strain.Whole-genome sequencing and comparative transcriptomics identified highly-upregulated degradation pathways and putative transporters for phenol in both adapted strains, highlighting the important linkage between mechanisms of regulated phenol uptake, utilization, and evolved tolerance. Our study shows that the R. opacus mutants are likely to use their transporters to import phenol rather than export them, suggesting a new aromatic tolerance mechanism. The identified tolerance genes and pathways are promising candidates for future metabolic engineering in R. opacus for improved lignin conversion to lipid-based products.« less

  17. Comparative transcriptomics elucidates adaptive phenol tolerance and utilization in lipid-accumulating Rhodococcus opacus PD630.

    PubMed

    Yoneda, Aki; Henson, William R; Goldner, Nicholas K; Park, Kun Joo; Forsberg, Kevin J; Kim, Soo Ji; Pesesky, Mitchell W; Foston, Marcus; Dantas, Gautam; Moon, Tae Seok

    2016-03-18

    Lignin-derived (e.g. phenolic) compounds can compromise the bioconversion of lignocellulosic biomass to fuels and chemicals due to their toxicity and recalcitrance. The lipid-accumulating bacterium Rhodococcus opacus PD630 has recently emerged as a promising microbial host for lignocellulose conversion to value-added products due to its natural ability to tolerate and utilize phenolics. To gain a better understanding of its phenolic tolerance and utilization mechanisms, we adaptively evolved R. opacus over 40 passages using phenol as its sole carbon source (up to 373% growth improvement over wild-type), and extensively characterized two strains from passages 33 and 40. The two adapted strains showed higher phenol consumption rates (∼20 mg/l/h) and ∼2-fold higher lipid production from phenol than the wild-type strain. Whole-genome sequencing and comparative transcriptomics identified highly-upregulated degradation pathways and putative transporters for phenol in both adapted strains, highlighting the important linkage between mechanisms of regulated phenol uptake, utilization, and evolved tolerance. Our study shows that the R. opacus mutants are likely to use their transporters to import phenol rather than export them, suggesting a new aromatic tolerance mechanism. The identified tolerance genes and pathways are promising candidates for future metabolic engineering in R. opacus for improved lignin conversion to lipid-based products.

  18. Molecular and biochemical analysis of phthalate and terephthalate degradation by Rhodococcus sp. strain DK17.

    PubMed

    Choi, Ki Young; Kim, Dockyu; Sul, Woo Jun; Chae, Jong-Chan; Zylstra, Gerben J; Kim, Young Min; Kim, Eungbin

    2005-11-15

    Alkylbenzene-degrading Rhodococcus sp. strain DK17 is able to utilize phthalate and terephthalate as growth substrates. The genes encoding the transformation of phthalate and terephthalate to protocatechuate are organized as two separate operons, located 6.7kb away from each other. Interestingly, both the phthalate and terephthalate operons are induced in response to terephthalate while expression of the terephthalate genes is undetectable in phthalate-grown cells. In addition to two known plasmids (380-kb pDK1 and 330-kb pDK2), a third megaplasmid (750-kb pDK3) was newly identified in DK17. The phthalate and terephthalate operons are duplicated and are present on both pDK2 and pDK3. RT-PCR experiments, coupled with sequence analysis, suggest that phthalate and terephthalate degradation in DK17 proceeds through oxygenation at carbons 3 and 4 and at carbons 1 and 2 to form 3,4-dihydro-3,4-dihydroxyphthalate and 1,2-dihydro-1,2-dihydroxyterephthalate, respectively. The 3,4-dihydroxyphthalate pathway was further corroborated through colorometric tests. Apparently, the two dihydrodiol metabolites are subsequently dehydrogenated and decarboxylated to form protocatechuate, which is further degraded by a protocatechuate 3,4-dioxygenase as confirmed by a ring-cleavage enzyme assay. PMID:16181748

  19. Biodesulfurization of a system containing synthetic fuel using Rhodococcus erythropolis ATCC 4277.

    PubMed

    Maass, Danielle; de Oliveira, Débora; de Souza, Antônio A Ulson; Souza, Selene M A Guelli U

    2014-11-01

    The burning of fossil fuels has released a large quantity of pollutants into the atmosphere. In this context, sulfur dioxide is one of the most noxious gas which, on reacting with moist air, is transformed into sulfuric acid, causing the acid rain. In response, many countries have reformulated their legislation in order to enforce the commercialization of fuels with very low sulfur levels. The existing desulfurization processes cannot remove such low levels of sulfur and thus a biodesulfurization has been developed, where the degradation of sulfur occurs through the action of microorganisms. Rhodococcus erythropolis has been identified as one of the most promising bacteria for use in the biodesulfurization. In this study, the effectiveness of the strain R. erythropolis ATCC 4277 in the desulfurization of dibenzothiophene (DBT) was evaluated in a batch reactor using an organic phase (n-dodecane or diesel) concentrations of 20, 80, and 100 % (v/v). This strain was able to degrade 93.3, 98.0, and 95.5 % of the DBT in the presence of 20, 80, and 100 % (v/v) of dodecane, respectively. The highest value for the specific DBT degradation rate was 44 mmol DBT · kg DCW(-1) · h(-1), attained in the reactor containing 80 % (v/v) of n-dodecane as the organic phase.

  20. Elucidation of the metabolic pathway for dibenzothiophene desulphurization by Rhodococcus sp. strain IGTS8 (ATCC 53968).

    PubMed

    Oldfield, C; Pogrebinsky, O; Simmonds, J; Olson, E S; Kulpa, C F

    1997-09-01

    Rhodococcus sp. strain IGTS8 (ATCC 53968) is able to utilize dibenzothiophene (DBT) as a sole source of sulphur. The carbon skeleton of DBT is not metabolized and is conserved as 2-hydroxybiphenyl (HBP), which accumulates in the medium. This phenotype is due to the expression of the plasmid-encoded DBT-desulphurization (dsz) operon, which encodes three proteins, DszA, B and C. In this paper it is shown, using [35S]DBT radiolabelling studies, that sulphur is released in the form of inorganic sulphite. The pathway of DBT desulphurization is described in detail. In summary, DszC catalyses the stepwise S-oxidation of DBT, first to dibenzothiophene 5-oxide (DBTO) and then to dibenzothiophene 5,5-dioxide (DBTO2); DszA catalyses the conversion of DBTO2 to 2-(2'-hydroxyphenyl)benzene sulphinate (HBPSi-) and DszB catalyses the desulphination of HBPSi- to give HBP and sulphite. Studies with cell-free extracts show that DszA and DszC, but not DszB, require NADH for activity. 18O2-labelling studies show that each incorporated oxygen atom is derived directly from molecular oxygen. These results are consistent with the role of DszC as a mono-oxygenase, of DszA as an apparently unique enzyme which catalyses the reductive hydroxylation of DBTO2 leading to cleavage of the thiophene ring, and of DszB as an aromatic sulphinic acid hydrolase.

  1. Aerobic biodegradation of N-nitrosodimethylamine by the propanotroph Rhodococcus ruber ENV425.

    PubMed

    Fournier, Diane; Hawari, Jalal; Halasz, Annamaria; Streger, Sheryl H; McClay, Kevin R; Masuda, Hisako; Hatzinger, Paul B

    2009-08-01

    The propanotroph Rhodococcus ruber ENV425 was observed to rapidly biodegrade N-nitrosodimethylamine (NDMA) after growth on propane, tryptic soy broth, or glucose. The key degradation intermediates were methylamine, nitric oxide, nitrite, nitrate, and formate. Small quantities of formaldehyde and dimethylamine were also detected. A denitrosation reaction, initiated by hydrogen atom abstraction from one of the two methyl groups, is hypothesized to result in the formation of n-methylformaldimine and nitric oxide, the former of which decomposes in water to methylamine and formaldehyde and the latter of which is then oxidized further to nitrite and then nitrate. Although the strain mineralized more than 60% of the carbon in [(14)C]NDMA to (14)CO(2), growth of strain ENV425 on NDMA as a sole carbon and energy source could not be confirmed. The bacterium was capable of utilizing NDMA, as well as the degradation intermediates methylamine and nitrate, as sources of nitrogen during growth on propane. In addition, ENV425 reduced environmentally relevant microgram/liter concentrations of NDMA to <2 ng/liter in batch cultures, suggesting that the bacterium may have applications for groundwater remediation. PMID:19542346

  2. Comparative transcriptomics elucidates adaptive phenol tolerance and utilization in lipid-accumulating Rhodococcus opacus PD630

    PubMed Central

    Yoneda, Aki; Henson, William R.; Goldner, Nicholas K.; Park, Kun Joo; Forsberg, Kevin J.; Kim, Soo Ji; Pesesky, Mitchell W.; Foston, Marcus; Dantas, Gautam; Moon, Tae Seok

    2016-01-01

    Lignin-derived (e.g. phenolic) compounds can compromise the bioconversion of lignocellulosic biomass to fuels and chemicals due to their toxicity and recalcitrance. The lipid-accumulating bacterium Rhodococcus opacus PD630 has recently emerged as a promising microbial host for lignocellulose conversion to value-added products due to its natural ability to tolerate and utilize phenolics. To gain a better understanding of its phenolic tolerance and utilization mechanisms, we adaptively evolved R. opacus over 40 passages using phenol as its sole carbon source (up to 373% growth improvement over wild-type), and extensively characterized two strains from passages 33 and 40. The two adapted strains showed higher phenol consumption rates (∼20 mg/l/h) and ∼2-fold higher lipid production from phenol than the wild-type strain. Whole-genome sequencing and comparative transcriptomics identified highly-upregulated degradation pathways and putative transporters for phenol in both adapted strains, highlighting the important linkage between mechanisms of regulated phenol uptake, utilization, and evolved tolerance. Our study shows that the R. opacus mutants are likely to use their transporters to import phenol rather than export them, suggesting a new aromatic tolerance mechanism. The identified tolerance genes and pathways are promising candidates for future metabolic engineering in R. opacus for improved lignin conversion to lipid-based products. PMID:26837573

  3. Immunogenicity of an electron beam inactivated Rhodococcus equi vaccine in neonatal foals.

    PubMed

    Bordin, Angela I; Pillai, Suresh D; Brake, Courtney; Bagley, Kaytee B; Bourquin, Jessica R; Coleman, Michelle; Oliveira, Fabiano N; Mwangi, Waithaka; McMurray, David N; Love, Charles C; Felippe, Maria Julia B; Cohen, Noah D

    2014-01-01

    Rhodococcus equi is an important pathogen of foals that causes severe pneumonia. To date, there is no licensed vaccine effective against R. equi pneumonia of foals. The objectives of our study were to develop an electron beam (eBeam) inactivated vaccine against R. equi and evaluate its immunogenicity. A dose of eBeam irradiation that inactivated replication of R. equi while maintaining outer cell wall integrity was identified. Enteral administration of eBeam inactivated R. equi increased interferon-γ production by peripheral blood mononuclear cells in response to stimulation with virulent R. equi and generated naso-pharyngeal R. equi-specific IgA in newborn foals. Our results indicate that eBeam irradiated R. equi administered enterally produce cell-mediated and upper respiratory mucosal immune responses, in the face of passively transferred maternal antibodies, similar to those produced in response to enteral administration of live organisms (a strategy which previously has been documented to protect foals against intrabronchial infection with virulent R. equi). No evidence of adverse effects was noted among vaccinated foals. PMID:25153708

  4. Immunogenicity of an Electron Beam Inactivated Rhodococcus equi Vaccine in Neonatal Foals

    PubMed Central

    Bordin, Angela I.; Pillai, Suresh D.; Brake, Courtney; Bagley, Kaytee B.; Bourquin, Jessica R.; Coleman, Michelle; Oliveira, Fabiano N.; Mwangi, Waithaka; McMurray, David N.; Love, Charles C.; Felippe, Maria Julia B.; Cohen, Noah D.

    2014-01-01

    Rhodococcus equi is an important pathogen of foals that causes severe pneumonia. To date, there is no licensed vaccine effective against R. equi pneumonia of foals. The objectives of our study were to develop an electron beam (eBeam) inactivated vaccine against R. equi and evaluate its immunogenicity. A dose of eBeam irradiation that inactivated replication of R. equi while maintaining outer cell wall integrity was identified. Enteral administration of eBeam inactivated R. equi increased interferon-γ production by peripheral blood mononuclear cells in response to stimulation with virulent R. equi and generated naso-pharyngeal R. equi-specific IgA in newborn foals. Our results indicate that eBeam irradiated R. equi administered enterally produce cell-mediated and upper respiratory mucosal immune responses, in the face of passively transferred maternal antibodies, similar to those produced in response to enteral administration of live organisms (a strategy which previously has been documented to protect foals against intrabronchial infection with virulent R. equi). No evidence of adverse effects was noted among vaccinated foals. PMID:25153708

  5. Viability of Rhodococcus equi and Parascaris equorum eggs exposed to high temperatures.

    PubMed

    Hébert, Laurent; Cauchard, Julien; Doligez, Pauline; Quitard, Lola; Laugier, Claire; Petry, Sandrine

    2010-01-01

    There is great concern about the potential pathogen contamination of horse manure compost spread in the same fields horses graze in. To ensure that pathogen destruction occurs, temperatures need to be sufficiently high during composting. Here, we investigated the survival rate of two marker organisms, Rhodococcus equi and Parascaris equorum eggs, exposed to temperatures potentially encountered during horse manure composting. Our results show that the time required to achieve a 1 log10 reduction in R. equi population (D-value) are 17.1 h (+/-1.47) at 45 degrees C, 8.6 h (+/-0.28) at 50 degrees C, 2.9 h (+/-0.04) at 55 degrees C and 0.7 h (+/-0.04) at 60 degrees C. For P. equorum eggs we show that at 45 and 50 degrees C, 2 log10 reduction of viability is reached between 8 and 24 h of incubation and that it takes less than 2 h at 55 and 60 degrees C to achieve a viability reduction of 2 log10. These results are useful for identifying composting conditions that will reduce the risk of environmental contamination by R. equi and P. equorum eggs.

  6. Label-free and redox proteomic analyses of the triacylglycerol-accumulating Rhodococcus jostii RHA1.

    PubMed

    Dávila Costa, José Sebastián; Herrero, O Marisa; Alvarez, Héctor M; Leichert, Lars

    2015-03-01

    The bacterium Rhodococcus jostii RHA1 synthesizes large amounts of triacylglycerols (TAGs) under conditions of nitrogen starvation. To better understand the molecular mechanisms behind this process, we performed proteomic studies in this oleaginous bacterium. Upon nitrogen starvation, we observed a re-routing of the carbon flux towards the formation of TAGs. Under these conditions, the cellular lipid content made up more than half of the cell's dry weight. On the proteome level, this coincided with a shift towards non-glycolytic carbohydrate-metabolizing pathways. These pathways (Entner-Doudoroff and pentose-phosphate shunt) contribute NADPH and precursors of glycerol 3-phosphate and acetyl-CoA to lipogenesis. The expression of proteins involved in the degradation of branched-chain amino acids and the methylmalonyl-CoA pathway probably provided propionyl-CoA for the biosynthesis of odd-numbered fatty acids, which make up almost 30 % of RHA1 fatty acid composition. Additionally, lipolytic and glycerol-degrading enzymes increased in abundance, suggesting a dynamic cycling of cellular lipids. Conversely, abundance of proteins involved in consuming intermediates of lipogenesis decreased. Furthermore, we identified another level of lipogenesis regulation through redox-mediated thiol modification in R. jostii. Enzymes affected included acetyl-CoA carboxylase and a β-ketoacyl-[acyl-carrier protein] synthase II (FabF). An integrative metabolic model for the oleaginous RHA1 strain is proposed on the basis of our results. PMID:25564499

  7. Biodesulfurization of a system containing synthetic fuel using Rhodococcus erythropolis ATCC 4277.

    PubMed

    Maass, Danielle; de Oliveira, Débora; de Souza, Antônio A Ulson; Souza, Selene M A Guelli U

    2014-11-01

    The burning of fossil fuels has released a large quantity of pollutants into the atmosphere. In this context, sulfur dioxide is one of the most noxious gas which, on reacting with moist air, is transformed into sulfuric acid, causing the acid rain. In response, many countries have reformulated their legislation in order to enforce the commercialization of fuels with very low sulfur levels. The existing desulfurization processes cannot remove such low levels of sulfur and thus a biodesulfurization has been developed, where the degradation of sulfur occurs through the action of microorganisms. Rhodococcus erythropolis has been identified as one of the most promising bacteria for use in the biodesulfurization. In this study, the effectiveness of the strain R. erythropolis ATCC 4277 in the desulfurization of dibenzothiophene (DBT) was evaluated in a batch reactor using an organic phase (n-dodecane or diesel) concentrations of 20, 80, and 100 % (v/v). This strain was able to degrade 93.3, 98.0, and 95.5 % of the DBT in the presence of 20, 80, and 100 % (v/v) of dodecane, respectively. The highest value for the specific DBT degradation rate was 44 mmol DBT · kg DCW(-1) · h(-1), attained in the reactor containing 80 % (v/v) of n-dodecane as the organic phase. PMID:25163887

  8. Disseminated rhodococcus equi infection in HIV infection despite highly active antiretroviral therapy

    PubMed Central

    2011-01-01

    Background Rhodococcus equi (R.equi) is an acid fast, GRAM + coccobacillus, which is widespread in the soil and causes pulmonary and extrapulmonary infections in immunocompromised people. In the context of HIV infection, R.equi infection (rhodococcosis) is regarded as an opportunistic disease, and its outcome is influenced by highly active antiretroviral therapy (HAART). Case presentation We report two cases of HIV-related rhodococcosis that disseminated despite suppressive HAART and anti-rhodococcal treatment; in both cases there was no immunological recovery, with CD4+ cells count below 200/μL. In the first case, pulmonary rhodococcosis presented 6 months after initiation of HAART, and was followed by an extracerebral intracranial and a cerebral rhodococcal abscess 1 and 8 months, respectively, after onset of pulmonary infection. The second case was characterized by a protracted course with spread of infection to various organs, including subcutaneous tissue, skin, colon and other intra-abdominal tissues, and central nervous system; the spread started 4 years after clinical resolution of a first pulmonary manifestation and progressed over a period of 2 years. Conclusions Our report highlights the importance of an effective immune recovery, despite fully suppressive HAART, along with anti-rhodococcal therapy, in order to clear rhodococcal infection. PMID:22168333

  9. Biodegradation of buprofezin by Rhodococcus sp. strain YL-1 isolated from rice field soil.

    PubMed

    Li, Chao; Zhang, Ji; Wu, Zhi-Guo; Cao, Li; Yan, Xin; Li, Shun-Peng

    2012-03-14

    A buprofezin-degrading bacterium, YL-1, was isolated from rice field soil. YL-1 was identified as Rhodococcus sp. on the basis of the comparative analysis of 16S rDNA sequences. The strain could use buprofezin as the sole source of carbon and nitrogen for growth and was able to degrade 92.4% of 50 mg L(-1) buprofezin within 48 h in liquid culture. During the degradation of buprofezin, four possible metabolites, 2-tert-butylimino-3-isopropyl-1,3,5-thiadiazinan-4-one, N-tert-butyl-thioformimidic acid formylaminomethyl ester, 2-isothiocyanato-2-methyl-propane, and 2-isothiocyanato-propane, were identified using gas chromatography-mass spectrometry (GC-MS) analysis. The catechol 2,3-dioxygenase activity was strongly induced during the degradation of buprofezin. A novel microbial biodegradation pathway for buprofezin was proposed on the basis of these metabolites. The inoculation of soils treated with buprofezin with strain YL-1 resulted in a higher degradation rate than that observed in noninoculated soils, indicating that strain YL-1 has the potential to be used in the bioremediation of buprofezin-contaminated environments.

  10. Evaluation of the Conformational Stability of Recombinant Desulfurizing Enzymes from a Newly Isolated Rhodococcus sp.

    PubMed

    Parravicini, Federica; Brocca, Stefania; Lotti, Marina

    2016-01-01

    Metabolic pathways of aerobic bacteria able to assimilate sulfur can provide biocatalysts for biodesulfurization of petroleum and of other sulfur-containing pollutants. Of major interest is the so-called "4S pathway," in that C-S bonds are specifically cleaved leaving the carbon skeleton of substrates intact. This pathway is carried out by four enzymes, named Dsz A, B, C, and D. In view of a possible application of recombinant Dsz enzymes in biodesulfurization treatments, we have investigated the structural features of enzymes cloned from a Rhodococcus strain isolated from polluted environmental samples and their resistance to temperature (20-95 °C) and to organic solvents (5, 10, and 20 % v/v methanol, acetonitrile, hexane, and toluene). Changes in protein structures were assessed by circular dichroism and intrinsic fluorescence spectroscopy. We found that all Dsz proteins are unfolded by temperatures in the range 45-60 °C and by all solvents tested, with the most dramatic effect being produced by toluene. These results suggest that stabilization of the biocatalysts by protein engineering will be necessary for developing biodesulfurization technologies based on Dsz enzymes.

  11. Isolation and characterization of aniline-degrading Rhodococcus sp. strain AN5.

    PubMed

    Zhuang, Rensheng; Zhong, Wenhui; Yao, Jun; Chen, Huilun; Tian, Lin; Zhou, Yong; Wang, Fei; Bramanti, Emilia; Zaray, Gyula

    2007-11-01

    A pure culture using aniline as a sole source of carbon and energy was isolated by selective enrichment culturing on a minimum salt medium (MSM) from the Nanjing Chemical Plant, Nanjing, Jiangsu Province, China. An analysis of the 16S rRNA gene sequence and morphological and physiological characteristics showed that this strain was a member of the genus Rhodococcus, and it was designated as strain AN5. Its optimal conditions for aniline biodegradation were 30 degrees C (pH 7.0). Due to the water insolubility of aniline, growth of strain AN5 at various aniline concentrations was studied via spectrophotometry and microcalorimetry in different culture mediums. Strain AN5 not only utilized aniline as its sole carbon and energy resources, but also degraded phenol, benzoic acid and naphthalin. Glucose, peptone and ammonium sulfate, when utilized as its secondary carbon and nitrogen sources, had no active effect on the aniline biodegradation. Such findings would be valuable in the application of strain AN5 to depurate industrial waste water. PMID:17990163

  12. [Effect of citric acid on synthesis of surfactants in Rhodococcus erythropolis IMV Ac-5017].

    PubMed

    Pyroh, T P; Shevchuk, T A; Shuliakova, M O; Tarasenko, D O

    2011-01-01

    Expediency of sodium citrate (regulator of lipids synthesis) substitution is shown in the medium of cultivation of Rhodococcus erythropolis IMV Ac-5017 with ethanol (or hexadecane) and fumarate (gluconeogenesis precursor) by citric acid for pH maintenance at the level optimal for synthesis of surfactants. It has been established the maximum synthesis of surfactants of R. erythropolis IMV Ac-5017 was observed at pH 8.0. Introduction of 0.2% sodium fumarate at the end of experimental growth phase of the strain IMV Ac-5017 in the medium with 2% of ethanol with further periodic acidification of culture liquid by citric acid up to pH 8.0 was accompanied by the increase of conditional concentration of surfactants by 30, 40 and 95% as compared with an analogous process without pH regulation, by the use of sodium citrate as the regulator of lipids synthesis on the medium with ethanol as well as without organic acids, respectively.

  13. A bifunctional enzyme from Rhodococcus erythropolis exhibiting secondary alcohol dehydrogenase-catalase activities.

    PubMed

    Martinez-Rojas, Enriqueta; Kurt, Tutku; Schmidt, Udo; Meyer, Vera; Garbe, Leif-Alexander

    2014-11-01

    Alcohol dehydrogenases have long been recognized as potential biocatalyst for production of chiral fine and bulk chemicals. They are relevant for industry in enantiospecific production of chiral compounds. In this study, we identified and purified a nicotinamide adenine dinucleotide (NAD)-dependent secondary alcohol dehydrogenase (SdcA) from Rhodococcus erythropolis oxidizing γ-lactols into γ-lactones. SdcA showed broad substrate specificity on γ-lactols; secondary aliphatic alcohols with 8 and 10 carbon atoms were also substrates and oxidized with (2S)-stereospecificity. The enzyme exhibited moderate stability with a half-life of 5 h at 40 °C and 20 days at 4 °C. Mass spectrometric identification revealed high sequence coverage of SdcA amino acid sequence to a highly conserved catalase from R. erythropolis. The corresponding encoding gene was isolated from genomic DNA and subsequently overexpressed in Escherichia coli BL21 DE3 cells. In addition, the recombinant SdcA was purified and characterized in order to confirm that the secondary alcohol dehydrogenase and catalase activity correspond to the same enzyme.

  14. Engineering L-arabinose metabolism in triacylglycerol-producing Rhodococcus opacus for lignocellulosic fuel production.

    PubMed

    Kurosawa, Kazuhiko; Plassmeier, Jens; Kalinowski, Jörn; Rückert, Christian; Sinskey, Anthony J

    2015-07-01

    Advanced biofuels from lignocellulosic biomass have been considered as a potential solution for the issues of energy sustainability and environmental protection. Triacylglycerols (TAGs) are potential precursors for the production of lipid-based liquid biofuels. Rhodococcus opacus PD630 can accumulate large amounts of TAGs when grown under physiological conditions of high carbon and low nitrogen. However, R. opacus PD630 does not utilize the sugar L-arabinose present in lignocellulosic hydrolysates. Here, we report the engineering of R. opacus to produce TAGs on L-arabinose. We constructed a plasmid (pASC8057) harboring araB, araD and araA genes derived from a Streptomyces bacterium, and introduced the genes into R. opacus PD630. One of the engineered strains, MITAE-348, was capable of growing on high concentrations (up to 100 g/L) of L-arabinose. MITAE-348 was grown in a defined medium containing 16 g/L L-arabinose or a mixture of 8 g/L L-arabinose and 8 g/L D-glucose. In a stationary phase occurring 3 days post-inoculation, the strain was able to completely utilize the sugar, and yielded 2.0 g/L for L-arabinose and 2.2 g/L for L-arabinose/D-glucose of TAGs, corresponding to 39.7% or 42.0%, respectively, of the cell dry weight.

  15. Metabolic responses of Rhodococcus erythropolis PR4 grown on diesel oil and various hydrocarbons.

    PubMed

    Laczi, Krisztián; Kis, Ágnes; Horváth, Balázs; Maróti, Gergely; Hegedüs, Botond; Perei, Katalin; Rákhely, Gábor

    2015-11-01

    Rhodococcus erythropolis PR4 is able to degrade diesel oil, normal-, iso- and cycloparaffins and aromatic compounds. The complete DNA content of the strain was previously sequenced and numerous oxygenase genes were identified. In order to identify the key elements participating in biodegradation of various hydrocarbons, we performed a comparative whole transcriptome analysis of cells grown on hexadecane, diesel oil and acetate. The transcriptomic data for the most prominent genes were validated by RT-qPCR. The expression of two genes coding for alkane-1-monooxygenase enzymes was highly upregulated in the presence of hydrocarbon substrates. The transcription of eight phylogenetically diverse cytochrome P450 (cyp) genes was upregulated in the presence of diesel oil. The transcript levels of various oxygenase genes were determined in cells grown in an artificial mixture, containing hexadecane, cycloparaffin and aromatic compounds and six cyp genes were induced by this hydrocarbon mixture. Five of them were not upregulated by linear and branched hydrocarbons. The expression of fatty acid synthase I genes was downregulated by hydrocarbon substrates, indicating the utilization of external alkanes for fatty acid synthesis. Moreover, the transcription of genes involved in siderophore synthesis, iron transport and exopolysaccharide biosynthesis was also upregulated, indicating their important role in hydrocarbon metabolism. Based on the results, complex metabolic response profiles were established for cells grown on various hydrocarbons. Our results represent a functional annotation of a rhodococcal genome, provide deeper insight into molecular events in diesel/hydrocarbon utilization and suggest novel target genes for environmental monitoring projects.

  16. Immunogenicity of an electron beam inactivated Rhodococcus equi vaccine in neonatal foals.

    PubMed

    Bordin, Angela I; Pillai, Suresh D; Brake, Courtney; Bagley, Kaytee B; Bourquin, Jessica R; Coleman, Michelle; Oliveira, Fabiano N; Mwangi, Waithaka; McMurray, David N; Love, Charles C; Felippe, Maria Julia B; Cohen, Noah D

    2014-01-01

    Rhodococcus equi is an important pathogen of foals that causes severe pneumonia. To date, there is no licensed vaccine effective against R. equi pneumonia of foals. The objectives of our study were to develop an electron beam (eBeam) inactivated vaccine against R. equi and evaluate its immunogenicity. A dose of eBeam irradiation that inactivated replication of R. equi while maintaining outer cell wall integrity was identified. Enteral administration of eBeam inactivated R. equi increased interferon-γ production by peripheral blood mononuclear cells in response to stimulation with virulent R. equi and generated naso-pharyngeal R. equi-specific IgA in newborn foals. Our results indicate that eBeam irradiated R. equi administered enterally produce cell-mediated and upper respiratory mucosal immune responses, in the face of passively transferred maternal antibodies, similar to those produced in response to enteral administration of live organisms (a strategy which previously has been documented to protect foals against intrabronchial infection with virulent R. equi). No evidence of adverse effects was noted among vaccinated foals.

  17. An Evaluation of Kinetic Models in the Biodesulfurization of Synthetic Oil by Rhodococcus erythropolis ATCC 4277.

    PubMed

    Maass, D; Mayer, D A; Moritz, D E; Oliveira, D; de Souza, A A Ulson; Souza, S M A Guelli

    2015-10-01

    Biodesulfurization is an eco-friendly technology applied in the removal of sulfur from fossil fuels. This technology is based on the use of microorganisms as biocatalysts to convert the recalcitrant sulfur compounds into others easily treatable, as sulfides. Despite it has been studied during the last decades, there are some unsolved questions, as per example the kinetic model which appropriately describes the biodesulfurization globally. In this work, different kinetic models were tested to a batch desulfurization process using dibenzothiophene (DBT) as a model compound, n-dodecane as organic solvent, and Rhodococcus erythropolis ATCC 4277 as biocatalyst. The models were solved by ODE45 function in the MATLAB. Monod model was capable to describe the biodesulfurization process predicting all experimental data with a very good fitting. The coefficients of determination achieved to organic phase concentrations of 20, 80, and 100 % (v/v) were 0.988, 0.995, and 0.990, respectively. R. erythropolis ATCC 4277 presented a good affinity with the substrate (DBT) since the coefficients of saturation obtained to reaction medium containing 20, 80, and 100 % (v/v) were 0.034, 0.07, and 0.116, respectively. This kinetic evaluation provides an improvement in the development of biodesulfurization technology because it showed that a simple model is capable to describe the throughout process.

  18. Characterization of the Gene Cluster Involved in Isoprene Metabolism in Rhodococcus sp. Strain AD45

    PubMed Central

    van Hylckama Vlieg, Johan E. T.; Leemhuis, Hans; Spelberg, Jeffrey H. Lutje; Janssen, Dick B.

    2000-01-01

    The genes involved in isoprene (2-methyl-1,3-butadiene) utilization in Rhodococcus sp. strain AD45 were cloned and characterized. Sequence analysis of an 8.5-kb DNA fragment showed the presence of 10 genes of which 2 encoded enzymes which were previously found to be involved in isoprene degradation: a glutathione S-transferase with activity towards 1,2-epoxy-2-methyl-3-butene (isoI) and a 1-hydroxy-2-glutathionyl-2-methyl-3-butene dehydrogenase (isoH). Furthermore, a gene encoding a second glutathione S-transferase was identified (isoJ). The isoJ gene was overexpressed in Escherichia coli and was found to have activity with 1-chloro-2,4-dinitrobenzene and 3,4-dichloro-1-nitrobenzene but not with 1,2-epoxy-2-methyl-3-butene. Downstream of isoJ, six genes (isoABCDEF) were found; these genes encoded a putative alkene monooxygenase that showed high similarity to components of the alkene monooxygenase from Xanthobacter sp. strain Py2 and other multicomponent monooxygenases. The deduced amino acid sequence encoded by an additional gene (isoG) showed significant similarity with that of α-methylacyl-coenzyme A racemase. The results are in agreement with a catabolic route for isoprene involving epoxidation by a monooxygenase, conjugation to glutathione, and oxidation of the hydroxyl group to a carboxylate. Metabolism may proceed by fatty acid oxidation after removal of glutathione by a still-unknown mechanism. PMID:10715003

  19. Mining the genome of Rhodococcus fascians, a plant growth-promoting bacterium gone astray.

    PubMed

    Francis, Isolde M; Stes, Elisabeth; Zhang, Yucheng; Rangel, Diana; Audenaert, Kris; Vereecke, Danny

    2016-09-25

    Rhodococcus fascians is a phytopathogenic Gram-positive Actinomycete with a very broad host range encompassing especially dicotyledonous herbaceous perennials, but also some monocots, such as the Liliaceae and, recently, the woody crop pistachio. The pathogenicity of R. fascians strain D188 is known to be encoded by the linear plasmid pFiD188 and to be dictated by its capacity to produce a mixture of cytokinins. Here, we show that D188-5, the nonpathogenic plasmid-free derivative of the wild-type strain D188 actually has a plant growth-promoting effect. With the availability of the genome sequence of R. fascians, the chromosome of strain D188 was mined for putative plant growth-promoting functions and the functionality of some of these activities was tested. This analysis together with previous results suggests that the plant growth-promoting activity of R. fascians is due to production of plant growth modulators, such as auxin and cytokinin, combined with degradation of ethylene through 1-amino-cyclopropane-1-carboxylic acid deaminase. Moreover, R. fascians has several functions that could contribute to efficient colonization and competitiveness, but there is little evidence for a strong impact on plant nutrition. Possibly, the plant growth promotion encoded by the D188 chromosome is imperative for the epiphytic phase of the life cycle of R. fascians and prepares the plant to host the bacteria, thus ensuring proper continuation into the pathogenic phase. PMID:26877150

  20. Induction of Viable but Nonculturable State in Rhodococcus and Transcriptome Analysis Using RNA-seq

    PubMed Central

    Su, Xiaomei; Guo, Li; Ding, Linxian; Qu, Kun; Shen, Chaofeng

    2016-01-01

    Viable but nonculturable (VBNC) bacteria, which maintain the viability with loss of culturability, universally exist in contaminated and non-contaminated environments. In this study, two strains, Rhodococcus sp. TG13 and TN3, which were isolated from PCB-contaminated sediment and non-contaminated sediment respectively, were investigated under low temperature and oligotrophic conditions. The results indicated that the two strains TG13 and TN3 could enter into the VBNC state with different incubation times, and could recover culturability by reversal of unfavourable factors and addition of resuscitation-promoting factor (Rpf), respectively. Furthermore, the gene expression variations in the VBNC response were clarified by Illumina high throughput RNA-sequencing. Genome-wide transcriptional analysis demonstrated that up-regulated genes in the VBNC cells of the strain TG13 related to protein modification, ATP accumulation and RNA polymerase, while all differentially expressed genes (DEGs) in the VBNC cells of the strain TN3 were down-regulated. However, the down-regulated genes in both the two strains mainly encoded NADH dehydrogenase subunit, catalase, oxidoreductase, which further verified that cold-induced loss of ability to defend oxidative stress may play an important role in induction of the VBNC state. This study further verified that the molecular mechanisms underlying the VBNC state varied with various bacterial species. Study on the VBNC state of non-pathogenic bacteria will provide new insights into the limitation of environmental micro-bioremediation and the cultivation of unculturable species. PMID:26808070

  1. Diversion of phagosome trafficking by pathogenic Rhodococcus equi depends on mycolic acid chain length.

    PubMed

    Sydor, Tobias; von Bargen, Kristine; Hsu, Fong-Fu; Huth, Gitta; Holst, Otto; Wohlmann, Jens; Becken, Ulrike; Dykstra, Tobias; Söhl, Kristina; Lindner, Buko; Prescott, John F; Schaible, Ulrich E; Utermöhlen, Olaf; Haas, Albert

    2013-03-01

    Rhodococcus equi is a close relative of Mycobacterium spp. and a facultative intracellular pathogen which arrests phagosome maturation in macrophages before the late endocytic stage. We have screened a transposon mutant library of R. equi for mutants with decreased capability to prevent phagolysosome formation. This screen yielded a mutant in the gene for β-ketoacyl-(acyl carrier protein)-synthase A (KasA), a key enzyme of the long-chain mycolic acid synthesizing FAS-II system. The longest kasA mutant mycolic acid chains were 10 carbon units shorter than those of wild-type bacteria. Coating of non-pathogenic E. coli with purified wild-type trehalose dimycolate reduced phagolysosome formation substantially which was not the case with shorter kasA mutant-derived trehalose dimycolate. The mutant was moderately attenuated in macrophages and in a mouse infection model, but was fully cytotoxic.Whereas loss of KasA is lethal in mycobacteria, R. equi kasA mutant multiplication in broth was normal proving that long-chain mycolic acid compounds are not necessarily required for cellular integrity and viability of the bacteria that typically produce them. This study demonstrates a central role of mycolic acid chain length in diversion of trafficking by R. equi. PMID:23078612

  2. Engineering of an L-arabinose metabolic pathway in Rhodococcus jostii RHA1 for biofuel production.

    PubMed

    Xiong, Xiaochao; Wang, Xi; Chen, Shulin

    2016-07-01

    The oleaginous bacterium, Rhodococcus jostii RHA1 has attracted considerable attention due to its capability to accumulate significant levels of triacylglycerol as renewable hydrocarbon. To enable the strain to utilize arabinose derived from lignocellulosic biomass, the metabolic pathway of L-arabinose utilization was introduced into R. jostii RHA1 by heterogenous expression of the operon, araBAD from Escherichia coli. The results showed that recombinant bearing araBAD could grow on L-arabinose as the sole carbon source, and additional expression of araFGH encoding the arabinose transporter from E. coli could improve the cell biomass yield from high contents of arabinose. We further increased the content of lipid produced from arabinose in the recombinants from 47.9 to 56.8 % of the cell dry weight (CDW) by overexpression of a gene, atf1 encoding a diglyceride acyltransferase from R. opacus PD630. This work demonstrated the feasibility of producing lipid from arabinose by genetic modification of the rhodococci strain.

  3. Aerobic biodegradation of N-nitrosodimethylamine by the propanotroph Rhodococcus ruber ENV425.

    PubMed

    Fournier, Diane; Hawari, Jalal; Halasz, Annamaria; Streger, Sheryl H; McClay, Kevin R; Masuda, Hisako; Hatzinger, Paul B

    2009-08-01

    The propanotroph Rhodococcus ruber ENV425 was observed to rapidly biodegrade N-nitrosodimethylamine (NDMA) after growth on propane, tryptic soy broth, or glucose. The key degradation intermediates were methylamine, nitric oxide, nitrite, nitrate, and formate. Small quantities of formaldehyde and dimethylamine were also detected. A denitrosation reaction, initiated by hydrogen atom abstraction from one of the two methyl groups, is hypothesized to result in the formation of n-methylformaldimine and nitric oxide, the former of which decomposes in water to methylamine and formaldehyde and the latter of which is then oxidized further to nitrite and then nitrate. Although the strain mineralized more than 60% of the carbon in [(14)C]NDMA to (14)CO(2), growth of strain ENV425 on NDMA as a sole carbon and energy source could not be confirmed. The bacterium was capable of utilizing NDMA, as well as the degradation intermediates methylamine and nitrate, as sources of nitrogen during growth on propane. In addition, ENV425 reduced environmentally relevant microgram/liter concentrations of NDMA to <2 ng/liter in batch cultures, suggesting that the bacterium may have applications for groundwater remediation.

  4. Transformation of Rhodococcus fascians by High-Voltage Electroporation and Development of R. fascians Cloning Vectors

    PubMed Central

    Desomer, Jan; Dhaese, Patrick; Montagu, Marc Van

    1990-01-01

    The analysis of the virulence determinants of phytopathogenic Rhodococcus fascians has been hampered by the lack of a system for introducing exogenous DNA. We investigated the possibility of genetic transformation of R. fascians by high-voltage electroporation of intact bacterial cells in the presence of plasmid DNA. Electrotransformation in R. fascians D188 resulted in transformation frequencies ranging from 105/μg of DNA to 107/μg of DNA, depending on the DNA concentration. The effects of different electrical parameters and composition of electroporation medium on transformation efficiency are presented. By this transformation method, a cloning vector (pRF28) for R. fascians based on an indigenous 160-kilobase (chloramphenicol and cadmium resistance-encoding) plasmid pRF2 from strain NCPPB 1675 was developed. The origin of replication and the chloramphenicol resistance gene on pRF28 were used to construct cloning vectors that are capable of replication in R. fascians and Escherichia coli. The electroporation method presented was efficient enough to allow detection of the rare integration of replication-deficient pRF28 derivatives in the R. fascians D188 genome via either homologous or illegitimate recombination. Images PMID:16348290

  5. [Effect of biosurfactants Acinetobacter calcoaceticus K-4 and Rhodococcus erythropolis EK-1 on some microorganisms].

    PubMed

    Pirog, T P; Konon, A D; Sofilkanich, A P; Skochko, A B

    2011-01-01

    It has been established that the preparations of biosurfactants Rhodococcus erythropolis EK-1 (0.61 -2.1 mg/ml) and Acinetobacter calcoaceticus K-4 (0.15 - 0.22 mg/ml) in a form of supernatants of the cultural liquid show antimicrobial effect in respect of a number of microorganisms (Bacillus subtilis BT-2, Escherichia coli IEM-1, Candida tropicalis BT-5, Candida albicans D6, Candida utilis BVC-65, Saccharomyces cerevisiae OB-3). No inhibiting effect of biosurfactant preparations of R. erythropolis EK-1 on the cells of S. cerevisiae OB-3 and E. coli IEM-I and antifungal effect of the both studied surfactants on Aspergillus niger P-3 and Fusarium culmorum T-7 were revealed. The survival of microbe cells depend on biosurfactants concentration in the preparations, on exposure time as well as on physiological state of test-cultures. It has been established that the surfactant preparations of A. calcoaceticus K-4 had a higher effect on the spores of B. subtilis BT-2, than on vegetative cells, thus decreasing the spore culture survival by 75% in 2 h of exposure.

  6. Aerobic debromination of BDE-209 by Rhodococcus sp. coupled with zerovalent iron/activated carbon.

    PubMed

    Liu, Lili; Zhang, Yacong; Liu, Ruihong; Wang, Zhiping; Xu, Feng; Chen, Yilun; Lin, Kuangfei

    2016-02-01

    In this study, an aerobic strain identified as Rhodococcus sp. was isolated from the sediment of a typical electronic waste disassemble site, Taizhou, China. This strain could use BDE-209 as the sole carbon and energy source and degrade 65.1% of BDE-209 (initial concentration being 50 mg/L) within 144 h. To explore the BDE-209 degradation properties of this strain with the co-existed electronic donor, zerovalent iron/activated carbon (ZVI/AC) was introduced to build a microbial-chemical coupling system, which was found to promote the degradation of BDE-209 slightly (74.7% in 144 h). Moreover, the debromination products in both of the batch experiments were determined with GC/MS, which showed that lower brominated PBDE congeners were produced almost in order of the number of bromine ions, ranged from nona- to di-BDEs. In addition, the possible debromination pathways of BDE-209 for each system were proposed respectively, which confirmed the microbial activity of BDE-209 debromination. Since some of the lower-brominated BDE congeners are much toxic than BDE-209, these microbial activities might bring potential hazards to the environment with BDE-209 contamination. It is the first time to investigate the transformation of BDE-209 with microbial-chemical coupling system, which is universal in the nature, thus suggesting that the ecological safety of environment exposed to PBDEs should be focused in the future.

  7. Hydrogen intercalation in MoS2

    NASA Astrophysics Data System (ADS)

    Zhu, Zhen; Peelaers, Hartwin; Van de Walle, Chris G.

    2016-08-01

    We investigate the structure and energetics of interstitial hydrogen and hydrogen molecules in layered 2 H -MoS2, an issue of interest both for hydrogen storage applications and for the use of MoS2 as an (opto)electronic material. Using first-principles density functional theory we find that hydrogen interstitials are deep donors. H2 molecules are electrically inactive and energetically more stable than hydrogen interstitials. Their equilibrium position is the hollow site of the MoS2 layers. The migration barrier of a hydrogen molecule is calculated to be smaller than 0.6 eV. We have also explored the insertion energies of hydrogen molecules as a function of hydrogen concentration in MoS2. For low concentrations, additional inserted H2 molecules prefer to be located in hollow sites (on top of the center of a hexagon) in the vicinity of an occupied site. Once two molecules have been inserted, the energy cost for inserting additional H2 molecules becomes much lower. Once all hollow sites are filled, the energy cost increases, but only by a modest amount. We find that up to 13 H2 molecules can be accommodated within the same interlayer spacing of an areal 3 ×3 supercell.

  8. Dioxygenases of Chlorobiphenyl-Degrading Species Rhodococcus wratislaviensis G10 and Chlorophenol-Degrading Species Rhodococcus opacus 1CP Induced in Benzoate-Grown Cells and Genes Potentially Involved in These Processes.

    PubMed

    Solyanikova, I P; Borzova, O V; Emelyanova, E V; Shumkova, E S; Prisyazhnaya, N V; Plotnikova, E G; Golovleva, L A

    2016-09-01

    Dioxygenases induced during benzoate degradation by the actinobacterium Rhodococcus wratislaviensis G10 strain degrading haloaromatic compounds were studied. Rhodococcus wratislaviensis G10 completely degraded 2 g/liter benzoate during 30 h and 10 g/liter during 200 h. Washed cells grown on benzoate retained respiration activity for more than 90 days, and a high activity of benzoate dioxygenase was recorded for 10 days. Compared to the enzyme activities with benzoate, the activity of benzoate dioxygenases was 10-30% with 13 of 35 substituted benzoate analogs. Two dioxygenases capable of cleaving the aromatic ring were isolated and characterized: protocatechuate 3,4-dioxygenase and catechol 1,2-dioxygenase. Catechol inhibited the activity of protocatechuate 3,4-dioxygenase. Protocatechuate did not affect the activity of catechol 1,2-dioxygenase. A high degree of identity was shown by MALDI-TOF mass spectrometry for protein peaks of the R. wratislaviensis G10 and Rhodococcus opacus 1CP cells grown on benzoate or LB. DNA from the R. wratislaviensis G10 strain was specifically amplified using specific primers to variable regions of genes coding α- and β-subunits of protocatechuate 3,4-dioxygenase and to two genes of the R. opacus 1CP coding catechol 1,2-dioxygenase. The products were 99% identical with the corresponding regions of the R. opacus 1CP genes. This high identity (99%) between the genes coding degradation of aromatic compounds in the R. wratislaviensis G10 and R. opacus 1CP strains isolated from sites of remote location (1400 km) and at different time (20-year difference) indicates a common origin of biodegradation genes of these strains and a wide distribution of these genes among rhodococci. PMID:27682171

  9. Ketoreductase TpdE from Rhodococcus jostii TMP1: characterization and application in the synthesis of chiral alcohols

    PubMed Central

    Kutanovas, Simonas; Rutkienė, Rasa; Tauraitė, Daiva; Striela, Romualdas; Meškys, Rolandas

    2015-01-01

    Background. Production of highly pure enantiomers of vicinal diols is desirable, but difficult to achieve. Enantiomerically pure diols and acyloins are valuable bulk chemicals, promising synthones and potential building blocks for chiral polymers. Enzymatic reduction of ketones is a useful technique for the synthesis of the desired enantiomeric alcohols. Here, we report on the characterization of a ketoreductase TpdE from Rhodococcus jostii TMP1 that is a prospective tool for the synthesis of such compounds. Results. In this study, NADPH-dependent short-chain dehydrogenase/reductase TpdE from Rhodococcus jostii TMP1 was characterized. The enzyme exhibited broad substrate specificity towards aliphatic 2,3-diketones, butan-3-one-2-yl alkanoates, as well as acetoin and its acylated derivatives. TpdE stereospecifically reduced α-diketones to the corresponding diols. The GC-MS analysis of the reduction products of 2,3- and 3,4-diketones indicated that TpdE is capable of reducing both keto groups in its substrate leading to the formation of two new chiral atoms in the product molecule. Bioconversions of diketones to corresponding diols occurred using either purified enzyme or a whole-cell Escherichia coli BL21 (DE3) biocatalyst harbouring recombinant TpdE. The optimum temperature and pH were determined to be 30–35 °C and 7.5, respectively. Conclusions. The broad substrate specificity and stereoselectivity of TpdE from Rhodococcus jostii TMP1 make it a promising biocatalyst for the production of enantiomerically pure diols that are difficult to obtain by chemical routes. PMID:26587349

  10. Biodegradation of atrazine by Rhodococcus sp. BCH2 to N-isopropylammelide with subsequent assessment of toxicity of biodegraded metabolites.

    PubMed

    Kolekar, Parag D; Phugare, Swapnil S; Jadhav, Jyoti P

    2014-02-01

    Atrazine is a persistent organic pollutant in the environment which affects not only terrestrial and aquatic biota but also human health. Since its removal from the environment is needed, atrazine biodegradation is achieved in the present study using the bacterium Rhodococcus sp. BCH2 isolated from soil, long-term treated with atrazine. The bacterium was capable of degrading about 75 % atrazine in liquid medium having pH 7 under aerobic and dark condition within 7 days. The degradation ability of the bacterium at various temperatures (20-60 °C), pH (range 3-11), carbon (glucose, fructose, sucrose, starch, lactose, and maltose), and nitrogen (ammonium molybdate, sodium nitrate, potassium nitrate, and urea) sources were studied for triumph optimum atrazine degradation. The results indicate that atrazine degradation at higher concentrations (100 ppm) was pH and temperature dependent. However, glucose and potassium nitrate were optimum carbon and nitrogen source, respectively. Atrazine biodegradation analysis was carried out by using high-performance thin-layer chromatography (HPTLC), Fourier transform infrared spectroscopy (FTIR), and liquid chromatography quadrupole time-of-flight (LC/Q-TOF-MS) techniques. LC/Q-TOF-MS analysis revealed formation of various intermediate metabolites including hydroxyatrazine, N-isopropylammelide, deisopropylhydroxyatrazine, deethylatrazine, deisopropylatrazine, and deisopropyldeethylatrazine which was helpful to propose biochemical degradation pathway of atrazine. Furthermore, the toxicological studies of atrazine and its biodegraded metabolites were executed on earthworm Eisenia foetida as a model organism with respect to enzymatic (SOD and Catalase) antioxidant defense mechanism and lipid peroxidation studies. These results suggest innocuous degradation of atrazine by Rhodococcus sp. BCH2 in nontoxic form. Therefore the Rhodococcus sp.BCH2 could prove a valuable source for the eco-friendly biodegradation of atrazine pesticide.

  11. Functional divergence of HBHA from Mycobacterium tuberculosis and its evolutionary relationship with TadA from Rhodococcus opacus.

    PubMed

    Lanfranconi, Mariana P; Alvarez, Héctor M

    2016-08-01

    Rhodococcus opacus PD630 and Rhodococcus jostii RHA1 are oleaginous bacteria able to synthesize and accumulate triacylglycerols (TAG) in lipid bodies (LB). Highly relevant to the structure of LB is a protein homologous to heparin-binding hemagglutinin (HBHA) (called TadA in rhodococci), which is a virulence factor found in Mycobacterium tuberculosis. HBHA is an adhesin involved in binding to non-phagocytic cells and extrapulmonary dissemination. We observed a conserved synteny of three genes encoding a transcriptional regulator (TR), the HBHA protein and a membrane protein (MP) between TAG-accumulating actinobacteria belonging to Rhodococcus, Mycobacterium, Nocardia and Dietzia genera, among others. A 354 bp-intergenic spacing containing a SigF-binding site was found between hbha and the TR genes in M. tuberculosis, which was absent in genomes of other investigated actinobacteria. Analyses of available "omic" information revealed that TadA and TR were co-induced in rhodococci under TAG-accumulating conditions; whereas in M. tuberculosis and Mycobacterium smegmatis, HBHA and TR were regulated independently under stress conditions occurring during infection. We also found differences in protein lengths, domain content and distribution between HBHA and TadA proteins from mycobacteria and rhodococci, which may explain their different roles in cells. Based on the combination of results obtained in model actinobacteria, we hypothesize that HBHA and TadA proteins originated from a common ancestor, but later suffered a process of functional divergence during evolution. Thus, rhodococcal TadA probably has maintained its original role; whereas HBHA may have evolved as a virulence factor in pathogenic mycobacteria.

  12. Isolation of Rhodococcus sp. Strain ECU0066, a New Sulfide Monooxygenase-Producing Strain for Asymmetric Sulfoxidation▿ †

    PubMed Central

    Li, Ai-Tao; Zhang, Jian-Dong; Xu, Jian-He; Lu, Wen-Ya; Lin, Guo-Qiang

    2009-01-01

    A new and efficient sulfide monooxygenase-producing strain, ECU0066, was isolated and identified as a Rhodococcus sp. that could transform phenylmethyl sulfide (PMS) to (S)-sulfoxide with 99% enantiomeric excess via two steps of enantioselective oxidations. Its enzyme activity could be effectively induced by adding PMS or phenylmethyl sulfoxide (PMSO) directly to a rich medium at the early log phase (6 h) of fermentation, resulting in over 10-times-higher production of the enzyme. This bacterial strain also displayed fairly good activity and enantioselectivity toward seven other sulfides, indicating a good potential for practical application in asymmetric synthesis of chiral sulfoxides. PMID:18836022

  13. Degradation of 2,4-dinitrophenol by two Rhodococcus erythropolis strains, HL 24-1 and HL 24-2.

    PubMed Central

    Lenke, H; Pieper, D H; Bruhn, C; Knackmuss, H J

    1992-01-01

    Two Rhodococcus erythropolis strains, HL 24-1 and HL 24-2, were isolated from soil and river water by their abilities to utilize 2,4-dinitrophenol (0.5 mM) as the sole source of nitrogen. Although succinate was supplied as a carbon and energy source during selection, both isolates could utilize 2,4-dinitrophenol also as the sole source of carbon. Both strains metabolized 2,4-dinitrophenol under concomitant liberation of stoichiometric amounts of nitrite and 4,6-dinitrohexanoate as a minor dead-end metabolite. PMID:1444407

  14. Comparative Genomics and Metabolic Analysis Reveals Peculiar Characteristics of Rhodococcus opacus Strain M213 Particularly for Naphthalene Degradation

    PubMed Central

    Blom, Jochen; Indest, Karl J.; Jung, Carina M.; Stothard, Paul; Bera, Gopal; Green, Stefan J.; Ogram, Andrew

    2016-01-01

    The genome of Rhodococcus opacus strain M213, isolated from a fuel-oil contaminated soil, was sequenced and annotated which revealed a genome size of 9,194,165 bp encoding 8680 putative genes and a G+C content of 66.72%. Among the protein coding genes, 71.77% were annotated as clusters of orthologous groups of proteins (COGs); 55% of the COGs were present as paralog clusters. Pulsed field gel electrophoresis (PFGE) analysis of M213 revealed the presence of three different sized replicons- a circular chromosome and two megaplasmids (pNUO1 and pNUO2) estimated to be of 750Kb 350Kb in size, respectively. Conversely, using an alternative approach of optical mapping, the plasmid replicons appeared as a circular ~1.2 Mb megaplasmid and a linear, ~0.7 Mb megaplasmid. Genome-wide comparative analysis of M213 with a cohort of sequenced Rhodococcus species revealed low syntenic affiliation with other R. opacus species including strains B4 and PD630. Conversely, a closer affiliation of M213, at the functional (COG) level, was observed with the catabolically versatile R. jostii strain RHA1 and other Rhodococcii such as R. wratislaviensis strain IFP 2016, R. imtechensis strain RKJ300, Rhodococcus sp. strain JVH1, and Rhodococcus sp. strain DK17, respectively. An in-depth, genome-wide comparison between these functional relatives revealed 971 unique genes in M213 representing 11% of its total genome; many associating with catabolic functions. Of major interest was the identification of as many as 154 genomic islands (GEIs), many with duplicated catabolic genes, in particular for PAHs; a trait that was confirmed by PCR-based identification of naphthalene dioxygenase (NDO) as a representative gene, across PFGE-resolved replicons of strain M213. Interestingly, several plasmid/GEI-encoded genes, that likely participate in degrading naphthalene (NAP) via a peculiar pathway, were also identified in strain M213 using a combination of bioinformatics, metabolic analysis and gene

  15. Fite stain positivity in Rhodococcus equi: yet another acid-fast organism in respiratory cytology--a case report.

    PubMed

    Echeverri, C; Matherne, J; Jorgensen, J H; Fowler, L J

    2001-04-01

    Rhodococcus equi is an aerobic Gram-positive and acid-fast coccobacillus that may cause cavitary pneumonia in immunocompromised hosts such as HIV-infected patients. Numerous Grocott's methenamine silver (GMS)-positive organisms were initially noted on the direct smear; a minor number of acid-fast organisms were seen in the Thin-Prep slide. Since the abundant mucous material with the attached organisms seen in conventional smears may be lost in liquid-based preparations, more sensitive stains such as Fite, as well as a more diligent search for organisms, is needed. This case illustrates the importance of careful selection and evaluation of special stains in sputum specimens.

  16. Comparative Genomics and Metabolic Analysis Reveals Peculiar Characteristics of Rhodococcus opacus Strain M213 Particularly for Naphthalene Degradation.

    PubMed

    Pathak, Ashish; Chauhan, Ashvini; Blom, Jochen; Indest, Karl J; Jung, Carina M; Stothard, Paul; Bera, Gopal; Green, Stefan J; Ogram, Andrew

    2016-01-01

    The genome of Rhodococcus opacus strain M213, isolated from a fuel-oil contaminated soil, was sequenced and annotated which revealed a genome size of 9,194,165 bp encoding 8680 putative genes and a G+C content of 66.72%. Among the protein coding genes, 71.77% were annotated as clusters of orthologous groups of proteins (COGs); 55% of the COGs were present as paralog clusters. Pulsed field gel electrophoresis (PFGE) analysis of M213 revealed the presence of three different sized replicons- a circular chromosome and two megaplasmids (pNUO1 and pNUO2) estimated to be of 750Kb 350Kb in size, respectively. Conversely, using an alternative approach of optical mapping, the plasmid replicons appeared as a circular ~1.2 Mb megaplasmid and a linear, ~0.7 Mb megaplasmid. Genome-wide comparative analysis of M213 with a cohort of sequenced Rhodococcus species revealed low syntenic affiliation with other R. opacus species including strains B4 and PD630. Conversely, a closer affiliation of M213, at the functional (COG) level, was observed with the catabolically versatile R. jostii strain RHA1 and other Rhodococcii such as R. wratislaviensis strain IFP 2016, R. imtechensis strain RKJ300, Rhodococcus sp. strain JVH1, and Rhodococcus sp. strain DK17, respectively. An in-depth, genome-wide comparison between these functional relatives revealed 971 unique genes in M213 representing 11% of its total genome; many associating with catabolic functions. Of major interest was the identification of as many as 154 genomic islands (GEIs), many with duplicated catabolic genes, in particular for PAHs; a trait that was confirmed by PCR-based identification of naphthalene dioxygenase (NDO) as a representative gene, across PFGE-resolved replicons of strain M213. Interestingly, several plasmid/GEI-encoded genes, that likely participate in degrading naphthalene (NAP) via a peculiar pathway, were also identified in strain M213 using a combination of bioinformatics, metabolic analysis and gene

  17. Adsorption of Rhodococcus Strain GIN-1 (NCIMB 40340) on Titanium Dioxide and Coal Fly Ash Particles

    PubMed Central

    Shabtai, Y.; Fleminger, G.

    1994-01-01

    Rhodococcus strain GIN-1 (NCIMB 40340) can be used to enrich and isolate a titanium-rich fraction from coal fly ash. The gram-positive bacterium was isolated by its ability to adhere strongly and rapidly to suspended particles of pure titanium dioxide or coal fly ash. Adsorption depends on the salt concentration and occurs in seawater. Lowering of the salt concentration or washing of particles with pure water did not, however, cause desorption of the bacteria from TiO2 particles; this was achieved by strong alkaline treatment or combined treatment with sodium dodecyl sulfate and urea but not with dilute acids, alcohols, or cationic or nonionic detergents. The bacterium exhibits higher affinity towards oxides of Ti and Zn than to other oxides with similar distribution of particle size. Moreover, it adheres much faster to TiO2 than to magnetite (Fe3O4) or Al2O3. After about 1 min, more than 85% of the cells were adsorbed on TiO2, compared with adsorption of only 10 and 8% to magnetite and Al2O3, respectively. Adsorption of the bacteria on TiO2 occurs over a pH range of 1.0 to 9.0 and at temperatures from 4 to over 80°C. Scanning electron microscopy combined with X-ray analysis revealed preferential adherence of the bacterium to coal ash particles richer in Ti. Stronger adhesion to TiO2 was also demonstrated in the translocation of bacteria, preadsorbed on magnetite, to TiO2 particles. The temporary co-adhesion to magnetite and TiO2 was exploited for the design of a prototype biomagnetic separation process in which bacterial cells serve as an adhesive mediator between magnetite and TiO2 particles in a mixture of Al, Si, and Ti oxides that simulates their proportion in the ash. Images PMID:16349369

  18. Plasmid Profiles of Virulent Rhodococcus equi Strains Isolated from Infected Foals in Poland.

    PubMed

    Kalinowski, Marcin; Grądzki, Zbigniew; Jarosz, Łukasz; Kato, Kiyoko; Hieda, Yu; Kakuda, Tsutomu; Takai, Shinji

    2016-01-01

    Rhodococcus equi is an important bacterial pathogen in foals up to 6 months old, widespread in horse farms all over the world. It was found that only virulent R. equi strains expressing 15-17 kDa virulence-associated protein (VapA) and having large virulence plasmid of 85-90 kb containing vapA gene are pathogenic for horses. To date, 12 plasmid types have been reported in VapA positive strains from horses. There are no data concerning plasmid types of Polish field R. equi strains isolated from horses and horse farm environment. The aim of the study is to determine plasmid profiles of virulent R. equi strains isolated in Poland from dead foals as well as from soil samples taken from horse breeding farms. Plasmid profiles of 10 clinical strains derived from 8 farms and 11 environmental strains from 3 farms, confirmed as virulent by PCR, were compared with 12 reference strains containing the known plasmid size and type. Plasmid DNAs were analysed by digestion with the restriction endonucleases BamHI, EcoRI, EcoT22I, and HindIII for detailed comparison and estimation of plasmid sizes. The results of RFLP analysis revealed that all except one isolates used in the study are classified as VapA 85 kb type I plasmid. One strain harboured VapA 87 kb type I plasmid. This is the first report of plasmid types of Polish field R. equi strains. The results of our preliminary investigations on horse farms located in central and eastern Poland indicate that the virulent R. equi strains thus far isolated from diseased foals and horse farms environment represent a highly uniform plasmid pattern. PMID:27074033

  19. Association between radiographic pattern and outcome in foals with pneumonia caused by Rhodococcus equi.

    PubMed

    Giguère, Steeve; Roberts, Gregory D

    2012-01-01

    Our objective was to characterize the association between types of radiographic findings and outcome in foals with pneumonia caused by Rhodococcus equi. Admission lateral thoracic radiographs of 62 foals with culture-confirmed R. equi pneumonia were reviewed retrospectively. A scoring system was developed to individually assess the severity of alveolar pattern, interstitial pattern, tracheobronchial lymphadenopathy, pleural effusion, and the number of nodular opacities and cavitary lesions. Individual scores were added to obtain a total radiographic score ranging from 0 (normal) to 22. Forty-three of 62 foals (69%) survived to discharge. The median total radiographic score of nonsurvivors (14; range, 9-16) was significantly (P = 0.007) higher than that of survivors (11; range, 4-15). Foals with a total radiographic score of greater than or equal to 15 were 6.15 times (95% CI: 1.35 to 28.2) less likely to survive than foals with a lower score (P = 0.019). A multivariate logistic regression model was used to identify the potential associations between specific types of radiographic lesions and outcome. The model was statistically significant (P = 0.002) and correctly classified 75.8% of foals. Only severity of alveolar pattern and number of cavitary lesions made statistically significant contributions to the model. There was no significant association between concurrent isolation of other bacteria along with R. equi and the types or severity of radiographic lesions. Based on the results of this study, severity of alveolar pattern and number of cavitary lesions are the radiographic findings significantly associated with a poor outcome in foals with R. equi pneumonia. PMID:22742474

  20. Catabolism of Benzoate and Phthalate in Rhodococcus sp. Strain RHA1: Redundancies and Convergence

    PubMed Central

    Patrauchan, Marianna A.; Florizone, Christine; Dosanjh, Manisha; Mohn, William W.; Davies, Julian; Eltis, Lindsay D.

    2005-01-01

    Genomic and proteomic approaches were used to investigate phthalate and benzoate catabolism in Rhodococcus sp. strain RHA1, a polychlorinated biphenyl-degrading actinomycete. Sequence analyses identified genes involved in the catabolism of benzoate (ben) and phthalate (pad), the uptake of phthalate (pat), and two branches of the β-ketoadipate pathway (catRABC and pcaJIHGBLFR). The regulatory and structural ben genes are separated by genes encoding a cytochrome P450. The pad and pat genes are contained on a catabolic island that is duplicated on plasmids pRHL1 and pRHL2 and includes predicted terephthalate catabolic genes (tpa). Proteomic analyses demonstrated that the β-ketoadipate pathway is functionally convergent. Specifically, the pad and pat gene products were only detected in phthalate-grown cells. Similarly, the ben and cat gene products were only detected in benzoate-grown cells. However, pca-encoded enzymes were present under both growth conditions. Activity assays for key enzymes confirmed these results. Disruption of pcaL, which encodes a fusion enzyme, abolished growth on phthalate. In contrast, after a lag phase, growth of the mutant on benzoate was similar to that of the wild type. Proteomic analyses revealed 20 proteins in the mutant that were not detected in wild-type cells during growth on benzoate, including a CatD homolog that apparently compensated for loss of PcaL. Analysis of completed bacterial genomes indicates that the convergent β-ketoadipate pathway and some aspects of its genetic organization are characteristic of rhodococci and related actinomycetes. In contrast, the high redundancy of catabolic pathways and enzymes appears to be unique to RHA1 and may increase its potential to adapt to new carbon sources. PMID:15937168

  1. Two Transporters Essential for Reassimilation of Novel Cholate Metabolites by Rhodococcus jostii RHA1

    PubMed Central

    Swain, Kendra; Casabon, Israël; Eltis, Lindsay D.

    2012-01-01

    The bacterial uptake of steroids and their metabolites remains poorly understood. We investigated two transporters associated with cholate catabolism in Rhodococcus jostii RHA1. Reverse transcriptase quantitative-PCR indicated that an ATP-binding cassette (ABC) transporter and a major facilitator superfamily (MFS) transporter were upregulated 16.7- and 174-fold, respectively, during the exponential phase of growth on cholate compared to growth on pyruvate. Gene knockout analysis established that these transporters are required for the reassimilation of distinct metabolites that accumulate during growth on cholate. The ABC transporter, encoded by camABCD, was essential for uptake of 1β(2′-propanoate)-3aα-H-4α(3″(R)-hydroxy-3″-propanoate)-7aβ-methylhexahydro-5-indanone and a desaturated analog. The MFS transporter, encoded by camM, was essential for uptake of 3,7(R),12(S)-trihydroxy-9-oxo-9,10-seco-23,24-bisnorchola-1,3,5(10)-trien-22-oate. These metabolites differ from cholate metabolites reported to be excreted by proteobacteria in that they retain an isopropanoyl side chain at C-17. The uptake of these metabolites was necessary for maximal growth on cholate: a ΔcamB mutant lacking the permease component of the ABC transporter and a ΔcamM mutant lacking the MFS transporter grew to 74% and 77%, respectively, of the yield of the wild type. This study demonstrates for the first time the requirement for specific transporters for uptake of cholate metabolites and highlights the importance and complexity of transport processes associated with bacterial steroid catabolism. PMID:23024344

  2. Foal Monocyte-Derived Dendritic Cells Become Activated upon Rhodococcus equi Infection▿ †

    PubMed Central

    Flaminio, M. Julia B. F.; Nydam, Daryl V.; Marquis, Hélène; Matychak, Mary Beth; Giguère, Steeve

    2009-01-01

    Susceptibility of foals to Rhodococcus equi pneumonia is exclusive to the first few months of life. The objective of this study was to investigate the immediate immunologic response of foal and adult horse antigen-presenting cells (APCs) upon infection with R. equi. We measured the activation of the antigen-presenting major histocompatibility complex (MHC) class II molecule, costimulatory molecules CD40 and CD86, the cytokine interleukin-12 (IL-12), and the transcriptional factor interferon regulatory factor 1 (IRF-1) in monocyte-derived macrophages (mMOs) and dendritic cells (mDCs) of adult horses and foals of different ages (from birth to 3 months of age) infected with virulent R. equi or its avirulent, plasmid-cured derivative. Infection with virulent or avirulent R. equi induced (P ≤ 0.01) the expression of IL-12p35 and IL-12p40 mRNAs in foal mMOs and mDCs at different ages. This response was likely mediated by the higher (P = 0.008) expression of IRF-1 in foal mDCs at birth than in adult horse mDCs. R. equi infection promoted comparable expression of costimulatory molecules CD86 and CD40 in foal and adult horse cells. The cytokine and costimulatory response by foal mDCs was not accompanied by robust MHC class II molecule expression. These data suggest that foal APCs detect the presence of R. equi and respond with the expression of the Th1-inducing cytokine IL-12. Nevertheless, there seems to be a limitation to MHC class II molecule expression which we hypothesize may compromise the efficient priming of naïve effector cells in early life. PMID:19109450

  3. Proteomic Analysis of Survival of Rhodococcus jostii RHA1 during Carbon Starvation

    PubMed Central

    Patrauchan, Marianna A.; Miyazawa, Daisuke; LeBlanc, Justin C.; Aiga, Carol; Florizone, Christine; Dosanjh, Manisha; Davies, Julian; Eltis, Lindsay D.

    2012-01-01

    Rhodococcus jostii RHA1, a catabolically diverse soil actinomycete, is highly resistant to long-term nutrient starvation. After 2 years of carbon starvation, 10% of the bacterial culture remained viable. To study the molecular basis of such resistance, we monitored the abundance of about 1,600 cytosolic proteins during a 2-week period of carbon source (benzoate) starvation. Hierarchical cluster analysis elucidated 17 major protein clusters and showed that most changes occurred during transition to stationary phase. We identified 196 proteins. A decrease in benzoate catabolic enzymes correlated with benzoate depletion, as did induction of catabolism of alternative substrates, both endogenous (lipids, carbohydrates, and proteins) and exogenous. Thus, we detected a transient 5-fold abundance increase for phthalate, phthalate ester, biphenyl, and ethyl benzene catabolic enzymes, which coincided with at least 4-fold increases in phthalate and biphenyl catabolic activities. Stationary-phase cells demonstrated an ∼250-fold increase in carbon monoxide dehydrogenase (CODH) concurrent with a 130-fold increase in CODH activity, suggesting a switch to CO or CO2 utilization. We observed two phases of stress response: an initial response occurred during the transition to stationary phase, and a second response occurred after the cells had attained stationary phase. Although SigG synthesis was induced during starvation, a ΔsigG deletion mutant showed only minor changes in cell survival. Stationary-phase cells underwent reductive cell division. The extreme capacity of RHA1 to survive starvation does not appear to involve novel mechanisms; rather, it seems to be due to the coordinated combination of earlier-described mechanisms. PMID:22798368

  4. Identification of genomic loci associated with Rhodococcus equi susceptibility in foals.

    PubMed

    McQueen, Cole M; Doan, Ryan; Dindot, Scott V; Bourquin, Jessica R; Zlatev, Zlatomir Z; Chaffin, M Keith; Blodgett, Glenn P; Ivanov, Ivan; Cohen, Noah D

    2014-01-01

    Pneumonia caused by Rhodococcus equi is a common cause of disease and death in foals. Although agent and environmental factors contribute to the incidence of this disease, the genetic factors influencing the clinical outcomes of R. equi pneumonia are ill-defined. Here, we performed independent single nucleotide polymorphism (SNP)- and copy number variant (CNV)-based genome-wide association studies to identify genomic loci associated with R. equi pneumonia in foals. Foals at a large Quarter Horse breeding farm were categorized into 3 groups: 1) foals with R. equi pneumonia (clinical group [N = 43]); 2) foals with ultrasonographic evidence of pulmonary lesions that never developed clinical signs of pneumonia (subclinical group [N = 156]); and, 3) foals without clinical signs or ultrasonographic evidence of pneumonia (unaffected group [N = 49]). From each group, 24 foals were randomly selected and used for independent SNP- and CNV-based genome-wide association studies (GWAS). The SNP-based GWAS identified a region on chromosome 26 that had moderate evidence of association with R. equi pneumonia when comparing clinical and subclinical foals. A joint analysis including all study foals revealed a 3- to 4-fold increase in odds of disease for a homozygous SNP within the associated region when comparing the clinical group with either of the other 2 groups of foals or their combination. The region contains the transient receptor potential cation channel, subfamily M, member 2 (TRPM2) gene, which is involved in neutrophil function. No associations were identified in the CNV-based GWAS. Collectively, these data identify a region on chromosome 26 associated with R. equi pneumonia in foals, providing evidence that genetic factors may indeed contribute to this important disease of foals. PMID:24892408

  5. Identification of Genomic Loci Associated with Rhodococcus equi Susceptibility in Foals

    PubMed Central

    McQueen, Cole M.; Doan, Ryan; Dindot, Scott V.; Bourquin, Jessica R.; Zlatev, Zlatomir Z.; Chaffin, M. Keith; Blodgett, Glenn P.; Ivanov, Ivan; Cohen, Noah D.

    2014-01-01

    Pneumonia caused by Rhodococcus equi is a common cause of disease and death in foals. Although agent and environmental factors contribute to the incidence of this disease, the genetic factors influencing the clinical outcomes of R. equi pneumonia are ill-defined. Here, we performed independent single nucleotide polymorphism (SNP)- and copy number variant (CNV)-based genome-wide association studies to identify genomic loci associated with R. equi pneumonia in foals. Foals at a large Quarter Horse breeding farm were categorized into 3 groups: 1) foals with R. equi pneumonia (clinical group [N = 43]); 2) foals with ultrasonographic evidence of pulmonary lesions that never developed clinical signs of pneumonia (subclinical group [N = 156]); and, 3) foals without clinical signs or ultrasonographic evidence of pneumonia (unaffected group [N = 49]). From each group, 24 foals were randomly selected and used for independent SNP- and CNV-based genome-wide association studies (GWAS). The SNP-based GWAS identified a region on chromosome 26 that had moderate evidence of association with R. equi pneumonia when comparing clinical and subclinical foals. A joint analysis including all study foals revealed a 3- to 4-fold increase in odds of disease for a homozygous SNP within the associated region when comparing the clinical group with either of the other 2 groups of foals or their combination. The region contains the transient receptor potential cation channel, subfamily M, member 2 (TRPM2) gene, which is involved in neutrophil function. No associations were identified in the CNV-based GWAS. Collectively, these data identify a region on chromosome 26 associated with R. equi pneumonia in foals, providing evidence that genetic factors may indeed contribute to this important disease of foals. PMID:24892408

  6. Transcriptomic Assessment of Isozymes in the Biphenyl Pathway of Rhodococcus sp. Strain RHA1†

    PubMed Central

    Gonçalves, Edmilson R.; Hara, Hirofumi; Miyazawa, Daisuke; Davies, Julian E.; Eltis, Lindsay D.; Mohn, William W.

    2006-01-01

    Rhodococcus sp. RHA1 grows on a broad range of aromatic compounds and vigorously degrades polychlorinated biphenyls (PCBs). Previous work identified RHA1 genes encoding multiple isozymes for most of the seven steps of the biphenyl (BPH) pathway, provided evidence for coexpression of some of these isozymes, and indicated the involvement of some of these enzymes in the degradation of BPH, ethylbenzene (ETB), and PCBs. To investigate the expression of these isozymes and better understand how they contribute to the robust degradative capacity of RHA1, we comprehensively analyzed the 9.7-Mb genome of RHA1 for BPH pathway genes and characterized the transcriptome of RHA1 growing on benzoate (BEN), BPH, and ETB. Sequence analyses revealed 54 potential BPH pathway genes, including 28 not previously reported. Transcriptomic analysis with a DNA microarray containing 70-mer probes for 8,213 RHA1 genes revealed a suite of 320 genes of diverse functions that were upregulated during growth both on BPH and on ETB, relative to growth on the control substrate, pyruvate. By contrast, only 65 genes were upregulated during growth on BEN. Quantitative PCR assays confirmed microarray results for selected genes and indicated that some of the catabolic genes were upregulated over 10,000-fold. Our analysis suggests that up to 22 enzymes, including 8 newly identified ones, may function in the BPH pathway of RHA1. The relative expression levels of catabolic genes did not differ for BPH and ETB, suggesting a common regulatory mechanism. This study delineated a suite of catabolic enzymes for biphenyl and alkyl-benzenes in RHA1, which is larger than previously recognized and which may serve as a model for catabolism in other environmentally important bacteria having large genomes. PMID:16957245

  7. Purification and properties of cholesterol oxidase and choline phosphohydrolase from Rhodococcus equi.

    PubMed Central

    Machang'u, R S; Prescott, J F

    1991-01-01

    Cholesterol oxidase (CO) and choline phosphohydrolase (CPH) exoenzymes were isolated from culture supernatants of Rhodococcus equi ATCC 33701 and their hemolytic and cytotoxic activities examined. The purifications involved differential ammonium sulphate precipitation, ion exchange and gel filtration chromatography. A purification of 32.8-fold and a yield of 0.3% of CO were determined by synergistic hemolysis of sheep red blood cells (SRBC) presensitized with Staphylococcus aureus beta toxin. The enzymatic activity of CO was also demonstrated by oxidation of aqueous cholesterol suspensions. The activity of CO was reversibly inhibited by concentration. A purification of 412.4-fold and a yield of 1.7% of CPH were determined by hydrolysis of p-nitrophenyphosphorylcholine. Purity of both exoenzymes was confirmed by immunoblotting. On sodium dodecyl sulphate polyacrylamide gel electrophoresis, the CO had a molecular mass (Mr) of 60 kd and the CPH a Mr of 65 kd. Choline phosphohydrolase did not hydrolyse sphingomyelin. Sphingomyelinase C (SMC) activity was however demonstrated in concentrated culture supernatants. This dissociation of SMC from CPH activity indicates that R. equi produces two distinct phospholipase C exoenzymes, a CPH and a SMC. Both CO and CPH combined, or individually, did not lyse native SRBC even with subsequent chilling of the cells at 4 degrees C ("hot-cold" treatment). Purified CO lysed beta toxin-sensitized SRBC. The CPH showed only minor hemolytic activity against such sensitized SRBC even at high concentrations. Combination of CO and CPH in lysis of beta toxin sensitized SRBC showed only minor additive rather than synergistic effects.(ABSTRACT TRUNCATED AT 250 WORDS) Images Fig. 2. Fig. 5. PMID:1790488

  8. Rhodococcus erythropolis BG43 Genes Mediating Pseudomonas aeruginosa Quinolone Signal Degradation and Virulence Factor Attenuation

    PubMed Central

    Müller, Christine; Birmes, Franziska S.; Rückert, Christian; Kalinowski, Jörn

    2015-01-01

    Rhodococcus erythropolis BG43 is able to degrade the Pseudomonas aeruginosa quorum sensing signal molecules PQS (Pseudomonas quinolone signal) [2-heptyl-3-hydroxy-4(1H)-quinolone] and HHQ [2-heptyl-4(1H)-quinolone] to anthranilic acid. Based on the hypothesis that degradation of HHQ might involve hydroxylation to PQS followed by dioxygenolytic cleavage of the heterocyclic ring and hydrolysis of the resulting N-octanoylanthranilate, the genome was searched for corresponding candidate genes. Two gene clusters, aqdA1B1C1 and aqdA2B2C2, each predicted to code for a hydrolase, a flavin monooxygenase, and a dioxygenase related to 1H-3-hydroxy-4-oxoquinaldine 2,4-dioxygenase, were identified on circular plasmid pRLCBG43 of strain BG43. Transcription of all genes was upregulated by PQS, suggesting that both gene clusters code for alkylquinolone-specific catabolic enzymes. An aqdR gene encoding a putative transcriptional regulator, which was also inducible by PQS, is located adjacent to the aqdA2B2C2 cluster. Expression of aqdA2B2C2 in Escherichia coli conferred the ability to degrade HHQ and PQS to anthranilic acid; however, for E. coli transformed with aqdA1B1C1, only PQS degradation was observed. Purification of the recombinant AqdC1 protein verified that it catalyzes the cleavage of PQS to form N-octanoylanthranilic acid and carbon monoxide and revealed apparent Km and kcat values for PQS of ∼27 μM and 21 s−1, respectively. Heterologous expression of the PQS dioxygenase gene aqdC1 or aqdC2 in P. aeruginosa PAO1 quenched the production of the virulence factors pyocyanin and rhamnolipid and reduced the synthesis of the siderophore pyoverdine. Thus, the toolbox of quorum-quenching enzymes is expanded by new PQS dioxygenases. PMID:26319870

  9. Detection of virulent Rhodococcus equi in exhaled air samples from naturally infected foals.

    PubMed

    Muscatello, G; Gilkerson, J R; Browning, G F

    2009-03-01

    Virulent Rhodococcus equi causes pyogranulomatous bronchopneumonia in foals. The route of infection of foals has been considered to be inhalation of aerosolized bacteria from soil that is contaminated with equine feces. Thus, disease caused by R. equi has been regarded as an opportunistic infection of environmental origin and not a contagious disease. In this study, we report the exhalation of virulent R. equi from the respiratory tract of naturally infected foals. A handheld air-monitoring system was used to recover virulent R. equi from the exhaled breath of foals, and the concentration of virulent R. equi organisms in exhaled air was compared to the concentration in environmental air samples taken from the holding pens and lane areas on farms. R. equi strains carrying the vapA gene of the virulence plasmid were detected by using colony blotting and DNA hybridization techniques in cultures of exhaled air from 67% (37/55) of foals tested. The concentration of virulent R. equi organisms in exhaled air from foals was significantly higher than that in environmental air (P<0.001). There were no significant differences in the median concentrations of virulent R. equi bacteria exhaled by clinically healthy or diseased foals. The high concentrations of virulent R. equi bacteria in exhaled air suggested that aerosol transmission between foals is possible and may have a significant impact on the prevalence of R. equi pneumonia on farms. The air sampling technique described is potentially useful as a noninvasive method for the detection and quantification of virulent R. equi in the respiratory tract of foals.

  10. Rhodococcus erythropolis BG43 Genes Mediating Pseudomonas aeruginosa Quinolone Signal Degradation and Virulence Factor Attenuation.

    PubMed

    Müller, Christine; Birmes, Franziska S; Rückert, Christian; Kalinowski, Jörn; Fetzner, Susanne

    2015-11-01

    Rhodococcus erythropolis BG43 is able to degrade the Pseudomonas aeruginosa quorum sensing signal molecules PQS (Pseudomonas quinolone signal) [2-heptyl-3-hydroxy-4(1H)-quinolone] and HHQ [2-heptyl-4(1H)-quinolone] to anthranilic acid. Based on the hypothesis that degradation of HHQ might involve hydroxylation to PQS followed by dioxygenolytic cleavage of the heterocyclic ring and hydrolysis of the resulting N-octanoylanthranilate, the genome was searched for corresponding candidate genes. Two gene clusters, aqdA1B1C1 and aqdA2B2C2, each predicted to code for a hydrolase, a flavin monooxygenase, and a dioxygenase related to 1H-3-hydroxy-4-oxoquinaldine 2,4-dioxygenase, were identified on circular plasmid pRLCBG43 of strain BG43. Transcription of all genes was upregulated by PQS, suggesting that both gene clusters code for alkylquinolone-specific catabolic enzymes. An aqdR gene encoding a putative transcriptional regulator, which was also inducible by PQS, is located adjacent to the aqdA2B2C2 cluster. Expression of aqdA2B2C2 in Escherichia coli conferred the ability to degrade HHQ and PQS to anthranilic acid; however, for E. coli transformed with aqdA1B1C1, only PQS degradation was observed. Purification of the recombinant AqdC1 protein verified that it catalyzes the cleavage of PQS to form N-octanoylanthranilic acid and carbon monoxide and revealed apparent Km and kcat values for PQS of ∼27 μM and 21 s(-1), respectively. Heterologous expression of the PQS dioxygenase gene aqdC1 or aqdC2 in P. aeruginosa PAO1 quenched the production of the virulence factors pyocyanin and rhamnolipid and reduced the synthesis of the siderophore pyoverdine. Thus, the toolbox of quorum-quenching enzymes is expanded by new PQS dioxygenases. PMID:26319870

  11. Seroepidemiological survey of Rhodococcus equi infection in asymptomatic horses and donkeys from southeast Turkey.

    PubMed

    Tel, O Y; Arserim, N B; Keskin, O

    2011-12-01

    In order to assess the level of Rhodococcus equi infection in southeast Turkey, 679 sera from healthy foals and adult horses and 78 sera from donkeys were tested by indirect ELISA using a R. equi reference strain (ATCC 33701) as antigen. Eighty (11.7%) sera from horses and 9 (11.5%) sera from donkeys with titres >0.85 were positive. The prevalence of seropositive horses in Sanliurfa Province was higher than in Diyarbakir Province; 56 (13.9%) horses in Sanliurfa Province and 24 (8.7%) horses in Diyarbakir Province were defined as seropositive. In Sanliurfa Province 14.5% of female (n=343) and 10.1% of male (n = 59) horses tested were defined as seropositive, while in Diyarbakir Province more males (11.4%, n=114) were seropositive than females (6.7%, n=163). Horses 1 to 5 years of age were found to have the highest seropositivity rate in both provinces. A total of 78 sera from donkeys were investigated in Sanliurfa Province, of which 9 (11.5%) were positive by ELISA. Among the 9 positive sera, 6 (12.8%) were from donkeys 1-5 years old and 3 (13.6%) were from donkeys >5 years of age. No positive sera were found in donkeys less than 1 year old. Five (12.5%) sera of females and 4 (10.5%) sera of males tested were positive. These results indicate the existence of R. equi in the horse populations in Sanliurfa and Diyarbakir Provinces. Similar infection rates were found for donkeys in Sanliurfa. This suggests the importance of serological surveys to diagnose R. equi infection in the region and to prevent the zoonotic risk.

  12. γ-Resorcylate Catabolic-Pathway Genes in the Soil Actinomycete Rhodococcus jostii RHA1

    PubMed Central

    Kasai, Daisuke; Araki, Naoto; Motoi, Kota; Yoshikawa, Shota; Iino, Toju; Imai, Shunsuke; Masai, Eiji

    2015-01-01

    The Rhodococcus jostii RHA1 gene cluster required for γ-resorcylate (GRA) catabolism was characterized. The cluster includes tsdA, tsdB, tsdC, tsdD, tsdR, tsdT, and tsdX, which encode GRA decarboxylase, resorcinol 4-hydroxylase, hydroxyquinol 1,2-dioxygenase, maleylacetate reductase, an IclR-type regulator, a major facilitator superfamily transporter, and a putative hydrolase, respectively. The tsdA gene conferred GRA decarboxylase activity on Escherichia coli. Purified TsdB oxidized NADH in the presence of resorcinol, suggesting that tsdB encodes a unique NADH-specific single-component resorcinol 4-hydroxylase. Mutations in either tsdA or tsdB resulted in growth deficiency on GRA. The tsdC and tsdD genes conferred hydroxyquinol 1,2-dioxygenase and maleylacetate reductase activities, respectively, on E. coli. Inactivation of tsdT significantly retarded the growth of RHA1 on GRA. The growth retardation was partially suppressed under acidic conditions, suggesting the involvement of tsdT in GRA uptake. Reverse transcription-PCR analysis revealed that the tsd genes constitute three transcriptional units, the tsdBADC and tsdTX operons and tsdR. Transcription of the tsdBADC and tsdTX operons was induced during growth on GRA. Inactivation of tsdR derepressed transcription of the tsdBADC and tsdTX operons in the absence of GRA, suggesting that tsd gene transcription is negatively regulated by the tsdR-encoded regulator. Binding of TsdR to the tsdR-tsdB and tsdT-tsdR intergenic regions was inhibited by the addition of GRA, indicating that GRA interacts with TsdR as an effector molecule. PMID:26319878

  13. Plasmid Profiles of Virulent Rhodococcus equi Strains Isolated from Infected Foals in Poland

    PubMed Central

    Kalinowski, Marcin; Grądzki, Zbigniew; Jarosz, Łukasz; Kato, Kiyoko; Hieda, Yu; Kakuda, Tsutomu; Takai, Shinji

    2016-01-01

    Rhodococcus equi is an important bacterial pathogen in foals up to 6 months old, widespread in horse farms all over the world. It was found that only virulent R. equi strains expressing 15–17 kDa virulence-associated protein (VapA) and having large virulence plasmid of 85–90 kb containing vapA gene are pathogenic for horses. To date, 12 plasmid types have been reported in VapA positive strains from horses. There are no data concerning plasmid types of Polish field R. equi strains isolated from horses and horse farm environment. The aim of the study is to determine plasmid profiles of virulent R. equi strains isolated in Poland from dead foals as well as from soil samples taken from horse breeding farms. Plasmid profiles of 10 clinical strains derived from 8 farms and 11 environmental strains from 3 farms, confirmed as virulent by PCR, were compared with 12 reference strains containing the known plasmid size and type. Plasmid DNAs were analysed by digestion with the restriction endonucleases BamHI, EcoRI, EcoT22I, and HindIII for detailed comparison and estimation of plasmid sizes. The results of RFLP analysis revealed that all except one isolates used in the study are classified as VapA 85 kb type I plasmid. One strain harboured VapA 87 kb type I plasmid. This is the first report of plasmid types of Polish field R. equi strains. The results of our preliminary investigations on horse farms located in central and eastern Poland indicate that the virulent R. equi strains thus far isolated from diseased foals and horse farms environment represent a highly uniform plasmid pattern. PMID:27074033

  14. Isolation and Characterization of Carbendazim-degrading Rhodococcus erythropolis djl-11

    PubMed Central

    Harvey, Paul R.; Li, Hongmei; Ren, Yan; Li, Jishun; Wang, Jianing; Yang, Hetong

    2013-01-01

    Carbendazim (methyl 1H-benzimidazol-2-yl carbamate) is one of the most widely used fungicides in agriculture worldwide, but has been reported to have adverse effects on animal health and ecosystem function. A highly efficient carbendazim-degrading bacterium (strain dj1-11) was isolated from carbendazim-contaminated soil samples via enrichment culture. Strain dj1-11 was identified as Rhodococcus erythropolis based on morphological, physiological and biochemical characters, including sequence analysis of the 16S rRNA gene. In vitro degradation of carbendazim (1000 mg·L−1) by dj1-11 in minimal salts medium (MSM) was highly efficient, and with an average degradation rate of 333.33 mg·L−1·d−1 at 28°C. The optimal temperature range for carbendazim degradation by dj1-11 in MSM was 25–30°C. Whilst strain dj1-11 was capable of metabolizing cabendazim as the sole source of carbon and nitrogen, degradation was significantly (P<0.05) increased by addition of 12.5 mM NH4NO3. Changes in MSM pH (4–9), substitution of NH4NO3 with organic substrates as N and C sources or replacing Mg2+ with Mn2+, Zn2+ or Fe2+ did not significantly affect carbendazim degradation by dj1-11. During the degradation process, liquid chromatography-mass spectrometry (LC-MS) detected the metabolites 2-aminobenzimidazole and 2-hydroxybenzimidazole. A putative carbendazim-hydrolyzing esterase gene was cloned from chromosomal DNA of djl-11 and showed 99% sequence homology to the mheI carbendazim-hydrolyzing esterase gene from Nocardioides sp. SG-4G. PMID:24098350

  15. Biofilm formation and partial biodegradation of polystyrene by the actinomycete Rhodococcus ruber: biodegradation of polystyrene.

    PubMed

    Mor, Roi; Sivan, Alex

    2008-11-01

    Polystyrene, which is one of the most utilized thermoplastics, is highly durable and is considered to be non-biodegradable. Hence, polystyrene waste accumulates in the environment posing an increasing ecological threat. In a previous study we have isolated a biofilm-producing strain (C208) of the actinomycete Rhodococcus ruber that degraded polyethylene films. Formation of biofilm, by C208, improved the biodegradation of polyethylene. Consequently, the present study aimed at monitoring the kinetics of biofilm formation by C208 on polystyrene, determining the physiological activity of the biofilm and analyzing its capacity to degrade polystyrene. Quantification of the biofilm biomass was performed using a modified crystal violet (CV) staining or by monitoring the protein content in the biofilm. When cultured on polystyrene flakes, most of the bacterial cells adhered to the polystyrene surface within few hours, forming a biofilm. The growth of the on polystyrene showed a pattern similar to that of a planktonic culture. Furthermore, the respiration rate, of the biofilm, exhibited a pattern similar to that of the biofilm growth. In contrast, the respiration activity of the planktonic population showed a constant decline with time. Addition of mineral oil (0.005% w/v), but not non-ionic surfactants, increased the biofilm biomass. Extended incubation of the biofilm for up to 8 weeks resulted in a small reduction in the polystyrene weight (0.8% of gravimetric weight loss). This study demonstrates the high affinity of C208 to polystyrene which lead to biofilm formation and, presumably, induced partial biodegradation. PMID:18401686

  16. Methylated Cytokinins from the Phytopathogen Rhodococcus fascians Mimic Plant Hormone Activity1[OPEN

    PubMed Central

    Radhika, Venkatesan; Ueda, Nanae; Tsuboi, Yuuri; Kojima, Mikiko; Kikuchi, Jun; Kudo, Takuji; Sakakibara, Hitoshi

    2015-01-01

    Cytokinins (CKs), a class of phytohormones that regulate plant growth and development, are also synthesized by some phytopathogens to disrupt the hormonal balance and to facilitate niche establishment in their hosts. Rhodococcus fascians harbors the fasciation (fas) locus, an operon encoding several genes homologous to CK biosynthesis and metabolism. This pathogen causes unique leafy gall symptoms reminiscent of CK overproduction; however, bacterial CKs have not been clearly correlated with the severe symptoms, and no virulence-associated unique CKs or analogs have been identified. Here, we report the identification of monomethylated N6-(∆2-isopentenyl)adenine and dimethylated N6-(∆2-isopentenyl)adenine (collectively, methylated cytokinins [MeCKs]) from R. fascians. MeCKs were recognized by a CK receptor and up-regulated type-A ARABIDOPSIS THALIANA RESPONSE REGULATOR genes. Treatment with MeCKs inhibited root growth, a hallmark of CK action, whereas the receptor mutant was insensitive. MeCKs were retained longer in planta than canonical CKs and were poor substrates for a CK oxidase/dehydrogenase, suggesting enhanced biological stability. MeCKs were synthesized by S-adenosyl methionine-dependent methyltransferases (MT1 and MT2) that are present upstream of the fas genes. The best substrate for methylation was isopentenyl diphosphate. MT1 and MT2 catalyzed distinct methylation reactions; only the MT2 product was used by FAS4 to synthesize monomethylated N6-(∆2-isopentenyl)adenine. The MT1 product was dimethylated by MT2 and used as a substrate by FAS4 to produce dimethylated N6-(∆2-isopentenyl)adenine. Chemically synthesized MeCKs were comparable in activity. Our results strongly suggest that MeCKs function as CK mimics and play a role in this plant-pathogen interaction. PMID:26251309

  17. The Intracellular Pathogen Rhodococcus equi Produces a Catecholate Siderophore Required for Saprophytic Growth▿

    PubMed Central

    Miranda-CasoLuengo, Raúl; Prescott, John F.; Vázquez-Boland, José A.; Meijer, Wim G.

    2008-01-01

    Little is known about the iron acquisition systems of the soilborne facultative intracellular pathogen Rhodococcus equi. We previously reported that expression of iupABC, encoding a putative siderophore ABC transporter system, is iron regulated and required for growth at low iron concentrations. Here we show that disruption of iupA leads to the concomitant accumulation of catecholates and a chromophore with absorption maxima at 341 and 528 nm during growth under iron-replete conditions. In contrast, the wild-type strain produces these compounds only in iron-depleted medium. Disruption of iupU and iupS, encoding nonribosomal peptide synthetases, prevented growth of the corresponding R. equi SID1 and SID3 mutants at low iron concentrations. However, only R. equi SID3 did not produce the chromophore produced by the wild-type strain during growth at low iron concentrations. The phenotype of R. equi SID3, but not that of R. equi SID1, could be rescued by coculture with the wild type, allowing growth at low iron concentrations. This strongly suggests that the product of the iupS gene is responsible for the synthesis of a diffusible compound required for growth at low iron concentrations. Transcription of iupU was constitutive, but that of iupS was iron regulated, with an induction of 3 orders of magnitude during growth in iron-depleted compared to iron-replete medium. Neither mutant was attenuated in vivo in a mouse infection model, indicating that the iupU- and iupS-encoded iron acquisition systems are primarily involved in iron uptake during saprophytic life. PMID:18156254

  18. Reduction kinetics of 3-hydroxybenzoate 6-hydroxylase from Rhodococcus jostii RHA1.

    PubMed

    Sucharitakul, Jeerus; Wongnate, Thanyaporn; Montersino, Stefania; van Berkel, Willem J H; Chaiyen, Pimchai

    2012-05-29

    3-Hydroxybenzoate 6-hydroxylase (3HB6H) from Rhodococcus jostii RHA1 is a nicotinamide adenine dinucleotide (NADH)-specific flavoprotein monooxygenase involved in microbial aromatic degradation. The enzyme catalyzes the para hydroxylation of 3-hydroxybenzoate (3-HB) to 2,5-dihydroxybenzoate (2,5-DHB), the ring-fission fuel of the gentisate pathway. In this study, the kinetics of reduction of the enzyme-bound flavin by NADH was investigated at pH 8.0 using a stopped-flow spectrophotometer, and the data were analyzed comprehensively according to kinetic derivations and simulations. Observed rate constants for reduction of the free enzyme by NADH under anaerobic conditions were linearly dependent on NADH concentrations, consistent with a one-step irreversible reduction model with a bimolecular rate constant of 43 ± 2 M(-1) s(-1). In the presence of 3-HB, observed rate constants for flavin reduction were hyperbolically dependent on NADH concentrations and approached a limiting value of 48 ± 2 s(-1). At saturating concentrations of NADH (10 mM) and 3-HB (10 mM), the reduction rate constant is ~51 s(-1), whereas without 3-HB, the rate constant is 0.43 s(-1) at a similar NADH concentration. A similar stimulation of flavin reduction was found for the enzyme-product (2,5-DHB) complex, with a rate constant of 45 ± 2 s(-1). The rate enhancement induced by aromatic ligands is not due to a thermodynamic driving force because Em 0 for the enzyme-substrate complex is -179 ± 1 mV compared to an E(m)(0) of -175 ± 2 mV for the free enzyme. It is proposed that the reduction mechanism of 3HB6H involves an isomerization of the initial enzyme-ligand complex to a fully activated form before flavin reduction takes place. PMID:22559817

  19. Ultralow Density, Monolithic WS2, MoS2, and MoS2/Graphene Aerogels.

    PubMed

    Worsley, Marcus A; Shin, Swanee J; Merrill, Matthew D; Lenhardt, Jeremy; Nelson, Art J; Woo, Leta Y; Gash, Alex E; Baumann, Theodore F; Orme, Christine A

    2015-05-26

    We describe the synthesis and characterization of monolithic, ultralow density WS2 and MoS2 aerogels, as well as a high surface area MoS2/graphene hybrid aerogel. The monolithic WS2 and MoS2 aerogels are prepared via thermal decomposition of freeze-dried ammonium thio-molybdate (ATM) and ammonium thio-tungstate (ATT) solutions, respectively. The densities of the pure dichalcogenide aerogels represent 0.4% and 0.5% of full density MoS2 and WS2, respectively, and can be tailored by simply changing the initial ATM or ATT concentrations. Similar processing in the presence of the graphene aerogel results in a hybrid structure with MoS2 sheets conformally coating the graphene scaffold. This layered motif produces a ∼50 wt % MoS2 aerogel with BET surface area of ∼700 m(2)/g and an electrical conductivity of 112 S/m. The MoS2/graphene aerogel shows promising results as a hydrogen evolution reaction catalyst with low onset potential (∼100 mV) and high current density (100 mA/cm(2) at 260 mV).

  20. Isolation and characterization of styrene metabolism genes from styrene-assimilating soil bacteria Rhodococcus sp. ST-5 and ST-10.

    PubMed

    Toda, Hiroshi; Itoh, Nobuya

    2012-01-01

    Styrene metabolism genes were isolated from styrene-assimilating bacteria Rhodococcus sp. ST-5 and ST-10. Strain ST-5 had a gene cluster containing four open reading frames which encoded styrene degradation enzymes. The genes showed high similarity to styABCD of Pseudomonas sp. Y2. On the other hand, strain ST-10 had only two genes which encoded styrene monooxygenase and flavin oxidoreductase (styAB). Escherichia coli transformants possessing the sty genes of strains ST-5 and ST-10 produced (S)-styrene oxide from styrene, indicating that these genes function as styrene degradation enzymes. Metabolite analysis by resting-cell reaction with gas chromatography-mass spectrometry revealed that strain ST-5 converts styrene to phenylacetaldehyde via styrene oxide by styrene oxide isomerase (styC) reaction. On the other hand, strain ST-10 lacked this enzyme, and thus accumulated styrene oxide as an intermediate. HPLC analysis showed that styrene oxide was spontaneously isomerized to phenylacetaldehyde by chemical reaction. The produced phenylacetaldehyde was converted to phenylacetic acid (PAA) in strain ST-10 as well as in strain ST-5. Furthermore, phenylacetic acid was converted to phenylacetyl-CoA by the catalysis of phenylacetate-CoA ligase in strains ST-5 and ST-10. This study proposes possible styrene metabolism pathways in Rhodococcus sp. strains ST-5 and ST-10. PMID:21996027

  1. Expression and characterization of styrene monooxygenases of Rhodococcus sp. ST-5 and ST-10 for synthesizing enantiopure (S)-epoxides.

    PubMed

    Toda, Hiroshi; Imae, Ryouta; Komio, Tomoko; Itoh, Nobuya

    2012-10-01

    Styrene monooxygenase (StyA, SMOA)- and flavin oxidoreductase (StyB, SMOB)-coding genes of styrene-assimilating bacteria Rhodococcus sp. ST-5 and ST-10 were successfully expressed in Escherichia coli. Determined amino acid sequences of StyAs and StyBs of ST-5 and ST-10 showed more similarity with those of Pseudomonas than with self-sufficient styrene monooxygenase (StyA2B) of Rhodococcus. Recombinant enzymes were purified from E. coli cells as functional proteins, and their properties were characterized in detail. StyBs (flavin oxidoreductase) of strains ST-5 and ST-10 have similar enzymatic properties to those of Pseudomonas, but StyB of strain ST-10 exhibited higher temperature stability than that of strain ST-5. StyAs of strains ST-5 and ST-10 catalyzed the epoxidation of vinyl side-chain of styrene and its derivatives and produced (S)-epoxides from styrene derivatives and showed high stereoselectivity. Both StyAs showed higher specific activity on halogenated styrene derivatives than on styrene itself. Additionally, the enzymes could catalyze the epoxidation of short-chain 1-alkenes to the corresponding (S)-epoxides. Aromatic compounds including styrene, 3-chlorostyrene, styrene oxide, and benzene exhibited marked inhibition of SMO reaction, although linear 1-alkene showed no inhibition of SMO activity at any concentration. PMID:22258641

  2. Draft Genome Sequence of a Versatile Hydrocarbon-Degrading Bacterium, Rhodococcus pyridinivorans Strain KG-16, Collected from Oil Fields in India

    PubMed Central

    Dawar, Chhavi; Phanindranath, R.; Mutnuri, Lakshmi; Dayal, Anurodh M.

    2016-01-01

    We describe here a 5.8-Mb draft genome sequence of Rhodococcus pyridinivorans strain KG-16, which was obtained from the soil samples collected from the oilfields of Krishna-Godavari basin in India. This genomic resource can provide insights into the pathways and mechanisms of hydrocarbon degradation and potentially aid in bioremediation applications. PMID:26868394

  3. High-Quality TiS2 For Li/TiS2 Cells

    NASA Technical Reports Server (NTRS)

    Huang, Chen-Kuo; Surampudi, Subbarao; Shen, David H.; Delgiannis, Fotios; Halpert, Gerald

    1992-01-01

    Modified process for synthesis of battery-grade titanium sulfide (TiS2) yields substantially improved material for Li/TiS2 electrochemical cells. Includes all-vapor-phase reaction between sulfur and titanium. Product less dense and more homogeneous, consists of smaller particles of higher crystalline quality, and purer. Cells have high cathode utilization and long cycle life performance. Expected to find applications in rechargeable lithium batteries for spacecraft, military equipment, telecommunication systems, automobiles, and consumer products.

  4. Gauge theory on fuzzy S2 × S2 and regularization on noncommutative Bbb R4

    NASA Astrophysics Data System (ADS)

    Behr, Wolfgang; Meyer, Frank; Steinacker, Harold

    2005-07-01

    We define U(n) gauge theory on fuzzy S2N × S2N as a multi-matrix model, which reduces to ordinary Yang-Mills theory on S2 × S2 in the commutative limit N→∞. The model can be used as a regularization of gauge theory on noncommutative Bbb R4θ in a particular scaling limit, which is studied in detail. We also find topologically non-trivial U(1) solutions, which reduce to the known ``fluxon'' solutions in the limit of Bbb R4θ, reproducing their full moduli space. Other solutions which can be interpreted as 2-dimensional branes are also found. The quantization of the model is defined non-perturbatively in terms of a path integral which is finite. A gauge-fixed BRST-invariant action is given as well. Fermions in the fundamental representation of the gauge group are included using a formulation based on SO(6), by defining a fuzzy Dirac operator which reduces to the standard Dirac operator on S2 × S2 in the commutative limit. The chirality operator and Weyl spinors are also introduced.

  5. Engineering xylose metabolism in triacylglycerol-producing Rhodococcus opacus for lignocellulosic fuel production

    PubMed Central

    2013-01-01

    Background There has been a great deal of interest in fuel productions from lignocellulosic biomass to minimize the conflict between food and fuel use. The bioconversion of xylose, which is the second most abundant sugar present after glucose in lignocellulosic biomass, is important for the development of cost effective bioprocesses to fuels. Rhodococcus opacus PD630, an oleaginous bacterium, accumulates large amounts of triacylglycerols (TAGs), which can be processed into advanced liquid fuels. However, R. opacus PD630 does not metabolize xylose. Results We generated DNA libraries from a Streptomyces bacterium capable of utilizing xylose and introduced them into R. opacus PD630. Xsp8, one of the engineered strains, was capable of growing on up to 180 g L-1 of xylose. Xsp8 grown in batch-cultures derived from unbleached kraft hardwood pulp hydrolysate containing 70 g L-1 total sugars was able to completely and simultaneously utilize xylose and glucose present in the lignocellulosic feedstock, and yielded 11.0 g L-1 of TAGs as fatty acids, corresponding to 45.8% of the cell dry weight. The yield of total fatty acids per gram of sugars consumed was 0.178 g, which consisted primarily of palmitic acid and oleic acid. The engineered strain Xsp8 was introduced with two heterologous genes from Streptomyces: xylA, encoding xylose isomerase, and xylB, encoding xylulokinase. We further demonstrated that in addition to the introduction and the concomitant expression of heterologous xylA and xylB genes, there is another molecular target in the R. opacus genome which fully enables the functionality of xylA and xylB genes to generate the robust xylose-fermenting strain capable of efficiently producing TAGs at high xylose concentrations. Conclusion We successfully engineered a R. opacus strain that is capable of completely utilizing high concentrations of xylose or mixed xylose/glucose simultaneously, and substantiated its suitability for TAG production. This study demonstrates

  6. A potential role for indoleamine 2,3-dioxygenase (IDO) in Rhodococcus equi infection.

    PubMed

    Heller, M C; Drew, C P; Jackson, K A; Griffey, S; Watson, J L

    2010-12-01

    Rhodococcus equi is a facultative intracellular bacterial pathogen of foals and immunocompromised humans that infects and proliferates within host macrophages and dendritic cells (DC). Indoleamine 2,3-dioxygenase (IDO), the initial enzyme in the tryptophan catabolism pathway, is upregulated in R. equi infected equine monocyte-derived DC and alveolar macrophages. Tryptophan requirement of R. equi for extracellular and intracellular growth was assessed. Growth of R. equi in minimal media did not require tryptophan and pharmacologic inhibition of IDO had no effect on intracellular proliferation of R. equi in equine alveolar macrophages. To investigate an immune-regulatory role for INDO in R. equi infection, IDO(-/-) (B6.129-(Indotm1Alm)/J) (n=22) and strain matched control (C57BL/6J) (n=20) mice were infected with R. equi by intraperitoneal injection, for 3 and 6 days. There was no difference in bacterial counts in liver or spleen between the two groups. Histological sections of liver and spleen were assigned inflammation scores and RT-PCR for interferon-gamma (IFNγ), tumor necrosis factor-alpha (TNFα), IL-4, IL-6, IL-10, IL-12, IL-23, forkhead box P3 (FoxP3), and transforming growth factor-beta (TGFβ) was performed on liver and spleen. Liver tissue of IDO(-/-) had higher inflammation scores at 6 days post-infection (PI) (P=0.05) and had decreased expression of TGFβ at 3 days PI (P=0.01), and FOXP3 at 3 days (P=0.02) and 6 days (P=0.03) compared to control mice. Immunostaining for FOXP3 showed lower numbers of FOXP3+ regulatory T cells in liver of IDO(-/-) mice 6 days PI. Prolonged inflammation in the liver tissue of IDO(-/-) mice corresponded with lower expression of FOXP3 and TGFβ in that tissue, and also with lower numbers of FOXP3+ regulatory T cells. We conclude that IDO expression by activated macrophages and DC plays a role in dampening the inflammatory response to R. equi infection in mice.

  7. Identification of Atypical Rhodococcus-Like Clinical Isolates as Dietzia spp. by 16S rRNA Gene Sequencing▿

    PubMed Central

    Pilares, Lilian; Agüero, Jesús; Vázquez-Boland, José A.; Martínez-Martínez, Luis; Navas, Jesús

    2010-01-01

    Rhodococcus equi and Dietzia spp. are closely related actinomycetes that show similar phenotypic properties. In humans, R. equi is an opportunistic pathogen associated with severe immunodeficiency. Dietzia spp. are environmental bacteria that have been isolated recently from clinical material and are presumptively associated with human infections. During the last 5 years, 15 bacterial isolates from human clinical samples collected at the Hospital Marqués de Valdecilla, Santander, Spain, were identified as R. equi by the API Coryne test. 16S rRNA gene sequencing confirmed seven isolates to be true R. equi strains, whereas the other eight were identified as members of the genus Dietzia, including Dietzia maris (four isolates), Dietzia natronolimnaea (two isolates), and Dietzia timorensis and Dietzia sp. (one isolate each). The eight Dietzia isolates were highly sensitive to 12 antimicrobial compounds. PMID:20220156

  8. [Synthesis of surfactants acinetobacter calcoaceticus IMV B-7241 and Rhodococcus erythropolis IMV Ac-5070 in the medium with glycerol].

    PubMed

    Pirog, T P; Shevchuk, T A; Konon, A D; Shuliakova, M A; Iutinskaia, G A

    2012-01-01

    It was established that glycerol, a byproduct of biodiesel production, may be used as substrate for synthesis of surfactants Rhodococcus erythropolis IMV Ac-5017 and Acinetobacter calcoaceticus IMV B-7241. Maximum indices of surfactants synthesis by the strain IMV B-7241 have been fixed, when the medium with glycerol included yeast autolysate and trace elements. It was shown that the surfactants synthesis could be intensified when cultivating A. calcoaceticus IMV B-7241 and R. erythropolis IMV Ac-5017 on the mixture of hexadecane and glycerol in concentration of 0.5-1.0% (in volume). When using inoculate grown on hexadecane, the conditional concentration of the surfactant A.calcoaceticus IMV B-7241 on the mixed substrate was higher by 56-100, and that of R. erythropolis IMVAc-5017 by 260-320 % than on the monosubstrate glycerol. The paper is presented in Russian.

  9. Multiple reuses of Rhodococcus ruber TH3 free cells to produce acrylamide in a membrane dispersion microreactor.

    PubMed

    Li, Jiahui; Liu, Junqi; Chen, Jie; Wang, Yujun; Luo, Guangsheng; Yu, Huimin

    2015-01-01

    In this work, multiple reuses of Rhodococcus ruber TH3 free cells for the hydration of acrylonitrile to produce acrylamide in a membrane dispersion microreactor were carried out. Through using a centrifuge, the reactions reached 39.9, 39.5, 38.6 and 38.0wt% of the final acrylamide product concentration respectively within 35min in a four cycle reuse of free cells. In contrast, using a stirring tank, free cells could only be used once with the same addition speed of acrylonitrile with a microreactor. Through observing the dissolution behavior of acrylonitrile microdroplets in a free cell solution using a coaxial microfluidic device and microscope, it was found that the acrylonitrile microdroplets with a diameter of 75μm were rarely observed within a length of 2cm channel within 10s, which illustrated that the microreactor can intensify the reaction rate to reduce the inhibition of acrylonitrile and acrylamide.

  10. The Rhodococcus opacus TadD protein mediates triacylglycerol metabolism by regulating intracellular NAD(P)H pools

    PubMed Central

    2013-01-01

    Background The Gram-positive actinomycete Rhodococcus opacus is widely studied for its innate ability to store large amounts of carbon in the form of triacylglycerol (TAG). Several groups have demonstrated that R. opacus PD630 is capable of storing anywhere from 50 to 76% of its cell dry weight as TAG. While numerous studies have focused on phenomenological aspects of this process, few have sought to identify the underlying molecular and biochemical mechanisms responsible for the biosynthesis and storage of this molecule. Results Herein we further our previous efforts to illuminate the black box that is lipid metabolism in actinomycetes using a genetic approach. Utilizing a simple, colorimetric genetic screen, we have identified a gene, referred to herein as tadD (triacylglycerol accumulation deficient), which is critical for TAG biosynthesis in R. opacus PD630. Furthermore, we demonstrate that the purified protein product of this gene is capable of oxidizing glyceraldehyde-3-phosphate, while simultaneously reducing NAD(P)+ to NAD(P)H. Supporting this biochemical data, we observed that the ratio of NAD(P)H to NAD(P)+ is elevated in wildtype cultures grown under lipid production conditions as compared to cultures grown under vegetative growth conditions, while the mutant strain demonstrated no change irrespective of growth conditions. Finally, we demonstrate that over-expressing a putative phosphorylative glyceraldehyde-3-phosphate dehydrogenase leads to decreased TAG production during growth on TAG accumulation conditions. Conclusion Taken together, the data support the identification of a key metabolic branch point separating vegetative growth and lipid accumulation lifestyles in Rhodococcus. PMID:24209886

  11. An Invertron-Like Linear Plasmid Mediates Intracellular Survival and Virulence in Bovine Isolates of Rhodococcus equi

    PubMed Central

    Valero-Rello, Ana; Hapeshi, Alexia; Anastasi, Elisa; Alvarez, Sonsiray; Scortti, Mariela; Meijer, Wim G.; MacArthur, Iain

    2015-01-01

    We report a novel host-associated virulence plasmid in Rhodococcus equi, pVAPN, carried by bovine isolates of this facultative intracellular pathogenic actinomycete. Surprisingly, pVAPN is a 120-kb invertron-like linear replicon unrelated to the circular virulence plasmids associated with equine (pVAPA) and porcine (pVAPB variant) R. equi isolates. pVAPN is similar to the linear plasmid pNSL1 from Rhodococcus sp. NS1 and harbors six new vap multigene family members (vapN to vapS) in a vap pathogenicity locus presumably acquired via en bloc mobilization from a direct predecessor of equine pVAPA. Loss of pVAPN rendered R. equi avirulent in macrophages and mice. Mating experiments using an in vivo transconjugant selection strategy demonstrated that pVAPN transfer is sufficient to confer virulence to a plasmid-cured R. equi recipient. Phylogenetic analyses assigned the vap multigene family complement from pVAPN, pVAPA, and pVAPB to seven monophyletic clades, each containing plasmid type-specific allelic variants of a precursor vap gene carried by the nearest vap island ancestor. Deletion of vapN, the predicted “bovine-type” allelic counterpart of vapA, essential for virulence in pVAPA, abrogated pVAPN-mediated intramacrophage proliferation and virulence in mice. Our findings support a model in which R. equi virulence is conferred by host-adapted plasmids. Their central role is mediating intracellular proliferation in macrophages, promoted by a key vap determinant present in the common ancestor of the plasmid-specific vap islands, with host tropism as a secondary trait selected during coevolution with specific animal species. PMID:25895973

  12. Deep-sea Rhodococcus sp. BS-15, lacking the phytopathogenic fas genes, produces a novel glucotriose lipid biosurfactant.

    PubMed

    Konishi, Masaaki; Nishi, Shinro; Fukuoka, Tokuma; Kitamoto, Dai; Watsuji, Tomo-O; Nagano, Yuriko; Yabuki, Akinori; Nakagawa, Satoshi; Hatada, Yuji; Horiuchi, Jun-Ichi

    2014-08-01

    Glycolipid biosurfactant-producing bacteria were isolated from deep-sea sediment collected from the Okinawa Trough. Isolate BS15 produced the largest amount of the glycolipid, generating up to 6.31 ± 1.15 g l(-1) after 4 days at 20 °C. Glucose was identified in the hydrolysate of the purified major component of the biosurfactant glycolipid. According to gas chromatography/mass spectrometry analysis, the hydrophobic moieties in the major component were hexadecanoate, octadecanoate, 3-hydroxyhexadecanoate, 2-hydroxyoctanoate, and succinate. The molecular weight of the purified major glycolipid was calculated to be 1,211, while (1)H and (13)C nuclear magnetic resonance spectra confirmed that the major component consisted of 2 mol of α-glucoside and 1 mol of β-glucoside. The molecular structure was assigned as novel trisaccharide-type glycolipid biosurfactant, glucotriose lipids. The critical micelle concentration of the purified major glycolipid was 2.3 × 10(-6) M, with a surface tension of 29.5 mN m(-1). Phylogenetic analysis showed isolate BS15 was closely related to a Rhodococcus strains isolated from Antarctica, and to Rhodococcus fascians, a phytopathogen. PCR analysis showed that the fasA, fasB, fasC, fasD, fasE, and fasF genes, which are involved in phytohormone-like cytokinin production, were not present in the genome of BS15; however, analysis of a draft genome sequence of BS15 (5.5 Mb) identified regions with 31 %, 53 %, 46 %, 30 %, and 31 % DNA sequence identity to the fasA, fasB, fasC, and fasD genes, respectively.

  13. Superstring theory on AdS 2× S2 as a coset supermanifold

    NASA Astrophysics Data System (ADS)

    Berkovits, N.; Bershadsky, M.; Hauer, T.; Zhukov, S.; Zwiebach, B.

    We quantize the superstring on the AdS 2× S2 background with Ramond-Ramond flux using a PSU(1,1|2)/ U(1)× U(1) sigma model with a WZ term. One-loop conformal invariance of the model is guaranteed by a general mechanism which holds for coset spaces G/ H where G is Ricci-flat and H is the invariant locus of a Z4 automorphism of G. This mechanism gives conformal theories for the PSU(1,1|2)× PSU(2|2)/ SU(2)× SU(2) and PSU(2,2|4)/ SO(4,1)× SO(5) coset spaces, suggesting our results might be useful for quantizing the superstring on AdS 3× S3 and AdS 5× S5 backgrounds.

  14. [Variation in the composition of Rhodococcus rodochrous GNP-OHP-38r cell membrane fatty acids in response to temperature and salinity].

    PubMed

    Pucci, G N; Pucci, H

    2004-01-01

    The members of the genus Rhodococcus are frequent and abundant inhabitants of polluted areas with hydrocarbons and they resist the salinity present in the central Patagonia. This genus has good capacity to eliminate pollution produced by hydrocarbons that constitutes the biggest pollutant agent in the region. The present work studies the answer in the composition of its fatty acids under the combined action of the temperature and saline concentration of an isolated stump of a landfarming system. The strategy of Rhodococcus rodochrous strain GNP-OHP-38r in front of the thermal-osmotic stress is the increase of the percentage of the total saturated fatty acids (n:0); fatty acids branched in the terminal carbon with hidroxyl group in position 2 (n:0 iso 2 OH) and saturated with group methyl in carbon 10 (n:0 10 metil) when the temperature is increased. These acids increase while the percentage of n:1 cis decrease.

  15. Biodegradation of variable-chain-length n-alkanes in Rhodococcus opacus R7 and the involvement of an alkane hydroxylase system in the metabolism

    PubMed Central

    2014-01-01

    Rhodococcus opacus R7 is a Gram-positive bacterium isolated from a polycyclic aromatic hydrocarbon contaminated soil for its versatile metabolism; indeed the strain is able to grow on naphthalene, o-xylene, and several long- and medium-chain n-alkanes. In this work we determined the degradation of n-alkanes in Rhodococcus opacus R7 in presence of n-dodecane (C12), n-hexadecane (C16), n-eicosane (C20), n-tetracosane (C24) and the metabolic pathway in presence of C12. The consumption rate of C12 was 88%, of C16 was 69%, of C20 was 51% and of C24 it was 78%. The decrement of the degradation rate seems to be correlated to the length of the aliphatic chain of these hydrocarbons. On the basis of the metabolic intermediates determined by the R7 growth on C12, our data indicated that R. opacus R7 metabolizes medium-chain n-alkanes by the primary alcohol formation. This represents a difference in comparison with other Rhodococcus strains, in which a mixture of the two alcohols was observed. By GC-MSD analysis we also identified the monocarboxylic acid, confirming the terminal oxidation. Moreover, the alkB gene cluster from R. opacus R7 was isolated and its involvement in the n-alkane degradation system was investigated by the cloning of this genomic region into a shuttle-vector E. coli-Rhodococcus to evaluate the alkane hydroxylase activity. Our results showed an increased biodegradation of C12 in the recombinant strain R. erythropolis AP (pTipQT1-alkR7) in comparison with the wild type strain R. erythropolis AP. These data supported the involvement of the alkB gene cluster in the n-alkane degradation in the R7 strain. PMID:25401074

  16. Draft Genome Sequence of the Endophytic Strain Rhodococcus kyotonensis KB10, a Potential Biodegrading and Antibacterial Bacterium Isolated from Arabidopsis thaliana

    PubMed Central

    Hong, Chi Eun; Jo, Sung Hee

    2016-01-01

    Rhodococcus kyotonensis KB10 is an endophytic bacterium isolated from Arabidopsis thaliana. The organism showed mild antibacterial activity against the phytopathogen Pseudomonas syringae pv. tomato DC3000. This study reports the genome sequence of R. kyotonensis KB10. This bacterium contains an ectoine biosynthesis gene cluster and has the potential to degrade nitroaromatic compounds. The identified bacterium may be a suitable biocontrol agent and degrader of environmental pollutants. PMID:27389269

  17. The modulation of Schottky barriers of metal-MoS2 contacts via BN-MoS2 heterostructures.

    PubMed

    Su, Jie; Feng, Liping; Zhang, Yan; Liu, Zhengtang

    2016-06-22

    Using first-principles calculations within density functional theory, we systematically studied the effect of BN-MoS2 heterostructure on the Schottky barriers of metal-MoS2 contacts. Two types of FETs are designed according to the area of the BN-MoS2 heterostructure. Results show that the vertical and lateral Schottky barriers in all the studied contacts, irrespective of the work function of the metal, are significantly reduced or even vanish when the BN-MoS2 heterostructure substitutes the monolayer MoS2. Only the n-type lateral Schottky barrier of Au/BN-MoS2 contact relates to the area of the BN-MoS2 heterostructure. Notably, the Pt-MoS2 contact with n-type character is transformed into a p-type contact upon substituting the monolayer MoS2 by a BN-MoS2 heterostructure. These changes of the contact natures are ascribed to the variation of Fermi level pinning, work function and charge distribution. Analysis demonstrates that the Fermi level pinning effects are significantly weakened for metal/BN-MoS2 contacts because no gap states dominated by MoS2 are formed, in contrast to those of metal-MoS2 contacts. Although additional BN layers reduce the interlayer interaction and the work function of the metal, the Schottky barriers of metal/BN-MoS2 contacts still do not obey the Schottky-Mott rule. Moreover, different from metal-MoS2 contacts, the charges transfer from electrodes to the monolayer MoS2, resulting in an increment of the work function of these metals in metal/BN-MoS2 contacts. These findings may prove to be instrumental in the future design of new MoS2-based FETs with ohmic contact or p-type character.

  18. S -matrix algebra of the AdS2×S2 superstring

    NASA Astrophysics Data System (ADS)

    Hoare, Ben; Pittelli, Antonio; Torrielli, Alessandro

    2016-03-01

    In this paper, we find the Yangian algebra responsible for the integrability of the AdS2×S2×T6 superstring in the planar limit. We demonstrate the symmetry of the corresponding exact S matrix in the massive sector, including the presence of the secret symmetry. We give two alternative presentations of the Hopf algebra. The first takes the usual canonical form, which, as the relevant representations are long, leads to a Yangian representation that is not of evaluation type. After investigating the relationship between cocommutativity, evaluation representations and the shortening condition, we find an alternative realization of the Yangian whose representation is of the evaluation type. Finally, we explore two limits of the S matrix. The first is the classical r matrix, where we rediscover the need for a secret symmetry also in this context. The second is the simplifying zero-coupling limit. In this limit, taking the S matrix as a generating R matrix for the algebraic Bethe ansatz, we obtain an effective model of free fermions on a periodic spin-chain. This limit should provide hints to the one-loop anomalous dimension of the mysterious superconformal quantum mechanics dual to the superstring theory in this geometry.

  19. The ρ(1S, 2S), ψ(1S, 2S), Υ(1S, 2S) and ψ t (1S, 2S) Mesons in a Double Pole QCD Sum Rule

    NASA Astrophysics Data System (ADS)

    Maior de Sousa, M. S.; da Silva, R. Rodrigues

    2016-09-01

    We use the method of double pole QCD sum rule, which is basically a fit with two exponentials of the correlation function, where we can extract the masses and decay constants of mesons as a function of the Borel mass. We apply this method to study the mesons: ρ(1S,2S), ψ(1S,2S), Υ(1S,2S), and ψ t (1S,2S). We also present predictions for the toponiuns masses ψ t (1S,2S) of m(1S)=357 GeV and m(2S)=374 GeV.

  20. Characterization of biphenyl catabolic genes of gram-positive polychlorinated biphenyl degrader rhodococcus sp. strain RHA1

    SciTech Connect

    Masai, Eiji; Hatta, Takashi; Kimbara, Kazuhide

    1995-06-01

    Rhodococcus sp. strain RHA1 is a gram-positive polychlorinated biphenyl (PCB) degrader which can degrade 10 ppm of PCB-48 (equivalent to Aroclor 1248), including tri-, tetra-, and pentachlorobiphenyls, in a few days. We isolated the 7.6-kb EcoRI-BamHI fragment carrying the biphenyl catabolic genes of RHA1 and determined their nucleotide sequence. On the basis of deduced amino acid sequence homology, we identified six bph genes, bphA1A2A3A4, bphB, and bphC, that are responsible for the initial three steps of biphenyl degradation. The order of bph genes in RHA1 is bphA1A2A3A4-bphC-bphB. This gene order differs from that of other PCB degraders reported previously. The amino acid sequences deduced from the RHA1 bph genes have a higher degree of homology with the tod genes from Pseudomonas putida F1 (49 to 79%) than with the bph genes of Pseudomonas sp. strains KF707 and KKS102 (30-65%). FIn Escherichia coli, bphA gene activity was not observed even when expression vectors were used. The activities of bphB and bphC, however, were confirmed by observing the transformation of biphenyl to a meta-cleavage compound with the aid of benzene dioxygenase activity that complemented the bphA gene activity (S. Irie, S. Djoi, T. Yorifuji, M. Takagi, and K. Yano, J. Bacteriol. 169:5174-5179, 1987). The expected products of the cloned bph genes, except bphA3, were observed in E. coli in an in vitro transcription-translation system. Insertion mutations of bphA1 and bphC of Rhodococcus sp. strain RHA1 were constructed by gene replacement with cloned gene fragments. The bphA1 and bphC insertion mutants lost the ability to grow on biphenyl, demonstrating that the cloned bph genes are essential for biphenyl catabolism in this strain. 31 refs., 5 figs., 2 tabs.

  1. Hemolytic activity of a bacterial trehalose lipid biosurfactant produced by Rhodococcus sp.: evidence for a colloid-osmotic mechanism.

    PubMed

    Zaragoza, Ana; Aranda, Francisco J; Espuny, María J; Teruel, José A; Marqués, Ana; Manresa, Angeles; Ortiz, Antonio

    2010-06-01

    A succinoyl trehalose lipid produced by Rhodococcus sp. behaves as a biological surfactant and also displays various interesting biological activities. Trehalose lipid has been shown to have a great tendency to partition into phospholipid membranes; therefore, the characterization of its interaction with biological membranes is of central importance. In this work, human red blood cells have been used as an experimental model. Trehalose lipid causes the swelling of human erythrocytes followed by hemolysis at concentrations well below its critical micellar concentration. Kinetic measurements show that, upon addition of trehalose lipid, K(+) release precedes that of hemoglobin. Osmotic protectants of the appropriate size added to the external medium make it possible to avoid hemolysis. The results indicate that trehalose lipid causes the hemolysis of human erythrocytes by a colloid-osmotic mechanism, most likely by formation of enhanced permeability domains, or "pores" enriched in the biosurfactant, within the erythrocyte membrane. Scanning electron microscopy shows trehalose lipid-induced spherocytosis and echinocytosis of red blood cells, which fits well within the framework of the bilayer-couple hypothesis. The presented results contribute to establishing a molecular basis for the biological properties of this trehalose lipid biosurfactant. PMID:20146489

  2. Electrical resistivity tomography to monitor enhanced biodegradation of hydrocarbons with Rhodococcus erythropolis T902.1 at a pilot scale.

    PubMed

    Masy, Thibaut; Caterina, David; Tromme, Olivier; Lavigne, Benoît; Thonart, Philippe; Hiligsmann, Serge; Nguyen, Frédéric

    2016-01-01

    Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of such a technique (by biostimulation or bioaugmentation) strongly depends on the environment affected and is still difficult to predict a priori. In order to overcome these uncertainties, Electrical Resistivity Tomography (ERT) appears as a valuable non-invasive tool to detect soil heterogeneities and to monitor biodegradation. The main objective of this study was to isolate an electrical signal linked to an enhanced bacterial activity with ERT, in an aged HC-contaminated clay loam soil. To achieve this, a pilot tank was built to mimic field conditions. Compared to a first insufficient biostimulation phase, bioaugmentation with Rhodococcus erythropolis T902.1 led to a HC depletion of almost 80% (6900 to 1600ppm) in 3months in the center of the contaminated zone, where pollutants were less bioavailable. In the meantime, lithological heterogeneities and microbial activities (growth and biosurfactant production) were successively discriminated by ERT images. In the future, this cost-effective technique should be more and more transferred to the field in order to monitor biodegradation processes and assist in selecting the most appropriate remediation technique.

  3. Adaptive response of Rhodococcus opacus PWD4 to salt and phenolic stress on the level of mycolic acids.

    PubMed

    de Carvalho, Carla C C R; Fischer, Martin A; Kirsten, Sandra; Würz, Birgit; Wick, Lukas Y; Heipieper, Hermann J

    2016-12-01

    Mycolata form a group of Gram-positive bacteria with unique cell envelope structures that are known for their high tolerance against antibiotics and both aromatic and aliphatic hydrocarbons. An important part of the unique surface structure of the mycolata is the presence of long chain α-alkyl-β-hydroxy fatty acids, the mycolic acids. In order to investigate the adaptive changes in the mycolic acid composition, we investigated the composition of mycolic acids during the response both to osmotic stress caused by NaCl and to 4-chlorophenol in Rhodococcus opacus PWD4. This bacterium was chosen as it is known to adapt to different kinds of stresses. In addition, it is a potential biocatalyst in bioremediation as well as for biotechnological applications. In the present study, cells of R. opacus PWD4, grown in liquid cultures, responded to toxic concentrations of NaCl by increasing the ratio between mycolic acids and membrane phospholipid fatty acids (MA/PLFA-ratio). Cells reacted to both NaCl and 4-chlorophenol by decreasing both the average chain length and the unsaturation index of their mycolic acids. These changes in mycolic acid composition correlated with increases in cell surface hydrophobicity and saturation of membrane fatty acids, demonstrating the relation between mycolic acid and phospholipid synthesis and their contribution to cell surface properties of R. opacus PWD4. PMID:27620730

  4. Crystallization and preliminary X-ray analysis of a bacterial l-amino-acid oxidase from Rhodococcus opacus

    SciTech Connect

    Faust, Annette; Geueke, Birgit; Niefind, Karsten; Hummel, Werner; Schomburg, Dietmar

    2006-03-01

    The crystallization and preliminary X-ray analysis of a bacterial l-amino acid oxidase from R. opacus is described. The homodimeric protein contains one molecule of non-covalently bound FAD per monomer. Crystals with good diffraction properties were grown in two different orthorhombic space groups (P2{sub 1}2{sub 1}2{sub 1} and C222{sub 1}). l-Amino-acid oxidases (EC 1.4.3.2) catalyse the stereospecific oxidative deamination of an l-amino-acid substrate to an α-keto acid with the production of ammonia and hydrogen peroxide. In this study, the crystallization and preliminary X-ray analysis of a bacterial l-amino-acid oxidase from Rhodococcus opacus (RoLAAO) is described. RoLAAO is a dimeric protein consisting of two identical subunits of 489 amino acids with a calculated molecular weight of 54.2 kDa and a non-covalently bound FAD molecule. RoLAAO was crystallized by the vapour-diffusion method in two different space groups: P2{sub 1}2{sub 1}2{sub 1} (unit-cell parameters a = 65.7, b = 109.7, c = 134.4 Å) and C222{sub 1} (unit-cell parameters a = 68.3, b = 88.4, c = 186.6 Å). Both crystal forms diffracted X-rays to a resolution of at least 1.6 Å.

  5. Modulation of the Hormone Setting by Rhodococcus fascians Results in Ectopic KNOX Activation in Arabidopsis1[W][OA

    PubMed Central

    Depuydt, Stephen; Doležal, Karel; Van Lijsebettens, Mieke; Moritz, Thomas; Holsters, Marcelle; Vereecke, Danny

    2008-01-01

    The biotrophic actinomycete Rhodococcus fascians has a profound impact on plant development and a common aspect of the symptomatology is the deformation of infected leaves. In Arabidopsis (Arabidopsis thaliana), the serrated leaf margins formed upon infection resemble the leaf phenotype of transgenic plants with ectopic expression of KNOTTED-like homeobox (KNOX) genes. Through transcript profiling, we demonstrate that class-I KNOX genes are transcribed in symptomatic leaves. Functional analysis revealed that BREVIPEDICELLUS/KNOTTED-LIKE1 and mainly SHOOT MERISTEMLESS were essential for the observed leaf dissection. However, these results also positioned the KNOX genes downstream in the signaling cascade triggered by R. fascians infection. The much faster activation of ARABIDOPSIS RESPONSE REGULATOR5 and the establishment of homeostatic and feedback mechanisms to control cytokinin (CK) levels support the overrepresentation of this hormone in infected plants due to the secretion by the pathogen, thereby placing the CK response high up in the cascade. Hormone measurements show a net decrease of tested CKs, indicating either that secretion by the bacterium and degradation by the plant are in balance, or, as suggested by the strong reaction of 35S:CKX plants, that other CKs are at play. At early time points of the interaction, activation of gibberellin 2-oxidase presumably installs a local hormonal setting favorable for meristematic activity that provokes leaf serrations. The results are discussed in the context of symptom development, evasion of plant defense, and the establishment of a specific niche by R. fascians. PMID:18184732

  6. Simple Preparation of Rhodococcus erythropolis DSM 44534 as Biocatalyst to Oxidize Diols into the Optically Active Lactones.

    PubMed

    Martinez-Rojas, Enriqueta; Olejniczak, Teresa; Neumann, Konrad; Garbe, Leif-Alexander; Boratyñski, Filip

    2016-09-01

    In the current study, we present a green toolbox to produce ecological compounds like lactone moiety. Rhodococcus erythropolis DSM 44534 cells have been used to oxidize both decane-1,4-diol () and decane-1,5-diol () into the corresponding γ- () and δ-decalactones () with yield of 80% and enantiomeric excess (ee) = 75% and ee = 90%, respectively. Among oxidation of meso diols, (-)-(1S,5R)-cis-3-oxabicyclo[4.3.0]non-7-en-2-one (5a) with 56% yield and ee = 76% as well as (-)-(2R,3S)-cis-endo-3-oxabicyclo[2.2.1]dec-7-en-2-one (6a) with 100% yield and ee = 90% were formed. It is worth mentioning that R. erythropolis DSM 44534 grew in a mineral medium containing ethanol as the sole source of energy and carbon Chirality 28:623-627, 2016. © 2016 Wiley Periodicals, Inc. PMID:27496202

  7. Electrical resistivity tomography to monitor enhanced biodegradation of hydrocarbons with Rhodococcus erythropolis T902.1 at a pilot scale.

    PubMed

    Masy, Thibaut; Caterina, David; Tromme, Olivier; Lavigne, Benoît; Thonart, Philippe; Hiligsmann, Serge; Nguyen, Frédéric

    2016-01-01

    Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of such a technique (by biostimulation or bioaugmentation) strongly depends on the environment affected and is still difficult to predict a priori. In order to overcome these uncertainties, Electrical Resistivity Tomography (ERT) appears as a valuable non-invasive tool to detect soil heterogeneities and to monitor biodegradation. The main objective of this study was to isolate an electrical signal linked to an enhanced bacterial activity with ERT, in an aged HC-contaminated clay loam soil. To achieve this, a pilot tank was built to mimic field conditions. Compared to a first insufficient biostimulation phase, bioaugmentation with Rhodococcus erythropolis T902.1 led to a HC depletion of almost 80% (6900 to 1600ppm) in 3months in the center of the contaminated zone, where pollutants were less bioavailable. In the meantime, lithological heterogeneities and microbial activities (growth and biosurfactant production) were successively discriminated by ERT images. In the future, this cost-effective technique should be more and more transferred to the field in order to monitor biodegradation processes and assist in selecting the most appropriate remediation technique. PMID:26697744

  8. Adaptive response of Rhodococcus opacus PWD4 to salt and phenolic stress on the level of mycolic acids.

    PubMed

    de Carvalho, Carla C C R; Fischer, Martin A; Kirsten, Sandra; Würz, Birgit; Wick, Lukas Y; Heipieper, Hermann J

    2016-12-01

    Mycolata form a group of Gram-positive bacteria with unique cell envelope structures that are known for their high tolerance against antibiotics and both aromatic and aliphatic hydrocarbons. An important part of the unique surface structure of the mycolata is the presence of long chain α-alkyl-β-hydroxy fatty acids, the mycolic acids. In order to investigate the adaptive changes in the mycolic acid composition, we investigated the composition of mycolic acids during the response both to osmotic stress caused by NaCl and to 4-chlorophenol in Rhodococcus opacus PWD4. This bacterium was chosen as it is known to adapt to different kinds of stresses. In addition, it is a potential biocatalyst in bioremediation as well as for biotechnological applications. In the present study, cells of R. opacus PWD4, grown in liquid cultures, responded to toxic concentrations of NaCl by increasing the ratio between mycolic acids and membrane phospholipid fatty acids (MA/PLFA-ratio). Cells reacted to both NaCl and 4-chlorophenol by decreasing both the average chain length and the unsaturation index of their mycolic acids. These changes in mycolic acid composition correlated with increases in cell surface hydrophobicity and saturation of membrane fatty acids, demonstrating the relation between mycolic acid and phospholipid synthesis and their contribution to cell surface properties of R. opacus PWD4.

  9. Functional characterization and stability improvement of a ‘thermophilic-like’ ene-reductase from Rhodococcus opacus 1CP

    PubMed Central

    Riedel, Anika; Mehnert, Marika; Paul, Caroline E.; Westphal, Adrie H.; van Berkel, Willem J. H.; Tischler, Dirk

    2015-01-01

    Ene-reductases (ERs) are widely applied for the asymmetric synthesis of relevant industrial chemicals. A novel ER OYERo2 was found within a set of 14 putative old yellow enzymes (OYEs) obtained by genome mining of the actinobacterium Rhodococcus opacus 1CP. Multiple sequence alignment suggested that the enzyme belongs to the group of ‘thermophilic-like’ OYEs. OYERo2 was produced in Escherichia coli and biochemically characterized. The enzyme is strongly NADPH dependent and uses non-covalently bound FMNH2 for the reduction of activated α,β-unsaturated alkenes. In the active form OYERo2 is a dimer. Optimal catalysis occurs at pH 7.3 and 37°C. OYERo2 showed highest specific activities (45-50 U mg-1) on maleimides, which are efficiently converted to the corresponding succinimides. The OYERo2-mediated reduction of prochiral alkenes afforded the (R)-products with excellent optical purity (ee > 99%). OYERo2 is not as thermo-resistant as related OYEs. Introduction of a characteristic intermolecular salt bridge by site-specific mutagenesis raised the half-life of enzyme inactivation at 32°C from 28 to 87 min and improved the tolerance toward organic co-solvents. The suitability of OYERo2 for application in industrial biocatalysis is discussed. PMID:26483784

  10. Fasciation induction by the phytopathogen Rhodococcus fascians depends upon a linear plasmid encoding a cytokinin synthase gene.

    PubMed Central

    Crespi, M; Messens, E; Caplan, A B; van Montagu, M; Desomer, J

    1992-01-01

    Rhodococcus fascians is a nocardiform bacteria that induces leafy galls (fasciation) on dicotyledonous and several monocotyledonous plants. The wild-type strain D188 contained a conjugative, 200 kb linear extrachromosomal element, pFiD188. Linear plasmid-cured strains were avirulent and reintroduction of this linear element restored virulence. Pulsed field electrophoresis indicated that the chromosome might also be a linear molecule of 4 megabases. Three loci involved in phytopathogenicity have been identified by insertion mutagenesis of this Fi plasmid. Inactivation of the fas locus resulted in avirulent strains, whereas insertions in the two other loci affected the degree of virulence, yielding attenuated (att) and hypervirulent (hyp) bacteria. One of the genes within the fas locus encoded an isopentenyltranferase (IPT) with low homology to analogous proteins from Gram-negative phytopathogenic bacteria. IPT activity was detected after expression of this protein in Escherichia coli cells. In R.fascians, ipt expression could only be detected in bacteria induced with extracts from fasciated tissue. R.fascians strains without the linear plasmid but containing this fas locus alone could not provoke any phenotype on plants, indicating additional genes from the linear plasmid were also essential for virulence. These studies, the first genetic analysis of the interaction of a Gram-positive bacterium with plants, suggest that a novel mechanism for plant tumour induction has evolved in R.fascians independently from the other branches of the eubacteria. Images PMID:1547783

  11. Purification, crystallization and preliminary X-ray crystallographic analysis of 3-ketosteroid Δ1-dehydrogenase from Rhodococcus erythropolis SQ1

    PubMed Central

    Rohman, Ali; van Oosterwijk, Niels; Dijkstra, Bauke W.

    2012-01-01

    3-Ketosteroid Δ1-dehydrogenase plays a crucial role in the early steps of steroid degradation by introducing a double bond between the C1 and C2 atoms of the A-ring of its 3-ketosteroid substrates. The 3-ketosteroid Δ1-dehydrogenase from Rhodococcus erythropolis SQ1, a 56 kDa flavoprotein, was crystallized using the sitting-drop vapour-diffusion method at room temperature. The crystals grew in various buffers over a wide pH range (from pH 5.5 to 10.5), but the best crystallization condition consisted of 2%(v/v) PEG 400, 0.1 M HEPES pH 7.5, 2.0 M ammonium sulfate. A native crystal diffracted X-rays to 2.0 Å resolution. It belonged to the primitive orthorhombic space group P212121, with unit-cell parameters a = 107.4, b = 131.6, c = 363.2 Å, and contained eight molecules in the asymmetric unit. The initial structure of the enzyme was solved using multi-wavelength anomalous dispersion (MAD) data collected from a Pt-derivatized crystal. PMID:22691786

  12. Biocatalytic Properties and Structural Analysis of Eugenol Oxidase from Rhodococcus jostii RHA1: A Versatile Oxidative Biocatalyst.

    PubMed

    Nguyen, Quoc-Thai; de Gonzalo, Gonzalo; Binda, Claudia; Rioz-Martínez, Ana; Mattevi, Andrea; Fraaije, Marco W

    2016-07-15

    Eugenol oxidase (EUGO) from Rhodococcus jostii RHA1 had previously been shown to convert only a limited set of phenolic compounds. In this study, we have explored the biocatalytic potential of this flavoprotein oxidase, resulting in a broadened substrate scope and a deeper insight into its structural properties. In addition to the oxidation of vanillyl alcohol and the hydroxylation of eugenol, EUGO can efficiently catalyze the dehydrogenation of various phenolic ketones and the selective oxidation of a racemic secondary alcohol-4-(1-hydroxyethyl)-2-methoxyphenol. EUGO was also found to perform the kinetic resolution of a racemic secondary alcohol. Crystal structures of the enzyme in complexes with isoeugenol, coniferyl alcohol, vanillin, and benzoate have been determined. The catalytic center is a remarkable solvent-inaccessible cavity on the si side of the flavin cofactor. Structural comparison with vanillyl alcohol oxidase from Penicillium simplicissimum highlights a few localized changes that correlate with the selectivity of EUGO for phenolic substrates bearing relatively small p-substituents while tolerating o-methoxy substituents. PMID:27123962

  13. Electrical resistivity tomography to monitor enhanced biodegradation of hydrocarbons with Rhodococcus erythropolis T902.1 at a pilot scale

    NASA Astrophysics Data System (ADS)

    Masy, Thibaut; Caterina, David; Tromme, Olivier; Lavigne, Benoît; Thonart, Philippe; Hiligsmann, Serge; Nguyen, Frédéric

    2016-01-01

    Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of such a technique (by biostimulation or bioaugmentation) strongly depends on the environment affected and is still difficult to predict a priori. In order to overcome these uncertainties, Electrical Resistivity Tomography (ERT) appears as a valuable non-invasive tool to detect soil heterogeneities and to monitor biodegradation. The main objective of this study was to isolate an electrical signal linked to an enhanced bacterial activity with ERT, in an aged HC-contaminated clay loam soil. To achieve this, a pilot tank was built to mimic field conditions. Compared to a first insufficient biostimulation phase, bioaugmentation with Rhodococcus erythropolis T902.1 led to a HC depletion of almost 80% (6900 to 1600 ppm) in 3 months in the center of the contaminated zone, where pollutants were less bioavailable. In the meantime, lithological heterogeneities and microbial activities (growth and biosurfactant production) were successively discriminated by ERT images. In the future, this cost-effective technique should be more and more transferred to the field in order to monitor biodegradation processes and assist in selecting the most appropriate remediation technique.

  14. Optimization of macroelement concentrations, pH and osmolarity for triacylglycerol accumulation in Rhodococcus opacus strain PD630

    PubMed Central

    2013-01-01

    The refinement of biodiesel or renewable diesel from bacterial lipids has a great potential to make a contribution for energy production in the future. This study provides new data concerning suitable nutrient concentrations for cultivation of the Gram-positive Rhodococcus opacus PD630, which is able to accumulate large amounts of lipids during nitrogen limitation. Enhanced concentrations of magnesium have been shown to increase the final optical density and the lipid content of the cells. Elevated phosphate concentrations slowed down the onset of the accumulation phase, without a clear effect on the final optical density and the cell’s lipid content. A robust growth of R. opacus was possible in the presence of ammonium concentrations of up to 1.4 g l-1 and sucrose concentrations of up to 240 g l-1, with an optimum regarding growth and lipid storage observed in the range of 0.2 to 0.4 g l-1 ammonium and 20 to 40 g l-1 sucrose, respectively. Moreover, R. opacus showed tolerance to high salt concentrations. PMID:23855965

  15. Degradation of recalcitrant aliphatic and aromatic hydrocarbons by a dioxin-degrader Rhodococcus sp. strain p52.

    PubMed

    Yang, Hai-Yan; Jia, Rui-Bao; Chen, Bin; Li, Li

    2014-09-01

    This study investigates the ability of Rhodococcus sp. strain p52, a dioxin degrader, to biodegrade petroleum hydrocarbons. Strain p52 can use linear alkanes (tetradecane, tetracosane, and dotriacontane), branched alkane (pristane), and aromatic hydrocarbons (naphthalene and phenanthrene) as sole carbon and energy sources. Specifically, the strain removes 85.7 % of tetradecane within 48 h at a degradation rate of 3.8 mg h(-1) g(-1) dry cells, and 79.4 % of tetracosane, 66.4 % of dotriacontane, and 63.9 % of pristane within 9-11 days at degradation rates of 20.5, 14.7, and 20.3 mg day(-1) g(-1) dry cells, respectively. Moreover, strain p52 consumes 100 % naphthalene and 55.3 % phenanthrene within 9-11 days at respective degradation rates of 16 and 12.9 mg day(-1) g(-1) dry cells. Metabolites of the petroleum hydrocarbons by strain p52 were analyzed. Genes encoding alkane-hydroxylating enzymes, including cytochrome P450 (CYP450) enzyme (CYP185) and two alkane-1-monooxygenases, were amplified by polymerase chain reaction. The transcriptional activities of these genes in the presence of petroleum hydrocarbons were detected by reverse transcription-polymerase chain reaction. The results revealed potential of strain p52 to degrade petroleum hydrocarbons. PMID:24859700

  16. Isolation, characterization of Rhodococcus sp. P14 capable of degrading high-molecular-weight polycyclic aromatic hydrocarbons and aliphatic hydrocarbons.

    PubMed

    Song, Xiaohui; Xu, Yan; Li, Gangmin; Zhang, Ying; Huang, Tongwang; Hu, Zhong

    2011-10-01

    Rhodococcus sp. P14 was isolated from crude oil-contaminated sediments. This strain was capable of utilizing three to five rings polycyclic aromatic hydrocarbons (PAHs) including phenanthrene (Phe), pyrene (Pyr), and benzo[a]pyrene (BaP) as a sole carbon and energy source. After cultivated with 50mg/L of each PAH, strain P14 removed 43% Phe, 34% Pyr and 30% BaP in 30 d. Four different hydroxyphenanthrene products derived from Phe by strain P14 (1,2,3,4-hydroxyphenanthrene) were detected using SPME-GC-MS. Strain P14 also was capable of degrading mineral oil with n-alkanes of C17 to C21 carbon chain length. Compared with glucose-grown cells, PAHs-grown cells had decreased contents of shorter-chain length fatty acids (≤ C16:0), increased contents of C18:0, Me-C19:0 and disappeared odd-number carbon chain fatty acids. The contents of unsaturated C19:1, Me-C19:0 increased and C18:0 decreased in mineral oil-grown cells. At the same time, the strain P14 tended to float when cultivated in mineral oil-supplemented liquid medium. The degradation capability of P14 to alkane and PAHs and its floating characteristics will be very helpful for future's application in oil-spill bioremediation. PMID:21871639

  17. Regulation of plasmid-encoded isoprene metabolism in Rhodococcus, a representative of an important link in the global isoprene cycle

    PubMed Central

    Crombie, Andrew T; Khawand, Myriam El; Rhodius, Virgil A; Fengler, Kevin A; Miller, Michael C; Whited, Gregg M; McGenity, Terry J; Murrell, J Colin

    2015-01-01

    Emissions of biogenic volatile organic compounds (VOCs) form an important part of the global carbon cycle, comprising a significant proportion of net ecosystem productivity. They impact atmospheric chemistry and contribute directly and indirectly to greenhouse gases. Isoprene, emitted largely from plants, comprises one third of total VOCs, yet in contrast to methane, which is released in similar quantities, we know little of its biodegradation. Here, we report the genome of an isoprene degrading isolate, Rhodococcus sp. AD45, and, using mutagenesis shows that a plasmid-encoded soluble di-iron centre isoprene monooxygenase (IsoMO) is essential for isoprene metabolism. Using RNA sequencing (RNAseq) to analyse cells exposed to isoprene or epoxyisoprene in a substrate-switch time-course experiment, we show that transcripts from 22 contiguous genes, including those encoding IsoMO, were highly upregulated, becoming among the most abundant in the cell and comprising over 25% of the entire transcriptome. Analysis of gene transcription in the wild type and an IsoMO-disrupted mutant strain showed that epoxyisoprene, or a subsequent product of isoprene metabolism, rather than isoprene itself, was the inducing molecule. We provide a foundation of molecular data for future research on the environmental biological consumption of this important, climate-active compound. PMID:25727256

  18. Enhancement and stabilization of desulfurization activity of Rhodococcus erythropolis KA2-5-1 by feeding ethanol and sulfur components.

    PubMed

    Yoshikawa, Osamu; Ishii, Yoshitaka; Koizumi, Ken-Ichi; Ohshiro, Takashi; Izumi, Yoshikazu; Maruhashi, Kenji

    2002-01-01

    We developed a fed-batch culture system fed with ethanol and restricted amounts of sulfur compounds to enhance and stabilize the desulfurizing activity in bacterial cells. In this system using dibenzothiophene (DBT) as the sole sulfur source, a desulfurizing bacterium Rhodococcus erythropolis KA2-5-1 cultivated with small amounts of sulfur showed stable desulfurizing activity and a low rate of growth. However, the cells cultured with excess amounts of sulfur showed unstable activity and a high growth rate. DBT had disadvantages as a sulfur source for cultivation because it is immiscible with water and toxic to cells. We then investigated water-soluble sulfur compounds for use as the sole sulfur source for the cultivation of R. erythropolis KA2-5-1 with desulfurizing activity, and found 2-aminoethanesulfonic acid to be the most effective. When 2-aminoethanesulfonic acid was used instead of DBT as the sole sulfur source in the fed-batch fermentation system, R. erythropolis KA2-5-1 showed the highest desulfurizing activity, 111 mmol of 2-HBP/kg-cells/h, a high growth rate (mu = 0.37/h) and a final cell concentration of 20.0 g-dry cells/l during 89 h of cultivation. The production levels of the desulfurizing enzymes in the bacterial cells cultivated with DBT or 2-aminoethanesulfonic acid were evaluated by immunoblot analysis with specific antisera, indicating that the same quantity of desulfurizing enzymes was expressed in both cases.

  19. Pulmonary disposition of tilmicosin in foals and in vitro activity against Rhodococcus equi and other common equine bacterial pathogens.

    PubMed

    Womble, A; Giguère, S; Murthy, Y V S N; Cox, C; Obare, E

    2006-12-01

    The objectives of this study were to determine the serum and pulmonary disposition of tilmicosin in foals and to investigate the in vitro activity of the drug against Rhodococcus equi and other common bacterial pathogens of horses. A single dose of a new fatty acid salt formulation of tilmicosin (10 mg/kg of body weight) was administered to seven healthy 5- to 8-week-old foals by the intramuscular route. Concentrations of tilmicosin were measured in serum, lung tissue, pulmonary epithelial lining fluid (PELF), bronchoalveolar lavage (BAL) cells, and blood neutrophils. Mean peak tilmicosin concentrations were significantly different between sampling sites with highest concentrations measured in blood neutrophils (66.01+/-15.97 microg/mL) followed by BAL cells (20.1+/-5.1 microg/mL), PELF (2.91+/-1.15 microg/mL), lung tissue (1.90+/-0.65 microg/mL), and serum (0.19+/-0.09 microg/mL). Harmonic mean terminal half-life in lung tissue (193.3 h) was significantly longer than that of PELF (73.3 h), bronchoalveolar cells (62.2 h), neutrophils (47.9 h), and serum (18.4 h). The MIC90 of 56 R. equi isolates was 32 microg/mL. Tilmicosin was active in vitro against most streptococci, Staphylococcus spp., Actinobacillus spp., and Pasteurella spp. The drug was not active against Enterococcus spp., Pseudomonas spp., and Enterobacteriaceae.

  20. Genetic and Biochemical Characterization of a Novel Monoterpene ɛ-Lactone Hydrolase from Rhodococcus erythropolis DCL14

    PubMed Central

    van der Vlugt-Bergmans, Cécile J. B; van der Werf, Mariët J.

    2001-01-01

    A monoterpene ɛ-lactone hydrolase (MLH) from Rhodococcus erythropolis DCL14, catalyzing the ring opening of lactones which are formed during degradation of several monocyclic monoterpenes, including carvone and menthol, was purified to apparent homogeneity. It is a monomeric enzyme of 31 kDa that is active with (4R)-4-isopropenyl-7-methyl-2-oxo-oxepanone and (6R)-6-isopropenyl-3-methyl-2-oxo-oxepanone, lactones derived from (4R)-dihydrocarvone, and 7-isopropyl-4-methyl-2-oxo-oxepanone, the lactone derived from menthone. Both enantiomers of 4-, 5-, 6-, and 7-methyl-2-oxo-oxepanone were converted at equal rates, suggesting that the enzyme is not stereoselective. Maximal enzyme activity was measured at pH 9.5 and 30°C. Determination of the N-terminal amino acid sequence of purified MLH enabled cloning of the corresponding gene by a combination of PCR and colony screening. The gene, designated mlhB (monoterpene lactone hydrolysis), showed up to 43% similarity to members of the GDXG family of lipolytic enzymes. Sequencing of the adjacent regions revealed two other open reading frames, one encoding a protein with similarity to the short-chain dehydrogenase reductase family and the second encoding a protein with similarity to acyl coenzyme A dehydrogenases. Both enzymes are possibly also involved in the monoterpene degradation pathways of this microorganism. PMID:11157238

  1. A novel method to generate unmarked gene deletions in the intracellular pathogen Rhodococcus equi using 5-fluorocytosine conditional lethality

    PubMed Central

    van der Geize, R.; de Jong, W.; Hessels, G. I.; Grommen, A. W. F.; Jacobs, A. A. C.; Dijkhuizen, L.

    2008-01-01

    A novel method to efficiently generate unmarked in-frame gene deletions in Rhodococcus equi was developed, exploiting the cytotoxic effect of 5-fluorocytosine (5-FC) by the action of cytosine deaminase (CD) and uracil phosphoribosyltransferase (UPRT) enzymes. The opportunistic, intracellular pathogen R. equi is resistant to high concentrations of 5-FC. Introduction of Escherichia coli genes encoding CD and UPRT conferred conditional lethality to R. equi cells incubated with 5-FC. To exemplify the use of the codA::upp cassette as counter-selectable marker, an unmarked in-frame gene deletion mutant of R. equi was constructed. The supA and supB genes, part of a putative cholesterol catabolic gene cluster, were efficiently deleted from the R. equi wild-type genome. Phenotypic analysis of the generated ΔsupAB mutant confirmed that supAB are essential for growth of R. equi on cholesterol. Macrophage survival assays revealed that the ΔsupAB mutant is able to survive and proliferate in macrophages comparable to wild type. Thus, cholesterol metabolism does not appear to be essential for macrophage survival of R. equi. The CD-UPRT based 5-FC counter-selection may become a useful asset in the generation of unmarked in-frame gene deletions in other actinobacteria as well, as actinobacteria generally appear to be 5-FC resistant and 5-FU sensitive. PMID:18984616

  2. Identification of pathogens and virulence profile of Rhodococcus equi and Escherichia coli strains obtained from sand of parks

    PubMed Central

    Fernandes, M.C.; Takai, S.; Leite, D.S.; Pinto, J.P.A.N.; Brandão, P.E.; Santarém, V.A.; Listoni, F.J.P.; Da Silva, A.V.; Ribeiro, M.G.

    2013-01-01

    The identification of pathogens of viral (Rotavirus, Coronavirus), parasitic (Toxocara spp.) and bacterial (Escherichia coli, Salmonella spp., Rhodococcus equi) origin shed in feces, and the virulence profile of R. equi and E. coli isolates were investigated in 200 samples of sand obtained from 40 parks, located in central region of state of Sao Paulo, Brazil, using different diagnostic methods. From 200 samples analyzed, 23 (11.5%) strains of R. equi were isolated. None of the R. equi isolates showed a virulent (vapA gene) or intermediately virulent (vapB gene) profiles. Sixty-three (31.5%) strains of E. coli were identified. The following genes encoding virulence factors were identified in E. coli: eae, bfp, saa, iucD, papGI, sfa and hly. Phylogenetic classification showed that 63 E. coli isolates belonged to groups B1 (52.4%), A (25.4%) and B2 (22.2%). No E. coli serotype O157:H7 was identified. Eggs of Toxocara sp. were found in three parks and genetic material of bovine Coronavirus was identified in one sample of one park. No Salmonella spp. and Rotavirus isolates were identified in the samples of sand. The presence of R. equi, Toxocara sp, bovine Coronavirus and virulent E. coli isolates in the environment of parks indicates that the sanitary conditions of the sand should be improved in order to reduce the risks of fecal transmission of pathogens of zoonotic potential to humans in these places. PMID:24294244

  3. Limonene-1,2-Epoxide Hydrolase from Rhodococcus erythropolis DCL14 Belongs to a Novel Class of Epoxide Hydrolases

    PubMed Central

    van der Werf, Mariët J.; Overkamp, Karin M.; de Bont, Jan A. M.

    1998-01-01

    An epoxide hydrolase from Rhodococcus erythropolis DCL14 catalyzes the hydrolysis of limonene-1,2-epoxide to limonene-1,2-diol. The enzyme is induced when R. erythropolis is grown on monoterpenes, reflecting its role in the limonene degradation pathway of this microorganism. Limonene-1,2-epoxide hydrolase was purified to homogeneity. It is a monomeric cytoplasmic enzyme of 17 kDa, and its N-terminal amino acid sequence was determined. No cofactor was required for activity of this colorless enzyme. Maximal enzyme activity was measured at pH 7 and 50°C. None of the tested inhibitors or metal ions inhibited limonene-1,2-epoxide hydrolase activity. Limonene-1,2-epoxide hydrolase has a narrow substrate range. Of the compounds tested, only limonene-1,2-epoxide, 1-methylcyclohexene oxide, cyclohexene oxide, and indene oxide were substrates. This report shows that limonene-1,2-epoxide hydrolase belongs to a new class of epoxide hydrolases based on (i) its low molecular mass, (ii) the absence of any significant homology between the partial amino acid sequence of limonene-1,2-epoxide hydrolase and amino acid sequences of known epoxide hydrolases, (iii) its pH profile, and (iv) the inability of 2-bromo-4′-nitroacetophenone, diethylpyrocarbonate, 4-fluorochalcone oxide, and 1,10-phenanthroline to inhibit limonene-1,2-epoxide hydrolase activity. PMID:9748436

  4. [Effect of Cu2+ on synthesis of biosurfactants of Acinetobacter calcoaceticus IMV B-7241 and Rhodococcus erythropolis IMV Ac-5017].

    PubMed

    Pirog, T P; Konon, A D; Sofilkanich, A P; Shevchuk, T A; Parfeniuk, S A

    2013-01-01

    Synthesis of biosurfactants (surface-active substances, SAS) was investigated under the conditions of growth of Rhodococcus erythropolis IMV Ac-5017 and Acinetobacter calcoaceticus IMV B-7241 on hydrophobic (n-hexadecane, liquid paraffins, sunflower oil) and hydrophilic (ethanol) substrates depending on concentration (0.01-0.5 mM) and time of copper cations introduction in the medium. It is established that Cu2+ addition in the exponential phase of growth of the strains IMV B-7241 and IMV Ac-5017 on all studied substrates was accompanied by the increase of conventional concentration of SAS by 25-140% as compared with the indices in the medium without copper cations. Maximum synthesis intensification of SAS of A. calcoaceticus IMV B-7241 and R. erythropolis IMV Ac-5017 was observed in the case of Cu2+ introduction in the medium with hydrocarbons. The increase of SAS synthesis in the presence of copper cations is determined by their activating effect on activity of alkane hydroxylase of the both strains, as well as 4-nitroso-N,N-dimethylaniline-dependent alcohol dehydrogenase and enzymes of biosynthesis of surface active glyco-(phosphoenolpyruvate-synthetase) and aminolipids (NADP(+)-dependent glutamate dehydrogenase) in A. calcoaceticus IMV B-7241.

  5. Rolling Up a Monolayer MoS2 Sheet.

    PubMed

    Meng, Jianling; Wang, Guole; Li, Xiaomin; Lu, Xiaobo; Zhang, Jing; Yu, Hua; Chen, Wei; Du, Luojun; Liao, Mengzhou; Zhao, Jing; Chen, Peng; Zhu, Jianqi; Bai, Xuedong; Shi, Dongxia; Zhang, Guangyu

    2016-07-01

    MoS2 nanoscrolls are formed by argon plasma treatment on monolayer MoS2 sheet. The nanoscale scroll formation is attributed to the partial removal of top sulfur layer in MoS2 during the argon plasma treatment process. This convenient, solvent-free, and high-yielding nanoscroll formation technique is also feasible for other 2D transition metal dichalcogenides.

  6. Recombinant DNA encoding a desulfurization biocatalyst

    DOEpatents

    Rambosek, John; Piddington, Chris S.; Kovacevich, Brian R.; Young, Kevin D.; Denome, Sylvia A.

    1994-01-01

    This invention relates to a recombinant DNA molecule containing a gene or genes which encode a biocatalyst capable of desulfurizing a fossil fuel which contains organic sulfur molecules. For example, the present invention encompasses a recombinant DNA molecule containing a gene or genes of a strain of Rhodococcus rhodochrous.

  7. Recombinant DNA encoding a desulfurization biocatalyst

    DOEpatents

    Rambosek, J.; Piddington, C.S.; Kovacevich, B.R.; Young, K.D.; Denome, S.A.

    1994-10-18

    This invention relates to a recombinant DNA molecule containing a gene or genes which encode a biocatalyst capable of desulfurizing a fossil fuel which contains organic sulfur molecules. For example, the present invention encompasses a recombinant DNA molecule containing a gene or genes of a strain of Rhodococcus rhodochrous. 13 figs.

  8. Highly enantioselective oxidation of phenyl methyl sulfide and its derivatives into optically pure (S)-sulfoxides with Rhodococcus sp. CCZU10-1 in an n-octane-water biphasic system.

    PubMed

    He, Yu-Cai; Ma, Cui-Luan; Yang, Zhen-Xing; Zhou, Min; Xing, Zhen; Ma, Jiang-Tao; Yu, Hui-Lei

    2013-12-01

    Enantiopure sulfoxides can be prepared via the asymmetric oxidation of sulfides using sulfide monooxygenases. The n-octane-water biphasic system was chosen for the bio-oxidation of a water-insoluble phenyl methyl sulfide (PMS) by Rhodococcus sp. CCZU10-1. In this n-octane-water system, the optimum reaction conditions were obtained. (S)-phenyl methyl sulfoxide ((S)-PMSO) with >99.9 % enantiomeric excess formed at 55.3 mM in the n-octane-water biphasic system. Using fed-batch method, a total of 118 mM (S)-PMSO accumulated in 1-L reaction mixture after the 7th feed, and no (R)-PMSO and sulfone were detected. Moreover, Rhodococcus sp. CCZU10-1 displayed fairly good activity and enantioselectivity toward other sulfides. In conclusion, Rhodococcus sp. CCZU10-1 is a promising biocatalyst for synthesizing highly optically active sulfoxides.

  9. Bending response of single layer MoS2.

    PubMed

    Xiong, Si; Cao, Guoxin

    2016-03-11

    Using molecular mechanics (or dynamics) simulations, three different approaches, including the targeted molecular mechanics, four-point bending and nanotube methods, are employed to investigate the bending response of single layer MoS2 (SLMoS2), among which four-point bending is the most accurate approach to determine the bending stiffness according to the continuum theory. It is found that when the bending curvature radius is large enough (e.g. >4 nm), three approaches will give the same bending stiffness of SLMoS2 and the bending behavior is isotropic for SLMoS2, whereas the nanotube method with small tubes (e.g. <4 nm) cannot give the correct bending stiffness. Compared with the reported result from the MoS2 nanotube calculated by density functional theory, the revised Stillinger-Weber (SW) and reactive empirical bond-order (REBO) potentials can give the reasonable bending stiffness of SLMoS2 (8.7-13.4 eV) as well as the effective deformed conformation. In addition, since the Mo-S bond deformation of SLMoS2 under bending is similar to that under in-plane tension/compression, the continuum bending theory can quite accurately predict the bending stiffness of SLMoS2 if a reasonable thickness of SLMoS2 is given. For SLMoS2, the reasonable thickness should be larger than the distance between its two S atomic planes and lower than the distance between two Mo atomic planes of bulk MoS2 crystal, e.g. 0.375-0.445 nm. PMID:26861930

  10. Magnetoresistance in Co/2D MoS2/Co and Ni/2D MoS2/Ni junctions.

    PubMed

    Zhang, Han; Ye, Meng; Wang, Yangyang; Quhe, Ruge; Pan, Yuanyuan; Guo, Ying; Song, Zhigang; Yang, Jinbo; Guo, Wanlin; Lu, Jing

    2016-06-28

    Semiconducting single-layer (SL) and few-layer MoS2 have a flat surface, free of dangling bonds. Using density functional theory coupled with non-equilibrium Green's function method, we investigate the spin-polarized transport properties of Co/2D MoS2/Co and Ni/2D MoS2/Ni junctions with MoS2 layer numbers of N = 1, 3, and 5. Well-defined interfaces are formed between MoS2 and metal electrodes. The junctions with a SL MoS2 spacer are almost metallic owing to the strong coupling between MoS2 and the ferromagnets, while those are tunneling with a few layer MoS2 spacer. Both large magnetoresistance and tunneling magnetoresistance are found when fcc or hcp Co is used as an electrode. Therefore, flat single- and few-layer MoS2 can serve as an effective nonmagnetic spacer in a magnetoresistance or tunneling magnetoresistance device with a well-defined interface.

  11. Magnetoresistance in Co/2D MoS2/Co and Ni/2D MoS2/Ni junctions.

    PubMed

    Zhang, Han; Ye, Meng; Wang, Yangyang; Quhe, Ruge; Pan, Yuanyuan; Guo, Ying; Song, Zhigang; Yang, Jinbo; Guo, Wanlin; Lu, Jing

    2016-06-28

    Semiconducting single-layer (SL) and few-layer MoS2 have a flat surface, free of dangling bonds. Using density functional theory coupled with non-equilibrium Green's function method, we investigate the spin-polarized transport properties of Co/2D MoS2/Co and Ni/2D MoS2/Ni junctions with MoS2 layer numbers of N = 1, 3, and 5. Well-defined interfaces are formed between MoS2 and metal electrodes. The junctions with a SL MoS2 spacer are almost metallic owing to the strong coupling between MoS2 and the ferromagnets, while those are tunneling with a few layer MoS2 spacer. Both large magnetoresistance and tunneling magnetoresistance are found when fcc or hcp Co is used as an electrode. Therefore, flat single- and few-layer MoS2 can serve as an effective nonmagnetic spacer in a magnetoresistance or tunneling magnetoresistance device with a well-defined interface. PMID:27257639

  12. MoS2 Surface Structure Tailoring via Carbonaceous Promoter

    NASA Astrophysics Data System (ADS)

    Shi, Yumeng; Li, Henan; Wong, Jen It; Zhang, Xiaoting; Wang, Ye; Song, Huaihe; Yang, Hui Ying

    2015-05-01

    Atomically thin semiconducting transition-metal dichalcogenides have been attracting lots of attentions, particularly, molybdenum disulfide (MoS2) monolayers show promising applications in field effect transistors, optoelectronics and valleytronics. However, the controlled synthesis of highly crystalline MoS2 remain a challenge especially the systematic approach to manipulate its structure and morphology. Herein, we report a method for controlled synthesis of highly crystalline MoS2 by using chemical vapor deposition method with carbonaceous materials as growth promoter. A uniform and highly crystalline MoS2 monolayer with the grain size close to 40 μm was achieved. Furthermore, we extend the method to the manipulation of MoS2 morphology, flower-shape vertical grown MoS2 layers were obtained on growth promoting substrates. This simple approach allows an easy access of highly crystalline MoS2 layers with morphology tuned in a controllable manner. Moreover, the flower-shape MoS2 grown on graphene oxide film used as an anode material for lithium-ion batteries showed excellent electrochemical performance.

  13. Vertically Conductive MoS2 Spiral Pyramid.

    PubMed

    Ly, Thuc Hue; Zhao, Jiong; Kim, Hyun; Han, Gang Hee; Nam, Honggi; Lee, Young Hee

    2016-09-01

    MoS2 spirals grown by the chemical vapor deposition method, driven by a threading dislocation, has a peculiar rhombohedral-like structure. This threading dislocation can carry helical current in the vertical direction and greatly enhances the vertical conductance in the MoS2 multilayer samples.

  14. MoS2 Surface Structure Tailoring via Carbonaceous Promoter

    PubMed Central

    Shi, Yumeng; Li, Henan; Wong, Jen It; Zhang, Xiaoting; Wang, Ye; Song, Huaihe; Yang, Hui Ying

    2015-01-01

    Atomically thin semiconducting transition-metal dichalcogenides have been attracting lots of attentions, particularly, molybdenum disulfide (MoS2) monolayers show promising applications in field effect transistors, optoelectronics and valleytronics. However, the controlled synthesis of highly crystalline MoS2 remain a challenge especially the systematic approach to manipulate its structure and morphology. Herein, we report a method for controlled synthesis of highly crystalline MoS2 by using chemical vapor deposition method with carbonaceous materials as growth promoter. A uniform and highly crystalline MoS2 monolayer with the grain size close to 40 μm was achieved. Furthermore, we extend the method to the manipulation of MoS2 morphology, flower-shape vertical grown MoS2 layers were obtained on growth promoting substrates. This simple approach allows an easy access of highly crystalline MoS2 layers with morphology tuned in a controllable manner. Moreover, the flower-shape MoS2 grown on graphene oxide film used as an anode material for lithium-ion batteries showed excellent electrochemical performance. PMID:25994238

  15. Synthesis and characterization of MoS2 nanosheets.

    PubMed

    Deokar, G; Vignaud, D; Arenal, R; Louette, P; Colomer, J-F

    2016-02-19

    Here, we report on the synthesis of MoS2 nanosheets using a simple two-step additive-free growth technique. The as-synthesized nanosheets were characterized to determine their structure and composition, as well as their optical properties. The MoS2 nanosheets were analyzed by scanning electron microscopy, transmission electron microscopy (TEM), including high-resolution scanning TEM imaging and energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy (XPS), Raman spectroscopy and photoluminescence (PL). The as-produced MoS2 nanosheets are vertically aligned with curved edges and are densely populated. The TEM measurements confirmed that the nanosheets have the 2H-MoS2 crystal structure in agreement with the Raman results. The XPS results revealed the presence of high purity MoS2. Moreover, a prominent PL similar to mechanically exfoliated few and mono-layer MoS2 was observed for the as-grown nanosheets. For the thin (≤50 nm) nanosheets, the PL feature was observed at the same energy as that for a direct band-gap monolayer MoS2 (1.83 eV). Thus, the as-produced high-quality, large-area, MoS2 nanosheets could be potentially useful for various optoelectronic and catalysis applications.

  16. Toward Ferroelectric Control of Monolayer MoS2.

    PubMed

    Nguyen, Ariana; Sharma, Pankaj; Scott, Thomas; Preciado, Edwin; Klee, Velveth; Sun, Dezheng; Lu, I-Hsi Daniel; Barroso, David; Kim, SukHyun; Shur, Vladimir Ya; Akhmatkhanov, Andrey R; Gruverman, Alexei; Bartels, Ludwig; Dowben, Peter A

    2015-05-13

    The chemical vapor deposition (CVD) of molybdenum disulfide (MoS2) single-layer films onto periodically poled lithium niobate is possible while maintaining the substrate polarization pattern. The MoS2 growth exhibits a preference for the ferroelectric domains polarized "up" with respect to the surface so that the MoS2 film may be templated by the substrate ferroelectric polarization pattern without the need for further lithography. MoS2 monolayers preserve the surface polarization of the "up" domains, while slightly quenching the surface polarization on the "down" domains as revealed by piezoresponse force microscopy. Electrical transport measurements suggest changes in the dominant carrier for CVD MoS2 under application of an external voltage, depending on the domain orientation of the ferroelectric substrate. Such sensitivity to ferroelectric substrate polarization opens the possibility for ferroelectric nonvolatile gating of transition metal dichalcogenides in scalable devices fabricated free of exfoliation and transfer.

  17. Photoluminescence from chemically exfoliated MoS2.

    PubMed

    Eda, Goki; Yamaguchi, Hisato; Voiry, Damien; Fujita, Takeshi; Chen, Mingwei; Chhowalla, Manish

    2011-12-14

    A two-dimensional crystal of molybdenum disulfide (MoS2) monolayer is a photoluminescent direct gap semiconductor in striking contrast to its bulk counterpart. Exfoliation of bulk MoS2 via Li intercalation is an attractive route to large-scale synthesis of monolayer crystals. However, this method results in loss of pristine semiconducting properties of MoS2 due to structural changes that occur during Li intercalation. Here, we report structural and electronic properties of chemically exfoliated MoS2. The metastable metallic phase that emerges from Li intercalation was found to dominate the properties of as-exfoliated material, but mild annealing leads to gradual restoration of the semiconducting phase. Above an annealing temperature of 300 °C, chemically exfoliated MoS2 exhibit prominent band gap photoluminescence, similar to mechanically exfoliated monolayers, indicating that their semiconducting properties are largely restored.

  18. Vaporization of ices containing S2 - Implications for comets

    NASA Technical Reports Server (NTRS)

    Moore, M. H.; Donn, B.; Hudson, R. L.

    1988-01-01

    An effort is made to ascertain whether the S2 detected in Comet IRAS-Araki-Alcock 1983d can be stored in ices during warming, and is released during the vaporization of its water ice matrix, in view of data on the UV spectrum of S2 in Ar and Kr matrices and water ice in which the ratio of matrix or molecular ice to S2 is of the order of 500:1. The results obtained support the hypothesis that the S2:H2O ratio in the solid phase may not be a predictor of the gas phase ratio. It is concluded that similar vaporization from a cometary nucleus would not release most of the S2 contained in the ice.

  19. Assessment of alkaline cholesterol oxidase purified from Rhodococcus sp. PKPD-CL for its halo tolerance, detergent and organic solvent stability.

    PubMed

    Kasabe, Pramod J; Mali, Geetanjali T; Dandge, Padma B

    2015-12-01

    The novel bacterium, Rhodococcus sp. PKPD-CL was isolated and identified from the 'Chilika Lake' located at Odisha state of India, which is a largest brackish water habitat in Asia. Rhodococcus sp. PKPD-CL produces extracellular halo tolerant, detergent and organic solvent stable alkaline cholesterol oxidase. It has apparent molecular weight of 60 kDa and was purified 59 fold by using 60% saturated ammonium sulfate fractionation, anion exchange followed by size exclusion chromatographic techniques with 37% recovery. It showed substrate specificity for 3β-hydroxysteroids with Km of 1.1 × 10(-4)M for cholesterol. The pH, 8.0 and the temperature, 37 °C were required for its optimum activity. Enzyme is considerably stable at pH 6.0-8.5 and temperature up to 50 °C. At 4 and 30 °C it maintained its 100% activity up to 60 days. The isoelectric point of the enzyme was 9.5. It showed 80% residual activity with 20% NaCl (3.42 M) and 83% relative activity with 12% NaCl (2.05 M) concentration. The metal ions like Zn(2+), Cu(2+), Ag+, Fe(3+), Ba(2+) inhibited the enzyme activity >60% while Hg(2+) served a potent inhibitor whereas Mg(2+) found to be a good enhancer for it. The enzyme was stable in presence of chemical reagents (NaN3, EDTA), detergents (Tween-80, Tween-20, Triton X-100, sodium cholate) and various organic solvents (isopropanol, ethanol, benzene, chloroform, methanol, toluene, ethyl acetate, butanol and dimethylsulfoxide). Such a multi stress tolerant and versatile enzyme produced by Rhodococcus sp. PKPD-CL may serve as a good choice for industrial applications.

  20. Assessment of alkaline cholesterol oxidase purified from Rhodococcus sp. PKPD-CL for its halo tolerance, detergent and organic solvent stability.

    PubMed

    Kasabe, Pramod J; Mali, Geetanjali T; Dandge, Padma B

    2015-12-01

    The novel bacterium, Rhodococcus sp. PKPD-CL was isolated and identified from the 'Chilika Lake' located at Odisha state of India, which is a largest brackish water habitat in Asia. Rhodococcus sp. PKPD-CL produces extracellular halo tolerant, detergent and organic solvent stable alkaline cholesterol oxidase. It has apparent molecular weight of 60 kDa and was purified 59 fold by using 60% saturated ammonium sulfate fractionation, anion exchange followed by size exclusion chromatographic techniques with 37% recovery. It showed substrate specificity for 3β-hydroxysteroids with Km of 1.1 × 10(-4)M for cholesterol. The pH, 8.0 and the temperature, 37 °C were required for its optimum activity. Enzyme is considerably stable at pH 6.0-8.5 and temperature up to 50 °C. At 4 and 30 °C it maintained its 100% activity up to 60 days. The isoelectric point of the enzyme was 9.5. It showed 80% residual activity with 20% NaCl (3.42 M) and 83% relative activity with 12% NaCl (2.05 M) concentration. The metal ions like Zn(2+), Cu(2+), Ag+, Fe(3+), Ba(2+) inhibited the enzyme activity >60% while Hg(2+) served a potent inhibitor whereas Mg(2+) found to be a good enhancer for it. The enzyme was stable in presence of chemical reagents (NaN3, EDTA), detergents (Tween-80, Tween-20, Triton X-100, sodium cholate) and various organic solvents (isopropanol, ethanol, benzene, chloroform, methanol, toluene, ethyl acetate, butanol and dimethylsulfoxide). Such a multi stress tolerant and versatile enzyme produced by Rhodococcus sp. PKPD-CL may serve as a good choice for industrial applications. PMID:26276474

  1. Genomic and Functional Analyses of Rhodococcus equi Phages ReqiPepy6, ReqiPoco6, ReqiPine5, and ReqiDocB7 ▿

    PubMed Central

    Summer, E. J.; Liu, M.; Gill, J. J.; Grant, M.; Chan-Cortes, T. N.; Ferguson, L.; Janes, C.; Lange, K.; Bertoli, M.; Moore, C.; Orchard, R. C.; Cohen, N. D.; Young, R.

    2011-01-01

    The isolation and results of genomic and functional analyses of Rhodococcus equi phages ReqiPepy6, ReqiDocB7, ReqiPine5, and ReqiPoco6 (hereafter referred to as Pepy6, DocB7, Pine5, and Poco6, respectively) are reported. Two phages, Pepy6 and Poco6, more than 75% identical, exhibited genome organization and protein sequence likeness to Lactococcus lactis phage 1706 and clostridial prophage elements. An unusually high fraction, 27%, of Pepy6 and Poco6 proteins were predicted to possess at least one transmembrane domain, a value much higher than the average of 8.5% transmembrane domain-containing proteins determined from a data set of 36,324 phage protein entries. Genome organization and protein sequence comparisons place phage Pine5 as the first nonmycobacteriophage member of the large Rosebush cluster. DocB7, which had the broadest host range among the four isolates, was not closely related to any phage or prophage in the database, and only 23 of 105 predicted encoded proteins could be assigned a functional annotation. Because of the relationship of Rhodococcus to Mycobacterium, it was anticipated that these phages should exhibit some of the features characteristic of mycobacteriophages. Traits that were identified as shared by the Rhodococcus phages and mycobacteriophages include the prevalent long-tailed morphology and the presence of genes encoding LysB-like mycolate-hydrolyzing lysis proteins. Application of DocB7 lysates to soils amended with a host strain of R. equi reduced recoverable bacterial CFU, suggesting that phage may be useful in limiting R. equi load in the environment while foals are susceptible to infection. PMID:21097585

  2. Importance of Rhodococcus strains in a bacterial consortium degrading a mixture of hydrocarbons, gasoline, and diesel oil additives revealed by metatranscriptomic analysis.

    PubMed

    Auffret, Marc D; Yergeau, Etienne; Labbé, Diane; Fayolle-Guichard, Françoise; Greer, Charles W

    2015-03-01

    A bacterial consortium (Mix3) composed of microorganisms originating from different environments (soils and wastewater) was obtained after enrichment in the presence of a mixture of 16 hydrocarbons, gasoline, and diesel oil additives. After addition of the mixture, the development of the microbial composition of Mix3 was monitored at three different times (35, 113, and 222 days) using fingerprinting method and dominant bacterial species were identified. In parallel, 14 bacteria were isolated after 113 days and identified. Degradation capacities for Mix3 and the isolated bacterial strains were characterized and compared. At day 113, we induced the expression of catabolic genes in Mix3 by adding the substrate mixture to resting cells and the metatranscriptome was analyzed. After addition of the substrate mixture, the relative abundance of Actinobacteria increased at day 222 while a shift between Rhodococcus and Mycobacterium was observed after 113 days. Mix3 was able to degrade 13 compounds completely, with partial degradation of isooctane and 2-ethylhexyl nitrate, but tert-butyl alcohol was not degraded. Rhodococcus wratislaviensis strain IFP 2016 isolated from Mix3 showed almost the same degradation capacities as Mix3: these results were not observed with the other isolated strains. Transcriptomic results revealed that Actinobacteria and in particular, Rhodococcus species, were major contributors in terms of total and catabolic gene transcripts while other species were involved in cyclohexane degradation. Not all the microorganisms identified at day 113 were active except R. wratislaviensis IFP 2016 that appeared to be a major player in the degradation activity observed in Mix3.

  3. Mg2+-Dependent Control of the Spatial Arrangement of Rhodococcus erythropolis PR4 Cells in Aqueous-Alkane Two Phase Culture Containing n-Dodecane

    PubMed Central

    Takihara, Hayato; Akase, Yumiko; Sunairi, Michio; Iwabuchi, Noriyuki

    2016-01-01

    We recently reported that a close relationship exists between alkane carbon-chain length, cell growth, and translocation frequency in Rhodococcus. In the present study, we examined the regulation of the spatial arrangement of cells in aqueous-alkane two phase cultures. An analysis of the effects of minerals on cell localization revealed that changes in the concentration of MgSO4 in two phase cultures containing n-dodecane (C12) altered cell localization from translocation to adhesion and vice versa. Our results indicate that the spatial arrangement of cells in two phase culture systems is controlled through the regulation of MgSO4 concentrations. PMID:27180641

  4. Structural and electronic properties of germanene/MoS2 monolayer and silicene/MoS2 monolayer superlattices.

    PubMed

    Li, Xiaodan; Wu, Shunqing; Zhou, Sen; Zhu, Zizhong

    2014-03-08

    Superlattice provides a new approach to enrich the class of materials with novel properties. Here, we report the structural and electronic properties of superlattices made with alternate stacking of two-dimensional hexagonal germanene (or silicene) and a MoS2 monolayer using the first principles approach. The results are compared with those of graphene/MoS2 superlattice. The distortions of the geometry of germanene, silicene, and MoS2 layers due to the formation of the superlattices are all relatively small, resulting from the relatively weak interactions between the stacking layers. Our results show that both the germanene/MoS2 and silicene/MoS2 superlattices are manifestly metallic, with the linear bands around the Dirac points of the pristine germanene and silicene seem to be preserved. However, small band gaps are opened up at the Dirac points for both the superlattices due to the symmetry breaking in the germanene and silicene layers caused by the introduction of the MoS2 sheets. Moreover, charge transfer happened mainly within the germanene (or silicene) and the MoS2 layers (intra-layer transfer), as well as some part of the intermediate regions between the germanene (or silicene) and the MoS2 layers (inter-layer transfer), suggesting more than just the van der Waals interactions between the stacking sheets in the superlattices.

  5. Plasma nanocoating of thiophene onto MoS2 nanotubes

    NASA Astrophysics Data System (ADS)

    Türkaslan, Banu Esencan; Dikmen, Sibel; Öksüz, Lütfi; Öksüz, Aysegul Uygun

    2015-12-01

    MoS2 nanotubes were coated with conductive polymer thiophene by atmospheric pressure radio-frequency (RF) glow discharge. MoS2 nanotubes were prepared by thermal decomposition of hexadecylamine (HDA) intercalated laminar MoS2 precursor on anodized aluminum oxide template and the thiophene was polymerized directly on surface of these nanotubes as in situ by plasma method. The effect of plasma power on PTh/MoS2 nanocomposite properties has been investigated by means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM and EDX), and X-ray diffraction spectroscopy (XRD). The presence of PTh bands in the FTIR spectra of PTh/MoS2 nanotube nanocomposites corresponding XRD results indicates that the polythiophene coating onto MoS2 nanotube. The chemical structure of PTh is not changed when the plasma power of discharge differ from 117 to 360 W. SEM images of nanocomposites show that when the discharge power is increased between 117 and 360 W the average diameter of PTh/MoS2 nanotube nanocomposites are changed and the structure become more uniformly.

  6. Imaging spectroscopic ellipsometry of MoS2

    NASA Astrophysics Data System (ADS)

    Funke, S.; Miller, B.; Parzinger, E.; Thiesen, P.; Holleitner, A. W.; Wurstbauer, U.

    2016-09-01

    Micromechanically exfoliated mono- and multilayers of molybdenum disulfide (MoS2) are investigated by spectroscopic imaging ellipsometry. In combination with knife edge illumination, MoS2 flakes can be detected and classified on arbitrary flat and also transparent substrates with a lateral resolution down to 1-2 µm. The complex dielectric functions from mono- and trilayer MoS2 are presented. They are extracted from a multilayer model to fit the measured ellipsometric angles employing an anisotropic and an isotropic fit approach. We find that the energies of the critical points of the optical constants can be treated to be independent of the utilized model, whereas the magnitude of the optical constants varies with the used model. The anisotropic model suggests a maximum absorbance for a MoS2 sheet supported by sapphire of about 14% for monolayer and of 10% for trilayer MoS2. Furthermore, the lateral homogeneity of the complex dielectric function for monolayer MoS2 is investigated with a spatial resolution of 2 µm. Only minor fluctuations are observed. No evidence for strain, for a significant amount of disorder or lattice defects can be found in the wrinkle-free regions of the MoS2 monolayer from complementary µ-Raman spectroscopy measurements. We assume that the minor lateral variation in the optical constants are caused by lateral modification in the van der Waals interaction presumably caused by the preparation using micromechanical exfoliation and viscoelastic stamping.

  7. Imaging spectroscopic ellipsometry of MoS2

    NASA Astrophysics Data System (ADS)

    Funke, S.; Miller, B.; Parzinger, E.; Thiesen, P.; Holleitner, A. W.; Wurstbauer, U.

    2016-09-01

    Micromechanically exfoliated mono- and multilayers of molybdenum disulfide (MoS2) are investigated by spectroscopic imaging ellipsometry. In combination with knife edge illumination, MoS2 flakes can be detected and classified on arbitrary flat and also transparent substrates with a lateral resolution down to 1–2 µm. The complex dielectric functions from mono- and trilayer MoS2 are presented. They are extracted from a multilayer model to fit the measured ellipsometric angles employing an anisotropic and an isotropic fit approach. We find that the energies of the critical points of the optical constants can be treated to be independent of the utilized model, whereas the magnitude of the optical constants varies with the used model. The anisotropic model suggests a maximum absorbance for a MoS2 sheet supported by sapphire of about 14% for monolayer and of 10% for trilayer MoS2. Furthermore, the lateral homogeneity of the complex dielectric function for monolayer MoS2 is investigated with a spatial resolution of 2 µm. Only minor fluctuations are observed. No evidence for strain, for a significant amount of disorder or lattice defects can be found in the wrinkle-free regions of the MoS2 monolayer from complementary µ-Raman spectroscopy measurements. We assume that the minor lateral variation in the optical constants are caused by lateral modification in the van der Waals interaction presumably caused by the preparation using micromechanical exfoliation and viscoelastic stamping.

  8. Imaging spectroscopic ellipsometry of MoS2.

    PubMed

    Funke, S; Miller, B; Parzinger, E; Thiesen, P; Holleitner, A W; Wurstbauer, U

    2016-09-28

    Micromechanically exfoliated mono- and multilayers of molybdenum disulfide (MoS2) are investigated by spectroscopic imaging ellipsometry. In combination with knife edge illumination, MoS2 flakes can be detected and classified on arbitrary flat and also transparent substrates with a lateral resolution down to 1-2 µm. The complex dielectric functions from mono- and trilayer MoS2 are presented. They are extracted from a multilayer model to fit the measured ellipsometric angles employing an anisotropic and an isotropic fit approach. We find that the energies of the critical points of the optical constants can be treated to be independent of the utilized model, whereas the magnitude of the optical constants varies with the used model. The anisotropic model suggests a maximum absorbance for a MoS2 sheet supported by sapphire of about 14% for monolayer and of 10% for trilayer MoS2. Furthermore, the lateral homogeneity of the complex dielectric function for monolayer MoS2 is investigated with a spatial resolution of 2 µm. Only minor fluctuations are observed. No evidence for strain, for a significant amount of disorder or lattice defects can be found in the wrinkle-free regions of the MoS2 monolayer from complementary µ-Raman spectroscopy measurements. We assume that the minor lateral variation in the optical constants are caused by lateral modification in the van der Waals interaction presumably caused by the preparation using micromechanical exfoliation and viscoelastic stamping.

  9. Emergence of topological and topological crystalline phases in TlBiS2 and TlSbS2.

    PubMed

    Zhang, Qingyun; Cheng, Yingchun; Schwingenschlögl, Udo

    2015-02-11

    Using first-principles calculations, we investigate the band structure evolution and topological phase transitions in TlBiS2 and TlSbS2 under hydrostatic pressure as well as uniaxial and biaxial strain. The phase transitions are identified by parity analysis and by calculating the surface states. Zero, one, and four Dirac cones are found for the (111) surfaces of both TlBiS2 and TlSbS2 when the pressure grows, which confirms trivial-nontrivial-trivial phase transitions. The Dirac cones at the points are anisotropic with large out-of-plane component. TlBiS2 shows normal, topological, and topological crystalline insulator phases under hydrostatic pressure, thus being the first compound to exhibit a phase transition from a topological to a topological crystalline insulator.

  10. Emergence of topological and topological crystalline phases in TlBiS2 and TlSbS2

    PubMed Central

    Zhang, Qingyun; Cheng, Yingchun; Schwingenschlögl, Udo

    2015-01-01

    Using first-principles calculations, we investigate the band structure evolution and topological phase transitions in TlBiS2 and TlSbS2 under hydrostatic pressure as well as uniaxial and biaxial strain. The phase transitions are identified by parity analysis and by calculating the surface states. Zero, one, and four Dirac cones are found for the (111) surfaces of both TlBiS2 and TlSbS2 when the pressure grows, which confirms trivial-nontrivial-trivial phase transitions. The Dirac cones at the points are anisotropic with large out-of-plane component. TlBiS2 shows normal, topological, and topological crystalline insulator phases under hydrostatic pressure, thus being the first compound to exhibit a phase transition from a topological to a topological crystalline insulator. PMID:25669914

  11. Distribution of a Nocardia brasiliensis catalase gene fragment in members of the genera Nocardia, Gordona, and Rhodococcus.

    PubMed

    Vera-Cabrera, L; Johnson, W M; Welsh, O; Resendiz-Uresti, F L; Salinas-Carmona, M C

    1999-06-01

    An immunodominant protein from Nocardia brasiliensis, P61, was subjected to amino-terminal and internal sequence analysis. Three sequences of 22, 17, and 38 residues, respectively, were obtained and compared with the protein database from GenBank by using the BLAST system. The sequences showed homology to some eukaryotic catalases and to a bromoperoxidase-catalase from Streptomyces violaceus. Its identity as a catalase was confirmed by analysis of its enzymatic activity on H2O2 and by a double-staining method on a nondenaturing polyacrylamide gel with 3,3'-diaminobenzidine and ferricyanide; the result showed only catalase activity, but no peroxidase. By using one of the internal amino acid sequences and a consensus catalase motif (VGNNTP), we were able to design a PCR assay that generated a 500-bp PCR product. The amplicon was analyzed, and the nucleotide sequence was compared to the GenBank database with the observation of high homology to other bacterial and eukaryotic catalases. A PCR assay based on this target sequence was performed with primers NB10 and NB11 to confirm the presence of the NB10-NB11 gene fragment in several N. brasiliensis strains isolated from mycetoma. The same assay was used to determine whether there were homologous sequences in several type strains from the genera Nocardia, Rhodococcus, Gordona, and Streptomyces. All of the N. brasiliensis strains presented a positive result but only some of the actinomycetes species tested were positive in the PCR assay. In order to confirm these findings, genomic DNA was subjected to Southern blot analysis. A 1.7-kbp band was observed in the N. brasiliensis strains, and bands of different molecular weight were observed in cross-reacting actinomycetes. Sequence analysis of the amplicons of selected actinomycetes showed high homology in this catalase fragment, thus demonstrating that this protein is highly conserved in this group of bacteria. PMID:10325357

  12. [Conversion of soybean sterols into 3,17-diketosteroids using actinobacteria Mycobacterium neoaurum, Pimelobacter simplex, and Rhodococcus erythropolis].

    PubMed

    Andriushina, V A; Rodina, N V; Stytsenko, T C; Luu, Duc Huy; Druzhinina, A V; Iaderets, V V; Voîshvillo, N E

    2011-01-01

    Abstract-Soybean sterols were converted into androst-4-ene-3,17-dione (AD) and 9alpha-hydroxyandrost-4-ene-3,17-dione (9-OH-AD) using three actinobacterium strains. The transformation of a microcrystallic substrate (particle size 5-15 nm) or the transformation in the presence of randomly methylated beta-cyclodextrin (MCD) were carried out by Mycobacterium neoaurum with a phytosterol load of 30 g/l over 144 h with an AD content of 14.5 and 15.2 g/l, respectively. AD obtained in the presence of MCD was transformed into ADD (13.5 g/l) by Pimelobacter simplex cells over 3 h and into 9-OH-AD by Rhodococcus erythropolis cells after 22 h without the isolation of AD from the cultural liquid. The technical product ADD was obtained in 75% yield, based on phytosterol. It contained as impurity 1.25% of AD and 1.5% of 1,2-dehydrotestosterone. In a control experiment-the process of 1,2-dehydrogenation of 20 g/l AD in the water solution of MCD-no by products were isolated. Thus, it is more expedient to introduce the 1,2-double bond into pure AD, whereas R. erythropolis strain with low destructive activity towards steroid nucleus can be used in the mixed culture with M. neoaurum. The crystal product contained, according to HPLC, 80% of 9-OH-AD, and 1.5 AD was combined. The yield of 9-OH-AD (m.p. 218-220 degrees C) based on transformed phytosterol was 56%. PMID:21790029

  13. Biodegradation of 4-nitrotoluene with biosurfactant production by Rhodococcus pyridinivorans NT2: metabolic pathway, cell surface properties and toxicological characterization.

    PubMed

    Kundu, Debasree; Hazra, Chinmay; Dandi, Navin; Chaudhari, Ambalal

    2013-11-01

    A novel 4-nitrotoluene-degrading bacterial strain was isolated from pesticides contaminated effluent-sediment and identified as Rhodococcus pyridinivorans NT2 based on morphological and biochemical properties and 16S rDNA sequencing. The strain NT2 degraded 4-NT (400 mg l(-1)) with rapid growth at the end of 120 h, reduced surface tension of the media from 71 to 29 mN m(-1) and produced glycolipidic biosurfactants (45 mg l(-1)). The biosurfactant was purified and characterized as trehalose lipids. The biosurfactant was stable in high salinity (10 % w/v NaCl), elevated temperatures (120 °C for 15 min) and a wide pH range (2.0-10.0). The noticeable changes during biodegradation were decreased hydrophobicity; an increase in degree of fatty acid saturation, saturated/unsaturated ratio and cyclopropane fatty acid. Biodegradation of 4-NT was accompanied by the accumulation of ammonium (NH4 (+)) and negligible amount of nitrite ion (NO2 (-)). Product stoichiometry showed a carbon (C) and nitrogen (N) mass balance of 37 and 35 %, respectively. Biodegradation of 4-NT proceeded by oxidation at the methyl group to form 4-nitrobenzoate, followed by reduction and hydrolytic deamination yielding protocatechuate, which was metabolized through β-ketoadipate pathway. In vitro and in vivo acute toxicity assays in adult rat (Rattus norvegicus) showed sequential detoxification and the order of toxicity was 4-NT >4-nitrobenzyl alcohol >4-nitrobenzaldehyde >4-nitrobenzoate > protocatechuate. Taken together, the strain NT2 could be used as a potential bioaugmentation candidate for the bioremediation of contaminated sites.

  14. Structural characterisation of the virulence-associated protein VapG from the horse pathogen Rhodococcus equi

    PubMed Central

    Okoko, Tebekeme; Blagova, Elena V.; Whittingham, Jean L.; Dover, Lynn G.; Wilkinson, Anthony J.

    2015-01-01

    Virulence and host range in Rhodococcus equi depends on the variable pathogenicity island of their virulence plasmids. Notable gene products are a family of small secreted virulence-associated proteins (Vaps) that are critical to intramacrophagic proliferation. Equine-adapted strains, which cause severe pyogranulomatous pneumonia in foals, produce a cell-associated VapA that is necessary for virulence, alongside five other secreted homologues. In the absence of biochemical insight, attention has turned to the structures of these proteins to develop a functional hypothesis. Recent studies have described crystal structures for VapD and a truncate of the VapA orthologue of porcine-adapted strains, VapB. Here, we crystallised the full-length VapG and determined its structure by molecular replacement. Electron density corresponding to the N-terminal domain was not visible suggesting that it is disordered. The protein core adopted a compact elliptical, anti-parallel β-barrel fold with β1–β2–β3–β8–β5–β6–β7–β4 topology decorated by a single peripheral α-helix unique to this family. The high glycine content of the protein allows close packing of secondary structural elements. Topologically, the surface has no indentations that indicate a nexus for molecular interactions. The distribution of polar and apolar groups on the surface of VapG is markedly uneven. One-third of the surface is dominated by exposed apolar side-chains, with no ionisable and only four polar side-chains exposed, giving rise to an expansive flat hydrophobic surface. Other surface regions are more polar, especially on or near the α-helix and a belt around the centre of the β-barrel. Possible functional significance of these recent structures is discussed. PMID:25746683

  15. Transcriptome of the quorum-sensing signal-degrading Rhodococcus erythropolis responds differentially to virulent and avirulent Pectobacterium atrosepticum.

    PubMed

    Kwasiborski, A; Mondy, S; Chong, T-M; Barbey, C; Chan, K-G; Beury-Cirou, A; Latour, X; Faure, D

    2015-05-01

    Social bacteria use chemical communication to coordinate and synchronize gene expression via the quorum-sensing (QS) regulatory pathway. In Pectobacterium, a causative agent of the blackleg and soft-rot diseases on potato plants and tubers, expression of the virulence factors is collectively controlled by the QS-signals N-acylhomoserine lactones (NAHLs). Several soil bacteria, such as the actinobacterium Rhodococcus erythropolis, are able to degrade NAHLs, hence quench the chemical communication and virulence of Pectobacterium. Here, next-generation sequencing was used to investigate structural and functional genomics of the NAHL-degrading R. erythropolis strain R138. The R. erythropolis R138 genome (6.7 Mbp) contained a single circular chromosome, one linear (250 kbp) and one circular (84 kbp) plasmid. Growth of R. erythropolis and P. atrosepticum was not altered in mixed-cultures as compared with monocultures on potato tuber slices. HiSeq-transcriptomics revealed that no R. erythropolis genes were differentially expressed when R. erythropolis was cultivated in the presence vs absence of the avirulent P. atrosepticum mutant expI, which is defective for QS-signal synthesis. By contrast 50 genes (<1% of the R. erythropolis genome) were differentially expressed when R. erythropolis was cultivated in the presence vs absence of the NAHL-producing virulent P. atrosepticum. Among them, quantitative real-time reverse-transcriptase-PCR confirmed that the expression of some alkyl-sulfatase genes decreased in the presence of a virulent P. atrosepticum, as well as deprivation of organic sulfur such as methionine, which is a key precursor in the synthesis of NAHL by P. atrosepticum.

  16. Metabolism of 2-Chloro-4-Nitroaniline via Novel Aerobic Degradation Pathway by Rhodococcus sp. Strain MB-P1

    PubMed Central

    Khan, Fazlurrahman; Pal, Deepika; Vikram, Surendra; Cameotra, Swaranjit Singh

    2013-01-01

    2-chloro-4-nitroaniline (2-C-4-NA) is used as an intermediate in the manufacture of dyes, pharmaceuticals, corrosion inhibitor and also used in the synthesis of niclosamide, a molluscicide. It is marked as a black-listed substance due to its poor biodegradability. We report biodegradation of 2-C-4-NA and its pathway characterization by Rhodococcus sp. strain MB-P1 under aerobic conditions. The strain MB-P1 utilizes 2-C-4-NA as the sole carbon, nitrogen, and energy source. In the growth medium, the degradation of 2-C-4-NA occurs with the release of nitrite ions, chloride ions, and ammonia. During the resting cell studies, the 2-C-4-NA-induced cells of strain MB-P1 transformed 2-C-4-NA stoichiometrically to 4-amino-3-chlorophenol (4-A-3-CP), which subsequently gets transformed to 6-chlorohydroxyquinol (6-CHQ) metabolite. Enzyme assays by cell-free lysates prepared from 2-C-4-NA-induced MB-P1 cells, demonstrated that the first enzyme in the 2-C-4-NA degradation pathway is a flavin-dependent monooxygenase that catalyzes the stoichiometric removal of nitro group and production of 4-A-3-CP. Oxygen uptake studies on 4-A-3-CP and related anilines by 2-C-4-NA-induced MB-P1 cells demonstrated the involvement of aniline dioxygenase in the second step of 2-C-4-NA degradation. This is the first report showing 2-C-4-NA degradation and elucidation of corresponding metabolic pathway by an aerobic bacterium. PMID:23614030

  17. Identification and characterization of another 4-nitrophenol degradation gene cluster, nps, in Rhodococcus sp. strain PN1.

    PubMed

    Yamamoto, Kenta; Nishimura, Munehiro; Kato, Dai-ichiro; Takeo, Masahiro; Negoro, Seiji

    2011-06-01

    4-Nitrophenol (4-NP) is a toxic compound formed in soil by the hydrolysis of organophosphorous pesticides, such as parathion. We previously reported the presence of the 4-NP degradation gene cluster (nphRA1A2) in Rhodococcus sp. strain PN1, which encodes a two-component 4-NP hydroxylase system that oxidizes 4-NP into 4-nitrocatechol. In the current study, another gene cluster (npsC and npsRA2A1B) encoding a similar 4-NP hydroxylase system was cloned from strain PN1. The enzymes from this 4-NP hydroxylase system (NpsA1 and NpsA2) were purified as histidine-tagged (His-) proteins and then characterized. His-NpsA2 showed NADH/FAD oxidoreductase activity, and His-NpsA1 showed 4-NP oxidizing activity in the presence of His-NpsA2. In the 4-NP oxidation using the reconstituted enzyme system (His-NpsA1 and His-NpsA2), hydroquinone (35% of 4-NP disappeared) and hydroxyquinol (59% of 4-NP disappeared) were detected in the presence of ascorbic acid as a reducing reagent, suggesting that, without the reducing reagent, 4-NP was converted into their oxidized forms, 1,4-benzoquinone and 2-hydroxy-1,4-benzoquinone. In addition, in the cell extract of recombinant Escherichia coli expressing npsB, a typical spectral change showing conversion of hydroxyquinol into maleylacetate was observed. These results indicate that this nps gene cluster, in addition to the nph gene cluster, is also involved in 4-NP degradation in strain PN1.

  18. Extracellular production of Streptomyces exfoliatus poly(3-hydroxybutyrate) depolymerase in Rhodococcus sp. T104: determination of optimal biocatalyst conditions.

    PubMed

    García-Hidalgo, Javier; Hormigo, Daniel; Prieto, María Auxiliadora; Arroyo, Miguel; de la Mata, Isabel

    2012-03-01

    The phaZ ( Sex ) gene encoding poly(3-hydroxybutyrate) depolymerase from Streptomyces exfoliatus has been successfully cloned and expressed in Rhodococcus sp. T104 for the first time. Likewise, the recombinant enzyme was efficiently produced as an extracellular active form and purified to homogeneity by two hydrophobic chromatographic steps. MALDI-TOF analysis showed that the native enzyme is a monomer. Circular dichroism studies have revealed a secondary structure showing 25.6% α-helix, 21.4% β-sheet, 17.1% β-turns, and 35.2% random coil, with a midpoint transition temperature (T (m)) of 55.8 °C. Magnesium and calcium ions enhanced the enzyme activity, whereas manganese inhibited it. EDTA moderately decreased the activity, and the enzyme was completely deactivated at 3 M NaCl. Chemical modification studies indicated the presence of the catalytic triad serine-histidine-carboxylic acid in the active site. High-performance liquid chromatography (HPLC)-mass spectrometry (MS) analysis of PHB products of enzymatic hydrolysis showed monomers and dimers of 3-hydroxybutyric acid, demonstrating that PHB depolymerase is an exo-hydrolase. Addition of methyl-β-cyclodextrin simultaneously increased the activity as well as preserved the enzyme during lyophilization. Finally, thermoinactivation studies showed that the enzyme is highly stable at 40 °C. All these features support the potential industrial application of this recombinant enzyme in the production of (R)-3-hydroxyalkanoic acid derivatives as well as in the degradation of bioplastics. PMID:21845385

  19. Isolation and characterization of a thermotolerant ene reductase from Geobacillus sp. 30 and its heterologous expression in Rhodococcus opacus.

    PubMed

    Tsuji, Naoto; Honda, Kohsuke; Wada, Mayumi; Okano, Kenji; Ohtake, Hisao

    2014-07-01

    Rhodococcus opacus B-4 cells are adhesive to and even dispersible in water-immiscible hydrocarbons owing to their highly lipophilic nature. In this study, we focused on the high operational stability of thermophilic enzymes and applied them to a biocatalytic conversion in an organic reaction medium using R. opacus B-4 as a lipophilic capsule of enzymes to deliver them into the organic medium. A novel thermo- and organic-solvent-tolerant ene reductase, which can catalyze the enantioselective reduction of ketoisophorone to (6R)-levodione, was isolated from Geobacillus sp. 30, and the gene encoding the enzyme was heterologously expressed in R. opacus B-4. Another thermophilic enzyme which catalyzes NAD(+)-dependent dehydrogenation of cyclohexanol was identified from the gene-expression library of Thermus thermophilus and the gene was coexpressed in R. opacus B-4 for cofactor regeneration. While the recombinant cells were not viable in the mixture due to high reaction temperature, 634 mM of (6R)-levodione could be produced with an enantiopurity of 89.2 % ee by directly mixing the wet cells of the recombinant R. opacus with a mixture of ketoisophorone and cyclohexanol at 50 °C. The conversion rate observed with the heat-killed recombinant cells was considerably higher than that obtained with a cell-free enzyme solution, demonstrating that the accessibility between the substrates and enzymes could be improved by employing R. opacus cells as a lipophilic enzyme capsule. These results imply that a combination of thermophilic enzymes and lipophilic cells can be a promising approach for the biocatalytic production of water-insoluble chemicals.

  20. Molecular characterization of Rhodococcus equi from horse-breeding farms by means of multiplex PCR for the vap gene family.

    PubMed

    Monego, Fernanda; Maboni, Franciele; Krewer, Cristina; Vargas, Agueda; Costa, Mateus; Loreto, Elgion

    2009-04-01

    This study evaluated the molecular characteristics of Rhodococcus equi isolates obtained from horses by a multiplex PCR assay that amplifies the vap gene family (vapA, -B, -C, -D, -E, -F, -G, and -H). A total of 180 R. equi isolates were studied from four different sources, namely healthy horse feces (112), soil (12), stalls (23), and clinical isolates (33) from horse-breeding farms. The technique was performed and confirmed by sequencing of amplified vap gene family controls. Thirty-two (17.8%) of the R. equi isolates were positive for the vapA gene and carried at least three other vap genes. All 147 isolates from equine feces, stalls, and soil failed to demonstrate any genes associated with virulence-inducing proteins. About 32 (97.0%) out of the 33 clinical equine isolates tested positive for the multiplex PCR assay for the vap gene family. They demonstrated six molecular profiles: 100% featured the vapA, vapD, and vapG genes, 86.6% vapF, 76.6% vapH, 43.3% vapC, 36.6% vapE, and none vapB. The most frequent molecular profile was vap A, -D, -F, G, and -H, where this profile was present in 37.5% of the strains. Moreover, there was no molecular epidemiological pattern for R. equi isolates that uniquely mapped to each horse-breeding farm studied. Our proposed technique allows the identification of eight members of the vap gene family (vapA, B, -C, -D, -E, -F, -G, and -H). It is a practical and efficient method of conducting clinical and epidemiological studies on R. equi isolates.

  1. Age-Related Changes following In Vitro Stimulation with Rhodococcus equi of Peripheral Blood Leukocytes from Neonatal Foals

    PubMed Central

    Kachroo, Priyanka; Ivanov, Ivan; Seabury, Ashley G.; Liu, Mei; Chowdhary, Bhanu P.; Cohen, Noah D.

    2013-01-01

    Rhodococcus equi is an intracellular bacterium primarily known as an equine pathogen that infects young foals causing a pyogranulomatuous pneumonia. The molecular mechanisms mediating the immune response of foals to R. equi are not fully elucidated. Hence, global genomic high-throughput tools like gene expression microarrays might identify age-related gene expression signatures and molecular pathways that contribute to the immune mechanisms underlying the inherent susceptibility of foals to disease caused by R. equi. The objectives of this study were 2-fold: 1) to compare the expression profiles at specific ages of blood leukocytes from foals stimulated with virulent R. equi with those of unstimulated leukocytes; and, 2) to characterize the age-related changes in the gene expression profile associated with blood leukocytes in response to stimulation with virulent R. equi. Peripheral blood leukocytes were obtained from 6 foals within 24 hours (h) of birth (day 1) and 2, 4, and 8 weeks after birth. The samples were split, such that half were stimulated with live virulent R. equi, and the other half served as unstimulated control. RNA was extracted and the generated cDNA was labeled with fluorescent dyes for microarray hybridizations using an equine microarray. Our findings suggest that there is age-related differential expression of genes involved in host immune response and immunity. We found induction of genes critical for host immunity against pathogens (MHC class II) only at the later time-points (compared to birth). While it appears that foals up to 8-weeks of age are able to initiate a protective inflammatory response against the bacteria, relatively decreased expression of various other immune-related genes points toward inherent diminished immune responses closer to birth. These genes and pathways may contribute to disease susceptibility in foals if infected early in life, and might thus be targeted for developing preventative or therapeutic strategies. PMID

  2. Photoconductivities in MoS2 Nanoflake Photoconductors

    NASA Astrophysics Data System (ADS)

    Shen, Wei-Chu; Chen, Ruei-San; Huang, Ying-Sheng

    2016-03-01

    Photoconductivities in molybdenum disulfide (MoS2) layered nanostructures with two-hexagonal crystalline structure prepared by mechanical exfoliation were investigated. The photoconductor-type MoS2 nanoflakes exhibit remarkable photoresponse under the above bandgap excitation wavelength of 532 nm at different optical intensity. The photocurrent responsivity and photoconductive gain of nanoflakes can reach, respectively, 30 AW-1 and 103 at the intensity of 50 Wm-2, which are several orders of magnitude higher than those of their bulk counterparts. The vacuum-enhanced photocurrent and power-independent responsivity/gain indicate a surface-controlled photoconduction mechanism in the MoS2 nanomaterial.

  3. The elusive S2 state, the S1/S2 splitting, and the excimer states of the benzene dimer.

    PubMed

    Balmer, Franziska A; Trachsel, Maria A; van der Avoird, Ad; Leutwyler, Samuel

    2015-06-21

    We observe the weak S0 → S2 transitions of the T-shaped benzene dimers (Bz)2 and (Bz-d6)2 about 250 cm(-1) and 220 cm(-1) above their respective S0 → S1 electronic origins using two-color resonant two-photon ionization spectroscopy. Spin-component scaled (SCS) second-order approximate coupled-cluster (CC2) calculations predict that for the tipped T-shaped geometry, the S0 → S2 electronic oscillator strength fel(S2) is ∼10 times smaller than fel(S1) and the S2 state lies ∼240 cm(-1) above S1, in excellent agreement with experiment. The S0 → S1 (ππ(∗)) transition is mainly localized on the "stem" benzene, with a minor stem → cap charge-transfer contribution; the S0 → S2 transition is mainly localized on the "cap" benzene. The orbitals, electronic oscillator strengths fel(S1) and fel(S2), and transition frequencies depend strongly on the tipping angle ω between the two Bz moieties. The SCS-CC2 calculated S1 and S2 excitation energies at different T-shaped, stacked-parallel and parallel-displaced stationary points of the (Bz)2 ground-state surface allow to construct approximate S1 and S2 potential energy surfaces and reveal their relation to the "excimer" states at the stacked-parallel geometry. The fel(S1) and fel(S2) transition dipole moments at the C2v-symmetric T-shape, parallel-displaced and stacked-parallel geometries are either zero or ∼10 times smaller than at the tipped T-shaped geometry. This unusual property of the S0 → S1 and S0 → S2 transition-dipole moment surfaces of (Bz)2 restricts its observation by electronic spectroscopy to the tipped and tilted T-shaped geometries; the other ground-state geometries are impossible or extremely difficult to observe. The S0 → S1/S2 spectra of (Bz)2 are compared to those of imidazole ⋅ (Bz)2, which has a rigid triangular structure with a tilted (Bz)2 subunit. The S0 → S1/ S2 transitions of imidazole-(benzene)2 lie at similar energies as those of (Bz)2, confirming our assignment of the

  4. Discovery and Classification of DES15S2kqw

    NASA Astrophysics Data System (ADS)

    Kasai, E.; Bassett, B.; Crawford, S.; Kniazev, A.; Childress, M.; D'Andrea, C.; Smith, M.; Sullivan, M.; Maartens, R.; Gupta, R.; Kovacs, E.; Kuhlmann, S.; Spinka, H.; Ahn, E.; Finley, D. A.; Frieman, J.; Marriner, J.; Wester, W.; Aldering, G.; Kim, A. G.; Thomas, R. C.; Barbary, K.; Bloom, J. S.; Goldstein, D.; Nugent, P.; Perlmutter, S.; Foley, R. J.; Casas, R.; Castander, F. J.; Desai, S.; Paech, K.; Smith, R. C.; Schubnell, M.; Kessler, R.; Lasker, J.; Scolnic, D.; Brout, D. J.; Gladney, L.; Sako, M.; Wolf, R. C.; Brown, P. J.; Krisciunas, K.; Suntzeff, N.; Nichol, R.; Papadopoulos, A.

    2015-10-01

    We report optical spectroscopy of DES15S2kqw discovered by the Dark Energy Survey. The spectrum (380-820nm) was obtained using the Robert Stobie Spectrograph (RSS) on the South African Large Telescope (SALT).

  5. Discovery of gaseous S2 in Io's Pele plume.

    PubMed

    Spencer, J R; Jessup, K L; McGrath, M A; Ballester, G E; Yelle, R

    2000-05-19

    Spectroscopy of Io's Pele plume against Jupiter by the Hubble Space Telescope in October 1999 revealed absorption due to S2 gas, with a column density of 1.0 +/- 0.2 x 10(16) per square centimeter, and probably also SO(2) gas with a column density of 7 +/- 3 x 10(16) per square centimeter. This SO2/S2 ratio (3 to 12) is expected from equilibration with silicate magmas near the quartz-fayalite-magnetite or wüstite-magnetite buffers. Condensed S3 and S4, probable coloring agents in Pele's red plume deposits, may form by polymerization of the S2, which is unstable to ultraviolet photolysis. Diffuse red deposits near other Io volcanoes suggest that venting and polymerization of S2 gas is a widespread feature of Io volcanism. PMID:10817990

  6. Precision polarizability measurements of atomic cesium's 8 s 2S1 / 2 and 9 s 2S1 / 2 states

    NASA Astrophysics Data System (ADS)

    Weaver, Hannah; Kortyna, Andrew

    2013-05-01

    We report hyperfine-resolved scalar polarizabilities for cesium's 8 s 2S1 / 2 and 9 s 2S1 / 2 states using resonant two-photon spectroscopy. Two single-mode, external-cavity diode lasers drive the 6 s 2S1 / 2 --> 6 p 2P1 / 2 --> ns 2S1 / 2 transition (n = 8 or 9). Both laser beams are split and counter-propagate through an effusive beam and a vapor cell. An electric field applied across two parallel plates imposes Stark shifts on the ns 2S1 / 2 levels in the effusive beam. Electric-field strengths are measured in situ. The laser frequency is calibrated in the vapor cell using a phase modulation technique, with the modulation frequency referenced to the ground-state hyperfine splitting of atomic rubidium. Our measured 8 s 2S1 / 2 polarizability, 38370 +/- 380 a03, agrees with previous theory and experiments. Our measured 9 s 2S1 / 2 polarizability, 150700 +/- 1100 a03, agrees within two sigma of theory, but we are unaware of previous measurements. We also verify that these polarizabilities are independent of the hyperfine levels, placing upper limits on the differential polarizabilities of 200 +/- 260 a03 for the 8 s 2S1 / 2 state and 490 +/- 450 a03 for the 9 s 2S1 / 2 state. Supported by the National Science Foundation under Grant PHY-0653107.

  7. Few-layer HfS2 transistors

    PubMed Central

    Kanazawa, Toru; Amemiya, Tomohiro; Ishikawa, Atsushi; Upadhyaya, Vikrant; Tsuruta, Kenji; Tanaka, Takuo; Miyamoto, Yasuyuki

    2016-01-01

    HfS2 is the novel transition metal dichalcogenide, which has not been experimentally investigated as the material for electron devices. As per the theoretical calculations, HfS2 has the potential for well-balanced mobility (1,800 cm2/V·s) and bandgap (1.2 eV) and hence it can be a good candidate for realizing low-power devices. In this paper, the fundamental properties of few-layer HfS2 flakes were experimentally evaluated. Micromechanical exfoliation using scotch tape extracted atomically thin HfS2 flakes with varying colour contrasts associated with the number of layers and resonant Raman peaks. We demonstrated the I-V characteristics of the back-gated few-layer (3.8 nm) HfS2 transistor with the robust current saturation. The on/off ratio was more than 104 and the maximum drain current of 0.2 μA/μm was observed. Moreover, using the electric double-layer gate structure with LiClO4:PEO electrolyte, the drain current of the HfS2 transistor significantly increased to 0.75 mA/μm and the mobility was estimated to be 45 cm2/V·s at least. This improved current seemed to indicate superior intrinsic properties of HfS2. These results provides the basic information for the experimental researches of electron devices based on HfS2. PMID:26926098

  8. Few-layer HfS2 transistors

    NASA Astrophysics Data System (ADS)

    Kanazawa, Toru; Amemiya, Tomohiro; Ishikawa, Atsushi; Upadhyaya, Vikrant; Tsuruta, Kenji; Tanaka, Takuo; Miyamoto, Yasuyuki

    2016-03-01

    HfS2 is the novel transition metal dichalcogenide, which has not been experimentally investigated as the material for electron devices. As per the theoretical calculations, HfS2 has the potential for well-balanced mobility (1,800 cm2/V·s) and bandgap (1.2 eV) and hence it can be a good candidate for realizing low-power devices. In this paper, the fundamental properties of few-layer HfS2 flakes were experimentally evaluated. Micromechanical exfoliation using scotch tape extracted atomically thin HfS2 flakes with varying colour contrasts associated with the number of layers and resonant Raman peaks. We demonstrated the I-V characteristics of the back-gated few-layer (3.8 nm) HfS2 transistor with the robust current saturation. The on/off ratio was more than 104 and the maximum drain current of 0.2 μA/μm was observed. Moreover, using the electric double-layer gate structure with LiClO4:PEO electrolyte, the drain current of the HfS2 transistor significantly increased to 0.75 mA/μm and the mobility was estimated to be 45 cm2/V·s at least. This improved current seemed to indicate superior intrinsic properties of HfS2. These results provides the basic information for the experimental researches of electron devices based on HfS2.

  9. Pressure confinement effect in MoS2 monolayers.

    PubMed

    Li, Fangfei; Yan, Yalan; Han, Bo; Li, Liang; Huang, Xiaoli; Yao, Mingguang; Gong, Yuanbo; Jin, Xilian; Liu, Baoli; Zhu, Chuanrui; Zhou, Qiang; Cui, Tian

    2015-05-21

    With ever increasing interest in layered materials, molybdenum disulfide has been widely investigated due to its unique optoelectronic properties. Pressure is an effective technique to tune the lattice and electronic structure of materials such that high pressure studies can disclose new structural and optical phenomena. In this study, taking MoS2 as an example, we investigate the pressure confinement effect on monolayer MoS2 by in situ high pressure Raman and photoluminescence (PL) measurements. Our results reveal a structural deformation of monolayer MoS2 starting from 0.84 GPa, which is evidenced by the splitting of E(1)2g and A1g modes. A further compression leads to a transition from the 1H-MoS2 phase to a novel structure evidenced by the appearance of two new peaks located at 200 and 240 cm(-1). This is a distinct feature of monolayer MoS2 compared with bulk MoS2. The new structure is supposed to have a distorted unit with the S atoms slided within a single layer like that of metastable 1T'-MoS2. However, unlike the non-photoluminescent 1T'-MoS2 structure, our monolayer shows a remarkable PL peak and a pressure-induced blue shift up to 13.1 GPa. This pressure-dependent behavior might enable the development of novel devices with multiple phenomena involving the strong coupling of the mechanical, electrical and optical properties of layered nanomaterials.

  10. Crystal structure of new AsS2 compound

    NASA Astrophysics Data System (ADS)

    Bolotina, N. B.; Brazhkin, V. V.; Dyuzheva, T. I.; Lityagina, L. M.; Kulikova, L. F.; Nikolaev, N. A.; Verin, I. A.

    2013-01-01

    AsS2 single crystals have been obtained for the first time from an As2S3 melt at pressures above 6 GPa and temperatures above 800 K in the As2S3 → AsS + AsS2 reaction. The monoclinic structure of the new high-pressure phase is solved by X-ray diffraction analysis and compared to the structure of high-pressure AsS phase, which was studied previously.

  11. Electrical Transport Properties of Polymorphic MoS2.

    PubMed

    Kim, Jun Suk; Kim, Jaesu; Zhao, Jiong; Kim, Sungho; Lee, Jin Hee; Jin, Youngjo; Choi, Homin; Moon, Byoung Hee; Bae, Jung Jun; Lee, Young Hee; Lim, Seong Chu

    2016-08-23

    The engineering of polymorphs in two-dimensional layered materials has recently attracted significant interest. Although the semiconducting (2H) and metallic (1T) phases are known to be stable in thin-film MoTe2, semiconducting 2H-MoS2 is locally converted into metallic 1T-MoS2 through chemical lithiation. In this paper, we describe the observation of the 2H, 1T, and 1T' phases coexisting in Li-treated MoS2, which result in unusual transport phenomena. Although multiphase MoS2 shows no transistor-gating response, the channel resistance decreases in proportion to the temperature, similar to the behavior of a typical semiconductor. Transmission electron microscopy images clearly show that the 1T and 1T' phases are randomly distributed and intervened with 2H-MoS2, which is referred to as the 1T and 1T' puddling phenomenon. The resistance curve fits well with 2D-variable range-hopping transport behavior, where electrons hop over 1T domains that are bounded by semiconducting 2H phases. However, near 30 K, electrons hop over charge puddles. The large temperature coefficient of resistance (TCR) of multiphase MoS2, -2.0 × 10(-2) K(-1) at 300 K, allows for efficient IR detection at room temperature by means of the photothermal effect. PMID:27399325

  12. Electrical Transport Properties of Polymorphic MoS2.

    PubMed

    Kim, Jun Suk; Kim, Jaesu; Zhao, Jiong; Kim, Sungho; Lee, Jin Hee; Jin, Youngjo; Choi, Homin; Moon, Byoung Hee; Bae, Jung Jun; Lee, Young Hee; Lim, Seong Chu

    2016-08-23

    The engineering of polymorphs in two-dimensional layered materials has recently attracted significant interest. Although the semiconducting (2H) and metallic (1T) phases are known to be stable in thin-film MoTe2, semiconducting 2H-MoS2 is locally converted into metallic 1T-MoS2 through chemical lithiation. In this paper, we describe the observation of the 2H, 1T, and 1T' phases coexisting in Li-treated MoS2, which result in unusual transport phenomena. Although multiphase MoS2 shows no transistor-gating response, the channel resistance decreases in proportion to the temperature, similar to the behavior of a typical semiconductor. Transmission electron microscopy images clearly show that the 1T and 1T' phases are randomly distributed and intervened with 2H-MoS2, which is referred to as the 1T and 1T' puddling phenomenon. The resistance curve fits well with 2D-variable range-hopping transport behavior, where electrons hop over 1T domains that are bounded by semiconducting 2H phases. However, near 30 K, electrons hop over charge puddles. The large temperature coefficient of resistance (TCR) of multiphase MoS2, -2.0 × 10(-2) K(-1) at 300 K, allows for efficient IR detection at room temperature by means of the photothermal effect.

  13. Spin polarized transport in MoS2

    NASA Astrophysics Data System (ADS)

    Dankert, André; Pashaei, Parham; Mutta, Venkata Kamalakar; Dash, Saroj Prasad; Spintronic SPD Team

    The two-dimensional (2D) semiconductor MoS2 possesses a high potential for spintronic devices due to a rich spin-valley physics and large spin-orbit coupling. While there have been significant advances in studying the spin and valley dynamics in MoS2 using optical spectroscopy techniques, electronic spin transport in semiconducting MoS2 or its heterostructures have not yet been demonstrated. Here we report the electronic and spin transport properties in MoS2 employing ferromagnetic electrodes in a vertical device geometry. Such vertical devices with MoS2 channel length defined by the thickness of the 2D layer allow to investigate the spin injection, transport and detection. We observe a magnetoresistance effect over a large temperature range up to 300 K and investigate the temperature and bias dependence behavior. Using magnetotransport data and calculations we extract spin parameters in the MoS2 spin valve devices. These findings can open new avenues for exploring spin functionalities in 2D semiconductor heterostructures for spin logic applications.

  14. Lipid storage in high-altitude Andean Lakes extremophiles and its mobilization under stress conditions in Rhodococcus sp. A5, a UV-resistant actinobacterium.

    PubMed

    Bequer Urbano, Susana; Albarracín, Virginia H; Ordoñez, Omar F; Farías, María E; Alvarez, Héctor M

    2013-03-01

    The production of triacylglycerols (TAG) or wax esters (WS) seems to be a widespread feature among extremophile bacteria living in high-altitude Andean Lakes (HAAL), Argentina. Twelve out of twenty bacterial strains isolated from HAAL were able to produce TAG or WS (between 2 and 17 % of cellular dry weight) under nitrogen-limiting culture conditions. Among these strains, the extremophile Rhodococcus sp. A5 accumulated significant amounts of TAG during growth on glucose (17 %, CDW) and hexadecane (32 %, CDW) as sole carbon sources. The role of accumulated TAG in the response to carbon starvation, osmotic stress, UV-radiation and desiccation was investigated in Rhodococcus sp. A5 using an inhibitor of TAG degradation. Cells degraded TAG during these stresses in the absence of the inhibitor. The inhibition of TAG mobilization affected cell survival during osmotic stress only during the initial growth stage. Little or no surviving cells were observed after carbon starvation, UV-treatment and desiccation, when TAG mobilization was inhibited. These results suggested that TAG metabolism is relevant for the adaptation and survival of A5 cells under carbon starvation, osmotic stress and UV irradiation, and essential under desiccation conditions, which prevail in HAAL environments.

  15. Biotechnological methods for chalcone reduction using whole cells of Lactobacillus, Rhodococcus and Rhodotorula strains as a way to produce new derivatives.

    PubMed

    Stompor, Monika; Kałużny, Mateusz; Żarowska, Barbara

    2016-10-01

    Microbial strains of the genera Dietzia, Micrococcus, Pseudomonas, Rhodococcus, Gordonia, Streptomyces, Pseudomonas, Bacillus, Penicillium, Rhodotorula and Lactobacillus were screened for the ability to convert chalcones. Synthesis of chalcones was performed by the Claisen-Schmidt reaction. There were three groups of chalcones obtained as the products, which included the derivatives containing 4-substituted chalcone, 2'-hydroxychalcone and 4'-methoxychalcone. The B ring of the chalcones was substituted in the para position with different groups, such as halide, hydroxyl, nitro, methyl, ethyl and ethoxy one. The structure-activity relationship of the tested chalcones in biotransformation processes was studied. It has been proven that Gram-positive bacterial strains Rhodococcus and Lactobacillus catalyzed reduction of C=C bond in the chalcones to give respective dihydrochalcones. The strain Rhodotorula rubra AM 82 transformed chalcones into dihydrochalcones and respective secondary alcohols. These results suggest that the probiotic strain of Lactobacillus can be used for biotransformations of chalcones, which has not been described before. The structure of new metabolites 14a and 15b were established as 4-ethoxy-4'-methoxydihydrochalcone and 3-(4-bromophenyl)-1-(4'-O-methylphenyl)-2-propan-1-ol, respectively, which was confirmed by (1)H NMR and (13)C NMR analysis.

  16. Methylation of halogenated phenols and thiophenols by cell extracts of gram-positive and gram-negative bacteria. [Rhodococcus sp. ; Pseudomonas sp. ; Acinetobacter sp

    SciTech Connect

    Neilson, A.H.; Lindgren, C.; Hynning, P.A.; Remberger, M.

    1988-02-01

    O-methylation of 2,6-dibromophenol was studied in cell extracts prepared from Rhodococcus sp. strain 1395. O-methylation activity was also demonstrated in extracts from two other Rhodococcus sp. strains, an Acinetobacter sp. strain, and a Pseudomonas sp. strain. A diverse range of chloro- and bromophenols, chlorothiophenols, chloro- and bromoguaiacols, and chloro- and bromocatechols were assayed as the substrates by using extracts prepared from strain 1395; all of the compounds were methylated to the corresponding anisoles, veratroles, or guaiacols. The specific activity of the enzyme towards the thiophenols was significantly higher than it was towards all the other substrates-high activity was found with pentafluorothiophenol, although the activity with pentafluorophenol was undetectable with the incubation times used. For the chlorophenols, the position of the substituents was of cardinal importance. The enzyme had higher activity towards the halogenated catechols than towards the corresponding guaiacols, and selective O-methylation of the 3,4,5-trihalogenocatechols yielded predominantly the 3,4,5-trihalogenoguaiacols. Neither 2,4-dinitrophenol, hexachlorophene, nor 5-chloro- or 5-bromovanillin was O-methylated. The results showed conclusively that the methylation reactions were enzymatic and confirmed the conclusion from extensive studies using whole cells that methylation of halogenated phenols may be a significant alternative to biodegradation.

  17. Biotechnological methods for chalcone reduction using whole cells of Lactobacillus, Rhodococcus and Rhodotorula strains as a way to produce new derivatives.

    PubMed

    Stompor, Monika; Kałużny, Mateusz; Żarowska, Barbara

    2016-10-01

    Microbial strains of the genera Dietzia, Micrococcus, Pseudomonas, Rhodococcus, Gordonia, Streptomyces, Pseudomonas, Bacillus, Penicillium, Rhodotorula and Lactobacillus were screened for the ability to convert chalcones. Synthesis of chalcones was performed by the Claisen-Schmidt reaction. There were three groups of chalcones obtained as the products, which included the derivatives containing 4-substituted chalcone, 2'-hydroxychalcone and 4'-methoxychalcone. The B ring of the chalcones was substituted in the para position with different groups, such as halide, hydroxyl, nitro, methyl, ethyl and ethoxy one. The structure-activity relationship of the tested chalcones in biotransformation processes was studied. It has been proven that Gram-positive bacterial strains Rhodococcus and Lactobacillus catalyzed reduction of C=C bond in the chalcones to give respective dihydrochalcones. The strain Rhodotorula rubra AM 82 transformed chalcones into dihydrochalcones and respective secondary alcohols. These results suggest that the probiotic strain of Lactobacillus can be used for biotransformations of chalcones, which has not been described before. The structure of new metabolites 14a and 15b were established as 4-ethoxy-4'-methoxydihydrochalcone and 3-(4-bromophenyl)-1-(4'-O-methylphenyl)-2-propan-1-ol, respectively, which was confirmed by (1)H NMR and (13)C NMR analysis. PMID:27209040

  18. Ln3I5(S2N2)(S2)(THF)10 - a new type of molecular compounds.

    PubMed

    Fagin, A A; Fukin, G K; Cherkasov, A V; Shestakov, A F; Pushkarev, A P; Balashova, T V; Maleev, A A; Bochkarev, M N

    2016-03-21

    Unprecedented complexes of the composition Ln3I5(S2N2)(S2)(THF)10 were obtained in the reactions of neodymium and dysprosium iodide-nitrides with sulfur. The inorganic core of the molecules contains the cyclic fragments Ln(μ-S2)Ln, LnSNSN and LnSN. Ten of the fourteen atoms of the core are coplanar, the remaining four S2 and I2 atoms lie in the other two orthogonal planes. The dysprosium complex upon excitation with UV light exhibits the metal-centered luminescence characteristic of the Dy(3+) ion. Geometric parameters of the molecules, computational data, electron spectroscopy and fluorescence suggest the existence of some conjugation in the mentioned heterocycles. PMID:26842841

  19. Beam-foil spectroscopical study of the 1s2s2p and 1s2p 2 quartet levels of Mg 9+ and Al 10+

    NASA Astrophysics Data System (ADS)

    Hellmann, H.; Träbert, E.

    1985-07-01

    Results of recent measurements of the fine structure and multiplet separation of the lowest quartet terms of doubly excited three-electron ions of Mg and Al are compared with other experiments and with theory. Preliminary results of lifetime measurements of 1s2p 24P 1/2.3/2 levels are presented. They confirm the recent calculation by Chen. Crasemann and Mark and contradict older calculations by Tunnell and Bhalla.

  20. Measurement of Absolute Cross Sections for Excitation of the 2s^2 ^1S - 2s2p ^1P^o Transition in O^4+

    NASA Astrophysics Data System (ADS)

    Smith, Steven J.; Berrington, K. A.

    2005-05-01

    Experimental electron excitation cross sections are reported for the 2s^2 1S - 2s2p^ 1P^o transitions in O^4+ located at 19.689 eV. The JPL electron-cyclotron resonance ion source is utilized [1], along with the electron energy loss method, in a merged electron-ion beams geometry[2]. The center-of-mass interaction energies for the measurements are in the range 18 eV (below threshold) to 30 eV. Data are compared with results of a 26-term R-matrix calculation that includes fine structure explicitly via the Breit-Pauli Hamiltonian [3]. There is good agreement with theoretical results and with previous electron energy-loss measurements [3]. Clear resonance enhancement is observed in both experiment and theoretical results near threshold for this ^1S - ^1P^o transition. J. Lozano and N. Djuric acknowledge support through the NASA-NRC program. This work was carried out at JPL/Caltech and was supported by NASA. [1] J. B. Greenwood, S. J. Smith, A.Chutjian, and E. Pollack, Phys. Rev. A 59 1348, (1999). [2] A. Chutjian, Physica Scripta T110, 203 (2004). [3] M. Bannister et al., Int.J. Mass Spectrometry 192, 39 (1999).

  1. Structure and dielectric behavior of TlSbS2

    NASA Astrophysics Data System (ADS)

    Parto, M.; Deger, D.; Ulutas, K.; Yakut, Ş.

    2013-09-01

    A comparison of structure and dielectric properties of TlSbS2 thin films, deposited in different thicknesses (400-4100 Å) by thermal evaporation of TlSbS2 crystals that were grown by the Stockbarger-Bridgman technique and the bulk material properties of TlSbS2 are presented. Dielectric constant ɛ 1 and dielectric loss ɛ 2 have been calculated by measuring capacitance and dielectric loss factor in the frequency range 20 Hz-10 KHz and in the temperature range 273-433 K. It is observed that at 1 kHz frequency and 293 K temperature the dielectric constant of TlSbS2 thin films is ɛ 1=1.8-6 and the dielectric loss of TlSbS2 thin films is ɛ 2=0.5-3 depending on film thickness. In the given intervals, both of dielectric constant and dielectric loss decrease with frequency, but increase with temperature. The maximum barrier height W m is calculated from the dielectric measurements. The values of W m for TlSbS2 films and bulk are obtained as 0.56 eV and 0.62 eV at room temperature, respectively. The obtained values agree with those proposed by the theory of hopping over the potential barrier. The temperature variation of ac conductivity can be reasonably interpreted in terms of the correlated barrier hopping model since it obeys the ω s law with a temperature dependent s ( s<1) and going down as the temperature is increased. The temperature coefficient of capacitance (TCC) and permittivity (TCP) are evaluated for both thin films and bulk material of TlSbS2.

  2. Ultrasensitive photodetectors based on monolayer MoS2.

    PubMed

    Lopez-Sanchez, Oriol; Lembke, Dominik; Kayci, Metin; Radenovic, Aleksandra; Kis, Andras

    2013-07-01

    Two-dimensional materials are an emerging class of new materials with a wide range of electrical properties and potential practical applications. Although graphene is the most well-studied two-dimensional material, single layers of other materials, such as insulating BN (ref. 2) and semiconducting MoS2 (refs 3, 4) or WSe2 (refs 5, 6), are gaining increasing attention as promising gate insulators and channel materials for field-effect transistors. Because monolayer MoS2 is a direct-bandgap semiconductor due to quantum-mechanical confinement, it could be suitable for applications in optoelectronic devices where the direct bandgap would allow a high absorption coefficient and efficient electron-hole pair generation under photoexcitation. Here, we demonstrate ultrasensitive monolayer MoS2 phototransistors with improved device mobility and ON current. Our devices show a maximum external photoresponsivity of 880 A W(-1) at a wavelength of 561 nm and a photoresponse in the 400-680 nm range. With recent developments in large-scale production techniques such as liquid-scale exfoliation and chemical vapour deposition-like growth, MoS2 shows important potential for applications in MoS2-based integrated optoelectronic circuits, light sensing, biomedical imaging, video recording and spectroscopy.

  3. High frequency MoS2 nanomechanical resonators.

    PubMed

    Lee, Jaesung; Wang, Zenghui; He, Keliang; Shan, Jie; Feng, Philip X-L

    2013-07-23

    Molybdenum disulfide (MoS2), a layered semiconducting material in transition metal dichalcogenides (TMDCs), as thin as a monolayer (consisting of a hexagonal plane of Mo atoms covalently bonded and sandwiched between two planes of S atoms, in a trigonal prismatic structure), has demonstrated unique properties and strong promises for emerging two-dimensional (2D) nanodevices. Here we report on the demonstration of movable and vibrating MoS2 nanodevices, where MoS2 diaphragms as thin as 6 nm (a stack of 9 monolayers) exhibit fundamental-mode nanomechanical resonances up to f0 ~ 60 MHz in the very high frequency (VHF) band, and frequency-quality (Q) factor products up to f0 × Q ~ 2 × 10(10)Hz, all at room temperature. The experimental results from many devices with a wide range of thicknesses and lateral sizes, in combination with theoretical analysis, quantitatively elucidate the elastic transition regimes in these ultrathin MoS2 nanomechanical resonators. We further delineate a roadmap for scaling MoS2 2D resonators and transducers toward microwave frequencies. This study also opens up possibilities for new classes of vibratory devices to exploit strain- and dynamics-engineered ultrathin semiconducting 2D crystals.

  4. Channel length scaling of MoS2 MOSFETs.

    PubMed

    Liu, Han; Neal, Adam T; Ye, Peide D

    2012-10-23

    In this article, we investigate electrical transport properties in ultrathin body (UTB) MoS(2) two-dimensional (2D) crystals with channel lengths ranging from 2 μm down to 50 nm. We compare the short channel behavior of sets of MOSFETs with various channel thickness, and reveal the superior immunity to short channel effects of MoS(2) transistors. We observe no obvious short channel effects on the device with 100 nm channel length (L(ch)) fabricated on a 5 nm thick MoS(2) 2D crystal even when using 300 nm thick SiO(2) as gate dielectric, and has a current on/off ratio up to ~10(9). We also observe the on-current saturation at short channel devices with continuous scaling due to the carrier velocity saturation. Also, we reveal the performance limit of short channel MoS(2) transistors is dominated by the large contact resistance from the Schottky barrier between Ni and MoS(2) interface, where a fully transparent contact is needed to achieve a high-performance short channel device.

  5. S2PLOT: Three-dimensional (3D) Plotting Library

    NASA Astrophysics Data System (ADS)

    Barnes, D. G.; Fluke, C. J.; Bourke, P. D.; Parry, O. T.

    2011-03-01

    We present a new, three-dimensional (3D) plotting library with advanced features, and support for standard and enhanced display devices. The library - S2PLOT - is written in C and can be used by C, C++ and FORTRAN programs on GNU/Linux and Apple/OSX systems. S2PLOT draws objects in a 3D (x,y,z) Cartesian space and the user interactively controls how this space is rendered at run time. With a PGPLOT inspired interface, S2PLOT provides astronomers with elegant techniques for displaying and exploring 3D data sets directly from their program code, and the potential to use stereoscopic and dome display devices. The S2PLOT architecture supports dynamic geometry and can be used to plot time-evolving data sets, such as might be produced by simulation codes. In this paper, we introduce S2PLOT to the astronomical community, describe its potential applications, and present some example uses of the library.

  6. Ferromagnetism in Single Crystal MoS2

    NASA Astrophysics Data System (ADS)

    Saeidi Varnoosfaderani, Sima; Tongay, Sefaattin; Appleton, Bill; Wu, Junqiao; Hebard, Arthur

    2013-03-01

    We report on the magnetic properties of MoS2 flakes measured from room temperature down to 10 K and magnetic fields up to 5 Tesla. Molybdenum disulfide (MoS2) is one of the most stable layered transition metal dichalcogenides, which has a finite band gap and is regarded as a complementary (quasi-) 2D material to graphene. We find that single crystals of MoS2 display ferromagnetism superimposed onto a large temperature-dependent diamagnetism and observe that ferromagnetism persists from 10 K up to room temperature. We attribute the existence of ferromagnetism partly to the presence of zigzag edges in the magnetic ground state at the grain boundaries. Since the magnetic measurements are relatively insensitive to the interlayer coupling, these results are expected to be also valid in the single layer limit. This work is supported by the Office of Naval Research and National Science Foundation

  7. Towards an optimised sputtered MoS2 lubricant film

    NASA Technical Reports Server (NTRS)

    Roberts, E. W.

    1986-01-01

    It is shown that the tribological quality of MoS2 lubricant films formed by magnetron sputtering is determined by the choice of sputtering conditions. By selecting the appropriate conditions, films of extremely high lubricity and endurance (in vacuum), which are well suited to many space applications, are obtained. Such MoS2 films, when applied to precision ball hearings, give rise to the lowest torques (for the given test conditions) yet seen in our laboratory. While a remarkably good performance is obtained in vacuum, tests in air show a marked deterioration in lubricating qualities. It is demonstrated that this is attributable to the adsorption of water vapor on MoS2 surfaces and that the degree of deterioration is related to the partial pressure of water vapor present. Analysis of results indicates that the factors relevant to obtaining optimum films are deposition rate and film composition.

  8. Single-layer MoS2 electronics.

    PubMed

    Lembke, Dominik; Bertolazzi, Simone; Kis, Andras

    2015-01-20

    CONSPECTUS: Atomic crystals of two-dimensional materials consisting of single sheets extracted from layered materials are gaining increasing attention. The most well-known material from this group is graphene, a single layer of graphite that can be extracted from the bulk material or grown on a suitable substrate. Its discovery has given rise to intense research effort culminating in the 2010 Nobel Prize in physics awarded to Andre Geim and Konstantin Novoselov. Graphene however represents only the proverbial tip of the iceberg, and increasing attention of researchers is now turning towards the veritable zoo of so-called "other 2D materials". They have properties complementary to graphene, which in its pristine form lacks a bandgap: MoS2, for example, is a semiconductor, while NbSe2 is a superconductor. They could hold the key to important practical applications and new scientific discoveries in the two-dimensional limit. This family of materials has been studied since the 1960s, but most of the research focused on their tribological applications: MoS2 is best known today as a high-performance dry lubricant for ultrahigh-vacuum applications and in car engines. The realization that single layers of MoS2 and related materials could also be used in functional electronic devices where they could offer advantages compared with silicon or graphene created a renewed interest in these materials. MoS2 is currently gaining the most attention because the material is easily available in the form of a mineral, molybdenite, but other 2D transition metal dichalcogenide (TMD) semiconductors are expected to have qualitatively similar properties. In this Account, we describe recent progress in the area of single-layer MoS2-based devices for electronic circuits. We will start with MoS2 transistors, which showed for the first time that devices based on MoS2 and related TMDs could have electrical properties on the same level as other, more established semiconducting materials. This

  9. MoS2 sputtering coating for ultrahigh vacuum manipulation

    NASA Astrophysics Data System (ADS)

    Maruyama, Toshiyuki; Nakagawa, Jun; Endo, Katsumi; Kasahara, Akira; Goto, Masahiro; Tosa, Masahiro

    2013-03-01

    Lubrication applied to sliding part is one of the key components for the development of high performance driving mechanism and manipulator in ultrahigh vacuum. Some solid lubrication has been widely used for this purpose, especially molybdenum disulfide (MoS2). Low friction, low wear and low outgassing during the sliding motion on lubrication are required for a high performance manipulation in ultrahigh vacuum. Although the tribology of MoS2 has been reported to be suitable in a vacuum, the outgassing characteristics while sliding are not clean, in this work, we investigate the characteristics of MoS2 sputtering coating in order to develop high performance ultrahigh vacuum driving mechanism. Their friction and outgassing characteristics were evaluated and we have found out suitable parameters for manipulation.

  10. Electrical characteristics of multilayer MoS2 FET's with MoS2/graphene heterojunction contacts.

    PubMed

    Kwak, Joon Young; Hwang, Jeonghyun; Calderon, Brian; Alsalman, Hussain; Munoz, Nini; Schutter, Brian; Spencer, Michael G

    2014-08-13

    The electrical properties of multilayer MoS2/graphene heterojunction transistors are investigated. Temperature-dependent I-V measurements indicate the concentration of unintentional donors in exfoliated MoS2 to be 3.57 × 10(11) cm(-2), while the ionized donor concentration is determined as 3.61 × 10(10) cm(-2). The temperature-dependent measurements also reveal two dominant donor levels, one at 0.27 eV below the conduction band and another located at 0.05 eV below the conduction band. The I-V characteristics are asymmetric with drain bias voltage and dependent on the junction used for the source or drain contact. I-V characteristics of the device are consistent with a long channel one-dimensional field-effect transistor model with Schottky contact. Utilizing devices, which have both graphene/MoS2 and Ti/MoS2 contacts, the Schottky barrier heights of both interfaces are measured. The charge transport mechanism in both junctions was determined to be either thermionic-field emission or field emission depending on bias voltage and temperature. On the basis of a thermionic field emission model, the barrier height at the graphene/MoS2 interface was determined to be 0.23 eV, while the barrier height at the Ti/MoS2 interface was 0.40 eV. The value of Ti/MoS2 barrier is higher than previously reported values, which did not include the effects of thermionic field emission.

  11. Excitation intensity dependence of photoluminescence from monolayers of MoS2 and WS2/MoS2 heterostructures

    NASA Astrophysics Data System (ADS)

    Kaplan, D.; Gong, Y.; Mills, K.; Swaminathan, V.; Ajayan, P. M.; Shirodkar, S.; Kaxiras, E.

    2016-03-01

    A detailed study of the excitation dependence of the photoluminescence (PL) from monolayers of MoS2 and WS2/MoS2 heterostructures grown by chemical vapor deposition on Si substrates has revealed that the luminescence from band edge excitons from MoS2 monolayers shows a linear dependence on excitation intensity for both above band gap and resonant excitation conditions. In particular, a band separated by ∼55 meV from the A exciton, referred to as the C band, shows the same linear dependence on excitation intensity as the band edge excitons. A band similar to the C band has been previously ascribed to a trion, a charged, three-particle exciton. However, in our study the C band does not show the 3/2 power dependence on excitation intensity as would be expected for a three-particle exciton. Further, the PL from the MoS2 monolayer in a bilayer WS2/MoS2 heterostructure, under resonant excitation conditions where only the MoS2 absorbs the laser energy, also revealed a linear dependence on excitation intensity for the C band, confirming that its origin is not due to a trion but instead a bound exciton, presumably of an unintentional impurity or a native point defect such as a sulfur vacancy. The PL from the WS2/MoS2 heterostructure, under resonant excitation conditions also showed additional features which are suggested to arise from the interface states at the heteroboundary. Further studies are required to clearly identify the origin of these features.

  12. MoS2 actuators: reversible mechanical responses of MoS2-polymer nanocomposites to photons

    NASA Astrophysics Data System (ADS)

    Fan, Xiaoming; Khosravi, Farhad; Rahneshin, Vahid; Shanmugam, Mariyappan; Loeian, Masoud; Jasinski, Jacek; Cohn, Robert W.; Terentjev, Eugene; Panchapakesan, Balaji

    2015-07-01

    New molybdenum disulfide (MoS2)-based polymer composites and their reversible mechanical responses to light are presented, suggesting MoS2 as an excellent candidate for energy conversion. Homogeneous mixtures of MoS2/polydimethylsiloxane (PDMS) nanocomposites (0.1-5 wt.%) were prepared and their near infrared (NIR) mechanical responses studied with increasing pre-strains. NIR triggering resulted in an extraordinary change in stress levels of the actuators by ~490 times. Actuation responses of MoS2 polymer composites depended on applied pre-strains. At lower levels of pre-strains (3-9%) the actuators showed reversible expansion while at high levels (15-50%), the actuators exhibited reversible contraction. An opto-mechanical conversion (η)˜0.5-3 MPa W-1 was calculated. The ratio of maximum stress due to photo-actuation (σmax) at 50% strain to the minimum stress due to photo-actuation (σmin) at 3% strain was found to be ˜315-322% for MoS2 actuators (for 0.1 to 5 wt.% additive), greater than single layer graphene (˜188%) and multi-wall nanotube (˜172%) photo-mechanical actuators. Unlike other photomechanical actuators, the MoS2 actuators exhibited strong light-matter interactions and an unambiguous increase in amplitude of photomechanical response with increasing strains. A power law dependence of σmax/σmin on strains with a scaling exponent of β = 0.87-1.32 was observed, suggesting that the origin of photomechanical response is intertwined dynamically with the molecular mechanisms at play in MoS2 actuators.

  13. Molecular characterization of a lipid-modified virulence-associated protein of Rhodococcus equi and its potential in protective immunity.

    PubMed

    Tan, C; Prescott, J F; Patterson, M C; Nicholson, V M

    1995-01-01

    Virulent strains of Rhodococcus equi produce plasmid-mediated 15- and 17-kDa proteins, which are thermoregulated and apparently surface-expressed. We demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) that R. equi produce three antigenically-related virulence-associated proteins, a diffuse 18-22-kDa, a 17.5-kDa and a 15-kDa protein. Phase partitioning of whole cells of R. equi strain 103 with Triton X-114 (TX-114) and labelling with [3H]-labelled palmitic acid showed that the two higher molecular weight proteins are hydrophobic and lipid modified. The 15-kDa protein did not partition into TX-114 and was not lipid modified. Cloning and expression of a fragment of the R. equi virulence plasmid in Escherichia coli showed that the three proteins were expressed from a single gene. Sequence analysis of this gene (designated vapA) revealed a 570-bp open reading frame encoding a polypeptide of 189 amino acids with a calculated molecular mass of 19,175 Da. The mature, nonlipid modified protein had a calculated mass of 16,246 Da. The 17.5- and 18-22-kDa forms of the protein are therefore due to lipid modification. No significant sequence homology of the vapA gene with other reported nucleotide sequences were found. Opsonization of virulent R. equi with an IgG1 mouse monoclonal antibody (MAb103) to the VapA protein significantly enhanced uptake in the murine macrophage cell line IC-21. Intraperitoneal injection of mice with Mab103 enhanced initial clearance from the liver of mice challenged intravenously with R. equi. Immunization of mice with the lipid-modified VapA purified by SDS-PAGE fractionation or with acetone precipitated VapA protein following TX-114 extraction resulted in significantly enhanced clearance from the liver and spleen following intravenous challenge. The VapA protein of R. equi appears therefore to be a protective immunogen. PMID:7704843

  14. Optimizing Polychlorinated Biphenyl Degradation by Flavonoid-Induced Cells of the Rhizobacterium Rhodococcus erythropolis U23A.

    PubMed

    Pham, Thi Thanh My; Pino Rodriguez, Nancy Johanna; Hijri, Mohamed; Sylvestre, Michel

    2015-01-01

    There is evidence that many plant secondary metabolites may act as signal molecules to trigger the bacterial ability to metabolize polychlorinated biphenyls (PCBs) during the rhizoremediation process. However, the bases for the PCB rhizoremediation process are still largely unknown. The rhizobacterium Rhodococcus erythropolis U23A is unable to use flavanone as a growth substrate. However, on the basis of an assay that monitors the amount of 4-chlorobenzoate produced from 4-chlorobiphenyl by cells grown co-metabolically on flavanone plus sodium acetate, this flavonoid was previously found to be a potential inducer of the U23A biphenyl catabolic pathway. In this work, and using the same assay, we identified ten other flavonoids that did not support growth, but that acted as inducers of the U23A biphenyl pathway, and we confirmed flavonoid induction of the biphenyl catabolic pathway using quantitative real-time polymerase chain reaction (RT-qPCR) on the bphA gene. We also examined the effect of the growth co-substrate on flavonoid induction. Sodium acetate was replaced by glucose, mannose, sucrose, or mannitol, which are sugars found in plant root exudates. The data showed that the level of induction of strain U23A biphenyl-degrading enzymes was significantly influenced by the nature and concentration of the flavonoid in the growth medium, as well as by the substrate used for growth. Sucrose allowed for an optimal induction response for most flavonoids. Some flavonoids, such as flavone and isoflavone, were better inducers of the biphenyl catabolic enzymes than biphenyl itself. We also found that all flavonoids tested in this work were metabolized by strain U23A during co-metabolic growth, but that the metabolite profiles, as well as the level of efficiency of degradation, differed for each flavonoid. To obtain insight into how flavonoids interact with strain U23A to promote polychlorinated biphenyl (PCB) degradation, we determined the concentration of flavanone at

  15. The Steroid Catabolic Pathway of the Intracellular Pathogen Rhodococcus equi Is Important for Pathogenesis and a Target for Vaccine Development

    PubMed Central

    van der Geize, R.; Grommen, A. W. F.; Hessels, G. I.; Jacobs, A. A. C.; Dijkhuizen, L.

    2011-01-01

    Rhodococcus equi causes fatal pyogranulomatous pneumonia in foals and immunocompromised animals and humans. Despite its importance, there is currently no effective vaccine against the disease. The actinobacteria R. equi and the human pathogen Mycobacterium tuberculosis are related, and both cause pulmonary diseases. Recently, we have shown that essential steps in the cholesterol catabolic pathway are involved in the pathogenicity of M. tuberculosis. Bioinformatic analysis revealed the presence of a similar cholesterol catabolic gene cluster in R. equi. Orthologs of predicted M. tuberculosis virulence genes located within this cluster, i.e. ipdA (rv3551), ipdB (rv3552), fadA6 and fadE30, were identified in R. equi RE1 and inactivated. The ipdA and ipdB genes of R. equi RE1 appear to constitute the α-subunit and β-subunit, respectively, of a heterodimeric coenzyme A transferase. Mutant strains RE1ΔipdAB and RE1ΔfadE30, but not RE1ΔfadA6, were impaired in growth on the steroid catabolic pathway intermediates 4-androstene-3,17-dione (AD) and 3aα-H-4α(3′-propionic acid)-5α-hydroxy-7aβ-methylhexahydro-1-indanone (5α-hydroxy-methylhexahydro-1-indanone propionate; 5OH-HIP). Interestingly, RE1ΔipdAB and RE1ΔfadE30, but not RE1ΔfadA6, also displayed an attenuated phenotype in a macrophage infection assay. Gene products important for growth on 5OH-HIP, as part of the steroid catabolic pathway, thus appear to act as factors involved in the pathogenicity of R. equi. Challenge experiments showed that RE1ΔipdAB could be safely administered intratracheally to 2 to 5 week-old foals and oral immunization of foals even elicited a substantial protective immunity against a virulent R. equi strain. Our data show that genes involved in steroid catabolism are promising targets for the development of a live-attenuated vaccine against R. equi infections. PMID:21901092

  16. Optimizing Polychlorinated Biphenyl Degradation by Flavonoid-Induced Cells of the Rhizobacterium Rhodococcus erythropolis U23A

    PubMed Central

    Hijri, Mohamed; Sylvestre, Michel

    2015-01-01

    There is evidence that many plant secondary metabolites may act as signal molecules to trigger the bacterial ability to metabolize polychlorinated biphenyls (PCBs) during the rhizoremediation process. However, the bases for the PCB rhizoremediation process are still largely unknown. The rhizobacterium Rhodococcus erythropolis U23A is unable to use flavanone as a growth substrate. However, on the basis of an assay that monitors the amount of 4-chlorobenzoate produced from 4-chlorobiphenyl by cells grown co-metabolically on flavanone plus sodium acetate, this flavonoid was previously found to be a potential inducer of the U23A biphenyl catabolic pathway. In this work, and using the same assay, we identified ten other flavonoids that did not support growth, but that acted as inducers of the U23A biphenyl pathway, and we confirmed flavonoid induction of the biphenyl catabolic pathway using quantitative real-time polymerase chain reaction (RT-qPCR) on the bphA gene. We also examined the effect of the growth co-substrate on flavonoid induction. Sodium acetate was replaced by glucose, mannose, sucrose, or mannitol, which are sugars found in plant root exudates. The data showed that the level of induction of strain U23A biphenyl-degrading enzymes was significantly influenced by the nature and concentration of the flavonoid in the growth medium, as well as by the substrate used for growth. Sucrose allowed for an optimal induction response for most flavonoids. Some flavonoids, such as flavone and isoflavone, were better inducers of the biphenyl catabolic enzymes than biphenyl itself. We also found that all flavonoids tested in this work were metabolized by strain U23A during co-metabolic growth, but that the metabolite profiles, as well as the level of efficiency of degradation, differed for each flavonoid. To obtain insight into how flavonoids interact with strain U23A to promote polychlorinated biphenyl (PCB) degradation, we determined the concentration of flavanone at

  17. Magnetic properties of MoS2: Existence of ferromagnetism

    NASA Astrophysics Data System (ADS)

    Tongay, Sefaattin; Varnoosfaderani, Sima S.; Appleton, Bill R.; Wu, Junqiao; Hebard, Arthur F.

    2012-09-01

    We report on the magnetic properties of MoS2 measured from room temperature down to 10 K and magnetic fields up to 5 T. We find that single crystals of MoS2 display ferromagnetism superimposed onto large temperature-dependent diamagnetism and have observed that ferromagnetism persists from 10 K up to room temperature. We attribute the existence of ferromagnetism partly to the presence of zigzag edges in the magnetic ground state at the grain boundaries. Since the magnetic measurements are relatively insensitive to the interlayer coupling, these results are expected to be valid in the single layer limit.

  18. Atomic layer deposition of MoS2 thin films

    NASA Astrophysics Data System (ADS)

    Browning, Robert; Padigi, Prasanna; Solanki, Raj; Tweet, Douglas J.; Schuele, Paul; Evans, David

    2015-03-01

    Atomic layer deposition (ALD) was used to grow thin films of MoS2 over 5 × 5 cm areas of silicon oxide coated silicon wafers. Smooth, uniform, and continuous films were produced over a temperature range of 350 °C-450 °C. The as-grown films were analyzed using x-ray photoelectron spectroscopy, Raman spectroscopy, photoluminescence, and x-ray diffraction. Electrical characteristics of the films were evaluated by fabricating a back gated field effect transistor. These analyses indicate that ALD technique can produce large area, high quality MoS2 films.

  19. Thermal Treatment Improvement of CuSbS2 Absorbers

    SciTech Connect

    de Souza Lucas, Francisco Willian; Welch, Adam W.; Baranowski, Lauryn L.; Dippo, Patricia C.; Mascaro, Lucia H.; Zakutayev, Andriy

    2015-06-14

    Thermal treatment in Sb2S3 vapor was used to improve the quality of CuSbS2 thin films, a promising non-toxic and earth-abundant absorber. A change in the CuSbS2 crystallographic texture and a decrease in the lattice stress were observed, as well as increases in the grain size, photoluminescence intensity and photoconductivity. To eliminate the influence of the possible Sb2S3 rich surface layer on photovoltaic performance, a selective chemical etching with KOH was developed.

  20. Conduction quantization in monolayer MoS2

    NASA Astrophysics Data System (ADS)

    Li, T. S.

    2016-10-01

    We study the ballistic conduction of a monolayer MoS2 subject to a spatially modulated magnetic field by using the Landauer-Buttiker formalism. The band structure depends sensitively on the field strength, and its change has profound influence on the electron conduction. The conductance is found to demonstrate multi-step behavior due to the discrete number of conduction channels. The sharp peak and rectangular structures of the conductance are stretched out as temperature increases, due to the thermal broadening of the derivative of the Fermi-Dirac distribution function. Finally, quantum behavior in the conductance of MoS2 can be observed at temperatures below 10 K.

  1. Self-assembled lamellar MoS2, SnS2 and SiO2 semiconducting polymer nanocomposites.

    PubMed

    Kirmayer, Saar; Aharon, Eyal; Dovgolevsky, Ekaterina; Kalina, Michael; Frey, Gitti L

    2007-06-15

    Lamellar nanocomposites based on semiconducting polymers incorporated into layered inorganic matrices are prepared by the co-assembly of organic and inorganic precursors. Semiconducting polymer-incorporated silica is prepared by introducing the semiconducting polymers into a tetrahydrofuran (THF)/water homogeneous sol solution containing silica precursor species and a surface-active agent. Semiconducting polymer-incorporated MoS(2) and SnS(2) are prepared by Li intercalation into the inorganic compound, exfoliation and restack in the presence of the semiconducting polymer. All lamellar nanocomposite films are organized in domains aligned parallel to the substrate surface plane. The incorporated polymers maintain their semiconducting properties, as evident from their optical absorption and photoluminescence spectra. The optoelectronic properties of the nanocomposites depend on the properties of both the inorganic host and the incorporated guest polymer as demonstrated by integrating the nanocomposite films into light-emitting diodes. Devices based on polymer-incorporated silica and polymer-incorporated MoS(2) show no diode behaviour and no light emission due to the insulating and metallic properties of the silica and MoS(2) hosts. In contrast, diode performance and electroluminescence are obtained from devices based on semiconducting polymer-incorporated semiconducting SnS(2), demonstrating that judicious selection of the composite components in combination with the optimization of material synthesis conditions allows new hierarchical structures to be tailored for electronic and optoelectronic applications.

  2. Formation of nanosized monolayer MoS2 by oxygen-assisted thinning of multilayer MoS2

    NASA Astrophysics Data System (ADS)

    Neupane, Guru P.; Dhakal, Krishna P.; Kim, Hyun; Lee, Jubok; Kim, Min Su; Han, Ganghee; Lee, Young Hee; Kim, Jeongyong

    2016-08-01

    We report the controllable nanosized local thinning of multi-layer (2 L and 3 L)-thickness MoS2 films down to the monolayer (1 L) thickness using the simple method of annealing in a dry oxygen atmosphere. The annealing temperature was optimized in the range of 240 °C to 270 °C for 1.5 h, and 1 L thick nanosized pits were developed on the uniform film of the 2 L and 3 L MoS2 grown using the chemical vapor deposition method. We characterized the formation of the 1 L nanosized pits using nanoscale confocal photoluminescence (PL) and Raman spectroscopy. We observed that the PL intensity increased and the Raman frequency shifted, representative of the characteristics of 1 L MoS2 films. A subsequent hydrogen treatment process was useful for removing the oxygen-induced doping effect resulting from the annealing.

  3. MoS2 transistors operating at gigahertz frequencies.

    PubMed

    Krasnozhon, Daria; Lembke, Dominik; Nyffeler, Clemens; Leblebici, Yusuf; Kis, Andras

    2014-10-01

    The presence of a direct band gap and an ultrathin form factor has caused a considerable interest in two-dimensional (2D) semiconductors from the transition metal dichalcogenides (TMD) family with molybdenum disulfide (MoS2) being the most studied representative of this family of materials. While diverse electronic elements, logic circuits, and optoelectronic devices have been demonstrated using ultrathin MoS2, very little is known about their performance at high frequencies where commercial devices are expected to function. Here, we report on top-gated MoS2 transistors operating in the gigahertz range of frequencies. Our devices show cutoff frequencies reaching 6 GHz. The presence of a band gap also gives rise to current saturation, allowing power and voltage gain, all in the gigahertz range. This shows that MoS2 could be an interesting material for realizing high-speed amplifiers and logic circuits with device scaling expected to result in further improvement of performance. Our work represents the first step in the realization of high-frequency analog and digital circuits based on 2D semiconductors. PMID:25243885

  4. Thermal conductivity of MoS2 polycrystalline nanomembranes

    NASA Astrophysics Data System (ADS)

    Sledzinska, M.; Graczykowski, B.; Placidi, M.; Saleta Reig, D.; El Sachat, A.; Reparaz, J. S.; Alzina, F.; Mortazavi, B.; Quey, R.; Colombo, L.; Roche, S.; Sotomayor Torres, C. M.

    2016-09-01

    Heat conduction in 2D materials can be effectively engineered by means of controlling nanoscale grain structure. A favorable thermal performance makes these structures excellent candidates for integrated heat management units. Here we show combined experimental and theoretical studies for MoS2 nanosheets in a nanoscale grain-size limit. We report thermal conductivity measurements on 5 nm thick polycrystalline MoS2 by means of 2-laser Raman thermometry. The free-standing, drum-like MoS2 nanomembranes were fabricated using a novel polymer- and residue-free, wet transfer, in which we took advantage of the difference in the surface energies between MoS2 and the growth substrate to transfer the CVD-grown nanosheets. The measurements revealed a strong reduction in the in-plane thermal conductivity down to about 0.73 ± 0.25 {{{W}}{{m}}}-1 {{{K}}}-1. The results are discussed theoretically using finite elements method simulations for a polycrystalline film, and a scaling trend of the thermally conductivity with grain size is proposed.

  5. AgGaS2 infrared parametric oscillator

    NASA Technical Reports Server (NTRS)

    Fan, Y. X.; Eckardt, R. C.; Byer, R. L.; Route, R. K.; Feigelson, R. S.

    1984-01-01

    A report is presented of the first operation of an optical parametric oscillator in a chalcopyrite crystal, AgGaS2. Tuning from 1.4 to 4.0 microns is demonstrated for 1.06-micron Nd:yttrium aluminum garnet pumping. The potential tuning range extends to the 12-micron transparency limit of the crystal.

  6. Moderate temperature rechargeable NaNiS2 cells

    NASA Technical Reports Server (NTRS)

    Abraham, K. M.

    1983-01-01

    A rechargeable sodium battery of the configuration, liquid Na/beta double prime -Al2O3/molten NaAlCl4, NiS2, operating in the temperature range of 170 to 190 C, is described. This battery is capable of delivering or = to 50 W-hr/1b and 1000 deep discharge/charge cycles.

  7. Cycle life characteristics of Li-TiS2 cells

    NASA Technical Reports Server (NTRS)

    Deligiannis, Frank; Shen, D.; Huang, C. K.; Surampudi, S.

    1991-01-01

    The development of lithium ambient temperature rechargeable cells is discussed. During the development process, we hope to gain a greater understanding of the materials and the properties of the Li-TiS2 cell and its components. The design will meet the requirements of 100 Wh/Kg and 1000 cycles, at 50 percent depth-of-discharge, by 1995.

  8. Extraordinary attributes of 2-dimensional MoS2 nanosheets

    NASA Astrophysics Data System (ADS)

    Rao, C. N. R.; Maitra, Urmimala; Waghmare, Umesh V.

    2014-08-01

    The discovery of the amazing properties of graphene has stimulated exploration of single- and few-layer structures of layered inorganic materials. Of all the inorganic 2D nanosheet structures, those of MoS2 have attracted great attention because of their novel properties such as the presence of a direct bandgap, good field-effect transistor characteristics, large spin-orbit splitting, intense photoluminescence, catalytic properties, magnetism, superconductivity, ferroelectricity and several other properties with potential applications in electronics, optoelectronics, energy devices and spintronics. MoS2 nanosheets have been used in lithium batteries, supercapacitors and to generate hydrogen. Highlights of the impressive properties of MoS2 nanosheets, along with their structural and spectroscopic features are presented in this Letter. MoS2 typifies the family of metal dichalcogenides such as MoSe2 and WS2 and there is much to be done on nanosheets of these materials. Linus Pauling would have been pleased to see how molybdenite whose structure he studied in 1923 has become so important today.

  9. Tribotronic Enhanced Photoresponsivity of a MoS2 Phototransistor

    PubMed Central

    Pang, Yaokun; Xue, Fei; Wang, Longfei; Chen, Jian; Luo, Jianjun; Jiang, Tao

    2016-01-01

    Molybdenum disulfide (MoS2) has attracted a great attention as an excellent 2D material for future optoelectronic devices. Here, a novel MoS2 tribotronic phototransistor is developed by a conjunction of a MoS2 phototransistor and a triboelectric nanogenerator (TENG) in sliding mode. When an external friction layer produces a relative sliding on the device, the induced positive charges on the back gate of the MoS2 phototransistor act as a “gate” to increase the channel conductivity as the traditional back gate voltage does. With the sliding distance increases, the photoresponsivity of the device is drastically enhanced from 221.0 to 727.8 A W−1 at the 100 mW cm−2 UV excitation intensity and 1 V bias voltage. This work has extended the emerging tribotronics to the field of photodetection based on 2D material, and demonstrated a new way to realize the adjustable photoelectric devices with high photoresponsivity via human interfacing. PMID:27812472

  10. Structural Properties of Finite MoS2 Nanowires

    NASA Astrophysics Data System (ADS)

    Clark, Shaylyn; Salgado, Andres; Fernandez-Seivane, Lucas; Lopez-Lozano, Xochitl

    2015-03-01

    Molybdenum disulfide (MoS2) has been one of the most important catalysts used in refineries worldwide for hydrodesulfurization over the past century. In the last decade, and with the advent of nanotechnology, there has been a special interest in MoS2 nanostructures due to their high potential as novel nanocatalysts. The study of the properties of these systems is of fundamental interest for the experimental design of their catalytic activity and efficiency. In this work, we have performed ab initio density-functional calculations (DFT) to investigate the structural properties of finite MoS2 nanostrutures. All the models here presented were based on newly experimentally observed morphologies in MoS2 industrial catalysts using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. We simulated STEM images of the theoretical models to compare it with the experimental ones. In contrast with infinite models, the finite models prefer a rippled/twisted structure morphology over the planar or helical ones. The rippled/twisted models appear to be structurally more stable.

  11. Chemical sensing with ultra-thin MoS2

    NASA Astrophysics Data System (ADS)

    Friedman, Adam; Perkins, Keith; Cobas, Enrique; Campbell, Paul; Jernigan, Glenn; Jonker, Berend

    2013-03-01

    Although the majority of focus and excitement in recent years has been on studying the remarkable properties of single atomic-layer graphene, there exists a whole class of materials called dichalcogenides that are relatively easily fabricated in single-crystal mono- or few-layer format. Graphene, being chemically inert, does not lend itself to chemical sensing applications. However, MoS2, a dichalcogenide of recent interest because of its potential for transistor applications, possesses many advantageous properties for chemical sensing. Two primary examples include a sizable bandgap, which is necessary for fabricating transistors with large on/off current ratios, and a chemically reactive surface, which is necessary for easy surface functionalization. In this talk, we discuss our current research effort on MoS2 chemical sensors. We discuss aspects of transistor device fabrication and chemical sensing experiments. We expose MoS2 chemical sensors to a variety of analytes, finding the best response to triethylamine, a nerve gas by product, and explain our results based on a donor-acceptor model. MoS2 sensors are compared to other similar low-dimensional sensors and found to be of comparable quality.

  12. Polarization-dependent photocurrent in MoS2 phototransistor

    NASA Astrophysics Data System (ADS)

    Li, Jiu; Yu, Wentao; Chu, Saisai; Yang, Hong; Shi, Kebin; Gong, Qihuang

    2015-03-01

    Monolayer or few-layer molybdenum disulfide (MoS2) has attracted increasing interests in studying light-induced electronic effect due to its prominent photo-responsivity at visible spectral range, fast photo-switching rate and high channel mobility. However, the atomically thin layers make the interaction between light and matter much weaker than that in bulk state, hampering its application in two-dimensional material optoelectronics. One of recent efforts was to utilize resonantly enhanced localized surface plasmon for boosting light-matter interaction in MoS2 thin layer phototransistor. Randomly deposited metallic nano-particles were previously reported to modify surface of a back-gated MoS2 transistor for increasing light absorption cross-section of the phototransistor. Wavelength-dependent photocurrent enhancement was observed. In this paper, we report on a back-gated multilayer MoS2 field-effect-transistor (FET), whose surface is decorated with oriented gold nanobar array, of which the size of a single nanobar is 60nm:60nm:120nm. With these oriented nanostructures, photocurrent of the MoS2 FET could be successfully manipulated by a linear polarized incident 633nm laser, which fell into the resonance band of nanobar structure. We find that the drain-source current follows cos2θ relationship with respect to the incident polarization angle. We attribute the polarization modulation effect to the localized enhancement nature of gold nanobar layer, where the plasmon enhancement occurs only when the polarization of incident laser parallels to the longitudinal axis of nanobars and when the incident wavelength matches the resonance absorption of nanobars simultaneously. Our results indicate a promising application of polarization-dependent plasmonic manipulation in two-dimension semiconductor materials and devices.

  13. Molecular biological enhancement of coal biodesulfurization. Quarterly technical report, September 1, 1993--November 30, 1993

    SciTech Connect

    Kilbane, J.J. II

    1993-12-31

    IGT has developed a microbial culture of Rhodococcus rhodochrous, designated as IGTS8, that is capable of specifically cleaving carbon-sulfur bonds in a range of organosulfur model compounds and is capable of removing organic sulfur from coal and petroleum without significantly sacrificing the calorific value of the fuel. Although IGTS8 possesses the ability to specifically remove organic sulfur from coal, a major research need is to develop improved strains of microorganisms that possess higher levels of desulfurization activity and therefore will permit more favorable biodesulfurization process conditions: faster rates, more complete removal, and smaller reactor size. strain improvement is the single most important aspect to the development of a practical coal biodesulfurization process and accordingly is the focus of research in this project. During this quarter the promoter probe vectors that were constructed last quarter were found to be unstable in E. coli. Fragments of R. rhodochrous IGTS8 chromosomal DNA were cloned into pRCAT3 and pRCM1 (previously described in final ICCI report 1993). Many derivatives of pRCM1 and pRCAT3 receiving inserts that regulated the expression of chloramphenicol resistance in Rhodococcus rhodochrous IGTS8 proved to be unstable in E. coli frequently yielding plasmids containing deletions. Stable inserts have been observed ranging from 100 bp to 2.0 kb that regulated expression in Rhodococcus rhodochrous IGTS8. Subtractive hybridization studies continue, several candidates have been isolated and are being confirmed for inducible promoters. Primer extension analysis of the Rhodococcus rhodochrous IGTS8 16S RNA promoter region was initiated this quarter.

  14. Optical response of the Cu2 S2 diamond core in Cu2II(NGuaS)2 Cl2.

    PubMed

    Witte, Matthias; Grimm-Lebsanft, Benjamin; Goos, Arne; Binder, Stephan; Rübhausen, Michael; Bernard, Martin; Neuba, Adam; Gorelsky, Serge; Gerstmann, Uwe; Henkel, Gerald; Gero Schmidt, Wolf; Herres-Pawlis, Sonja

    2016-09-15

    Density functional theory (DFT) and time-dependent DFT calculations are presented for the dicopper thiolate complex Cu2 (NGuaS)2 Cl2 [NGuaS=2-(1,1,3,3-tetramethylguanidino) benzenethiolate] with a special focus on the bonding mechanism of the Cu2 S2 Cl2 core and the spectroscopic response. This complex is relevant for the understanding of dicopper redox centers, for example, the CuA center. Its UV/Vis absorption is theoretically studied and found to be similar to other structural CuA models. The spectrum can be roughly divided in the known regions of metal d-d absorptions and metal to ligand charge transfer regions. Nevertheless the chloride ions play an important role as electron donors, with the thiolate groups as electron acceptors. The bonding mechanism is dissected by means of charge decomposition analysis which reveals the large covalency of the Cu2 S2 diamond core mediated between Cu dz2 and S-S π and π* orbitals forming Cu-S σ bonds. Measured resonant Raman spectra are shown for 360- and 720-nm excitation wavelength and interpreted using the calculated vibrational eigenmodes and frequencies. The calculations help to rationalize the varying resonant behavior at different optical excitations. Especially the phenylene rings are only resonant for 720 nm. © 2016 Wiley Periodicals, Inc. PMID:27362786

  15. Isolation of Rhodococcus equi from the feces of indigenous animals and soil from the Lower Zambezi National Park and Lochinvar National Park, Zambia.

    PubMed

    Takai, Shinji; Syakalima, Michelo; Yasuda, Jun; Sasaki, Yukako; Tsutsumi, Hisako; Miyagawa, Emiko; Wada, Kaya; Kakuda, Tsutomu; Tsubaki, Shiro; Sugimoto, Chihiro

    2004-06-01

    Rhodococcus equi is an important pathogen in foals; however, its incidence in African indigenous animals is poorly understood. Fecal samples (92 from nine indigenous species) and 43 soil samples were collected from two Zambian National Parks. The presence of R. equi was investigated and 533 isolates were tested for the presence of 15- to 17-kDa antigens (VapA) and a 20-kDa antigen (VapB) by immunoblotting and PCR. R. equi was isolated (10(2)-10(4) colony forming units/g) from 75% of fecal and 74% of soil samples. Neither antigen was detected; however, about 20% of the isolates contained cryptic plasmids of various sizes. There was no evidence of virulent R. equi, but the avirulent form was widespread in the animals and the soil.

  16. Spectrum of disease caused by Rhodococcus equi in human immunodeficiency virus infection: Report of a case and review of the literature

    PubMed Central

    Willsie-Ediger, Sandra K; Stanford, James F; Salzman, Gary A; Bamberger, David M

    1990-01-01

    Since the first report of Rhodococcus equi infection in an acquired immune deficiency syndrome patient in 1986, seven additional cases have been described. A patient is described in whom the diagnosis was delayed due to misidentification of the organism as an atypical mycobacterial species. The literature regarding R equi infection in persons infected with the human immunodeficiency virus is reviewed. The most common presentation is one of a chronic, indolent pulmonary infiltrative disease (78%). Fever (78%), cough (67%), and hemoptysis (44%) are frequently present. Coexistent opportunistic illnesses are common (67%). In the laboratory identification of this organism, it is important to communicate the clinical setting to the microbiologist and to recognize the potential for the organism to be overlooked as normal flora or a contaminant, or misidentified as an organism with similar phenotypic characteristics (Nocardia species or a rapidly growing mycobacterium). Based on experience in foals, therapy with erythromycin and rifampin is suggested. PMID:22553450

  17. Three different 2,3-dihydroxybiphenyl-1,2-dioxygenase genes in the gram-positive polychlorobiphenyl-degrading bacterium Rhodococcus globerulus P6.

    PubMed Central

    Asturias, J A; Timmis, K N

    1993-01-01

    Rhodococcus globerulus P6 (previously designated Acinetobacter sp. strain P6, Arthrobacter sp. strain M5, and Corynebacterium sp. strain MB1) is able to degrade a wide range of polychlorinated biphenyl (PCB) congeners. The genetic and biochemical analyses of the PCB catabolic pathway reported here have revealed the existence of a PCB gene cluster--bphBC1D--and two further bphC genes--bphC2 and bphC3--that encode three narrow-substrate-specificity enzymes (2,3-dihydroxybiphenyl dioxygenases) that meta cleave the first aromatic ring. None of the bphC genes show by hybridization homology to each other or to bphC genes in other bacteria, and the three bphC gene products have different kinetic parameters and sensitivities to inactivation by 3-chlorocatechol. This suggests that there exists a wide diversity in PCB meta cleavage enzymes. Images PMID:8335622

  18. Isolation of the fenoxaprop-ethyl (FE)-degrading bacterium Rhodococcus sp. T1, and cloning of FE hydrolase gene feh.

    PubMed

    Hou, Ying; Tao, Jian; Shen, Wenjing; Liu, Juan; Li, Jingquan; Li, Yongfeng; Cao, Hui; Cui, Zhongli

    2011-10-01

    An enrichment culture which completely degraded fenoxaprop-ethyl (FE) was acquired by using FE as sole carbon source. An efficient FE-degrading strain T1 was isolated from the enrichment culture and identified as Rhodococcus sp. Strain T1 could degrade 94% of 100 mg L(-1) FE within 24 h and the metabolite fenoxaprop acid (FA) was identified by HPLC/MS analysis. This strain converted FE by cleavage of the ester bond, but could not further degrade FA. Strain T1 could also efficiently degrade haloxyfop-R-methyl, quizalofop-p-ethyl, cyhalofop-butyl and clodinafop-propargyl. FE hydrolase capable of hydrolysing FE to FA was found in the cell-free extract of strain T1 by zymogram analysis. A novel gene feh encoding FE hydrolase was cloned by shotgun library construction and successfully expressed in Escherichia coli.

  19. [Effect of surface-active substances of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Ac-5017, and Nocardia vaccinii K-8 on phytopathogenic bacteria].

    PubMed

    Pirog, T P; Konon, A D; Sofilkanich, A P; Iutinskaia, G A

    2013-01-01

    The effect of surface-active substances (SAS's) of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Ac-5017, and Nocardia vaccinii K-8 on phytopathogenic bacteria has been studied. It was shown that the survival of cells (10(5)-10(7) in a milliliter) of the Pseudomonas and Xanthomonas phytopathogenic bacteria was found to be 0-33% after treatment with SAS preparations of the IMV Ac-5017 and IMV B-7241 strains for 2 h (0.15-0.4 mg/mL). In the presence of N. vaccinii K-8 SAS preparations (0.085-0.85 mg/mL), the number of cells of the majority of the studied phytopathogenic bacteria decreased by 95-100%. These data show prospects for using microbial SAS's for the construction of ecologically friendly drugs for regulating the number of phytopathogenic bacteria.

  20. [Synthesis of surfactants by Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii IMV B-7405 on industrial waste].

    PubMed

    Pirog, T P; Sofilkanich, A P; Pokora, K A; Shevchuk, T A; Iutinskaia, G A

    2014-01-01

    The synthesis of surfactants by Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii IMV B-7405 on industrial waste (food and oil-processing industry, production of biodiesel) was investigated. The possibility of replacing the expensive substrates (n-hexadecane and ethanol) by industrial waste (oil and fat industry, fried sunflower oil, glycerol, liquid paraffin) for the surfactant biosynthesis was established. The conditional concentration of surfactants was maximal on oil containing substrates and exceeded those on n-hexadecane and ethanol 2-3 times. The highest rates of surfactants synthesis were observed on fried sunflower oil with the use of inoculum grown on carbohydrate substrates (glucose, molasses). It was established that the addition of glucose (0.1%) was accompanied by 2-4-fold intensification of surfactants synthesis by R. erythropolis IMV Ac-5017 and N. vaccinii IMV B-7405 on fried sunflower oil (2%).

  1. Uptake of radioiodide by Paenibacillus sp., Pseudomonas sp., Burkholderia sp. and Rhodococcus sp. isolated from a boreal nutrient-poor bog.

    PubMed

    Lusa, Merja; Lehto, Jukka; Aromaa, Hanna; Knuutinen, Jenna; Bomberg, Malin

    2016-06-01

    Radionuclides, like radioiodine ((129)I), may escape deep geological nuclear waste repositories and migrate to the surface ecosystems. In surface ecosystems, microorganisms can affect their movement. Iodide uptake of six bacterial strains belonging to the genera Paenibacillus, Pseudomonas, Burkholderia and Rhodococcus isolated from an acidic boreal nutrient-poor bog was tested. The tests were run in four different growth media at three temperatures. All bacterial strains removed iodide from the solution with the highest efficiency shown by one of the Paenibacillus strains with >99% of iodide removed from the solution in one of the used growth media. Pseudomonas, Rhodococcus and one of the two Paenibacillus strains showed highest iodide uptake in 1% yeast extract with maximum values for the distribution coefficient (Kd) ranging from 90 to 270L/kg DW. The Burkholderia strain showed highest uptake in 1% Tryptone (maximum Kd 170L/kg DW). The Paenibacillus strain V0-1-LW showed exceptionally high uptake in 0.5% peptone +0.25% yeast extract broth (maximum Kd>1,000,000L/kg DW). Addition of 0.1% glucose to the 0.5% peptone +0.25% yeast extract broth reduced iodide uptake at 4°C and 20°C and enhanced iodide uptake at 37°C compared to the uptake without glucose. This indicates that the uptake of glucose and iodide may be competing processes in these bacteria. We estimated that in in situ conditions of the bog, the bacterial uptake of iodide accounts for approximately 0.1%-0.3% of the total sorption of iodide in the surface, subsurface peat, gyttja and clay layers.

  2. Extracellular biosynthesis of zinc oxide nanoparticles using Rhodococcus pyridinivorans NT2: multifunctional textile finishing, biosafety evaluation and in vitro drug delivery in colon carcinoma.

    PubMed

    Kundu, Debasree; Hazra, Chinmay; Chatterjee, Aniruddha; Chaudhari, Ambalal; Mishra, Satyendra

    2014-11-01

    In this study, zinc oxide (ZnO) nanoparticles (NPs) were rapidly synthesized from zinc sulfate solution at room temperature using a metabolically versatile actinobacteria Rhodococcus pyridinivorans NT2. The morphology, structure and stability of the synthesized ZnO NPs were studied using UV-visible absorption spectroscopy, X-ray Diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), Zeta potential, and thermogravimetry. The data indicated that the synthesized nanoparticles were moderately stable, hexagonal phase, roughly spherical with average particle diameter in the range of 100-120 nm. Results obtained on examination of protein expression revealed that cell enzymes and extracellular protein systems of Rhodococcus sp. may take part in synthesis process. Furthermore, the ZnO NPs were coated onto textile fabrics to enhance UV-blocking, self-cleaning and antibacterial properties. Ultraviolet protecting factor (UPF) indicating UV-blocking properties of ZnO NPs coated textile fabrics were determined as 65, 88, 121, 172 and 241 for 1, 2, 3, 4 and 5 gm(-2) of ZnO NPs, respectively. Besides, self-cleaning activity was assessed by investigating photocatalytic activity on malachite green as well as antibacterial activity against aerobic Gram-positive Staphylococcus epidermidis NCIM 2493 (ATCC 12228). The antibacterial effects of these textiles were evaluated using ISO 20743 standard. In addition, ZnO NPs exhibited a preferential ability to kill HT-29 cancerous cells as compared with normal peripheral blood mononuclear cells (PBMCs).

  3. Uptake of radioiodide by Paenibacillus sp., Pseudomonas sp., Burkholderia sp. and Rhodococcus sp. isolated from a boreal nutrient-poor bog.

    PubMed

    Lusa, Merja; Lehto, Jukka; Aromaa, Hanna; Knuutinen, Jenna; Bomberg, Malin

    2016-06-01

    Radionuclides, like radioiodine ((129)I), may escape deep geological nuclear waste repositories and migrate to the surface ecosystems. In surface ecosystems, microorganisms can affect their movement. Iodide uptake of six bacterial strains belonging to the genera Paenibacillus, Pseudomonas, Burkholderia and Rhodococcus isolated from an acidic boreal nutrient-poor bog was tested. The tests were run in four different growth media at three temperatures. All bacterial strains removed iodide from the solution with the highest efficiency shown by one of the Paenibacillus strains with >99% of iodide removed from the solution in one of the used growth media. Pseudomonas, Rhodococcus and one of the two Paenibacillus strains showed highest iodide uptake in 1% yeast extract with maximum values for the distribution coefficient (Kd) ranging from 90 to 270L/kg DW. The Burkholderia strain showed highest uptake in 1% Tryptone (maximum Kd 170L/kg DW). The Paenibacillus strain V0-1-LW showed exceptionally high uptake in 0.5% peptone +0.25% yeast extract broth (maximum Kd>1,000,000L/kg DW). Addition of 0.1% glucose to the 0.5% peptone +0.25% yeast extract broth reduced iodide uptake at 4°C and 20°C and enhanced iodide uptake at 37°C compared to the uptake without glucose. This indicates that the uptake of glucose and iodide may be competing processes in these bacteria. We estimated that in in situ conditions of the bog, the bacterial uptake of iodide accounts for approximately 0.1%-0.3% of the total sorption of iodide in the surface, subsurface peat, gyttja and clay layers. PMID:27266299

  4. On the Kinetic and Allosteric Regulatory Properties of the ADP-Glucose Pyrophosphorylase from Rhodococcus jostii: An Approach to Evaluate Glycogen Metabolism in Oleaginous Bacteria

    PubMed Central

    Cereijo, Antonela E.; Asencion Diez, Matías D.; Dávila Costa, José S.; Alvarez, Héctor M.; Iglesias, Alberto A.

    2016-01-01

    Rhodococcus spp. are oleaginous bacteria that accumulate glycogen during exponential growth. Despite the importance of these microorganisms in biotechnology, little is known about the regulation of carbon and energy storage, mainly the relationship between glycogen and triacylglycerols metabolisms. Herein, we report the molecular cloning and heterologous expression of the gene coding for ADP-glucose pyrophosphorylase (EC 2.7.7.27) of Rhodococcus jostii, strain RHA1. The recombinant enzyme was purified to electrophoretic homogeneity to accurately characterize its oligomeric, kinetic, and regulatory properties. The R. jostii ADP-glucose pyrophosphorylase is a homotetramer of 190 kDa exhibiting low basal activity to catalyze synthesis of ADP-glucose, which is markedly influenced by different allosteric effectors. Glucose-6P, mannose-6P, fructose-6P, ribose-5P, and phosphoenolpyruvate were major activators; whereas, NADPH and 6P-gluconate behaved as main inhibitors of the enzyme. The combination of glucose-6P and other effectors (activators or inhibitors) showed a cross-talk effect suggesting that the different metabolites could orchestrate a fine regulation of ADP-glucose pyrophosphorylase in R. jostii. The enzyme exhibited some degree of affinity toward ATP, GTP, CTP, and other sugar-1P substrates. Remarkably, the use of glucosamine-1P was sensitive to allosteric activation. The relevance of the fine regulation of R. jostii ADP-glucose pyrophosphorylase is further analyzed in the framework of proteomic studies already determined for the bacterium. Results support a critical role for glycogen as a temporal reserve that provides a pool of carbon able of be re-routed to produce long-term storage of lipids under certain conditions. PMID:27313571

  5. Overproduction of the Escherichia coli Chaperones GroEL-GroES in Rhodococcus ruber Improves the Activity and Stability of Cell Catalysts Harboring a Nitrile Hydratase.

    PubMed

    Tian, Yuxuan; Chen, Jie; Yu, Huimin; Shen, Zhongyao

    2016-02-01

    Three combinations of molecular chaperones from Escherichia coli (i.e., DnaK-DnaJ-GrpEGroEL- GroES, GroEL-GroES, and DnaK-DnaJ-GrpE) were overproduced in E. coli BL21, and their in vitro stabilizing effects on a nitrile hydratase (NHase) were assessed. The optimal gene combination, E. coli groEL-groES (ecgroEL-ES), was introduced into Rhodococcus ruber TH3. A novel engineered strain, R. ruber TH3G was constructed with the native NHase gene on its chromosome and the heterologous ecgroEL-ES genes in a shuttle plasmid. In R. ruber TH3G, NHase activity was enhanced 37.3% compared with the control, TH3. The in vivo stabilizing effect of ecGroEL-ES on the NHase was assessed using both acrylamide immersion and heat shock experiments. The inactivation behavior of the in vivo NHase after immersion in a solution of dynamically increased concentrations of acrylamide was particularly evident. When the acrylamide concentration was increased to 500 g/l (50%), the remaining NHase activity in TH3G was 38%, but in TH3, activity was reduced to 10%. Reactivation of the in vivo NHases after varying degrees of inactivation was further assessed. The activity of the reactivated NHase was more than 2-fold greater in TH3G than in TH3. The hydration synthesis of acrylamide catalyzed by the in vivo NHase was performed with continuous acrylonitrile feeding. The final concentration of acrylamide was 640 g/l when catalyzed by TH3G, compared with 490 g/l acrylamide by TH3. This study is the first to show that the chaperones ecGroEL-ES work well in Rhodococcus and simultaneously possess protein-folding assistance functions and the ability to stabilize and reactivate the native NHases. PMID:26562693

  6. Extracellular biosynthesis of zinc oxide nanoparticles using Rhodococcus pyridinivorans NT2: multifunctional textile finishing, biosafety evaluation and in vitro drug delivery in colon carcinoma.

    PubMed

    Kundu, Debasree; Hazra, Chinmay; Chatterjee, Aniruddha; Chaudhari, Ambalal; Mishra, Satyendra

    2014-11-01

    In this study, zinc oxide (ZnO) nanoparticles (NPs) were rapidly synthesized from zinc sulfate solution at room temperature using a metabolically versatile actinobacteria Rhodococcus pyridinivorans NT2. The morphology, structure and stability of the synthesized ZnO NPs were studied using UV-visible absorption spectroscopy, X-ray Diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), Zeta potential, and thermogravimetry. The data indicated that the synthesized nanoparticles were moderately stable, hexagonal phase, roughly spherical with average particle diameter in the range of 100-120 nm. Results obtained on examination of protein expression revealed that cell enzymes and extracellular protein systems of Rhodococcus sp. may take part in synthesis process. Furthermore, the ZnO NPs were coated onto textile fabrics to enhance UV-blocking, self-cleaning and antibacterial properties. Ultraviolet protecting factor (UPF) indicating UV-blocking properties of ZnO NPs coated textile fabrics were determined as 65, 88, 121, 172 and 241 for 1, 2, 3, 4 and 5 gm(-2) of ZnO NPs, respectively. Besides, self-cleaning activity was assessed by investigating photocatalytic activity on malachite green as well as antibacterial activity against aerobic Gram-positive Staphylococcus epidermidis NCIM 2493 (ATCC 12228). The antibacterial effects of these textiles were evaluated using ISO 20743 standard. In addition, ZnO NPs exhibited a preferential ability to kill HT-29 cancerous cells as compared with normal peripheral blood mononuclear cells (PBMCs). PMID:25169770

  7. MoS2 Heterojunctions by Thickness Modulation

    DOE PAGESBeta

    Tosun, Mahmut; Fu, Deyi; Desai, Sujay B.; Ko, Changhyun; Seuk Kang, Jeong; Lien, Der-Hsien; Najmzadeh, Mohammad; Tongay, Sefaattin; Wu, Junqiao; Javey, Ali

    2015-06-30

    In this work, we report lateral heterojunction formation in as-exfoliated MoS2 flakes by thickness modulation. Kelvin probe force microscopy is used to map the surface potential at the monolayer-multilayer heterojunction, and consequently the conduction band offset is extracted. Scanning photocurrent microscopy is performed to investigate the spatial photocurrent response along the length of the device including the source and the drain contacts as well as the monolayer-multilayer junction. The peak photocurrent is measured at the monolayer-multilayer interface, which is attributed to the formation of a type-I heterojunction. Finally, the work presents experimental and theoretical understanding of the band alignment andmore » photoresponse of thickness modulated MoS2 junctions with important implications for exploring novel optoelectronic devices.« less

  8. Magic Wavelength for the Hydrogen 1S-2S Transition

    NASA Astrophysics Data System (ADS)

    Kawasaki, Akio

    2016-05-01

    The state of the art precision measurement of the transition frequencies of neutral atoms is performed with atoms trapped by the magic wavelength optical lattice that cancels the ac Stark shift of the transitions. Trapping with magic wavelength lattice is also expected to improve the precision of the hydrogen 1S-2S transition frequency, which so far has been measured only with the atomic beam. In this talk, I discuss the magic wavelength for the hydrogen 1S-2S transition, and the possibility of implementing the optical lattice trapping for hydrogen. Optical trapping of hydrogen also opens the way to perform magnetic field free spectroscopy of antihydrogen for the test of CPT theorem.

  9. SnS2 Thin Film Deposition by Spray Pyrolysis

    NASA Astrophysics Data System (ADS)

    Yahia Jaber, Abdallah; Noaiman Alamri, Saleh; Salah Aida, Mohammed

    2012-06-01

    Tin disulfide (SnS2) thin films have been synthesized using a simplified spray pyrolysis technique using a perfume atomizer. The films were deposited using two different solutions prepared by the dilution of SnCl2 and thiourea in distilled water and in methanol. The obtained films have a microcrystalline structure. The film deposited using methanol as the solvent is nearly stochiometric SnS2 with a spinel phase having a (001) preferential orientation. The film prepared with an aqueous solution is Sn-rich. Scanning electronic microscopy (SEM) images reveal that the film deposited with the aqueous solution is rough and is formed with large wires. However, the film deposited with methanol is dense and smooth. Conductivity measurements indicate that the aqueous solution leads to an n-type semiconductor, while methanol leads to a p-type semiconductor.

  10. Superconductivity in layered BiS2-based compounds

    DOE PAGESBeta

    Yazici, D.; Jeon, I.; White, B. D.; Maple, M. B.

    2015-02-25

    Here, a novel family of superconductors based on BiS2-based superconducting layers were discovered in 2012. In short order, other BiS2-based superconductors with the same or related crystal structures were discovered with superconducting critical temperatures Tc of up to 10 K. Many experimental and theoretical studies have been carried out with the goal of establishing the basic properties of these new materials and understanding the underlying mechanism for superconductivity. In this selective review of the literature, we distill the central discoveries from this extensive body of work, and discuss the results from different types of experiments on these materials within themore » context of theoretical concepts and models.« less

  11. Unusual reactivity of MoS2 nanosheets

    NASA Astrophysics Data System (ADS)

    Mondal, Biswajit; Som, Anirban; Chakraborty, Indranath; Baksi, Ananya; Sarkar, Depanjan; Pradeep, Thalappil

    2016-05-01

    The reactivity of the 2D nanosheets of MoS2 with silver ions in solution, leading to their spontaneous morphological and chemical transformations, is reported. This unique reactivity of the nanoscale form of MoS2 was in stark contrast to its bulk counterpart. While the gradual morphological transformation involving several steps has been captured with an electron microscope, precise chemical identification of the species involved was achieved by electron spectroscopy and mass spectrometry. The energetics of the system investigated supports the observed chemical transformation. The reaction with mercury and gold ions shows similar and dissimilar reaction products, respectively and points to the stability of the metal-sulphur bond in determining the chemical compositions of the final products.The reactivity of the 2D nanosheets of MoS2 with silver ions in solution, leading to their spontaneous morphological and chemical transformations, is reported. This unique reactivity of the nanoscale form of MoS2 was in stark contrast to its bulk counterpart. While the gradual morphological transformation involving several steps has been captured with an electron microscope, precise chemical identification of the species involved was achieved by electron spectroscopy and mass spectrometry. The energetics of the system investigated supports the observed chemical transformation. The reaction with mercury and gold ions shows similar and dissimilar reaction products, respectively and points to the stability of the metal-sulphur bond in determining the chemical compositions of the final products. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00878j

  12. Discovery and Classification of DES15S2lam

    NASA Astrophysics Data System (ADS)

    Pan, Y.-C.; Foley, R. J.; Nichol, R.; Papadopoulos, A.; Childress, M.; D'Andrea, C.; Smith, M.; Sullivan, M.; Maartens, R.; Gupta, R.; Kovacs, E.; Kuhlmann, S.; Spinka, H.; Ahn, E.; Finley, D. A.; Frieman, J.; Marriner, J.; Wester, W.; Aldering, G.; Kim, A. G.; Thomas, R. C.; Barbary, K.; Bloom, J. S.; Goldstein, D.; Nugent, P.; Perlmutter, S.; Casas, R.; Castander, F. J.; Desai, S.; Paech, K.; Smith, R. C.; Schubnell, M.; Kessler, R.; Lasker, J.; Scolnic, D.; Brout, D. J.; Gladney, L.; Sako, M.; Wolf, R. C.; Brown, P. J.; Krisciunas, K.; Suntzeff, N.

    2015-10-01

    We report optical spectroscopy of DES15S2lam discovered by the Dark Energy Survey. The spectrum (540-965nm) was obtained using GMOS on Gemini-North. Object classification was performed using superfit (Howell et al, 2005, ApJ, 634, 1190) and SNID (Blondin & Tonry, 2007, ApJ, 666, 1024), the details of which are reported in the table below.

  13. Physics and chemistry of MoS2 intercalation compounds

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Somoano, R. B.

    1977-01-01

    An investigation is made of the physics and chemistry of MoS2 intercalation compounds. These compounds may be separated into two groups according to their stoichiometry, structure and superconducting properties. The first group consists of Na, Ca, and Sr intercalates, and the second group consists of K, Rb, and Cs intercalates. Particular attention is given to the structure of the electronic energy band and to the normal state and superconducting properties of these compounds.

  14. s2: Object oriented wrapper for functions on the sphere

    NASA Astrophysics Data System (ADS)

    McEwen, Jason C.

    2016-06-01

    The s2 package can represent any arbitrary function defined on the sphere. Both real space map and harmonic space spherical harmonic representations are supported. Basic sky representations have been extended to simulate full sky noise distributions and Gaussian cosmic microwave background realisations. Support for the representation and convolution of beams is also provided. The code requires HEALPix (ascl:1107.018) and CFITSIO (ascl:1010.001).

  15. Electrical properties of NiS2-xSex

    NASA Astrophysics Data System (ADS)

    Kwizera, P.; Dresselhaus, M. S.; Adler, D.

    1980-03-01

    We report results of measurements of electrical conductivity, thermoelectric power, and Hall effect on single crystals of NiS2-xSex (0.1<=x<=1.5). These results cannot be understood using the one-electron approximation but are explained quantitatively by assuming both strong electronic correlations and strong electron-phonon interactions in the 3d eg band associated with the nickel ions. The NiS2-xSex compounds are of particular interest insofar as they permit study of the effect of increasing bandwidth without a change of the basic occupation of states in the correlation-split eg bands. In our model, pure stoichiometric NiS2-xSex (x<0.6) is a Mott insulator with an energy gap due to the correlation splitting of the nickel eg band. However, in all real samples, nonstoichiometry and/or traces of impurities lead to a small concentration of free carriers at all temperatures. These carriers form small polarons, which ordinarily conduct only by means of thermally activated hopping in a very narrow band. For 0.45<=x<0.6, the conductivity decreases with increasing temperature below about 100 K. We interpret this unusual behavior as due to small-polaron band conduction, a phenomenon predicted by Holstein and others at low temperatures but heretofore unconfirmed. For x>=0.6, small polarons do not form, and the system is metallic at all temperatures.

  16. Ambipolar MoS2 thin flake transistors.

    PubMed

    Zhang, Yijin; Ye, Jianting; Matsuhashi, Yusuke; Iwasa, Yoshihiro

    2012-03-14

    Field effect transistors (FETs) made of thin flake single crystals isolated from layered materials have attracted growing interest since the success of graphene. Here, we report the fabrication of an electric double layer transistor (EDLT, a FET gated by ionic liquids) using a thin flake of MoS(2), a member of the transition metal dichalcogenides, an archetypal layered material. The EDLT of the thin flake MoS(2) unambiguously displayed ambipolar operation, in contrast to its commonly known bulk property as an n-type semiconductor. High-performance transistor operation characterized by a large "ON" state conductivity in the order of ~mS and a high on/off ratio >10(2) was realized for both hole and electron transport. Hall effect measurements revealed mobility of 44 and 86 cm(2) V(-1) s(-1) for electron and hole, respectively. The hole mobility is twice the value of the electron mobility, and the density of accumulated carrier reached 1 × 10(14) cm(-2), which is 1 order of magnitude larger than conventional FETs with solid dielectrics. The high-density carriers of both holes and electrons can create metallic transport in the MoS(2) channel. The present result is not only important for device applications with new functionalities, but the method itself would also act as a protocol to study this class of material for a broader scope of possibilities in accessing their unexplored properties.

  17. Advances in Li-TiS2 cell technology

    NASA Technical Reports Server (NTRS)

    Surampudi, S.; Shen, D. H.; Huang, C.-K.; Deligiannis, F.; Attia, A. I.; Halpert, G.

    1991-01-01

    Jet Propulsion Laboratories (JPL) is involved in a NASA sponsored program to develop ambient temperature secondary cells for future space missions. After several years of research on various cathode materials, titanium disulfide (TiS2) was selected in view of its intrinsic reversibility and high faradaic utilization. In the last two years, the efforts were focussed on improving the cycle life of the system and developing 1 Ah cells. Several approaches including the use of mixed solvent electrolytes, the operation of cells at low temperature, and the cycling of cells under different voltage limits, were initially examined to improve the cycle life performance of the Li/TiS2 system. Spiral wound 1 Ah cells fabricated incorporating the improvements from the above studies have delivered more than 600 cycles at 50 percent depth of discharge (DOD). Work is in progress to identify alternate anode materials that can improve the cycle life of the cells to 1000 cycles at 50 percent DOD. The advances made in the Li/TiS2 technology at JPL since 1989 are summarized.

  18. Advances in Li-TiS2 cell technology

    NASA Astrophysics Data System (ADS)

    Surampudi, S.; Shen, D. H.; Huang, C.-K.; Deligiannis, F.; Attia, A. I.; Halpert, G.

    1991-09-01

    Jet Propulsion Laboratories (JPL) is involved in a NASA sponsored program to develop ambient temperature secondary cells for future space missions. After several years of research on various cathode materials, titanium disulfide (TiS2) was selected in view of its intrinsic reversibility and high faradaic utilization. In the last two years, the efforts were focussed on improving the cycle life of the system and developing 1 Ah cells. Several approaches including the use of mixed solvent electrolytes, the operation of cells at low temperature, and the cycling of cells under different voltage limits, were initially examined to improve the cycle life performance of the Li/TiS2 system. Spiral wound 1 Ah cells fabricated incorporating the improvements from the above studies have delivered more than 600 cycles at 50 percent depth of discharge (DOD). Work is in progress to identify alternate anode materials that can improve the cycle life of the cells to 1000 cycles at 50 percent DOD. The advances made in the Li/TiS2 technology at JPL since 1989 are summarized.

  19. Visible Aligned Carbon Nanotube-MoS2 Hybrids

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Hong, Tu; Wang, Tianjiao; Ali, Ahmad Iffat; Chani, Devpaul Singh; Xu, Yaqiong

    Single-walled carbon nanotubes (SWNTs) have gained great interest due to their excellent electrical, mechanical and thermal properties. Recent progress in two-dimensional (2D) materials has opened up new horizons in the realm of physics and engineering that could lead to the revolution of future electronics and optoelectronics. Various hybrid structures have been developed for different applications. Here we report a facile method to synthesize ultrathin 2D hybrids between horizontally-aligned SWNT and monolayer molybdenum sulfide (MoS2) through chemical vapor deposition (CVD). These hybrid structures can be imaged under an optical microscope; and their Raman mapping indicates that MoS2 flakes are partially grown on top of SWNTs. Moreover, strong photocurrent signals have been observed in SWNT-MoS2 hybrids through scanning photocurrent measurements. These fundamental studies may provide a new way to fabricate 2D hybrids for future electronics and optoelectronics. Department of Electrical Engineering & Computer Science, Vanderbilt University, Nashville, TN 37235, USA.

  20. Monolayer MoS2 self-switching diodes

    NASA Astrophysics Data System (ADS)

    Al-Dirini, Feras; Hossain, Faruque M.; Mohammed, Mahmood A.; Hossain, Md Sharafat; Nirmalathas, Ampalavanapillai; Skafidas, Efstratios

    2016-01-01

    This paper presents a new molybdenum disulphide (MoS2) nanodevice that acts as a two-terminal field-effect rectifier. The device is an atomically-thin two-dimensional self-switching diode (SSD) that can be realized within a single MoS2 monolayer with very minimal process steps. Quantum simulation results are presented confirming the device's operation as a diode and showing strong non-linear I-V characteristics. Interestingly, the device shows p-type behavior, in which conduction is dominated by holes as majority charge carriers and the flow of reverse current is enhanced, while the flow of forward current is suppressed, in contrast to monolayer graphene SSDs, which behave as n-type devices. The presence of a large bandgap in monolayer MoS2 results in strong control over the channel, showing complete channel pinch-off in forward conduction, which was confirmed with transmission pathways plots. The device exhibited large leakage tunnelling current through the insulating trenches, which may have been due to the lack of passivation; nevertheless, reverse current remained to be 6 times higher than forward current, showing strong rectification. The effect of p-type substitutional channel doping of sulphur with phosphorus was investigated and showed that it greatly enhances the performance of the device, increasing the reverse-to-forward current rectification ratio more than an order of magnitude, up to a value of 70.

  1. Memristive Phenomena in Polycrystalline Single Layer MoS2

    NASA Astrophysics Data System (ADS)

    Sangwan, Vinod; Jariwala, Deep; Kim, In-Soo; Chen, Kan-Sheng; Marks, Tobin; Lauhon, Lincoln; Hersam, Mark; Hersam Laboratory Team

    Recently, a new class of layered two-dimensional semiconductors has shown promise for various electronic applications. In particular, single layer transition metal dichalcogenides (e.g. MoS2) present a host of attractive features such as high electrical conductivity, tunable band-gap, and strong light-matter interaction. However, available growth methods produce large-area polycrystalline films with grain-boundaries and point defects that can be detrimental in conventional electronic devices. In contrast, we have developed unconventional device structures that exploit these defects for useful electronic functions. In particular, we observe grain-boundary mediated memristive phenomena in single layer MoS2 transistors. Memristor current-voltage characteristics depend strongly on the topology of grain-boundaries in MoS2. A grain boundary directly connecting metal electrodes produces thermally assisted switching with dynamic negative differential resistance, whereas a grain boundary bisecting the channel shows non-filamentary soft-switching. In addition, devices with intersecting grain boundaries in the channel show bipolar resistive switching with high on/off ratios up to ~103. Furthermore, the gate electrode in the field-effect geometry can be used to control the absolute resistance of the on and off states. Complementary electrostatic force microscopy, photoluminescence, and Raman microscopy reveal the role of sulfur vacancies in the switching mechanism.

  2. Memristive Phenomena in Polycrystalline Single Layer MoS2

    NASA Astrophysics Data System (ADS)

    Sangwan, Vinod; Jariwala, Deep; Kim, In-Soo; Chen, Kan-Sheng; Marks, Tobin; Lauhon, Lincoln; Hersam, Mark; Hersam Laboratory Team

    Recently, a new class of layered two-dimensional semiconductors has shown promise for various electronic applications. In particular, ultrathin transition metal dichalcogenides (e.g. MoS2) present a host of attractive features such as high carrier mobility and tunable band-gap. However, available growth methods produce polycrystalline films with grain-boundaries and point defects that can be detrimental in conventional electronic devices. In contrast, we have developed unconventional device structures that exploit these defects for useful electronic functions. In particular, we observe grain-boundary mediated memristive phenomena in single layer MoS2 transistors. Memristor current-voltage characteristics depend strongly on the topology of grain-boundaries in MoS2. A grain boundary directly connecting metal electrodes produces thermally assisted switching with dynamic negative differential resistance, whereas a grain boundary bisecting the channel shows non-filamentary soft-switching. In addition, devices with intersecting grain boundaries in the channel show bipolar resistive switching with high on/off ratios up to ~103. Furthermore, the gate electrode in the field-effect geometry can be used to control the absolute resistance of the on and off states. Correlated electrostatic force microscopy, photoluminescence, and Raman microscopy reveal the role of sulfur vacancies in the switching mechanism. This abstract is replacing MAR16-2015-004166 that had exceeded the character limit.

  3. Graphene/MoS2 heterostructures for optoelectronics applications

    NASA Astrophysics Data System (ADS)

    Han, P.; Wong, Q.; El Fatimy, A.; Ishigami, M.; Barbara, P.

    Graphene and other atomically thin materials can be combined to make novel ultra-thin devices that are suitable for flexible substrates. However, fabricating these heterostructures is a challenge. Most previous work was done by stacking monolayers exfoliated from bulk materials , which is a very time-consuming, low-yield method. Large-area monolayer can also be grown by CVD and stacked, as demonstrated by the successful transfer of graphene on as-grown MoS2, yet the optical properties of some materials like MoS2 may be degraded by the processing required to detach them from the growth substrate, thereby limiting options in device architecture. Here we develop a method to transfer, align and stack large flakes and films of MoS2 and graphene after transferring both from the growth substrate onto an arbitrary substrate. The Raman and photoluminescence measurements show that the optical properties of the stacked monolayers are not degraded, making this method viable for fabrication of optoelectronics devices. . Work supported by the U.S. ONR (Award: N000141310865) and the NSF-REU (DMR-1358978).

  4. The roles of bacterial biofilm and oxidizing enzymes in the biodegradation of plastic by the bacterium Rhodococcus ruber (C208)

    NASA Astrophysics Data System (ADS)

    Sivan, A.; Gilan, I.; Santo, M.

    2011-12-01

    Synthetic polymers such as polyethylene are amongst the most durable plastic materials and, therefore are resistant to natural biodegradation resulting in their accumulation in the environment posing a global hazard. We have carried out a two-step enrichment procedure aimed at the isolation of polyethylene-degrading bacteria from soil. The initial enrichment was carried out in soil and the second, in a liquid mineral medium supplemented with linear low-density polyethylene (LDPE; MW 191,000) as the sole carbon source. UV-photooxidation may enhance biodegradation by the formation of carbonyl residues that can be utilized by microorganisms. This screening gave rise to several bacterial strains that were capable of degrading polyethylene. One of these strains (C208), identified as the actinomycete Rhodococcus ruber, colonized the polyethylene producing a biofilm which eventually lead to the degradation of the polyethylene. Adherence and colonization of planktonic C208 cells to the polyethylene surface occurred within minutes from exposure to the polyolefin. This resulted in formation of an initial biofilm that differentiated into cell-aggregation-forming microcolonies. Further organization yielded three-dimensional sessile structures as the mature biofilm. The ratio between the population densities, of the biofilm and planktonic, was about 60:1, indicating a high preference for the biofilm mode of growth. Analysis of the extra-cellular polymeric substances (EPS) in the biofilm of C208 revealed that the polysaccharides level was up to 2.5 folds higher than that of the protein. Surprisingly, the EPS also contained DNA that is actively excreted from live bacterial cells. This is supported by the reduction in biofilm content (but not in viability) following addition, of DNase 1 and RNAse A. The biofilm showed a high viability even after 60 days of incubation in a carbon free medium. This durability of the biofilm, can be attributed to biodegradation of polyethylene. A

  5. Exfoliated MoS2 in Water without Additives

    PubMed Central

    Forsberg, Viviane; Zhang, Renyun; Bäckström, Joakim; Dahlström, Christina; Andres, Britta; Norgren, Magnus; Andersson, Mattias; Hummelgård, Magnus; Olin, Håkan

    2016-01-01

    Many solution processing methods of exfoliation of layered materials have been studied during the last few years; most of them are based on organic solvents or rely on surfactants and other funtionalization agents. Pure water should be an ideal solvent, however, it is generally believed, based on solubility theories that stable dispersions of water could not be achieved and systematic studies are lacking. Here we describe the use of water as a solvent and the stabilization process involved therein. We introduce an exfoliation method of molybdenum disulfide (MoS2) in pure water at high concentration (i.e., 0.14 ± 0.01 g L−1). This was achieved by thinning the bulk MoS2 by mechanical exfoliation between sand papers and dispersing it by liquid exfoliation through probe sonication in water. We observed thin MoS2 nanosheets in water characterized by TEM, AFM and SEM images. The dimensions of the nanosheets were around 200 nm, the same range obtained in organic solvents. Electrophoretic mobility measurements indicated that electrical charges may be responsible for the stabilization of the dispersions. A probability decay equation was proposed to compare the stability of these dispersions with the ones reported in the literature. Water can be used as a solvent to disperse nanosheets and although the stability of the dispersions may not be as high as in organic solvents, the present method could be employed for a number of applications where the dispersions can be produced on site and organic solvents are not desirable. PMID:27120098

  6. A characteristic number of Hamiltonian bundles over S2

    NASA Astrophysics Data System (ADS)

    Viña, Andrés

    2006-11-01

    Each loop ψ in the group Ham(M) of Hamiltonian diffeomorphisms of a symplectic manifold M determines a fibration E on S2, whose coupling class [V. Guillemin, L. Lerman, S. Sternberg, Symplectic Fibrations and Multiplicity Diagrams, Cambridge U.P., Cambridge, 1996] is denoted by c. If VTE is the vertical tangent bundle of E, we relate the characteristic number ∫Ec1(VTE)cn to the Maslov index of the linearized flow ψ and the Chern class c1(TM). We give the value of this characteristic number for loops of Hamiltonian symplectomorphisms of Hirzebruch surfaces.

  7. Isolation and functional analysis of a glycolipid producing Rhodococcus sp. strain IITR03 with potential for degradation of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT).

    PubMed

    Bajaj, Abhay; Mayilraj, Shanmugam; Mudiam, Mohana Krishna Reddy; Patel, Devendra Kumar; Manickam, Natesan

    2014-09-01

    A 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) degrading bacterium strain IITR03 producing trehalolipid was isolated and characterized from a pesticides contaminated soil. The strain IITR03 was identified as a member of the genus Rhodococcus based on polyphasic studies. Under aqueous culture conditions, the strain IITR03 degraded 282 μM of DDT and could also utilize 10mM concentration each of 4-chlorobenzoic acid, 3-chlorobenzoic acid and benzoic acid as sole carbon and energy source. The catechol 1,2-dioxygenase enzyme activity resulted in conversion of catechol to form cis,cis-muconic acid. Cloning and sequencing of partial nucleotide sequence of catechol 1,2-dioxygenase gene (cat) from strain IITR03 revealed its similarity to catA gene present in Rhodococcus sp. strain Lin-2 (97% identity) and Rhodococcus strain AN22 (96% identity) degrading benzoate and aniline, respectively. The results suggest that the strain IITR03 could be useful for field bioremediation studies of DDT-residues and chlorinated aromatic compounds present in contaminated sites.

  8. Photoluminescence properties of S2 molecule trapped in Melanophlogite

    NASA Astrophysics Data System (ADS)

    Messina, Fabrizio; Todaro, Michela; Buscarino, Gianpiero; Vaccaro, Lavinia; Cannas, Marco; Gelardi, Franco M.

    2016-03-01

    We studied the photoluminescence properties of a sample of SiO2-clathrate Melanophlogite, a crystalline microporous material which is found in nature as a rare mineral. Upon β irradiation, the material displays an intense light emission under near-UV illumination. We studied in detail this optical activity by steady-state and time-resolved photoluminescence measurements as a function of temperature. The spectroscopic properties we find can be ascribed to a population of quasi-free molecules trapped within each of the two different types of cage available in the structure of this clathrate, although the spectroscopic properties of the guest molecules are affected by their interactions with the host matrix. Based on the available data, we attribute the observed photoluminescence to trapped S2 molecules, emitting from their excited 3Σ u - or 3Π u electronic states, depending on the cage they are trapped in and on temperature. Our results have an impact on the fundamental understanding of host-guest interactions characteristic of microporous systems such as clathrates. Indeed, the data highlight that even a relatively weak coupling between quasi-free S2 molecules and the two types of cages provided by the Melanophlogite host has a surprisingly complex influence on the optical properties of the guest.

  9. Fracture in MoS2 Solid Lubricant Films

    SciTech Connect

    Hilton, M.R.

    1995-09-01

    The fracture properties of sputter-deposited films of MoS2 as a function of the additive-controlled microstructure were assessed using brale indentation contact and scanning electron microscopy (SEM). Additives were incorporated as either co-sputtered species (Ni, SbO(x)) or as multilayers (Au-20%Pd, Ni). Undoped films were also examined as references. The undoped films and 3% co-sputtered Ni films (deposited at 2.66 Pa argon background pressure) showed zone 2 columnar plate morphologies with porosity. Co-sputtered films having higher concentrations of Ni or SbO(x) showed zone 1 dense cauliflower morphologies, while the multilayer films (and pure MoS2 films deposited at 0.266 Pa) exhibited dense, featureless morphologies. The porous zone 2 films generally resisted delamination better than the denser morphologies. High Ni concentrations increased spallation. The presence of SbO(x) affected fracture propagation and appeared to be more benign than Ni. The presence of multilayers also affected fracture and retarded spallation in dense microstructures. However, many multilayer structures showed significant delamination.

  10. Photoeffects in cobalt doped pyrite (FeS 2) films

    NASA Astrophysics Data System (ADS)

    Thomas, B.; Ellmer, K.; Bohne, W.; Röhrich, J.; Kunst, M.; Tributsch, H.

    1999-07-01

    By indiffusion of a thin metallic cobalt layer into a pyrite film deposited by metal organic chemical vapour deposition (MOCVD), cobalt doped pyrite (FeS 2) films have been prepared. The cobalt in these films acts as a donor and transforms the originally p-type into n-type conductivity. To our knowledge this is the first time that n-type pyrite films have been prepared. Compared to the undoped p-type pyrite films, the cobalt-diffused films exhibit a much higher photoconductivity, as revealed by time resolved microwave conductivity analysis. From Hall and conductivity measurements a charge carrier concentration of about 10 20 cm -3 and a Hall mobility of about 1.5 cm 2/(V s) was calculated. This has to be compared with p-type pyrite films which do not show a Hall mobility above 0.1 cm 2/(V s), the detection limit of our Hall system. By analytical techniques (Rutherford backscattering and photoelectron spectroscopy) it was confirmed that the increase of the photoactivity is a bulk property of the pyrite films and not merely due to a surface passivation (for instance, due to metallic CoS 2). The presented results stimulate further experiments on in-situ-doping of pyrite by MOCVD and open the opportunity for the preparation of pn-junctions and pn-solar cells with pyrite.

  11. MoS2 memristor with photoresistive switching.

    PubMed

    Wang, Wei; Panin, Gennady N; Fu, Xiao; Zhang, Lei; Ilanchezhiyan, P; Pelenovich, Vasiliy O; Fu, Dejun; Kang, Tae Won

    2016-01-01

    A MoS2 nanosphere memristor with lateral gold electrodes was found to show photoresistive switching. The new device can be controlled by the polarization of nanospheres, which causes resistance switching in an electric field in the dark or under white light illumination. The polarization charge allows to change the switching voltage of the photomemristor, providing its multi-level operation. The device, polarized at a voltage 6 V, switches abruptly from a high resistance state (HRSL6) to a low resistance state (LRSL6) with the On/Off resistance ratio of about 10 under white light and smooth in the dark. Analysis of device conductivity in different resistive states indicates that its resistive state could be changed by the modulation of the charge in an electric field in the dark or under light, resulting in the formation/disruption of filaments with high conductivity. A MoS2 photomemristor has great potential as a multifunctional device designed by using cost-effective fabrication techniques. PMID:27492593

  12. Open Standards and Technologies in the S2S Framework

    NASA Astrophysics Data System (ADS)

    Maffei, A. R.; Rozell, E. A.; West, P.; Zednik, S.; Fox, P. A.

    2011-12-01

    The S2S Search Interface Framework provides tools and services to build customized user interfaces. It also serves as a focal point for repository managers to develop science data services and reusable components for search interfaces. The framework has been used to design a faceted browsing platform for web services, including OpenSearch and SAWSDL. This exemplar faceted browsing platform has been applied in our development of search interfaces for 1) an international open government dataset catalog and 2) a metadata catalog for biological and chemical oceanography. S2S was designed from the ground up using open standards and technologies. The framework was initially created to develop "data dashboard" interfaces on top of OpenSearch services, but has been generalized to support web services and standards with semantic annotation capabilities. We apply OWL, a W3C standard for ontologies on the Web, to create a vocabulary for the description of framework metadata. Our faceted browsing platform is heavily focused on the use of jQuery; we have created reusable user interface "widgets" that leverage OpenLayers and MapServer technology in geospatial selection and visualization, which can be used in this and future platforms. The use of open standards and technologies has enabled rapid iterations over software development lifecycles, and has kept the framework agile as new use cases and ideas have emerged.

  13. MoS2 memristor with photoresistive switching

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Panin, Gennady N.; Fu, Xiao; Zhang, Lei; Ilanchezhiyan, P.; Pelenovich, Vasiliy O.; Fu, Dejun; Kang, Tae Won

    2016-08-01

    A MoS2 nanosphere memristor with lateral gold electrodes was found to show photoresistive switching. The new device can be controlled by the polarization of nanospheres, which causes resistance switching in an electric field in the dark or under white light illumination. The polarization charge allows to change the switching voltage of the photomemristor, providing its multi-level operation. The device, polarized at a voltage 6 V, switches abruptly from a high resistance state (HRSL6) to a low resistance state (LRSL6) with the On/Off resistance ratio of about 10 under white light and smooth in the dark. Analysis of device conductivity in different resistive states indicates that its resistive state could be changed by the modulation of the charge in an electric field in the dark or under light, resulting in the formation/disruption of filaments with high conductivity. A MoS2 photomemristor has great potential as a multifunctional device designed by using cost-effective fabrication techniques.

  14. S2HAT: Scalable Spherical Harmonic Transform Library

    NASA Astrophysics Data System (ADS)

    Stompor, Radek

    2011-10-01

    Many problems in astronomy and astrophysics require a computation of the spherical harmonic transforms. This is in particular the case whenever data to be analyzed are distributed over the sphere or a set of corresponding mock data sets has to be generated. In many of those contexts, rapidly improving resolutions of both the data and simulations puts increasingly bigger emphasis on our ability to calculate the transforms quickly and reliably. The scalable spherical harmonic transform library S2HAT consists of a set of flexible, massively parallel, and scalable routines for calculating diverse (scalar, spin-weighted, etc) spherical harmonic transforms for a class of isolatitude sky grids or pixelizations. The library routines implement the standard algorithm with the complexity of O(n^3/2), where n is a number of pixels/grid points on the sphere, however, owing to their efficient parallelization and advanced numerical implementation, they achieve very competitive performance and near perfect scalability. S2HAT is written in Fortran 90 with a C interface. This software is a derivative of the spherical harmonic transforms included in the HEALPix package and is based on both serial and MPI routines of its version 2.01, however, since version 2.5 this software is fully autonomous of HEALPix and can be compiled and run without the HEALPix library.

  15. MoS2 memristor with photoresistive switching.

    PubMed

    Wang, Wei; Panin, Gennady N; Fu, Xiao; Zhang, Lei; Ilanchezhiyan, P; Pelenovich, Vasiliy O; Fu, Dejun; Kang, Tae Won

    2016-08-05

    A MoS2 nanosphere memristor with lateral gold electrodes was found to show photoresistive switching. The new device can be controlled by the polarization of nanospheres, which causes resistance switching in an electric field in the dark or under white light illumination. The polarization charge allows to change the switching voltage of the photomemristor, providing its multi-level operation. The device, polarized at a voltage 6 V, switches abruptly from a high resistance state (HRSL6) to a low resistance state (LRSL6) with the On/Off resistance ratio of about 10 under white light and smooth in the dark. Analysis of device conductivity in different resistive states indicates that its resistive state could be changed by the modulation of the charge in an electric field in the dark or under light, resulting in the formation/disruption of filaments with high conductivity. A MoS2 photomemristor has great potential as a multifunctional device designed by using cost-effective fabrication techniques.

  16. MoS2 memristor with photoresistive switching

    PubMed Central

    Wang, Wei; Panin, Gennady N.; Fu, Xiao; Zhang, Lei; Ilanchezhiyan, P.; Pelenovich, Vasiliy O.; Fu, Dejun; Kang, Tae Won

    2016-01-01

    A MoS2 nanosphere memristor with lateral gold electrodes was found to show photoresistive switching. The new device can be controlled by the polarization of nanospheres, which causes resistance switching in an electric field in the dark or under white light illumination. The polarization charge allows to change the switching voltage of the photomemristor, providing its multi-level operation. The device, polarized at a voltage 6 V, switches abruptly from a high resistance state (HRSL6) to a low resistance state (LRSL6) with the On/Off resistance ratio of about 10 under white light and smooth in the dark. Analysis of device conductivity in different resistive states indicates that its resistive state could be changed by the modulation of the charge in an electric field in the dark or under light, resulting in the formation/disruption of filaments with high conductivity. A MoS2 photomemristor has great potential as a multifunctional device designed by using cost-effective fabrication techniques. PMID:27492593

  17. Thiophene hydrodesulfurization on MoS 2; Theoretical aspects

    NASA Astrophysics Data System (ADS)

    Zonnevylle, Marjanne C.; Hoffmann, Roald; Harris, Suzanne

    Hydrodesulfurization (HDS), the removal of sulfur in the form of H 2S from petroleum, is a crucial step in the industrial refinement process. Using the extended Hückel tight binding method, we have examined the nature of the active site and the mechanism of desulfurization in the case of thiophene on MoS 2. The η 5-bound sites, in which the thiophene ring lies parallel to the surface, are particularly advantageous to weakening the SC bond. η 1-bound sites are less active. The removal of sorrounding surface sulfurs increases the HDS potential of the η 5 geometry, but is ineffective at promoting the poorer adsorption modes. Surface reconstruction has also been examined; the possibility of MoMo pairing is suggested. The effect of poisons and promoters is considered. The role they play in HDS catalysis may be determined by the position they occupy in the MoS 2 lattice. Metals which replace a surface molybdenum tend to poison HDS, whereas those which "pseudo-intercalate" between the SS layers can serve to promote the reaction.

  18. Facile one-pot synthesis of CoS2-MoS2/CNTs as efficient electrocatalyst for hydrogen evolution reaction

    NASA Astrophysics Data System (ADS)

    Liu, Yan-Ru; Hu, Wen-Hui; Li, Xiao; Dong, Bin; Shang, Xiao; Han, Guan-Qun; Chai, Yong-Ming; Liu, Yun-Qi; Liu, Chen-Guang

    2016-10-01

    Ternary hybrid cobalt disulfide-molybdenum disulfides supported on carbon nanotubes (CoS2-MoS2/CNTs) electrocatalysts have been prepared via a simple hydrothermal method. CNTs as support may provide good conductivity and low the agglomeration of layered MoS2 structure. CoS2 with intrinsic metallic conductivity may enhance the activity of the ternary hybrid electrocatalysts for hydrogen evolution reaction (HER). X-ray diffraction (XRD) data confirm the formation of ternary hybrid nanocomposites composed of CNTs, CoS2 and amorphous MoS2. Scanning electron microscopy (SEM) images show that strong combination between MoS2, CNTs and regular orthohexagonal CoS2 has been obtained. The dispersion of each component is good and no obvious agglomeration can be observed. It is found that compared with CoS2/CNTs and MoS2/CNTs, the ternary CoS2-MoS2/CNTs have the better activity for HER with a low onset potential of 70 mV (vs. RHE) and a small Talel slope of 67 mV dec-1, and are extremely stable after 1000 cycles. In addition, the optimal doping ratio of Co to Mo is 2:1, which have better HER activity. It is proved that the introduction of carbon materials and Co atoms could improve the performances of MoS2-based electrocatalysts for HER.

  19. Perfect fluidity of a dissipative system: Analytical solution for the Boltzmann equation in AdS2S2

    DOE PAGESBeta

    Noronha, Jorge; Denicol, Gabriel S.

    2015-12-30

    In this paper we obtain an analytical solution of the relativistic Boltzmann equation under the relaxation time approximation that describes the out-of-equilibrium dynamics of a radially expanding massless gas. This solution is found by mapping this expanding system in flat spacetime to a static flow in the curved spacetime AdS2S2. We further derive explicit analytic expressions for the momentum dependence of the single-particle distribution function as well as for the spatial dependence of its moments. We find that this dissipative system has the ability to flow as a perfect fluid even though its entropy density does not matchmore » the equilibrium form. The nonequilibrium contribution to the entropy density is shown to be due to higher-order scalar moments (which possess no hydrodynamical interpretation) of the Boltzmann equation that can remain out of equilibrium but do not couple to the energy-momentum tensor of the system. Furthermore, in this system the slowly moving hydrodynamic degrees of freedom can exhibit true perfect fluidity while being totally decoupled from the fast moving, nonhydrodynamical microscopic degrees of freedom that lead to entropy production.« less

  20. MoS2 transistors with 1-nanometer gate lengths

    NASA Astrophysics Data System (ADS)

    Desai, Sujay B.; Madhvapathy, Surabhi R.; Sachid, Angada B.; Llinas, Juan Pablo; Wang, Qingxiao; Ahn, Geun Ho; Pitner, Gregory; Kim, Moon J.; Bokor, Jeffrey; Hu, Chenming; Wong, H.-S. Philip; Javey, Ali

    2016-10-01

    Scaling of silicon (Si) transistors is predicted to fail below 5-nanometer (nm) gate lengths because of severe short channel effects. As an alternative to Si, certain layered semiconductors are attractive for their atomically uniform thickness down to a monolayer, lower dielectric constants, larger band gaps, and heavier carrier effective mass. Here, we demonstrate molybdenum disulfide (MoS2) transistors with a 1-nm physical gate length using a single-walled carbon nanotube as the gate electrode. These ultrashort devices exhibit excellent switching characteristics with near ideal subthreshold swing of ~65 millivolts per decade and an On/Off current ratio of ~106. Simulations show an effective channel length of ~3.9 nm in the Off state and ~1 nm in the On state.

  1. Dicer assay in Drosophila S2 cell extract.

    PubMed

    Yang, Baojun; Li, Hongwei

    2011-01-01

    Double-stranded RNA (dsRNA) is the trigger of RNA interference (RNAi)-mediated gene regulation. Dicer processes dsRNAs into short interfering RNAs (siRNAs), which are incorporated into the effector RNA-induced silencing complex (RISC) and direct degradation of homologous target mRNAs. In plants and invertebrates, the RNAi machinery also acts as an antiviral mechanism through production of viral siRNAs by Dicer and silencing of replicating viruses. Viral suppressors of RNAi (VSRs) are encoded by some viruses and serve as a strategy to counteract the RNAi-based antiviral immunity. In this chapter, we describe a Dicer activity assay in extracts prepared from Drosophila melanogaster S2 cells. We also introduce a simple procedure to study VSR activity in the in vitro Dicer assay. PMID:21431688

  2. Metal-insulator crossover in multilayered MoS2.

    PubMed

    Park, Min Ji; Yi, Sum-Gyun; Kim, Joo Hyung; Yoo, Kyung-Hwa

    2015-10-01

    The temperature dependence of electrical transport properties was investigated for multilayered MoS2 field effect transistor devices with thicknesses of 3-22 nm. Some devices showed typical n-type semiconducting behavior, while others exhibited metal-insulator crossover (MIC) from metallic to insulating conduction at finite temperatures. The latter effect occurred near zero gate voltage or at high positive gate voltages. Analysis of Raman spectroscopy revealed the key difference that devices with MIC have a metallic 1T phase as well as a semiconducting 2H phase, whereas devices without the MIC did not have a metallic 1T phase. These results suggest that the metallic 1T phase may contribute to inducing the MIC.

  3. Search for Delta S = 2 nonleptonic hyperon decays

    SciTech Connect

    White, C.G.; Burnstein, R.A.; Chakravorty, A.; Chan, A.; Chen, Y.C.; Choong, W.S.; Clark, K.; Dukes, E.C.; Durandet, C.; Felix, J.; Gidal, G.; Gu, P.; Gustafson, H.R.; Ho, C.; Holmstrom, T.; Huang, M.; James, C.; Jenkins, C.M.; Kaplan, D.M.; Lederman, L.M.; Leros, N.; /Taiwan, Inst. Phys. /UC, Berkeley /Fermilab /Guanajuato U. /IIT, Chicago /Lausanne U. /LBL, Berkeley /Michigan U. /South Alabama U. /Virginia U.

    2005-03-01

    A sensitive search for the rare decays {Omega}{sup -} {yields} {Lambda}{pi}{sup -} and {Xi}{sup 0} {yields} p{pi}{sup -} has been performed using data from the 1997 run of the HyperCP (Fermilab E871) experiment. Limits on other such processes do not exclude the possibility of observable rates for |{Delta}S| = 2 nonleptonic hyperon decays, provided the decays occur through parity-odd operators. They obtain the branching-fraction limits {Beta}({Omega}{sup -} {yields} {Lambda}{pi}{sup -}) < 2.9 x 10{sup -6} and {Beta}({Xi}{sup 0} {yields} p{pi}{sup -}) < 8.2 x 10{sup -6}, both at 90% confidence level.

  4. An investigation of AdS2 backreaction and holography

    NASA Astrophysics Data System (ADS)

    Engelsöy, Julius; Mertens, Thomas G.; Verlinde, Herman

    2016-07-01

    We investigate a dilaton gravity model in AdS2 proposed by Almheiri and Polchinski [1] and develop a 1d effective description in terms of a dynamical boundary time with a Schwarzian derivative action. We show that the effective model is equivalent to a 1d version of Liouville theory, and investigate its dynamics and symmetries via a standard canonical framework. We include the coupling to arbitrary conformal matter and analyze the effective action in the presence of possible sources. We compute commutators of local operators at large time separation, and match the result with the time shift due to a gravitational shockwave interaction. We study a black hole evaporation process and comment on the role of entropy in this model.

  5. Exciton band structure of monolayer MoS2

    NASA Astrophysics Data System (ADS)

    Wu, Fengcheng; Qu, Fanyao; MacDonald, Allan

    2015-03-01

    We describe a theory of the momentum-dependent exciton spectrum of monolayer molybdenum disulfide. Low-energy excitons occur both at the Brillouin zone center and at the Brillouin-zone corners. We find that binding energies at the Brillouin-zone center deviate qualitatively from the (n - 1 / 2) - 2 pattern of the two-dimensional hydrogenic model. Moreover, the four 2 p states of A series are lower in energy than the corresponding 2 s states and not degenerate. The two-fold ground-state valley degeneracy is lifted linearly at small momenta by electron-hole exchange processes that establish inter valley coherence. We conclude that atlhough monolayer MoS2 is a direct-gap semiconductor when classified by its quasiparticle band structure it may well be an indirect gap material when classified by its excitation spectra, and speculate on the role of this property in luminescence characteristics.

  6. Morphological growth of sputtered MoS2 films

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1975-01-01

    Sputtered MoS2 films from 300 A to 20,000 A thick were deposited on metal and glass surfaces. The substrate effects such as surface temperature, finish, pretreatment, and chemistry as they affect the film formation characteristics were investigated by optical, electron transmission, electron diffraction, and scanning electron microscopy. Substrate temperature and surface chemistry were found to be the prime variables as to the formation of a crystalline or amorphous film. The friction characteristics are strictly influenced by the type of film formed. Surface chemistry and surface pretreatment account for compound formation and corresponding grain growth, which directly affect the adhesion characteristics, resulting in poor adherence. Scratches, impurities, inhomogeneities, etc., are favorable nucleation sites for the growth of isolated and complex nodules within the film.

  7. Lubrication with sputtered MoS2 films.

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1971-01-01

    Sputtered MoS2 films (2000-6500 A) were deposited on highly polished metal surfaces. These films have a low coefficient of friction (0.03-0.04) at speeds of 40-80 rpm and loads of 250-1000 grams. At loads of 250 grams the wear lives are over 0.5 million cycles, but at 1000 gram loads, it decreases to 38,000 cycles. Friction experiments and tensile tests have indicated that sputtered films have a strong adherence to metal surfaces. Electron transmission, diffraction and scanning electron microscopy show that these films have an extremely small particle size, less than 30 A in diameter, and are very dense and free from observable pinholes. The high kinetic energy of these sputtered species, the submicroscopic particle size and the sputter-etched substrate surface is responsible for strong adhesion and cohesion of the sputtered film.

  8. Morphological growth of sputtered MoS2 films

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1975-01-01

    Sputtered MoS2 films from 300 A to 20,000 A thick were deposited on metal and glass surfaces. The substrate effects such as surface temperature, finish, pretreatment and chemistry as they affect the film formation characteristics were investigated by optical, electron transmission, electron diffraction, and scanning electron microscopy. Substrate temperature and surface chemistry were found to be the prime variables as to the formation of a crystalline or amorphous film. The friction characteristics are strictly influenced by the type of film formed. Surface chemistry and surface pretreatment account for compound formation and corresponding grain growth, which directly affect the adhesion characteristics, resulting in poor adherence. The type of surface finish (topography) as related to scratches, impurities, inhomogeneities, etc., are favorable nucleation sites for the growth of isolated and complex nodules within the film, and various complex surface overgrowths on the film. These nodular growth features have progressively more undesirable effects on the film behavior as the film thickness increases.

  9. Lubrication with sputtered MoS2 films.

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1971-01-01

    Sputtered MoS2 films (2000-6500 A) were deposited on highly polished metal surfaces. These films have a low coefficient of friction (0.03-0.04) at speeds of 40-80 rpm and loads of 250-1000 grams. At loads of 250 grams, the wear lives are over 0.5 million cycles, but at 1000 gram loads, it decreases to 38,000 cycles. Friction experiments and tensile tests have indicated that sputtered films have a strong adherence to metal surfaces. Electron transmission, diffraction, and scanning electron microscopy show that these films have an extremely small particle size less than 30 A in diameter and are very dense and free from observable pinholes.

  10. Vibrational photodetachment spectroscopy near the electron affinity of S2

    NASA Astrophysics Data System (ADS)

    Barrick, J. B.; Yukich, J. N.

    2016-02-01

    We have conducted laser photodetachment spectroscopy near the detachment threshold of the electron affinity of S2 in a 1.8-T field. The ions are prepared by dissociative electron attachment to carbonyl sulfide. The experiment is conducted in a Penning ion trap and with a narrow-band, tunable, Ti:sapphire laser. A hybrid model for photodetachment in an ion trap is fit to the data using the appropriate Franck-Condon factors. The observations reveal detachment from and to the first few vibrational levels of the anion and the neutral molecule, respectively. Evaporative cooling of the anion ensemble condenses the thermal distribution to the lowest initial vibrational states. The subsequent detachment spectroscopy yields results consistent with a vibrationally cooled anion population.

  11. Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Nocardia, Rhodococcus, Kocuria, Gordonia, Tsukamurella, and Listeria Species

    PubMed Central

    Lee, Tai-Fen; Du, Shin-Hei; Teng, Shih-Hua; Liao, Chun-Hsing; Sheng, Wang-Hui; Teng, Lee-Jene

    2014-01-01

    We evaluated whether the Bruker Biotyper matrix-associated laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) system provides accurate species-level identifications of 147 isolates of aerobically growing Gram-positive rods (GPRs). The bacterial isolates included Nocardia (n = 74), Listeria (n = 39), Kocuria (n = 15), Rhodococcus (n = 10), Gordonia (n = 7), and Tsukamurella (n = 2) species, which had all been identified by conventional methods, molecular methods, or both. In total, 89.7% of Listeria monocytogenes, 80% of Rhodococcus species, 26.7% of Kocuria species, and 14.9% of Nocardia species (n = 11, all N. nova and N. otitidiscaviarum) were correctly identified to the species level (score values, ≥2.0). A clustering analysis of spectra generated by the Bruker Biotyper identified six clusters of Nocardia species, i.e., cluster 1 (N. cyriacigeorgica), cluster 2 (N. brasiliensis), cluster 3 (N. farcinica), cluster 4 (N. puris), cluster 5 (N. asiatica), and cluster 6 (N. beijingensis), based on the six peaks generated by ClinProTools with the genetic algorithm, i.e., m/z 2,774.477 (cluster 1), m/z 5,389.792 (cluster 2), m/z 6,505.720 (cluster 3), m/z 5,428.795 (cluster 4), m/z 6,525.326 (cluster 5), and m/z 16,085.216 (cluster 6). Two clusters of L. monocytogenes spectra were also found according to the five peaks, i.e., m/z 5,594.85, m/z 6,184.39, and m/z 11,187.31, for cluster 1 (serotype 1/2a) and m/z 5,601.21 and m/z 11,199.33 for cluster 2 (serotypes 1/2b and 4b). The Bruker Biotyper system was unable to accurately identify Nocardia (except for N. nova and N. otitidiscaviarum), Tsukamurella, or Gordonia species. Continuous expansion of the MALDI-TOF MS databases to include more GPRs is necessary. PMID:24759706

  12. Improving crystalline quality of sputtering-deposited MoS2 thin film by postdeposition sulfurization annealing using (t-C4H9)2S2

    NASA Astrophysics Data System (ADS)

    Ishihara, Seiya; Hibino, Yusuke; Sawamoto, Naomi; Suda, Kohei; Ohashi, Takumi; Matsuura, Kentarou; Machida, Hideaki; Ishikawa, Masato; Sudoh, Hiroshi; Wakabayashi, Hitoshi; Ogura, Atsushi

    2016-04-01

    A sputtered MoS2 thin film is a candidate for realizing enhancement-mode MoS2 metal-oxide-semiconductor field-effect transistors (MOSFETs). However, there are some sulfur vacancies in the film, which degrade the device performance. In this study, we performed postdeposition sulfurization annealing (PSA) on a sputtered MoS2 thin film in order to complement sulfur vacancies, and we investigated the fundamental properties of the MoS2 film. As a result, a high-quality crystalline 10-layer MoS2 film with an ideal stoichiometric composition was obtained at a relatively low process temperature (500 °C). The MoS2 film had an indirect bandgap of 1.36 eV and a high Hall mobility compared with the as-deposited sputtered MoS2 film.

  13. Monolayer-by-monolayer stacked pyramid-like MoS2 nanodots on monolayered MoS2 flakes with enhanced photoluminescence.

    PubMed

    Yuan, Cailei; Cao, Yingjie; Luo, Xingfang; Yu, Ting; Huang, Zhenping; Xu, Bo; Yang, Yong; Li, Qinliang; Gu, Gang; Lei, Wen

    2015-11-01

    The precise control of the morphology and crystal shape of MoS2 nanostructures is of particular importance for their application in nanoelectronic and optoelectronic devices. Here, we describe a single step route for the synthesis of monolayer-by-monolayer stacked pyramid-like MoS2 nanodots on monolayered MoS2 flakes using a chemical vapor deposition method. First-principles calculations demonstrated that the bandgap of the pyramid-like MoS2 nanodot is a direct bandgap. Enhanced local photoluminescence emission was observed in the pyramid-like MoS2 nanodot, in comparison with monolayered MoS2 flakes. The findings presented here provide new opportunities to tailor the physical properties of MoS2via morphology-controlled synthesis.

  14. Study of S = -2 baryonic states at FLAIR

    SciTech Connect

    Grzonka, D.; Gillitzer, A.; Kilian, K.; Oelert, W.; Ritman, J.; Sefzick, T.; Winter, P.; Bassalleck, B.; Kingsberry, P.

    2005-10-19

    At the future FAIR project in Darmstadt/Germany low energy antiprotons will be available at FLAIR, the Facility for Low energy Antiproton and Ion Research. Within the FLAIR LoI it is proposed to study the production of strangeness S = -2 baryonic states based on ideas proposed for LEAR.With stopped antiprotons a very efficient reaction chain for the production of slow {xi} hyperons can be initiated. The special feature of this reaction channel is the low momentum of the produced {xi} hyperon down to zero MeV/c recoil momentum. These slow {xi} particles can go into interacting {xi}N systems which can couple to YY or might also directly connect to the H particle, if it exists.From the experimental point of view the delayed decays of the strange exit particles allows a highly selective trigger on these reaction channels and the event reconstruction is relatively simple. A non magnetic detection system with track reconstruction ability is sufficient for the complete kinematical reconstruction.

  15. Two Dimensional Ising Superconductivity in Gated MoS2

    NASA Astrophysics Data System (ADS)

    Yuan, Noah; Lu, Jianming; Law, Kam Tuen; Zheliuk, Oleksandr; Leermakers, Inge; Zeitler, Ulrich; Ye, Jianting

    The Zeeman effect, which is usually considered to be detrimental to superconductivity, can surprisingly protect the superconducting states created by gating a layered transition metal dichalcogenide. This effective Zeeman field, which is originated from intrinsic spin orbit coupling induced by breaking in-plane inversion symmetry, can reach nearly a hundred Tesla in magnitude. It strongly pins the spin orientation of the electrons to the out-of-plane directions and protects the superconductivity from being destroyed by an in-plane external magnetic field. In magnetotransport experiments of ionic-gate MoS2 transistors, where gating prepares individual superconducting state with different carrier doping, we indeed observe a spin-protected superconductivity by measuring an in-plane critical field Bc 2 far beyond the Pauli paramagnetic limit. The gating-enhanced Bc 2 is more than an order of magnitude larger compared to the bulk superconducting phases where the effective Zeeman field is weakened by interlayer coupling. Our study gives the first experimental evidence of an Ising superconductor, in which spins of the pairing electrons are strongly pinned by an effective Zeeman field.

  16. RKKY interaction in triangular MoS2 nanoflakes

    NASA Astrophysics Data System (ADS)

    Mastrogiuseppe, Diego; Avalos-Ovando, Oscar; Ulloa, Sergio

    Transition-metal dichalcogenides (TMDs), such as MoS2, possess unique electronic and optical properties, making them promising for optospintronics. Exfoliation and CVD growth processes produce nanoflakes of different shapes, often triangular with zigzag edges. Magnetic impurities in this material interact indirectly through the TMD conduction electrons/holes. Using an effective 3-orbital tight-binding model, we study the Ruderman-Kittel-Kasuya-Yosida interaction between magnetic impurities in p-doped triangular flakes with zigzag termination. We analyze the interaction as function of impurity separation along high symmetry directions in the nanoflake, considering hybridization to different Mo orbitals, and different fillings. The interaction is anisotropic for impurities in the interior of the flake. However, when impurities lie on the edges of the crystallite, the effective exchange is Ising-like, reflecting the presence of z2-orbitals associated with edge states. Other interactions are possible by selecting impurity positions and orbital character of the states in their neighborhood. Our results can be tested with local probes, such as spin-polarized STM Supported by NSF DMR-1508325.

  17. Isolation of an aryloxyphenoxy propanoate (AOPP) herbicide-degrading strain Rhodococcus ruber JPL-2 and the cloning of a novel carboxylesterase gene (feh).

    PubMed

    Hongming, Liu; Xu, Lou; Zhaojian, Ge; Fan, Yang; Dingbin, Chen; Jianchun, Zhu; Jianhong, Xu; Shunpeng, Li; Qing, Hong

    2015-06-01

    The strain JPL-2, capable of degrading fenoxaprop-P-ethyl (FE), was isolated from the soil of a wheat field and identified as Rhodococcus ruber. This strain could utilize FE as its sole carbon source and degrade 94.6% of 100 mg L(-1) FE in 54 h. Strain JPL-2 could also degrade other aryloxyphenoxy propanoate (AOPP) herbicides. The initial step of the degradation pathway is to hydrolyze the carboxylic acid ester bond. A novel esterase gene feh, encoding the FE-hydrolyzing carboxylesterase (FeH) responsible for this initial step, was cloned from strain JPL-2. Its molecular mass was approximately 39 kDa, and the catalytic efficiency of FeH followed the order of FE > quizalofop-P-ethyl > clodinafop-propargyl > cyhalofop-butyl > fluazifop-P-butyl > haloxyfop-P-methyl > diclofop-methy, which indicated that the chain length of the alcohol moiety strongly affected the hydrolysis activity of the FeH toward AOPP herbicides.

  18. Production, Purification, and Identification of Cholest-4-en-3-one Produced by Cholesterol Oxidase from Rhodococcus sp. in Aqueous/Organic Biphasic System.

    PubMed

    Wu, Ke; Li, Wei; Song, Jianrui; Li, Tao

    2015-01-01

    Cholest-4-en-3-one has positive uses against obesity, liver disease, and keratinization. It can be applied in the synthesis of steroid drugs as well. Most related studies are focused on preparation of cholest-4-en-3-one by using whole cells as catalysts, but production of high-quality cholest-4-en-3-one directly from cholesterol oxidase (COD) using an aqueous/organic two-phase system has been rarely explored. This study set up an enzymatic reaction system to produce cholest-4-en-3-one. We developed and optimized the enzymatic reaction system using COD from COX5-6 (a strain of Rhodococcus) instead of whole-cell biocatalyst. This not only simplifies and accelerates the production but also benefits the subsequent separation and purification process. Through extraction, washing, evaporation, column chromatography, and recrystallization, we got cholest-4-en-3-one with purity of 99.78%, which was identified by nuclear magnetic resonance, mass spectroscopy, and infrared spectroscopy. In addition, this optimized process of cholest-4-en-3-one production and purification can be easily scaled up for industrial production, which can largely decrease the cost and guarantee the purity of the product.

  19. Degradation of 17α-methyltestosterone by Rhodococcus sp. and Nocardioides sp. isolated from a masculinizing pond of Nile tilapia fry.

    PubMed

    Homklin, Supreeda; Ong, Say Kee; Limpiyakorn, Tawan

    2012-06-30

    17α-Methyltestosterone (MT), a synthetic anabolic androgenic steroid, is widely used in aquafarming for the production of an all male fish population such as Nile tilapia. This study isolated, identified and characterized MT-degrading bacteria in the sediment and water from a masculinizing pond of Nile tilapia fry. Based on the phylogeny, physiological properties and cell morphology, the three isolated MT-degrading bacteria were related closely to Rhodococcus equi, Nocardioides aromaticivorans, and Nocardioides nitrophenolicus. Growth of the three isolated strains was found to be inhibited for MT concentrations in the range of 1.0-10mg/L. The inhibition of cell growth was found to be modeled using the Haldane's substrate inhibition model. The kinetic constants ranged from 0.13 to 0.19h(-1) for μ(max), 0.7-24.8mg/L for K(s) and 19.6-76.2mg/L for K(i). Androgenic activity using β-galactosidase assay showed that all strains degraded MT to the products with no androgenic potency.

  20. Oral Administration of Electron-Beam Inactivated Rhodococcus equi Failed to Protect Foals against Intrabronchial Infection with Live, Virulent R. equi.

    PubMed

    Rocha, Joana N; Cohen, Noah D; Bordin, Angela I; Brake, Courtney N; Giguère, Steeve; Coleman, Michelle C; Alaniz, Robert C; Lawhon, Sara D; Mwangi, Waithaka; Pillai, Suresh D

    2016-01-01

    There is currently no licensed vaccine that protects foals against Rhodococcus equi-induced pneumonia. Oral administration of live, virulent R. equi to neonatal foals has been demonstrated to protect against subsequent intrabronchial challenge with virulent R. equi. Electron beam (eBeam)-inactivated R. equi are structurally intact and have been demonstrated to be immunogenic when administered orally to neonatal foals. Thus, we investigated whether eBeam inactivated R. equi could protect foals against developing pneumonia after experimental infection with live, virulent R. equi. Foals (n = 8) were vaccinated by gavaging with eBeam-inactivated R. equi at ages 2, 7, and 14 days, or gavaged with equal volume of saline solution (n = 4), and subsequently infected intrabronchially with live, virulent R. equi at age 21 days. The proportion of vaccinated foals that developed pneumonia following challenge was similar among the vaccinated (7/8; 88%) and unvaccinated foals (3/4; 75%). This vaccination regimen did not appear to be strongly immunogenic in foals. Alternative dosing regimens or routes of administration need further investigation and may prove to be immunogenic and protective. PMID:26828865

  1. Structure and Catalytic Mechanism of 3-Ketosteroid-Δ4-(5α)-dehydrogenase from Rhodococcus jostii RHA1 Genome*

    PubMed Central

    van Oosterwijk, Niels; Knol, Jan; Dijkhuizen, Lubbert; van der Geize, Robert; Dijkstra, Bauke W.

    2012-01-01

    3-Ketosteroid Δ4-(5α)-dehydrogenases (Δ4-(5α)-KSTDs) are enzymes that introduce a double bond between the C4 and C5 atoms of 3-keto-(5α)-steroids. Here we show that the ro05698 gene from Rhodococcus jostii RHA1 codes for a flavoprotein with Δ4-(5α)-KSTD activity. The 1.6 Å resolution crystal structure of the enzyme revealed three conserved residues (Tyr-319, Tyr-466, and Ser-468) in a pocket near the isoalloxazine ring system of the FAD co-factor. Site-directed mutagenesis of these residues confirmed that they are absolutely essential for catalytic activity. A crystal structure with bound product 4-androstene-3,17-dione showed that Ser-468 is in a position in which it can serve as the base abstracting the 4β-proton from the C4 atom of the substrate. Ser-468 is assisted by Tyr-319, which possibly is involved in shuttling the proton to the solvent. Tyr-466 is at hydrogen bonding distance to the C3 oxygen atom of the substrate and can stabilize the keto-enol intermediate occurring during the reaction. Finally, the FAD N5 atom is in a position to be able to abstract the 5α-hydrogen of the substrate as a hydride ion. These features fully explain the reaction catalyzed by Δ4-(5α)-KSTDs. PMID:22833669

  2. Structure of Rhodococcus equi virulence-associated protein B (VapB) reveals an eight-stranded antiparallel β-barrel consisting of two Greek-key motifs

    SciTech Connect

    Geerds, Christina; Wohlmann, Jens; Haas, Albert; Niemann, Hartmut H.

    2014-06-18

    The structure of VapB, a member of the Vap protein family that is involved in virulence of the bacterial pathogen R. equi, was determined by SAD phasing and reveals an eight-stranded antiparallel β-barrel similar to avidin, suggestive of a binding function. Made up of two Greek-key motifs, the topology of VapB is unusual or even unique. Members of the virulence-associated protein (Vap) family from the pathogen Rhodococcus equi regulate virulence in an unknown manner. They do not share recognizable sequence homology with any protein of known structure. VapB and VapA are normally associated with isolates from pigs and horses, respectively. To contribute to a molecular understanding of Vap function, the crystal structure of a protease-resistant VapB fragment was determined at 1.4 Å resolution. The structure was solved by SAD phasing employing the anomalous signal of one endogenous S atom and two bound Co ions with low occupancy. VapB is an eight-stranded antiparallel β-barrel with a single helix. Structural similarity to avidins suggests a potential binding function. Unlike other eight- or ten-stranded β-barrels found in avidins, bacterial outer membrane proteins, fatty-acid-binding proteins and lysozyme inhibitors, Vaps do not have a next-neighbour arrangement but consist of two Greek-key motifs with strand order 41238567, suggesting an unusual or even unique topology.

  3. Biodegradation of butachlor by Rhodococcus sp. strain B1 and purification of its hydrolase (ChlH) responsible for N-dealkylation of chloroacetamide herbicides.

    PubMed

    Liu, Hong-Ming; Cao, Li; Lu, Peng; Ni, Haiyan; Li, Yun-Xiang; Yan, Xin; Hong, Qing; Li, Shun-Peng

    2012-12-19

    Rhodococcus sp. strain B1 could degrade 100 mg/L butachlor within 5 days. Butachlor was first hydrolyzed by strain B1 through N-dealkylation, which resulted in the production of butoxymethanol and 2-chloro-N-(2,6-dimethylphenyl)acetamide. Butoxymethanol could be further degraded and utilized as the carbon source for the growth of strain B1, whereas 2-chloro-N-(2,6-dimethylphenyl)acetamide could not be degraded further. The hydrolase designated ChlH, responsible for the N-dealkylation of the side chain of butachlor, was purified 185.1-fold to homogeneity with 16.1% recovery. The optimal pH and temperature of ChlH were observed to be 7.0-7.5 and 30 °C, respectively. This enzyme was also able to catalyze the N-dealkylation of other chloroacetamide herbicides; the catalytic efficiency followed the order alachlor > acetochlor >butachlor > pretilachlor, which indicated that the alkyl chain length influenced the N-dealkylation of the chloroacetamide herbicides. This is the first report on the biodegradation of chloroacetamide herbicides at the enzyme level.

  4. Structural basis for the substrate specificity and the absence of dehalogenation activity in 2-chloromuconate cycloisomerase from Rhodococcus opacus 1CP.

    PubMed

    Kolomytseva, Marina; Ferraroni, Marta; Chernykh, Alexey; Golovleva, Ludmila; Scozzafava, Andrea

    2014-09-01

    2-Chloromuconate cycloisomerase from the Gram-positive bacterium Rhodococcus opacus 1CP (Rho-2-CMCI) is an enzyme of a modified ortho-pathway, in which 2-chlorophenol is degraded using 3-chlorocatechol as the central intermediate. In general, the chloromuconate cycloisomerases catalyze not only the cycloisomerization, but also the process of dehalogenation of the chloromuconate to dienelactone. However Rho-2-CMCI, unlike the homologous enzymes from the Gram-negative bacteria, is very specific for only one position of the chloride on the substrate chloromuconate. Furthermore, Rho-2-CMCI is not able to dehalogenate the 5-chloromuconolactone and therefore it cannot generate the dienelactone. The crystallographic structure of the homooctameric Rho-2-CMCI was solved by molecular replacement using the coordinates of the structure of chloromuconate cycloisomerase from Pseudomonas putida PRS2000. The structure was analyzed and compared to the other already known structures of (chloro)muconate cycloisomerases. In addition to this, molecular docking calculations were carried out, which allowed us to determine the residues responsible for the high substrate specificity and the lack of dehalogenation activity of Rho-2-CMCI. Our studies highlight that a histidine, located in a loop that closes the active site cavity upon the binding of the substrate, could be related to the dehalogenation inability of Rho-2-CMCI and in general of the muconate cycloisomerases.

  5. Purification and characterization of a 14-kilodalton protein that is bound to the surface of polyhydroxyalkanoic acid granules in Rhodococcus ruber.

    PubMed Central

    Pieper-Fürst, U.; Madkour, M. H.; Mayer, F.; Steinbüchel, A.

    1994-01-01

    The N-terminal amino acid sequence of the polyhydroxyalkanoic acid (PHA) granule-associated M(r)-15,500 protein of Rhodococcus ruber (the GA14 protein) was analyzed. The sequence revealed that the corresponding structural gene is represented by open reading frame 3, encoding a protein with a calculated M(r) of 14,175 which was recently localized downstream of the PHA synthase gene (U. Pieper and A. Steinbüchel, FEMS Microbiol. Lett. 96:73-80, 1992). A recombinant strain of Escherichia coli XL1-Blue carrying the hybrid plasmid (pSKXA10*) with open reading frame 3 overexpressed the GA14 protein. The GA14 protein was subsequently purified in a three-step procedure including chromatography on DEAE-Sephacel, phenyl-Sepharose CL-4B, and Superose 12. Determination of the molecular weight by gel filtration as well as electron microscopic studies indicates that a tetrameric structure of the recombinant, native GA14 protein is most likely. Immunoelectron microscopy demonstrated a localization of the GA14 protein at the periphery of PHA granules as well as close to the cell membrane in R. ruber. Investigations of PHA-leaky and PHA-negative mutants of R. ruber indicated that expression of the GA14 protein depended strongly on PHA synthesis. Images PMID:8021220

  6. Characterization and genome functional analysis of a novel metamitron-degrading strain Rhodococcus sp. MET via both triazinone and phenyl rings cleavage

    NASA Astrophysics Data System (ADS)

    Fang, Hua; Xu, Tianheng; Cao, Duantao; Cheng, Longyin; Yu, Yunlong

    2016-08-01

    A novel bacterium capable of utilizing metamitron as the sole source of carbon and energy was isolated from contaminated soil and identified as Rhodococcus sp. MET based on its morphological characteristics, BIOLOG GP2 microplate profile, and 16S rDNA phylogeny. Genome sequencing and functional annotation of the isolate MET showed a 6,340,880 bp genome with a 62.47% GC content and 5,987 protein-coding genes. In total, 5,907 genes were annotated with the COG, GO, KEGG, Pfam, Swiss-Prot, TrEMBL, and nr databases. The degradation rate of metamitron by the isolate MET obviously increased with increasing substrate concentrations from 1 to 10 mg/l and subsequently decreased at 100 mg/l. The optimal pH and temperature for metamitron biodegradation were 7.0 and 20–30 °C, respectively. Based on genome annotation of the metamitron degradation genes and the metabolites detected by HPLC-MS/MS, the following metamitron biodegradation pathways were proposed: 1) Metamitron was transformed into 2-(3-hydrazinyl-2-ethyl)-hydrazono-2-phenylacetic acid by triazinone ring cleavage and further mineralization; 2) Metamitron was converted into 3-methyl-4-amino-6(2-hydroxy-muconic acid)-1,2,4-triazine-5(4H)-one by phenyl ring cleavage and further mineralization. The coexistence of diverse mineralization pathways indicates that our isolate may effectively bioremediate triazinone herbicide-contaminated soils.

  7. Nonlinear changes in the activity of the oxygen-dependent demethylase system in Rhodococcus erythropolis cells in the presence of low and very low doses of formaldehyde

    PubMed Central

    2011-01-01

    The effect of exogenous, highly diluted formaldehyde on the rate of demethylation/re-methylation of veratric acid by the bacteria Rhodococcus erythropolis was studied using electrophoretic and microscopic techniques. The activity of 4-O-demethylase, responsible for accumulation of vanillic acid, and the levels of veratric and vanillic acids were determined using capillary electrophoresis. Formaldehyde was serially diluted at 1:100 ratios, and the total number of iterations was 20. After incubation of the successive dilutions of formaldehyde with the bacteria, demethylase activity oscillated in a sinusoidal manner. It was established using capillary electrophoresis that methylation of vanillic acid to veratric acid occurred at a double rate, as shown by the doubled fluctuation in the concentration of veratrate. There were also changes in the NADH oxidase activity, which is associated with methylation processes. Microscopic observations revealed the presence of numerous enlarged vacuoles in bacterial cells during the accumulation of large amounts of vanillic acid, and their disappearance together with a decrease in 4-O-demethylase activity. The presented results give evidence for the ability of living cells to detect the presence of submolecular concentrations of biological effectors in their environment and provide a basis for a scientific explanation of the law of hormesis and the therapeutic effect of homeopathic dilutions. PMID:22104369

  8. Isolation of an aryloxyphenoxy propanoate (AOPP) herbicide-degrading strain Rhodococcus ruber JPL-2 and the cloning of a novel carboxylesterase gene (feh)

    PubMed Central

    Hongming, Liu; Xu, Lou; Zhaojian, Ge; Fan, Yang; Dingbin, Chen; Jianchun, Zhu; Jianhong, Xu; Shunpeng, Li; Qing, Hong

    2015-01-01

    The strain JPL-2, capable of degrading fenoxaprop-P-ethyl (FE), was isolated from the soil of a wheat field and identified as Rhodococcus ruber. This strain could utilize FE as its sole carbon source and degrade 94.6% of 100 mg L−1 FE in 54 h. Strain JPL-2 could also degrade other aryloxyphenoxy propanoate (AOPP) herbicides. The initial step of the degradation pathway is to hydrolyze the carboxylic acid ester bond. A novel esterase gene feh, encoding the FE-hydrolyzing carboxylesterase (FeH) responsible for this initial step, was cloned from strain JPL-2. Its molecular mass was approximately 39 kDa, and the catalytic efficiency of FeH followed the order of FE > quizalofop-P-ethyl > clodinafop-propargyl > cyhalofop-butyl > fluazifop-P-butyl > haloxyfop-P-methyl > diclofop-methy, which indicated that the chain length of the alcohol moiety strongly affected the hydrolysis activity of the FeH toward AOPP herbicides. PMID:26273257

  9. Metabolomic-Based Study of the Leafy Gall, the Ecological Niche of the Phytopathogen Rhodococcus Fascians, as a Potential Source of Bioactive Compounds

    PubMed Central

    Nacoulma, Aminata P.; Vandeputte, Olivier M.; De Lorenzi, Manuella; El Jaziri, Mondher; Duez, Pierre

    2013-01-01

    Leafy gall is a plant hyperplasia induced upon Rhodococcus fascians infection. Previously, by genomic and transcriptomic analysis, it has been reported that, at the early stage of symptom development, both primary and secondary metabolisms are modified. The present study is based on the hypothesis that fully developed leafy gall, could represent a potential source of new bioactive compounds. Therefore, non-targeted metabolomic analysis of aqueous and chloroform extracts of leafy gall and non-infected tobacco was carried out by 1H-NMR coupled to principal component analysis (PCA) and orthogonal projections to latent structures-discriminant analysis (OPLS-DA). Polar metabolite profiling reflects modifications mainly in the primary metabolites and in some polyphenolics. In contrast, main modifications occurring in non-polar metabolites concern secondary metabolites, and gas chromatography and mass spectrometry (GC-MS) evidenced alterations in diterpenoids family. Analysis of crude extracts of leafy galls and non-infected tobacco leaves exhibited a distinct antiproliferative activity against all four tested human cancer cell lines. A bio-guided fractionation of chloroformic crude extract yield to semi-purified fractions, which inhibited proliferation of glioblastoma U373 cells with IC50 between 14.0 and 2.4 μg/mL. Discussion is focused on the consequence of these metabolic changes, with respect to plant defense mechanisms following infection. Considering the promising role of diterpenoid family as bioactive compounds, leafy gall may rather be a propitious source for drug discovery. PMID:23771021

  10. A Glutathione S-Transferase with Activity towards cis-1,2-Dichloroepoxyethane Is Involved in Isoprene Utilization by Rhodococcus sp. Strain AD45

    PubMed Central

    van Hylckama Vlieg, Johan E. T.; Kingma, Jaap; van den Wijngaard, Arjan J.; Janssen, Dick B.

    1998-01-01

    Rhodococcus sp. strain AD45 was isolated from an enrichment culture on isoprene (2-methyl-1,3-butadiene). Isoprene-grown cells of strain AD45 oxidized isoprene to 3,4-epoxy-3-methyl-1-butene, cis-1,2-dichloroethene to cis-1,2-dichloroepoxyethane, and trans-1,2-dichloroethene to trans-1,2-dichloroepoxyethane. Isoprene-grown cells also degraded cis-1,2-dichloroepoxyethane and trans-1,2-dichloroepoxyethane. All organic chlorine was liberated as chloride during degradation of cis-1,2-dichloroepoxyethane. A glutathione (GSH)-dependent activity towards 3,4-epoxy-3-methyl-1-butene, epoxypropane, cis-1,2-dichloroepoxyethane, and trans-1,2-dichloroepoxyethane was detected in cell extracts of cultures grown on isoprene and 3,4-epoxy-3-methyl-1-butene. The epoxide-degrading activity of strain AD45 was irreversibly lost upon incubation of cells with 1,2-epoxyhexane. A conjugate of GSH and 1,2-epoxyhexane was detected in cell extracts of cells exposed to 1,2-epoxyhexane, indicating that GSH is the physiological cofactor of the epoxide-transforming activity. The results indicate that a GSH S-transferase is involved in the metabolism of isoprene and that the enzyme can detoxify reactive epoxides produced by monooxygenation of chlorinated ethenes. PMID:9687433

  11. Differences in Rhodococcus equi Infections Based on Immune Status and Antibiotic Susceptibility of Clinical Isolates in a Case Series of 12 Patients and Cases in the Literature

    PubMed Central

    Suzuki, Yasuhiro; Ribes, Julie A.; Thornton, Alice

    2016-01-01

    Rhodococcus equi is an unusual zoonotic pathogen that can cause life-threatening diseases in susceptible hosts. Twelve patients with R. equi infection in Kentucky were compared to 137 cases reported in the literature. Although lungs were the primary sites of infection in immunocompromised patients, extrapulmonary involvement only was more common in immunocompetent patients (P < 0.0001). Mortality in R. equi-infected HIV patients was lower in the HAART era (8%) than in pre-HAART era (56%) (P < 0.0001), suggesting that HAART improves prognosis in these patients. Most (85–100%) of clinical isolates were susceptible to vancomycin, clarithromycin, rifampin, aminoglycosides, ciprofloxacin, and imipenem. Interestingly, there was a marked difference in susceptibility of the isolates to cotrimoxazole between Europe (35/76) and the US (15/15) (P < 0.0001). Empiric treatment of R. equi infection should include a combination of two antibiotics, preferably selected from vancomycin, imipenem, clarithromycin/azithromycin, ciprofloxacin, rifampin, or cotrimoxazole. Local antibiograms should be checked prior to using cotrimoxazole due to developing resistance. PMID:27631004

  12. Involvement of a Novel ABC Transporter and Monoalkyl Phthalate Ester Hydrolase in Phthalate Ester Catabolism by Rhodococcus jostii RHA1▿

    PubMed Central

    Hara, Hirofumi; Stewart, Gordon R.; Mohn, William W.

    2010-01-01

    Phthalate esters (PEs) are important environmental pollutants. While the biodegradation of the parent compound, phthalate (PTH), is well characterized, the biodegradation of PEs is not well understood. In particular, prior to this study, genes involved in the uptake and hydrolysis of these compounds were not conclusively identified. We found that Rhodococcus jostii RHA1 could grow on a variety of monoalkyl PEs, including methyl, butyl, hexyl, and 2-ethylhexyl PTHs. Strain RHA1 could not grow on most dialkyl PEs, but suspensions of cells grown on PTH transformed dimethyl, diethyl, dipropyl, dibutyl, dihexyl and di-(2-ethylhexyl) PTHs. The major products of these dialkyl PEs were PTH and the corresponding monoalkyl PEs, and minor products resulted from the shortening of the alkyl side chains. RHA1 exhibited an inducible, ATP-dependent uptake system for PTH with a Km of 22 μM. The deletion and complementation of the patB gene demonstrated that the ATP-binding cassette (ABC) transporter encoded by patDABC is required for the uptake of PTH and monoalkyl PEs by RHA1. The hydrolase encoded by patE of RHA1 was expressed in Escherichia coli. PatE specifically hydrolyzed monoalkyl PEs to PTH but did not transform dialkyl PEs or other aromatic esters. This investigation of RHA1 elucidates key processes that are consistent with the environmental fate of PEs. PMID:20038686

  13. Biological activity and mechanical stability of sol-gel-based biofilters using the freeze-gelation technique for immobilization of Rhodococcus ruber.

    PubMed

    Pannier, Angela; Mkandawire, Martin; Soltmann, Ulrich; Pompe, Wolfgang; Böttcher, Horst

    2012-02-01

    Biofilters with long lifetime and high storage stability are very important for bioremediation processes to ensure the readiness at the occurrence of sudden contaminations. By using the freeze-gelation technique, living cells can be immobilized within a mechanically and chemically stable ceramic-like matrix. Due to a freeze-drying step, the embedded microorganisms are converted into a preserved form. In that way, they can be stored under dry conditions, which comply better with storage, transport, and handling requirements. Thus, in contrast to other immobilization techniques, there is no need for storage in liquid or under humid atmosphere. The biological activity, mechanical strength, and the structure of the biologically active ceramic-like composites (biocers) produced by freeze gelation have been investigated by using the phenol-degrading bacteria Rhodococcus ruber as model organism. Samples of freeze-gelation biocers have been investigated after defined storage periods, demonstrating nearly unchanged mechanical strength of the immobilization matrix as well as good storage stability of the activity of the immobilized cells over several months of storage at 4 °C. Repeated-batch tests demonstrated further that the freeze-gelation biocers can be repeatedly used over a period of more than 12 months without losing its bioactivity. Thus, these results show that freeze-gelation biocers have high potential of being scaled up from laboratory test systems to applications in real environment because of their long bioactivity as well as mechanical stability.

  14. Differences in Rhodococcus equi Infections Based on Immune Status and Antibiotic Susceptibility of Clinical Isolates in a Case Series of 12 Patients and Cases in the Literature

    PubMed Central

    Suzuki, Yasuhiro; Ribes, Julie A.; Thornton, Alice

    2016-01-01

    Rhodococcus equi is an unusual zoonotic pathogen that can cause life-threatening diseases in susceptible hosts. Twelve patients with R. equi infection in Kentucky were compared to 137 cases reported in the literature. Although lungs were the primary sites of infection in immunocompromised patients, extrapulmonary involvement only was more common in immunocompetent patients (P < 0.0001). Mortality in R. equi-infected HIV patients was lower in the HAART era (8%) than in pre-HAART era (56%) (P < 0.0001), suggesting that HAART improves prognosis in these patients. Most (85–100%) of clinical isolates were susceptible to vancomycin, clarithromycin, rifampin, aminoglycosides, ciprofloxacin, and imipenem. Interestingly, there was a marked difference in susceptibility of the isolates to cotrimoxazole between Europe (35/76) and the US (15/15) (P < 0.0001). Empiric treatment of R. equi infection should include a combination of two antibiotics, preferably selected from vancomycin, imipenem, clarithromycin/azithromycin, ciprofloxacin, rifampin, or cotrimoxazole. Local antibiograms should be checked prior to using cotrimoxazole due to developing resistance.

  15. Cytochrome P450-catalyzed dealkylation of atrazine by Rhodococcus sp. strain NI86/21 involves hydrogen atom transfer rather than single electron transfer.

    PubMed

    Meyer, Armin H; Dybala-Defratyka, Agnieszka; Alaimo, Peter J; Geronimo, Inacrist; Sanchez, Ariana D; Cramer, Christopher J; Elsner, Martin

    2014-08-28

    Cytochrome P450 enzymes are responsible for a multitude of natural transformation reactions. For oxidative N-dealkylation, single electron (SET) and hydrogen atom abstraction (HAT) have been debated as underlying mechanisms. Combined evidence from (i) product distribution and (ii) isotope effects indicate that HAT, rather than SET, initiates N-dealkylation of atrazine to desethyl- and desisopropylatrazine by the microorganism Rhodococcus sp. strain NI86/21. (i) Product analysis revealed a non-selective oxidation at both the αC and βC-atom of the alkyl chain, which is expected for a radical reaction, but not SET. (ii) Normal (13)C and (15)N as well as pronounced (2)H isotope effects (εcarbon: -4.0‰ ± 0.2‰; εnitrogen: -1.4‰ ± 0.3‰, KIEH: 3.6 ± 0.8) agree qualitatively with calculated values for HAT, whereas inverse (13)C and (15)N isotope effects are predicted for SET. Analogous results are observed with the Fe(iv)[double bond, length as m-dash]O model system [5,10,15,20-tetrakis(pentafluorophenyl)porphyrin-iron(iii)-chloride + NaIO4], but not with permanganate. These results emphasize the relevance of the HAT mechanism for N-dealkylation by P450.

  16. The cbs mutant strain of Rhodococcus erythropolis KA2-5-1 expresses high levels of Dsz enzymes in the presence of sulfate.

    PubMed

    Tanaka, Yasuhiro; Yoshikawa, Osamu; Maruhashi, Kenji; Kurane, Ryuichiro

    2002-11-01

    Two mutants of the dibenzothiophene-desulfurizing Rhodococcus erythropolis KA2-5-1, strains MS51 and MS316, which express a high level of desulfurizing activity in the presence of sulfate, were isolated using the transposome technique. The level of dibenzothiophene-desulfurization by cell-free extracts prepared from mutants MS51 and MS316 grown on sulfate was about five-fold higher than that by cell-free extracts of the wild-type. This result was consistent with results of Western-blot analysis using antisera specific for DszA, DszB and DszC, the enzymes involved in the desulfurization of dibenzothiophene. Gene analysis of the mutants revealed that the same gene was disrupted in mutants MS51 and MS316 and that the transposon-inserted gene in these strains was the gene for cystathionine beta-synthase, cbs. The cbs mutants also expressed high levels of Dsz enzymes when methionine was used as the sole source of sulfur.

  17. Characterization of Rhodococcus equi isolates from submaxillary lymph nodes of wild boars (Sus scrofa), red deer (Cervus elaphus) and roe deer (Capreolus capreolus).

    PubMed

    Rzewuska, Magdalena; Witkowski, Lucjan; Cisek, Agata A; Stefańska, Ilona; Chrobak, Dorota; Stefaniuk, Elżbieta; Kizerwetter-Świda, Magdalena; Takai, Shinji

    2014-08-01

    Rhodococcus equi is a soil saprophyte and an opportunistic pathogen causing infections in animals, and rarely in humans. The presence of R. equi in tissues and faeces of some wild animal species was demonstrated previously. In this study we characterized R. equi isolates from submaxillary lymph nodes of free-living wild boars (n=23), red deer (n=2) and roe deer (n=2). This is the first description of R. equi strains isolated from tissues of the Cervidae. All isolates were initially recognized as R. equi based on the phenotypic properties. Their identification was confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, detection of the choE gene and by sequence analysis of the 16S rRNA and rpoB genes. The presence of three plasmidic genes (traA, vapA and vapB) associated with R. equi virulence was investigated by PCR. In 16 wild boar isolates the traA and vapB genes were detected and they were located on virulence plasmids type 5, 7 or 11. The isolates from cervids and the remaining wild boar isolates were classified as avirulent based on a genotype traA(-)/vapA(-)B(-). In summary, these results confirm that wild boars can be a source of intermediately virulent R. equi strains, and indicate that red deer and roe deer can be a reservoir of avirulent R. equi strains. PMID:24878324

  18. Isolation of endosulfan sulfate-degrading Rhodococcus koreensis strain S1-1 from endosulfan contaminated soil and identification of a novel metabolite, endosulfan diol monosulfate.

    PubMed

    Ito, Koji; Kawashima, Fujimasa; Takagi, Kazuhiro; Kataoka, Ryota; Kotake, Masaaki; Kiyota, Hiromasa; Yamazaki, Kenichi; Sakakibara, Futa; Okada, Sanae

    2016-05-13

    An aerobic endosulfan sulfate-degrading bacterium, Rhodococcus koreensis strain S1-1, was isolated from soil to which endosulfan had been applied annually for more than 10 years until 2008. The strain isolated in this work reduced the concentration of endosulfan sulfate (2) from 12.25 μM to 2.11 μM during 14 d at 30 °C. Using ultra performance liquid chromatography-electrospray ionization-mass spectroscopy (UPLC-ESI-MS), a new highly water-soluble metabolite possessing six chlorine atoms was found to be endosulfan diol monosulfate (6), derived from 2 by hydrolysis of the cyclic sulfate ester ring. The structure of 6 was elucidated by chemical synthesis of the candidate derivatives and by HR-MS and UPLC-MS analyses. Therefore, it was suggested that the strain S1-1 has a new metabolic pathway of 2. In addition, 6 was expected to be less toxic among the metabolites of 1 because of its higher water-solubility. PMID:27073164

  19. Differences in Rhodococcus equi Infections Based on Immune Status and Antibiotic Susceptibility of Clinical Isolates in a Case Series of 12 Patients and Cases in the Literature.

    PubMed

    Gundelly, Praveen; Suzuki, Yasuhiro; Ribes, Julie A; Thornton, Alice

    2016-01-01

    Rhodococcus equi is an unusual zoonotic pathogen that can cause life-threatening diseases in susceptible hosts. Twelve patients with R. equi infection in Kentucky were compared to 137 cases reported in the literature. Although lungs were the primary sites of infection in immunocompromised patients, extrapulmonary involvement only was more common in immunocompetent patients (P < 0.0001). Mortality in R. equi-infected HIV patients was lower in the HAART era (8%) than in pre-HAART era (56%) (P < 0.0001), suggesting that HAART improves prognosis in these patients. Most (85-100%) of clinical isolates were susceptible to vancomycin, clarithromycin, rifampin, aminoglycosides, ciprofloxacin, and imipenem. Interestingly, there was a marked difference in susceptibility of the isolates to cotrimoxazole between Europe (35/76) and the US (15/15) (P < 0.0001). Empiric treatment of R. equi infection should include a combination of two antibiotics, preferably selected from vancomycin, imipenem, clarithromycin/azithromycin, ciprofloxacin, rifampin, or cotrimoxazole. Local antibiograms should be checked prior to using cotrimoxazole due to developing resistance. PMID:27631004

  20. Purification and characterization of a Baeyer-Villiger mono-oxygenase from Rhodococcus erythropolis DCL14 involved in three different monocyclic monoterpene degradation pathways.

    PubMed Central

    Van Der Werf, M J

    2000-01-01

    A Baeyer-Villiger mono-oxygenase (BVMO), catalysing the NADPH- and oxygen-dependent oxidation of the monocyclic monoterpene ketones 1-hydroxy-2-oxolimonene, dihydrocarvone and menthone, was purified to homogeneity from Rhodococcus erythropolis DCL14. Monocyclic monoterpene ketone mono-oxygenase (MMKMO) is a monomeric enzyme of molecular mass 60 kDa. It contains 1 mol of FAD/monomer as the prosthetic group. The N-terminal amino acid sequence showed homology with many other NADPH-dependent and FAD-containing (Type 1) BVMOs. Maximal enzyme activity was measured at pH 9 and 35 degrees C. MMKMO has a broad substrate specificity, catalysing the lactonization of a large number of monocyclic monoterpene ketones and substituted cyclohexanones. The natural substrates 1-hydroxy-2-oxolimonene, dihydrocarvone and menthone were converted stoichiometrically into 3-isopropenyl-6-oxoheptanoate (the spontaneous rearrangement product of the lactone formed by MMKMO), 4-isopropenyl-7-methyl-2-oxo-oxepanone and 7-isopropyl-4-methyl-2-oxo-oxepanone respectively. The MMKMO-catalysed conversion of iso-dihydrocarvone showed an opposite regioselectivity to that of dihydrocarvone; in this case, 6-isopropenyl-3-methyl-2-oxo-oxepanone was formed as the product. MMKMO converted all enantiomers of the natural substrates with almost equal efficiency. MMKMO is involved in the conversion of the monocyclic monoterpene ketone intermediates formed in the degradation pathways of all stereoisomers of three different monocyclic monoterpenes, i.e. limonene, (dihydro)carveol and menthol. PMID:10769172

  1. Molecular characterization of Rhodococcus equi Isolates of horse breeding farms from an endemic region in South of Brazil by multiplex PCR

    PubMed Central

    Krewer, Cristina da Costa; Spricigo, Dênis Augusto; de Avila Botton, Sônia; da Costa, Mateus Matiuzzi; Schrank, Irene; de Vargas, Agueda Castagna

    2008-01-01

    Rhodococcus equi is a gram-positive coco-bacillus and an intracellular opportunistic pathogen which causes pneumonia in foals. It is widely detected in environment and has been isolated from several sources, as soil, feces and gut from health and sick foals. The goal of this study was to characterize the epidemiological status (endemic, sporadic or no infection) of horse breeding farms from Bage County in South of Brazil, using a multiplex PCR. One hundred and eighteen R. equi isolates were identified by biochemical tests and submitted to a specie-specific and vapA multiplex PCR. These isolates were obtained from: three farms where the R. equi infection has been noticed, two farms where the disease has been not reported and one farm where the disease is frequent. All clinical isolates from horse breeding farms where the disease is endemic and/or sporadic were vapA-positive. None environmental isolates were vapA-positive. In three horse breeding farms with sporadic R. equi infection, 11.54% of the isolates from adult horse feces were vapA-positive. The multiplex PCR technique has proven to be effective for the molecular and epidemiological characterization of the R. equi isolates in horse breeding farms. An important finding in this study was the isolation of vapApositive R. equi from adult horse feces, which is an evidence for other routes of dissemination of this pathogen in the farms. PMID:24031201

  2. Bacterial and Plant Signal Integration via D3-Type Cyclins Enhances Symptom Development in the Arabidopsis-Rhodococcus fascians Interaction1[C][W

    PubMed Central

    Stes, Elisabeth; Biondi, Stefania; Holsters, Marcelle; Vereecke, Danny

    2011-01-01

    The phytopathogenic actinomycete Rhodococcus fascians drives its host to form a nutrient-rich niche by secreting a mixture of cytokinins that triggers plant cell division and shoot formation. The discrepancy between the relatively low amount of secreted cytokinins and the severe impact of R. fascians infection on plant development has puzzled researchers for a long time. Polyamine and transcript profiling of wild-type and cytokinin receptor mutant plants revealed that the bacterial cytokinins directly stimulated the biosynthesis of plant putrescine by activating arginine decarboxylase expression. Pharmacological experiments showed that the increased levels of putrescine contributed to the severity of the symptoms. Thus, putrescine functions as a secondary signal that impinges on the cytokinin-activated pathway, amplifying the hormone-induced changes that lead to the formation of a leafy gall. Exogenous putrescine and treatment with polyamine biosynthesis inhibitors combined with transcript and polyamine analyses of wild-type and mutant plants indicated that the direct target of both the bacterial cytokinins and plant putrescine was the expression of D3-type cyclins. Hence, the activated d-type cyclin/retinoblastoma/E2F transcription factor pathway integrates both external and internal hormonal signals, stimulating mitotic cell divisions and inducing pathological plant organogenesis. PMID:21459976

  3. Composition and Diversity of the Fecal Microbiome and Inferred Fecal Metagenome Does Not Predict Subsequent Pneumonia Caused by Rhodococcus equi in Foals

    PubMed Central

    Whitfield-Cargile, Canaan M.; Cohen, Noah D.; Suchodolski, Jan; Chaffin, M. Keith; McQueen, Cole M.; Arnold, Carolyn E.; Dowd, Scot E.; Blodgett, Glenn P.

    2015-01-01

    In equids, susceptibility to disease caused by Rhodococcus equi occurs almost exclusively in foals. This distribution might be attributable to the age-dependent maturation of immunity following birth undergone by mammalian neonates that renders them especially susceptible to infectious diseases. Expansion and diversification of the neonatal microbiome contribute to development of immunity in the gut. Moreover, diminished diversity of the gastrointestinal microbiome has been associated with risk of infections and immune dysregulation. We thus hypothesized that varying composition or reduced diversity of the intestinal microbiome of neonatal foals would contribute to increased susceptibility of their developing R. equi pneumonia. The composition and diversity indices of the fecal microbiota at 3 and 5 weeks of age were compared among 3 groups of foals: 1) foals that subsequently developed R. equi pneumonia after sampling; 2) foals that subsequently developed ultrasonographic evidence of pulmonary abscess formation or consolidation but not clinical signs (subclinical group); and, 3) foals that developed neither clinical signs nor ultrasonographic evidence of pulmonary abscess formation or consolidation. No significant differences were found among groups at either sampling time, indicating absence of evidence of an influence of composition or diversity of the fecal microbiome, or predicted fecal metagenome, on susceptibility to subsequent R. equi pneumonia. A marked and significant difference identified between a relatively short interval of time appeared to reflect ongoing adaptation to transition from a milk diet to a diet including available forage (including hay) and access to concentrate fed to the mare. PMID:26305682

  4. Oral Administration of Electron-Beam Inactivated Rhodococcus equi Failed to Protect Foals against Intrabronchial Infection with Live, Virulent R. equi

    PubMed Central

    Rocha, Joana N.; Cohen, Noah D.; Bordin, Angela I.; Brake, Courtney N.; Giguère, Steeve; Coleman, Michelle C.; Alaniz, Robert C.; Lawhon, Sara D.; Mwangi, Waithaka; Pillai, Suresh D.

    2016-01-01

    There is currently no licensed vaccine that protects foals against Rhodococcus equi–induced pneumonia. Oral administration of live, virulent R. equi to neonatal foals has been demonstrated to protect against subsequent intrabronchial challenge with virulent R. equi. Electron beam (eBeam)-inactivated R. equi are structurally intact and have been demonstrated to be immunogenic when administered orally to neonatal foals. Thus, we investigated whether eBeam inactivated R. equi could protect foals against developing pneumonia after experimental infection with live, virulent R. equi. Foals (n = 8) were vaccinated by gavaging with eBeam-inactivated R. equi at ages 2, 7, and 14 days, or gavaged with equal volume of saline solution (n = 4), and subsequently infected intrabronchially with live, virulent R. equi at age 21 days. The proportion of vaccinated foals that developed pneumonia following challenge was similar among the vaccinated (7/8; 88%) and unvaccinated foals (3/4; 75%). This vaccination regimen did not appear to be strongly immunogenic in foals. Alternative dosing regimens or routes of administration need further investigation and may prove to be immunogenic and protective. PMID:26828865

  5. Microbial production of aliphatic (S)-epoxyalkanes by using Rhodococcus sp. strain ST-10 styrene monooxygenase expressed in organic-solvent-tolerant Kocuria rhizophila DC2201.

    PubMed

    Toda, Hiroshi; Ohuchi, Takuya; Imae, Ryouta; Itoh, Nobuya

    2015-03-01

    We describe the development of biocatalysis for producing optically pure straight-chain (S)-epoxyalkanes using styrene monooxygenase of Rhodococcus sp. strain ST-10 (RhSMO). RhSMO was expressed in the organic solvent-tolerant microorganism Kocuria rhizophila DC2201, and the bioconversion reaction was performed in an organic solvent-water biphasic reaction system. The biocatalytic process enantioselectively converted linear terminal alkenes to their corresponding (S)-epoxyalkanes using glucose and molecular oxygen. When 1-heptene and 6-chloro-1-hexene were used as substrates (400 mM) under optimized conditions, 88.3 mM (S)-1,2-epoxyheptane and 246.5 mM (S)-1,2-epoxy-6-chlorohexane, respectively, accumulated in the organic phase with good enantiomeric excess (ee; 84.2 and 95.5%). The biocatalysis showed broad substrate specificity toward various aliphatic alkenes, including functionalized and unfunctionalized alkenes, with good to excellent ee. Here, we demonstrate that this biocatalytic system is environmentally friendly and useful for producing various enantiopure (S)-epoxyalkanes. PMID:25556188

  6. Microbial Production of Aliphatic (S)-Epoxyalkanes by Using Rhodococcus sp. Strain ST-10 Styrene Monooxygenase Expressed in Organic-Solvent-Tolerant Kocuria rhizophila DC2201

    PubMed Central

    Toda, Hiroshi; Ohuchi, Takuya; Imae, Ryouta

    2015-01-01

    We describe the development of biocatalysis for producing optically pure straight-chain (S)-epoxyalkanes using styrene monooxygenase of Rhodococcus sp. strain ST-10 (RhSMO). RhSMO was expressed in the organic solvent-tolerant microorganism Kocuria rhizophila DC2201, and the bioconversion reaction was performed in an organic solvent-water biphasic reaction system. The biocatalytic process enantioselectively converted linear terminal alkenes to their corresponding (S)-epoxyalkanes using glucose and molecular oxygen. When 1-heptene and 6-chloro-1-hexene were used as substrates (400 mM) under optimized conditions, 88.3 mM (S)-1,2-epoxyheptane and 246.5 mM (S)-1,2-epoxy-6-chlorohexane, respectively, accumulated in the organic phase with good enantiomeric excess (ee; 84.2 and 95.5%). The biocatalysis showed broad substrate specificity toward various aliphatic alkenes, including functionalized and unfunctionalized alkenes, with good to excellent ee. Here, we demonstrate that this biocatalytic system is environmentally friendly and useful for producing various enantiopure (S)-epoxyalkanes. PMID:25556188

  7. [Destruction of oil in the presence of Cu2+ and surfactants of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Ac-5017 and Nocardia vaccinii IMV B-7405].

    PubMed

    Pirog, T P; Konon, A D; Sofilkanich, A P; Shevchuk, T A; Iutinska, G O

    2015-01-01

    The effect of copper cations (0.01-1.0 mM) and surface-active agents (surfactants) of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Alc-5017 and Nocardia vaccinii IMV B-7405 in the form of culture liquid on the destruction of oil in water (3.0-6.0 g/L) and soil (20 g/kg), including in the presence of Cd2+ and Pb2+ (0.01-0.5 mM), was investigated. It was shown that the degree of oil degradation in water and soil after 20 days in the presence of low concentrations of Cu2+ (0.01-0.05 mM) and culture liquid of strains IMV B-7241, IMV Ac-5017, and IMV B-7405 was 15 - 25% higher than without copper cations. The activating effect of Cu2+ on the decomposition of complex oil and Cd2+ and Pb2+ pollution was established: after treatment with surfactant of A. calcoacelicus IMV B-7241 and R. erythropolis IMV Ac-5017 destruction of oil in water and soil was 85-95%, and after removal of the copper cations decreased to 45-70%. Intensification of oil destruction in the presence of copper cations may be due to their stimulating effect on the activity of alkane hydroxylases as in surfactant-producing strains, and natural (autochthonous) oxidizing microbiota.

  8. [Antiadhesive properties of the surfactants of Acinetobacter calcoaceticus IMB B-7241, Rhodococcus erythropolis IMB Ac-5017, and Nocardia vaccinii IMB B-7405].

    PubMed

    Pirog, T P; Konon, A D; Beregovaya, K A; Shulyakova, M A

    2014-01-01

    Attachment of the cells of some bacteria, yeasts, and micromycetes to various surfaces (catheters, dentures, plastic, polyvinyl chloride, tiles, and steel) treated with the surfactants fromAcinetobacter calcoace- ticus IMB B-7241, Rhodococcus erythropolis IMB Ac-5017, and Nocardia vaccinii IMB B-7405 was studied. Adhesion of microorganisms to all the studied surfaces depended on the surfactant concentration and purity, kind of surface, and the test culture. Treatment with the surfactants from N. vaccinii IMB B-7405 (0.005- 0.05 mg/mL), A. calcoaceticus IMB B-7241 (0.003-0.036 mg/mL), and R. erythropolis IMB Ac-5017 (0.03- 0.12 mg/mL) resulted in adhesion decreased respectively by 35-75, 60-75, and 25-90% for bacteria (Es- cherichia coli IEM-1, Bacillus subtilis BT-2, etc.), by 80-85, 55-90, and 15-60% for yeasts Candida albicans D-6, and by 40-50, 35-45, and 10-20% for micromycetes (Aspergillus niger P-3 and Fusarium culmorum T-7).

  9. Planar B3S2H3(-) and B3S2H3 clusters with a five-membered B3S2 ring: boron-sulfur hydride analogues of cyclopentadiene.

    PubMed

    Li, Da-Zhi; Li, Rui; Zhang, Li-Juan; Ou, Ting; Zhai, Hua-Jin

    2016-08-21

    Boron clusters can serve as inorganic analogues of hydrocarbons or polycyclic aromatic hydrocarbons (PAHs). We present herein, based upon global searches and electronic structural calculations at the B3LYP and CCSD(T) levels, the global-minimum structures of two boron-sulfur hydride clusters: C2v B3S2H3(-) (1, (2)B1) and C2v B3S2H3 (2, (1)A1). Both species are perfectly planar and feature a five-membered B3S2 ring as the structural core, with three H atoms attached terminally to the B sites. Chemical bonding analysis shows that C2v B3S2H3(-) (1) has a delocalized 5π system within a heteroatomic B3S2 ring, analogous to the π bonding in cyclopentadiene, D5h C5H5. The corresponding closed-shell C2v B3S2H3(2-) (3, (1)A1) dianion is only a local minimum. At the single-point CCSD(T) level, it is 5.7 kcal mol(-1) above the chain-like C1 ((1)A) open structure. This situation is in contrast to the cyclopentadienyl anion, C5H5(-), a prototypical aromatic hydrocarbon with a π sextet. The C2v B3S2H3 (2) neutral cluster is readily obtained upon removal of one π electron from C2v B3S2H3(-) (1). The anion photoelectron spectrum of C2v B3S2H3(-) (1) and the infrared absorption spectrum of C2v B3S2H3 (2) are predicted. The C2v B3S2H3(-) (1) species can be stabilized in sandwich-type C2h [(B3S2H3)2Fe](2-) and salt C2h [(B3S2H3)2Fe]Li2 complexes. An intriguing difference is observed between the pattern of π sextet in C2v B3S2H3(2-) (3) dianion and that in cyclopentadienyl anion. The present work also sheds light on the mechanism of structural evolution in the B3S2H3(0/-/2-) series with charge states. PMID:27424889

  10. Planar B3S2H3(-) and B3S2H3 clusters with a five-membered B3S2 ring: boron-sulfur hydride analogues of cyclopentadiene.

    PubMed

    Li, Da-Zhi; Li, Rui; Zhang, Li-Juan; Ou, Ting; Zhai, Hua-Jin

    2016-08-21

    Boron clusters can serve as inorganic analogues of hydrocarbons or polycyclic aromatic hydrocarbons (PAHs). We present herein, based upon global searches and electronic structural calculations at the B3LYP and CCSD(T) levels, the global-minimum structures of two boron-sulfur hydride clusters: C2v B3S2H3(-) (1, (2)B1) and C2v B3S2H3 (2, (1)A1). Both species are perfectly planar and feature a five-membered B3S2 ring as the structural core, with three H atoms attached terminally to the B sites. Chemical bonding analysis shows that C2v B3S2H3(-) (1) has a delocalized 5π system within a heteroatomic B3S2 ring, analogous to the π bonding in cyclopentadiene, D5h C5H5. The corresponding closed-shell C2v B3S2H3(2-) (3, (1)A1) dianion is only a local minimum. At the single-point CCSD(T) level, it is 5.7 kcal mol(-1) above the chain-like C1 ((1)A) open structure. This situation is in contrast to the cyclopentadienyl anion, C5H5(-), a prototypical aromatic hydrocarbon with a π sextet. The C2v B3S2H3 (2) neutral cluster is readily obtained upon removal of one π electron from C2v B3S2H3(-) (1). The anion photoelectron spectrum of C2v B3S2H3(-) (1) and the infrared absorption spectrum of C2v B3S2H3 (2) are predicted. The C2v B3S2H3(-) (1) species can be stabilized in sandwich-type C2h [(B3S2H3)2Fe](2-) and salt C2h [(B3S2H3)2Fe]Li2 complexes. An intriguing difference is observed between the pattern of π sextet in C2v B3S2H3(2-) (3) dianion and that in cyclopentadienyl anion. The present work also sheds light on the mechanism of structural evolution in the B3S2H3(0/-/2-) series with charge states.

  11. In Situ Synthesis of Carbon Nanotube Hybrids with Alternate MoC and MoS2 to Enhance the Electrochemical Activities of MoS2.

    PubMed

    Li, Xin; Zhang, Jinying; Wang, Rui; Huang, Hongyang; Xie, Chong; Li, Zhihui; Li, Jun; Niu, Chunming

    2015-08-12

    Molybdenum disulfides and carbides are effective catalysts for hydrogenation and hydridesulfurization, where MoS2 nanostructures are also highly promising materials for lithium ion batteries. High surface-to-volume ratio and strong interactions with conducting networks are crucial factors for their activities. A new hybrid structure of multiwalled carbon nanotube (MWCNT) with alternate MoC nanoparticles and MoS2 nanosheets (MoS2 + MoC-MWCNT) has been synthesized by controlled carburization of core-shell MoS2-MWCNT hybrid nanotubes and demonstrated by HRTEM, FFT, XRD, and Raman scattering. The MoS2 nanosheets (∼10 nm) remain tightly connected to MWCNT surfaces with {001} planes in parallel to MWCNT walls and the highly crystallized α-MoC particles (∼10 nm) are adhered to MWCNTs at angles of 60-80° between {111} planes and MWCNT walls. The electrochemical performances of the hybrid structures have been demonstrated as anodes for lithium ion batteries to be significantly increased by breaking MoS2 nanotubes into nanosheets (patches) on MWCNT surfaces, especially at high current rates. The specific capacities of MoS2 + MoC-MWCNT sample with ∼23% MoS2 have been demonstrated to be higher than those of MoS2-MWCNTs containing ∼70% MoS2.

  12. Structural analysis of the starfish SALMFamide neuropeptides S1 and S2: the N-terminal region of S2 facilitates self-association.

    PubMed

    Otara, Claire B; Jones, Christopher E; Younan, Nadine D; Viles, John H; Elphick, Maurice R

    2014-02-01

    The neuropeptides S1 (GFNSALMFamide) and S2 (SGPYSFNSGLTFamide), which share sequence similarity, were discovered in the starfish Asterias rubens and are prototypical members of the SALMFamide family of neuropeptides in echinoderms. SALMFamide neuropeptides act as muscle relaxants and both S1 and S2 cause relaxation of cardiac stomach and tube foot preparations in vitro but S2 is an order of magnitude more potent than S1. Here we investigated a structural basis for this difference in potency using spectroscopic techniques. Circular dichroism spectroscopy showed that S1 does not have a defined structure in aqueous solution and this was supported by 2D nuclear magnetic resonance experiments. In contrast, we found that S2 has a well-defined conformation in aqueous solution. However, the conformation of S2 was concentration dependent, with increasing concentration inducing a transition from an unstructured to a structured conformation. Interestingly, this property of S2 was not observed in an N-terminally truncated analogue of S2 (short S2 or SS2; SFNSGLTFamide). Collectively, the data obtained indicate that the N-terminal region of S2 facilitates peptide self-association at high concentrations, which may have relevance to the biosynthesis and/or bioactivity of S2 in vivo.

  13. Molecular biological enhancement of coal biodesulfurization. Seventh quarter report, May--July 1990

    SciTech Connect

    Kilbane, J.J.; Bielaga, B.A.

    1990-07-01

    The overall objective of this project is to sue molecular genetics to develop strains of bacteria with enhanced ability to remove sulfur from coal and to obtain data that will allow the performance and economics of a coal biodesulfurization process to be predicted. The work planned for the current quarter (May 1990 to July 1990) includes the following activities: (1) Construct a cloning vector that can be used in Rhodococcus rhodochrous IGTS8 from the small cryptic plasmid found in Rhodococcus rhodochrous ATCC 190607; (2) Develop techniques for the genetic analysis of IGTS8; (3) Continue biochemical experiments, particularly those that may allow the identification of desulfurization-related enzymes; (4) Continue experiments with coal to determine the kinetics of organic sulfur removal.

  14. The turbomachine blading design using S2-S1 approach

    NASA Technical Reports Server (NTRS)

    Luu, T. S.; Bencherif, L.; Viney, B.; Duc, J. M. Nguyen

    1991-01-01

    The boundary conditions corresponding to the design problem when the blades being simulated by the bound vorticity distribution are presented. The 3D flow is analyzed by the two steps S2 - S1 approach. In the first step, the number of blades is supposed to be infinite, the vortex distribution is transformed into an axisymmetric one, so that the flow field can be analyzed in a meridional plane. The thickness distribution of the blade producing the flow channel striction is taken into account by the modification of metric tensor in the continuity equation. Using the meridional stream function to define the flow field, the mass conservation is satisfied automatically. The governing equation is deduced from the relation between the azimuthal component of the vorticity and the meridional velocity. The value of the azimuthal component of the vorticity is provided by the hub to shroud equilibrium condition. This step leads to the determination of the axisymmetric stream sheets as well as the approximate camber surface of the blade. In the second step, the finite number of blades is taken into account, the inverse problem corresponding to the blade to blade flow confined in each stream sheet is analyzed. The momentum equation implies that the free vortex of the absolute velocity must be tangential to the stream sheet. The governing equation for the blade to blade flow stream function is deduced from this condition. At the beginning, the upper and the lower surfaces of the blades are created from the camber surface obtained from the first step with the assigned thickness distribution. The bound vorticity distribution and the penetrating flux conservation applied on the presumed blade surface constitute the boundary conditions of the inverse problem. The detection of this flux leads to the rectification of the geometry of the blades.

  15. In Vitro Study of SnS2, BiOCl and SnS2-Incorporated BiOCl Inorganic Nanoparticles Used as Doxorubicin Carrier.

    PubMed

    Deng, Jiangming; Mo, Yunfei; Liu, Jianghui; Guo, Rui; Zhang, Yi; Xue, Wei; Zhang, Yuanming

    2016-06-01

    Inorganic nanoparticles have been widely used in biomedical field. In this paper, we try to study the use of three types of inorganic nanoparticles (i.e., SnS2, BiOCl and SnS2-incorporated BiOCl (SnS2/BiOCl)) as doxorubicin (DOX) carriers. Firstly, SnS2, BiOCl and SnS2/BiOCl were synthesised, then were characterized by TEM, nanoparticles size and zeta potential. Next the drug release and cell viability test were carried out. The cell viability test indicated that the drug carriers can effectively kill HeLa cells while maintaining low cytotoxicity against normal cells-fibroblasts. The results show the potential of SnS2/BiOCl nanoparticles for antitumor applications.

  16. In Vitro Study of SnS2, BiOCl and SnS2-Incorporated BiOCl Inorganic Nanoparticles Used as Doxorubicin Carrier.

    PubMed

    Deng, Jiangming; Mo, Yunfei; Liu, Jianghui; Guo, Rui; Zhang, Yi; Xue, Wei; Zhang, Yuanming

    2016-06-01

    Inorganic nanoparticles have been widely used in biomedical field. In this paper, we try to study the use of three types of inorganic nanoparticles (i.e., SnS2, BiOCl and SnS2-incorporated BiOCl (SnS2/BiOCl)) as doxorubicin (DOX) carriers. Firstly, SnS2, BiOCl and SnS2/BiOCl were synthesised, then were characterized by TEM, nanoparticles size and zeta potential. Next the drug release and cell viability test were carried out. The cell viability test indicated that the drug carriers can effectively kill HeLa cells while maintaining low cytotoxicity against normal cells-fibroblasts. The results show the potential of SnS2/BiOCl nanoparticles for antitumor applications. PMID:27427625

  17. Hybrid S2/Carbon Epoxy Composite Armours Under Blast Loads

    NASA Astrophysics Data System (ADS)

    Dolce, F.; Meo, Michele; Wright, A.; French, M.; Bernabei, M.

    2012-06-01

    Civil and military structures, such as helicopters, aircrafts, naval ships, tanks or buildings are susceptible to blast loads as terroristic attacks increases, therefore there is the need to design blast resistant structures. During an explosion the peak pressure produced by shock wave is much greater than the static collapse pressure. Metallic structures usually undergo large plastic deformations absorbing blast energy before reaching equilibrium. Due to their high specific properties, fibre-reinforced polymers are being considered for energy absorption applications in blast resistant armours. A deep insight into the relationship between explosion loads, composite architecture and deformation/fracture behaviour will offer the possibility to design structures with significantly enhanced energy absorption and blast resistance performance. This study presents the results of a numerical investigation aimed at understanding the performance of a hybrid composite (glass/carbon fibre) plate subjected to blast loads using commercial LS-DYNA software. In particular, the paper deals with numerical 3D simulations of damages caused by air blast waves generated by C4 charges on two fully clamped rectangular plates made of steel and hybrid (S2/Carbon) composite, respectively. A Multi Materials Arbitrary Lagrangian Eulerian (MMALE) formulation was used to simulate the shock phenomenon. For the steel plates, the Johnson-Cook material model was employed. For the composite plates both in-plane and out-of-plane failure criteria were employed. In particular, a contact tiebreak formulation with a mixed mode failure criteria was employed to simulate delamination failure. As for the steel plates the results showed that excellent correlation with the experimental data for the two blast load conditions in terms of dynamic and residual deflection for two different C4 charges. For the composite plates the numerical results showed that, as expected, a wider delamination damage was observed

  18. First-principles study of the structural and electronic properties of MoS2-WS2 and MoS2-MoTe2 monolayer heterostructures

    NASA Astrophysics Data System (ADS)

    Wang, Qianwen; Wu, Ping; Cao, Gengyu; Huang, Min

    2013-12-01

    Using first-principles calculations, we have systematically investigated the geometric and electronic structure of MoS2-WS2 and MoS2-MoTe2 monolayer (ML) heterostructures. Analysis of the variation of the total density of states and partial density of states of the specific atoms in the interfaces demonstrates that the two heterostructures show rather different properties and different changes from the initial MoS2 ML. The MoS2-WS2 ML heterostructure is still a semiconductor with a band gap of 1.58 eV, which is smaller than that of MoS2 and WS2 MLs. However, the strong interactions between MoS2and MoTe2 at the interfacial sites induce the MoS2-MoTe2 ML heterostructure to display metallic characteristics. Our results indicate that the ML heterostructures of MoS2-WS2 and MoS2-MoTe2 are expected to be a possible way to extend the application of the transition-metal dichalcogenides.

  19. Superconductivity versus structural phase transition in the closely related Bi2Rh3.5S2 and Bi2Rh3S2

    DOE PAGESBeta

    Kaluarachchi, Udhara S.; Xie, Weiwei; Lin, Qisheng; Taufour, Valentin; Bud'ko, Sergey L.; Miller, Gordon J.; Canfield, Paul C.

    2015-05-19

    Single crystals of Bi2Rh3S2 and Bi2Rh3.5S2 were synthesized by solution growth, and the crystal structures and thermodynamic and transport properties of both compounds were studied. In the case of Bi2Rh3S2, a structural first-order transition at around 165 K is identified by single-crystal diffraction experiments, with clear signatures visible in resistivity, magnetization, and specific heat data. No superconducting transition for Bi2Rh3S2 was observed down to 0.5 K. In contrast, no structural phase transition at high temperature was observed for Bi2Rh3.5S2; however, bulk superconductivity with a critical temperature, Tc ≈ 1.7 K, was observed. The Sommerfeld coefficient γ and the Debye temperaturemore » (ΘD) were found to be 9.41 mJ mol–1K–2 and 209 K, respectively, for Bi2Rh3S2, and 22 mJ mol–1K–2 and 196 K, respectively, for Bi2Rh3.5S2. As a result, the study of the specific heat in the superconducting state of Bi2Rh3.5S2 suggests that Bi2Rh3.5S2 is a weakly coupled, BCS superconductor.« less

  20. Coherent quantum control of internal conversion: {S}_{2}\\;\\leftrightarrow \\;{S}_{1} in pyrazine via {S}_{0}\\;\\to \\;{S}_{2}/{S}_{1} weak field excitation

    NASA Astrophysics Data System (ADS)

    Grinev, Timur; Shapiro, Moshe; Brumer, Paul

    2015-09-01

    Coherent control of internal conversion (IC) between the first (S1) and second (S2) singlet excited electronic states in pyrazine, where the S2 state is populated from the ground singlet electronic state S0 by weak field excitation, is examined. Control is implemented by shaping the laser which excites S2. Excitation and IC are considered simultaneously, using the recently introduced resonance-based control approach. Highly successful control is achieved by optimizing both the amplitude and phase profiles of the laser spectrum. The dependence of control on the properties of resonances in S2 is demonstrated.

  1. Synthesis, growth and characterizations of AgGaS2 single crystals

    NASA Astrophysics Data System (ADS)

    Karunagaran, N.; Ramasamy, P.

    2015-06-01

    AgGaS2 is a I-III-VI2 ternary semiconducting compound with chalcopyrite type structure. The AgGaS2 polycrystalline charges were successfully synthesized from the high purity starting elements (Ag, Ga, S). The synthesized AgGaS2 polycrystalline charge was confirmed by powder XRD. Thermal property of AgGaS2 was analyzed using differential scanning calorimetry (DSC) technique. The melting point of AgGaS2 is 1002°C and the freezing point is 918°C. Transmittance of AgGaS2 is 65 % in the Mid IR region.

  2. Dual role of monolayer MoS2 in enhanced photocatalytic performance of hybrid MoS2/SnO2 nanocomposite

    NASA Astrophysics Data System (ADS)

    Ding, Shuang-Shuang; Huang, Wei-Qing; Yang, Yin-Cai; Zhou, Bing-Xin; Hu, Wang-Yu; Long, Meng-Qiu; Peng, P.; Huang, Gui-Fang

    2016-05-01

    The enhanced photocatalytic performance of various MoS2-based nanomaterials has recently been observed, but the role of monolayer MoS2 is still not well elucidated at the electronic level. Herein, focusing on a model system, hybrid MoS2/SnO2 nanocomposite, we first present a theoretical elucidation of the dual role of monolayer MoS2 as a sensitizer and a co-catalyst by performing density functional theory calculations. It is demonstrated that a type-II, staggered, band alignment of ˜0.49 eV exists between monolayer MoS2 and SnO2 with the latter possessing the higher electron affinity, or work function, leading to the robust separation of photoexcited charge carriers between the two constituents. Under irradiation, the electrons are excited from Mo 4d orbitals to SnO2, thus enhancing the reduction activity of latter, indicating that the monolayer MoS2 is an effective sensitizer. Moreover, the Mo atoms, which are catalytically inert in isolated monolayer MoS2, turn into catalytic active sites, making the monolayer MoS2 to be a highly active co-catalyst in the composite. The dual role of monolayer MoS2 is expected to arise in other MoS2-semiconductor nanocomposites. The calculated absorption spectra can be rationalized by available experimental results. These findings provide theoretical evidence supporting the experimental reports and pave the way for developing highly efficient MoS2-based photocatalysts.

  3. Mice lacking G0S2 are lean and cold-tolerant.

    PubMed

    Ma, Tian; Lopez-Aguiar, Alexandra G N; Li, Aihua; Lu, Yun; Sekula, David; Nattie, Eugene E; Freemantle, Sarah; Dmitrovsky, Ethan

    2014-05-01

    G 0/G 1 switch gene 2 (G0S2) is a protein that was first identified in a search for lymphocyte G 0/G 1 switch genes. A direct role for G0S2 in cell cycle regulation has proven elusive. Yet, there is prior evidence for G0S2 functioning in tumor suppression, immune regulation and lipolysis. To explore definitively G0S2 functions, mice lacking G0S2 were generated and characterized. G0S2(-/-) mice were born at a Mendelian ratio and were phenotypically normal, with the exception of a possible lactation defect. G0S2(-/-) female mice carried viable pups to term, but could not typically sustain them beyond 48 h. G0S2 is shown here to be most highly expressed in adipose tissue. It is also expressed in liver, skeletal muscle, lung, ventricles of the heart, and components of the kidney. G0S2 loss significantly decreased relative body weight gain as compared with wild-type (WT) (G0S2(+/+)) mice, with a significant decrease in gonadal fat pad weight and a significant increase in serum glycerol levels. This decreased relative body weight gain is not associated with a significant decrease in food intake or increase in activity of G0S2(-/-) mice. In fact, G0S2(-/-) mice were significantly less active at night than G0S2(+/+) mice. When fed with a high fat diet (45% fat diet), G0S2 loss did not prevent diet-induced obesity in mice. Intriguingly, G0S2 loss improved acute cold tolerance, augmenting expression of genes involved in thermogenesis. In summary, in vivo roles for G0S2 were found in lactation, energy balance, and thermogenesis. This study provides a basis for tumor suppressive effects of G0S2 by regulating lipolysis.

  4. Highly Enhanced Gas Adsorption Properties in Vertically Aligned MoS2 Layers.

    PubMed

    Cho, Soo-Yeon; Kim, Seon Joon; Lee, Youhan; Kim, Jong-Seon; Jung, Woo-Bin; Yoo, Hae-Wook; Kim, Jihan; Jung, Hee-Tae

    2015-09-22

    In this work, we demonstrate that gas adsorption is significantly higher in edge sites of vertically aligned MoS2 compared to that of the conventional basal plane exposed MoS2 films. To compare the effect of the alignment of MoS2 on the gas adsorption properties, we synthesized three distinct MoS2 films with different alignment directions ((1) horizontally aligned MoS2 (basal plane exposed), (2) mixture of horizontally aligned MoS2 and vertically aligned layers (basal and edge exposed), and (3) vertically aligned MoS2 (edge exposed)) by using rapid sulfurization method of CVD process. Vertically aligned MoS2 film shows about 5-fold enhanced sensitivity to NO2 gas molecules compared to horizontally aligned MoS2 film. Vertically aligned MoS2 has superior resistance variation compared to horizontally aligned MoS2 even with same surface area exposed to identical concentration of gas molecules. We found that electrical response to target gas molecules correlates directly with the density of the exposed edge sites of MoS2 due to high adsorption of gas molecules onto edge sites of vertically aligned MoS2. Density functional theory (DFT) calculations corroborate the experimental results as stronger NO2 binding energies are computed for multiple configurations near the edge sites of MoS2, which verifies that electrical response to target gas molecules (NO2) correlates directly with the density of the exposed edge sites of MoS2 due to high adsorption of gas molecules onto edge sites of vertically aligned MoS2. We believe that this observation extends to other 2D TMD materials as well as MoS2 and can be applied to significantly enhance the gas sensor performance in these materials.

  5. The splitting and oscillator strengths for the 2S/2/S-2p/2/P/0/ doublet in lithium-like sulfur. [during Skylab observed solar flares

    NASA Technical Reports Server (NTRS)

    Pegg, D. J.; Forester, J. P.; Elston, S. B.; Griffin, P. M.; Peterson, R. S.; Thoe, R. S.; Vane, C. R.; Sellin, I. A.; Groeneveld, K.-O.

    1977-01-01

    The beam-foil technique has been used to study the 2S(2)S-2p(2)P(0) doublet in S XIV. The results confirm the doublet splitting measured aboard Skylab during solar flare events. In addition, the oscillator strengths for the resonance transitions comprising this doublet have been measured and found to agree well with recent relativistic f-value calculations.

  6. Hierarchical MoS2-rGO nanosheets with high MoS2 loading with enhanced electro-catalytic performance

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Xiao, Han; Zhou, Bowen; Huang, Feifan; Zhou, Shoubin; Xiao, Wei; Wang, Dihua

    2015-12-01

    Incorporation of high-loading redox-active materials with small amounts of graphene is a general protocol to achieve high-performance catalysts. Herein, hierarchical MoS2-reduced graphene oxide nanosheet (denoted as MoS2-rGO nanosheets) hybrids with a loading of MoS2 as high as 94 wt% are synthesized. The obtained hierarchical MoS2-rGO nanosheets simultaneously integrate the structural and compositional design rationales for high-efficiency and durable electrocatalysts based on high weight ratio of MoS2 in hybrid composite, highly stable/conducting rGO, well-dispersed two-dimensional ultrathin MoS2 nanosheets, more exposed edge sites and micro/nano hierarchical structure. When evaluated as electrocatalysts for hydrogen evolution and oxygen reduction reactions, the hierarchical MoS2-rGO nanosheets demonstrates enhanced activity and excellent stability, promising their applications in MoS2 based electrochemical, photo-catalytic and photo-elecrocatalytic cells.

  7. Superconductivity in CeOBiS2 with cerium valence fluctuation

    NASA Astrophysics Data System (ADS)

    Nagao, Masanori; Miura, Akira; Ueta, Ikuo; Watauchi, Satoshi; Tanaka, Isao

    2016-11-01

    Resistivities of single-crystalline as well as poly-crystalline samples of CeOBiS2 without fluorine doping were measured at temperatures down to 0.13 K, and were compared with those of poly-crystalline LaOBiS2 and PrOBiS2. Both poly-crystalline and single-crystalline CeOBiS2 exhibited zero resistivity below 1.2 K while poly-crystalline LaOBiS2 and PrOBiS2 did not show zero resistivity down to 0.13 K. Superconducting transition temperature of CeOBiS2 was reduced by increasing the applied current density. The superconductivity of CeOBiS2 without chemical doping is likely triggered by the carriers induced by the valence fluctuation between Ce3+ and Ce4+.

  8. Interface modification of MoS2/SiO2 leading to conversion of conduction type of MoS2

    NASA Astrophysics Data System (ADS)

    Lin, Yow-Jon; Su, Ting-Hong

    2016-11-01

    Few-layer MoS2 prepared by the chemical vapor deposition method is deposited on SiO2 samples with/without sulfide treatment in order to experimentally study the mechanism of conduction-type conversion in MoS2. The MoS2 thin film deposited on a SiO2 substrate with sulfide treatment shows n-type behavior, whereas the MoS2 thin film deposited on a SiO2 substrate without sulfide treatment exhibits p-type behavior. Experimental identification confirms that n-type conversion is due to a combined effect of the broken Sisbnd O bonds and the formation of Sisbnd S bonds at the SiO2 surface that results in the removal of oxygen dangling bonds and a change in the MoS2sbnd SiO2 interaction.

  9. Characterization and genome functional analysis of a novel metamitron-degrading strain Rhodococcus sp. MET via both triazinone and phenyl rings cleavage

    PubMed Central

    Fang, Hua; Xu, Tianheng; Cao, Duantao; Cheng, Longyin; Yu, Yunlong

    2016-01-01

    A novel bacterium capable of utilizing metamitron as the sole source of carbon and energy was isolated from contaminated soil and identified as Rhodococcus sp. MET based on its morphological characteristics, BIOLOG GP2 microplate profile, and 16S rDNA phylogeny. Genome sequencing and functional annotation of the isolate MET showed a 6,340,880 bp genome with a 62.47% GC content and 5,987 protein-coding genes. In total, 5,907 genes were annotated with the COG, GO, KEGG, Pfam, Swiss-Prot, TrEMBL, and nr databases. The degradation rate of metamitron by the isolate MET obviously increased with increasing substrate concentrations from 1 to 10 mg/l and subsequently decreased at 100 mg/l. The optimal pH and temperature for metamitron biodegradation were 7.0 and 20–30 °C, respectively. Based on genome annotation of the metamitron degradation genes and the metabolites detected by HPLC-MS/MS, the following metamitron biodegradation pathways were proposed: 1) Metamitron was transformed into 2-(3-hydrazinyl-2-ethyl)-hydrazono-2-phenylacetic acid by triazinone ring cleavage and further mineralization; 2) Metamitron was converted into 3-methyl-4-amino-6(2-hydroxy-muconic acid)-1,2,4-triazine-5(4H)-one by phenyl ring cleavage and further mineralization. The coexistence of diverse mineralization pathways indicates that our isolate may effectively bioremediate triazinone herbicide-contaminated soils. PMID:27578531

  10. Crystal Structure and Site-directed Mutagenesis of 3-Ketosteroid Δ1-Dehydrogenase from Rhodococcus erythropolis SQ1 Explain Its Catalytic Mechanism*

    PubMed Central

    Rohman, Ali; van Oosterwijk, Niels; Thunnissen, Andy-Mark W. H.; Dijkstra, Bauke W.

    2013-01-01

    3-Ketosteroid Δ1-dehydrogenases are FAD-dependent enzymes that catalyze the 1,2-desaturation of 3-ketosteroid substrates to initiate degradation of the steroid nucleus. Here we report the 2.0 Å resolution crystal structure of the 56-kDa enzyme from Rhodococcus erythropolis SQ1 (Δ1-KSTD1). The enzyme contains two domains: an FAD-binding domain and a catalytic domain, between which the active site is situated as evidenced by the 2.3 Å resolution structure of Δ1-KSTD1 in complex with the reaction product 1,4-androstadiene-3,17-dione. The active site contains four key residues: Tyr119, Tyr318, Tyr487, and Gly491. Modeling of the substrate 4-androstene-3,17-dione at the position of the product revealed its interactions with these residues and the FAD. The C1 and C2 atoms of the substrate are at reaction distance to the N5 atom of the isoalloxazine ring of FAD and the hydroxyl group of Tyr318, respectively, whereas the C3 carbonyl group is at hydrogen bonding distance from the hydroxyl group of Tyr487 and the backbone amide of Gly491. Site-directed mutagenesis of the tyrosines to phenylalanines confirmed their importance for catalysis. The structural features and the kinetic properties of the mutants suggest a catalytic mechanism in which Tyr487 and Gly491 work in tandem to promote keto-enol tautomerization and increase the acidity of the C2 hydrogen atoms of the substrate. With assistance of Tyr119, the general base Tyr318 abstracts the axial β-hydrogen from C2 as a proton, whereas the FAD accepts the axial α-hydrogen from the C1 atom of the substrate as a hydride ion. PMID:24165124

  11. LplR, a Repressor Belonging to the TetR Family, Regulates Expression of the l-Pantoyl Lactone Dehydrogenase Gene in Rhodococcus erythropolis

    PubMed Central

    Si, Dayong; Urano, Nobuyuki; Shimizu, Sakayu

    2012-01-01

    The l-pantoyl lactone (l-PL) dehydrogenase (LPLDH) gene (lpldh) has been cloned from Rhodococcus erythropolis AKU2103, and addition of 1,2-propanediol (1,2-PD) was shown to be required for lpldh expression in this strain. In this study, based on an exploration of the nucleotide sequence around lpldh, a TetR-like regulator gene, which we designated lplR, was found upstream of lpldh, and three putative open reading frames existed between the two genes. Disruption of lplR led to 22.8 times higher lpldh expression, even without 1,2-PD induction, than that in wild-type R. erythropolis AKU2103 without 1,2-PD addition. Introduction of a multicopy vector carrying lplR (multi-lplR) into the wild-type and ΔlplR strains led to no detectable LPLDH activity even in the presence of 1,2-PD. The results of an electrophoretic mobility shift assay revealed that purified LplR bound to a 6-bp inverted-repeat sequence located in the promoter/operator region of the operon containing lpldh. These results indicated that LplR is a negative regulator in lpldh expression. Based on the clarification of the expression mechanism of lpldh, recombinant cells showing high LPLDH activity were constructed and used as a catalyst for the conversion of l-PL to ketopantoyl lactone. Finally, a promising production process of d-PL from dl-PL was constructed. PMID:22941082

  12. Involvement of the Cytochrome P450 System EthBAD in the N-Deethoxymethylation of Acetochlor by Rhodococcus sp. Strain T3-1

    PubMed Central

    Wang, Fei; Zhou, Jie; Li, Zhoukun; Dong, Weiliang; Hou, Ying; Huang, Yan

    2015-01-01

    Acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide] is a widely applied herbicide with potential carcinogenic properties. N-Deethoxymethylation is the key step in acetochlor biodegradation. N-Deethoxymethylase is a multicomponent enzyme that catalyzes the conversion of acetochlor to 2′-methyl-6′-ethyl-2-chloroacetanilide (CMEPA). Fast detection of CMEPA by a two-enzyme (N-deethoxymethylase–amide hydrolase) system was established in this research. Based on the fast detection method, a three-component enzyme was purified from Rhodococcus sp. strain T3-1 using ammonium sulfate precipitation and hydrophobic interaction chromatography. The molecular masses of the components of the purified enzyme were estimated to be 45, 43, and 11 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Based on the results of peptide mass fingerprint analysis, acetochlor N-deethoxymethylase was identified as a cytochrome P450 system, composed of a cytochrome P450 oxygenase (43-kDa component; EthB), a ferredoxin (45 kDa; EthA), and a reductase (11 kDa; EthD), that is involved in the degradation of methyl tert-butyl ether. The gene cluster ethABCD was cloned by PCR amplification and expressed in Escherichia coli BL21(DE3). Resting cells of a recombinant E. coli strain showed deethoxymethylation activity against acetochlor. Subcloning of ethABCD showed that ethABD expressed in E. coli BL21(DE3) has the activity of acetochlor N-deethoxymethylase and is capable of converting acetochlor to CMEPA. PMID:25595756

  13. Development and evaluation of the internal-controlled real-time PCR assay for Rhodococcus equi detection in various clinical specimens

    PubMed Central

    STEFAŃSKA, Ilona; WITKOWSKI, Lucjan; RZEWUSKA, Magdalena; DZIECIĄTKOWSKI, Tomasz

    2015-01-01

    Rhodococcus equi is the causative agent of rhodococcosis in horses, resulting in significant morbidity and mortality in foals. This bacterium has also been isolated from a variety of animals and is being increasingly reported as a cause of infection in humans, mainly in immunosuppressed individuals. Laboratory diagnostics of R. equi infections based only on conventional microbiological methods shows low accuracy and can lead to misidentification. The objective of the study was to develop and evaluate a real-time PCR assay for direct detection of R. equi in various clinical specimens, including tissue samples. The species-specific region of the gene encoding R. equi cholesterol oxidase, choE, was used as a qPCR-target. The diagnostic applicability of the assay was confirmed by testing various tissue specimens obtained from horses with clinical signs of rhodoccocal infection and swine submaxillary lymph nodes. The rate of R. equi detection in clinical specimens by the developed assay was higher in comparison to the culture method (90% vs. 60.0% of positive samples) and conventional PCR (90.0% vs. 20.0% of positive samples). In case of 13 samples that were negative in the culture-based method, R. equi was detected by the developed assay. Only in one case, it gave negative result for culture-positive sample. The assay may provide a simple and rapid tool to complement the classical methods of R. equi detection based on culture and phenotypic identification of isolates, as the performed evaluation indicated a high specificity and accuracy of the results. PMID:26655770

  14. Identification of the region of a 14-kilodalton protein of Rhodococcus ruber that is responsible for the binding of this phasin to polyhydroxyalkanoic acid granules.

    PubMed Central

    Pieper-Fürst, U; Madkour, M H; Mayer, F; Steinbüchel, A

    1995-01-01

    The function of the polyhydroxyalkanoic acid (PHA) granule-associated GA14 protein of Rhodococcus ruber was investigated in Escherichia coli XL1-Blue, which coexpressed this protein with the polyhydroxybutyric acid (PHB) biosynthesis operon of Alcaligenes eutrophus. The GA14 protein had no influence on the biosynthesis rate of PHB in E. coli XL1-Blue(pSKCO7), but this recombinant E. coli strain formed smaller PHB granules than were formed by an E. coli strain that expressed only the PHB operon. Immunoelectron microscopy with GA14-specific antibodies demonstrated the binding of GA14 protein to these mini granules. In a previous study, two hydrophobic domains close to the C terminus of the GA14 protein were analyzed, and a working hypothesis that suggested an anchoring of the GA14 protein in the phospholipid monolayer surrounding the PHA granule core by these hydrophobic domains was developed (U. Pieper-Fürst, M. H. Madkour, F. Mayer, and A. Steinbüchel, J. Bacteriol. 176:4328-4337, 1994). This hypothesis was confirmed by the construction of C-terminally truncated variants of the GA14 protein lacking the second or both hydrophobic domains and by the demonstration of their inability to bind to PHB granules. Further confirmation of the hypothesis was obtained by the construction of a fusion protein composed of the acetaldehyde dehydrogenase II of A. eutrophus and the C terminus of the GA14 protein containing both hydrophobic domains and by its affinity to native and artificial PHB granules. PMID:7730285

  15. Growth of Rhodococcus sp. strain BCP1 on gaseous n-alkanes: new metabolic insights and transcriptional analysis of two soluble di-iron monooxygenase genes

    PubMed Central

    Cappelletti, Martina; Presentato, Alessandro; Milazzo, Giorgio; Turner, Raymond J.; Fedi, Stefano; Frascari, Dario; Zannoni, Davide

    2015-01-01

    Rhodococcus sp. strain BCP1 was initially isolated for its ability to grow on gaseous n-alkanes, which act as inducers for the co-metabolic degradation of low-chlorinated compounds. Here, both molecular and metabolic features of BCP1 cells grown on gaseous and short-chain n-alkanes (up to n-heptane) were examined in detail. We show that propane metabolism generated terminal and sub-terminal oxidation products such as 1- and 2-propanol, whereas 1-butanol was the only terminal oxidation product detected from n-butane metabolism. Two gene clusters, prmABCD and smoABCD—coding for Soluble Di-Iron Monooxgenases (SDIMOs) involved in gaseous n-alkanes oxidation—were detected in the BCP1 genome. By means of Reverse Transcriptase-quantitative PCR (RT-qPCR) analysis, a set of substrates inducing the expression of the sdimo genes in BCP1 were assessed as well as their transcriptional repression in the presence of sugars, organic acids, or during the cell growth on rich medium (Luria–Bertani broth). The transcriptional start sites of both the sdimo gene clusters were identified by means of primer extension experiments. Finally, proteomic studies revealed changes in the protein pattern induced by growth on gaseous- (n-butane) and/or liquid (n-hexane) short-chain n-alkanes as compared to growth on succinate. Among the differently expressed protein spots, two chaperonins and an isocytrate lyase were identified along with oxidoreductases involved in oxidation reactions downstream of the initial monooxygenase reaction step. PMID:26029173

  16. Characterization and genome functional analysis of a novel metamitron-degrading strain Rhodococcus sp. MET via both triazinone and phenyl rings cleavage.

    PubMed

    Fang, Hua; Xu, Tianheng; Cao, Duantao; Cheng, Longyin; Yu, Yunlong

    2016-01-01

    A novel bacterium capable of utilizing metamitron as the sole source of carbon and energy was isolated from contaminated soil and identified as Rhodococcus sp. MET based on its morphological characteristics, BIOLOG GP2 microplate profile, and 16S rDNA phylogeny. Genome sequencing and functional annotation of the isolate MET showed a 6,340,880 bp genome with a 62.47% GC content and 5,987 protein-coding genes. In total, 5,907 genes were annotated with the COG, GO, KEGG, Pfam, Swiss-Prot, TrEMBL, and nr databases. The degradation rate of metamitron by the isolate MET obviously increased with increasing substrate concentrations from 1 to 10 mg/l and subsequently decreased at 100 mg/l. The optimal pH and temperature for metamitron biodegradation were 7.0 and 20-30 °C, respectively. Based on genome annotation of the metamitron degradation genes and the metabolites detected by HPLC-MS/MS, the following metamitron biodegradation pathways were proposed: 1) Metamitron was transformed into 2-(3-hydrazinyl-2-ethyl)-hydrazono-2-phenylacetic acid by triazinone ring cleavage and further mineralization; 2) Metamitron was converted into 3-methyl-4-amino-6(2-hydroxy-muconic acid)-1,2,4-triazine-5(4H)-one by phenyl ring cleavage and further mineralization. The coexistence of diverse mineralization pathways indicates that our isolate may effectively bioremediate triazinone herbicide-contaminated soils. PMID:27578531

  17. Identification of a novel dioxygenase involved in metabolism of o-xylene, toluene, and ethylbenzene by Rhodococcus sp. strain DK17.

    PubMed

    Kim, Dockyu; Chae, Jong-Chan; Zylstra, Gerben J; Kim, Young-Soo; Kim, Seong-Ki; Nam, Myung Hee; Kim, Young Min; Kim, Eungbin

    2004-12-01

    Rhodococcus sp. strain DK17 is able to grow on o-xylene, benzene, toluene, and ethylbenzene. DK17 harbors at least two megaplasmids, and the genes encoding the initial steps in alkylbenzene metabolism are present on the 330-kb pDK2. The genes encoding alkylbenzene degradation were cloned in a cosmid clone and sequenced completely to reveal 35 open reading frames (ORFs). Among the ORFs, we identified two nearly exact copies (one base difference) of genes encoding large and small subunits of an iron sulfur protein terminal oxygenase that are 6 kb apart from each other. Immediately downstream of one copy of the dioxygenase genes (akbA1a and akbA2a) is a gene encoding a dioxygenase ferredoxin component (akbA3), and downstream of the other copy (akbA1b and akbA2b) are genes putatively encoding a meta-cleavage pathway. RT-PCR experiments show that the two copies of the dioxygenase genes are operonic with the downstream putative catabolic genes and that both operons are induced by o-xylene. When expressed in Escherichia coli, AkbA1a-AkbA2a-AkbA3 transformed o-xylene into 2,3- and 3,4-dimethylphenol. These were apparently derived from an unstable o-xylene cis-3,4-dihydrodiol, which readily dehydrates. This indicates a single point of attack of the dioxygenase on the aromatic ring. In contrast, attack of AkbA1a-AkbA2a-AkbA3 on ethylbenzene resulted in the formation of two different cis-dihydrodiols resulting from an oxidation at the 2,3 and the 3,4 positions on the aromatic ring, respectively. PMID:15574904

  18. Rhodococcus equi pneumonia in foals: an assessment of the early diagnostic value of serum amyloid A and plasma fibrinogen concentrations in equine clinical practice.

    PubMed

    Passamonti, F; Vardi, D M; Stefanetti, V; Marenzoni, M L; Prato, S; Cévese, P; Coletti, M; Pepe, M; Casagrande Proietti, P; Olea-Popelka, F

    2015-02-01

    Early diagnosis and prevention of Rhodococcus equi pneumonia in foals represent important goals for equine clinicians. Recent protocols for diagnosis and treatment of Rhodococcosis in foals typically rely on a multimodal approach based on sonographic evidence suggestive of pyogranulomas, sonographic abscess scores and laboratory findings including plasma fibrinogen concentrations, blood biochemistry testing and platelet and leukocyte counts. The aim of this study was to assess the utility of weekly testing of serum amyloid A (SAA) and plasma fibrinogen concentrations in foals to achieve early diagnosis of R. equi pneumonia prior to the onset of clinical signs. This testing was used to simulate a clinically practical screening procedure and compared with thoracic ultrasonography performed in parallel. The present study suggests that SAA does not represent a reliable early marker of Rhodococcosis when plasma concentrations are tested weekly. However, when clinical signs of R. equi pneumonia are present, SAA concentrations may allow clinicians to obtain 'real-time' indications concerning both the progress of infection and the effectiveness of therapy. This study raises the possibility that plasma fibrinogen monitoring starting at 1 week of age and repeated on a weekly basis, could serve as a screening test allowing clinicians to identify foals as suspected of R. equi infection. Future investigations regarding both physiological plasma fibrinogen concentrations in foals as well as fibrinogen kinetics in foals affected with R. equi pneumonia, including the establishment of appropriate reference intervals for the test method employed in this study, will be necessary in order to clarify this possibility.

  19. A Two-Component para-Nitrophenol Monooxygenase Initiates a Novel 2-Chloro-4-Nitrophenol Catabolism Pathway in Rhodococcus imtechensis RKJ300

    PubMed Central

    Min, Jun; Zhang, Jun-Jie

    2015-01-01

    Rhodococcus imtechensis RKJ300 (DSM 45091) grows on 2-chloro-4-nitrophenol (2C4NP) and para-nitrophenol (PNP) as the sole carbon and nitrogen sources. In this study, by genetic and biochemical analyses, a novel 2C4NP catabolic pathway different from those of all other 2C4NP utilizers was identified with hydroxyquinol (hydroxy-1,4-hydroquinone or 1,2,4-benzenetriol [BT]) as the ring cleavage substrate. Real-time quantitative PCR analysis indicated that the pnp cluster located in three operons is likely involved in the catabolism of both 2C4NP and PNP. The oxygenase component (PnpA1) and reductase component (PnpA2) of the two-component PNP monooxygenase were expressed and purified to homogeneity, respectively. The identification of chlorohydroquinone (CHQ) and BT during 2C4NP degradation catalyzed by PnpA1A2 indicated that PnpA1A2 catalyzes the sequential denitration and dechlorination of 2C4NP to BT and catalyzes the conversion of PNP to BT. Genetic analyses revealed that pnpA1 plays an essential role in both 2C4NP and PNP degradations by gene knockout and complementation. In addition to catalyzing the oxidation of CHQ to BT, PnpA1A2 was also found to be able to catalyze the hydroxylation of hydroquinone (HQ) to BT, revealing the probable fate of HQ that remains unclear in PNP catabolism by Gram-positive bacteria. This study fills a gap in our knowledge of the 2C4NP degradation mechanism in Gram-positive bacteria and also enhances our understanding of the genetic and biochemical diversity of 2C4NP catabolism. PMID:26567304

  20. Degradation of 2,5-dimethylpyrazine by Rhodococcus erythropolis strain DP-45 isolated from a waste gas treatment plant of a fishmeal processing company.

    PubMed

    Rappert, Sugima; Li, Renjie; Kokova, Mariya; Antholz, Mathias; Nagorny, Stephanie; Francke, Wittko; Müller, Rudolf

    2007-10-01

    A bacterium, strain DP-45, capable of degrading 2,5-dimethylpyrazine (2,5-DMP) was isolated and identified as Rhodococcus erythropolis. The strain also grew on many other pyrazines found in the waste gases of food industries, like 2,3-dimethylpyrazine (2,3-DMP), 2,6-dimethylpyrazine (2,6-DMP), 2-ethyl-5(6)-dimethylpyrazine (EMP), 2-ethylpyrazine (EP), 2-methylpyrazine (MP), and 2,3,5-trimethylpyrazine (TMP). The strain utilized 2,5-DMP as sole source of carbon and nitrogen and grew optimally at 25 degrees C with a doubling time of 7.6 h. The degradation of 2,5-DMP was accompanied by the growth of the strain and by the accumulation of a first intermediate, identified as 2-hydroxy-3,6-dimethylpyrazine (HDMP). The disappearance of HDMP was accompanied by the release of ammonium into the medium. No other metabolite was detected. The degradation of 2,5-DMP and HDMP by strain DP-45 required molecular oxygen. The expression of the first enzyme in the pathway was induced by 2,5-DMP and HDMP whereas the second enzyme was constitutively expressed. The activity of the first enzyme was inhibited by diphenyliodonium (DPI), a flavoprotein inhibitor, methimazole, a competitive inhibitor of flavin-containing monooxygenases, and by cytochrome P450 inhibitors, 1-aminobenzotriazole (ABT) and phenylhydrazine (PHZ). The activity of the second enzyme was inhibited by DPI, ABT, and PHZ. Sodium tungstate, a specific antagonist of molybdate, had no influence on growth and consumption of 2,5-DMP by strain DP-45. These results led us to propose that a flavin-dependent monooxygenase or a cytochrome P450-dependent monooxygenase rather than a molybdenum hydroxylase catalyzed the initial hydroxylation step and that a cytochrome P450 enzyme is responsible for the transformation of HDMP in the second step.

  1. pS2 and response to adjuvant hormone therapy in primary breast cancer.

    PubMed Central

    Spyratos, F.; Andrieu, C.; Hacène, K.; Chambon, P.; Rio, M. C.

    1994-01-01

    We reviewed 319 primary breast tumours for cytosolic pS2 content, with a median follow-up of 6 years. pS2 status correlated positively with oestradiol and progesterone receptors and negatively with Scarff, Bloom and Richardson grade. pS2 positivity was associated with longer overall survival, particularly in patients who received hormone therapy, in whom pS2 status was also predictive of the response to therapy. PMID:8297741

  2. MoS2 -Based Tactile Sensor for Electronic Skin Applications.

    PubMed

    Park, Minhoon; Park, Yong Ju; Chen, Xiang; Park, Yon-Kyu; Kim, Min-Seok; Ahn, Jong-Hyun

    2016-04-01

    A conformal tactile sensor based on MoS2 and graphene is demonstrated. The MoS2 tactile sensor exhibits excellent sensitivity, high uniformity, and good repeatability in terms of various strains. In addition, the outstanding flexibility enables the MoS2 strain tactile sensor to be realized conformally on a finger tip. The MoS2 -based tactile sensor can be utilized for wearable electronics, such as electronic skin. PMID:26833813

  3. Excited state structural dynamics in higher lying electronic states: S2 state of malachite green

    NASA Astrophysics Data System (ADS)

    Laptenok, Sergey P.; Addison, Kiri; Heisler, Ismael A.; Meech, Stephen R.

    2014-06-01

    The S2 fluorescence of malachite green is measured with sub 100 fs time resolution. Ultrafast spectral dynamics in the S2 state preceding S2 decay are resolved. Measurements in different solvents show that these sub 100 fs dynamics are insensitive to medium polarity and viscosity. They are thus assigned to ultrafast structural evolution between the S2 Franck-Condon and equilibrium configurations.

  4. Defects Engineered Monolayer MoS2 for Improved Hydrogen Evolution Reaction

    DOE PAGESBeta

    Ye, Gonglan; Gong, Yongji; Lin, Junhao; Li, Bo; He, Yongmin; Pantelides, Sokrates T.; Zhou, Wu; Vajtai, Robert; Ajayan, Pulickel M.

    2016-01-13

    MoS2 is a promising, low-cost material for electrochemical hydrogen production due to its high activity and stability during the reaction. Our work represents an easy method to increase the hydrogen production in electrochemical reaction of MoS2 via defect engineering, and helps to understand the catalytic properties of MoS2.

  5. Morphology engineering of monolayer MoS2 by adjusting chemical environment during growth

    NASA Astrophysics Data System (ADS)

    Cao, Yingjie; Luo, Xingfang; Yuan, Cailei; Han, Shuming; Yu, Ting; Yang, Yong; Li, Qinliang

    2015-11-01

    The precise control of the morphology of monolayer MoS2 is of particular importance for their potential applications and device performance. In this work, we present an experimental method to study the shape evolution of the chemical vapor deposition (CVD) grown MoS2 flakes. We observed that the morphology of monolayer MoS2 flakes transformed from truncated triangular shape to triangular shape by increasing the stoichiometric ratio of S:Mo, and consequently tailor the optical properties of MoS2 flakes. The results suggest the possibility to engineer the morphology of monolayer MoS2 by adjusting the chemical environment during growth.

  6. Single step, bulk synthesis of engineered MoS2 quantum dots for multifunctional electrocatalysis

    NASA Astrophysics Data System (ADS)

    Tadi, Kiran Kumar; Palve, Anil M.; Pal, Shubhadeep; Sudeep, P. M.; Narayanan, Tharangattu N.

    2016-07-01

    Bi- or tri- functional catalysts based on atomic layers are receiving tremendous scientific attention due to their importance in various energy technologies. Recent studies on molybdenum disulphide (MoS2) nanosheets revealed that controlling the edge states and doping/modifying with suitable elements are highly important in tuning the catalytic activities of MoS2. Here we report a bulk, single step method to synthesize metal modified MoS2 quantum dots (QDs). Three elements, namely Fe, Mg and Li, are chosen to study the effects of dopants in the catalytic activities of MoS2. Fe and Mg are found to act like dopants in the MoS2 lattice forming respective doped MoS2 QDs, while Li formed an intercalated MoS2 QD. The efficacy and tunability of these luminescent doped QDs towards various electrocatalytic activities (hydrogen evolution reaction, oxygen evolution reaction and oxygen reduction action) are reported here.

  7. Layer-by-layer self-assembly of polyelectrolyte functionalized MoS2 nanosheets.

    PubMed

    Shen, Jianfeng; Pei, Yu; Dong, Pei; Ji, Jin; Cui, Zheng; Yuan, Junhua; Baines, Robert; Ajayan, Pulickel M; Ye, Mingxin

    2016-05-01

    Few-layered polyelectrolyte functionalized MoS2 nanosheets were obtained for the first time through in situ polymerization of MoS2 nanosheets with poly(acrylic acid) and poly(acrylamide), both of which demonstrated excellent dispersibility and stability in water. After designing and optimizing the components of this series of polyelectrolyte functionalized MoS2 nanosheets, by exploiting the electrostatic interactions present in the modified MoS2 nanosheets, we further created a series of layer-by-layer (LBL) self-assembling MoS2-based films. To this end, uniform MoS2 nanosheet-based LBL films were precisely deposited on substrates such as quartz, silicon, and ITO. The polyelectrolyte functionalized MoS2 nanosheet assembled LBL film-modified electrodes demonstrated enhanced electrocatalytic activity for H2O2. As such, they are conducive to efficient sensors and advanced biosensing systems.

  8. Single step, bulk synthesis of engineered MoS2 quantum dots for multifunctional electrocatalysis.

    PubMed

    Tadi, Kiran Kumar; Palve, Anil M; Pal, Shubhadeep; Sudeep, P M; Narayanan, Tharangattu N

    2016-07-01

    Bi- or tri- functional catalysts based on atomic layers are receiving tremendous scientific attention due to their importance in various energy technologies. Recent studies on molybdenum disulphide (MoS2) nanosheets revealed that controlling the edge states and doping/modifying with suitable elements are highly important in tuning the catalytic activities of MoS2. Here we report a bulk, single step method to synthesize metal modified MoS2 quantum dots (QDs). Three elements, namely Fe, Mg and Li, are chosen to study the effects of dopants in the catalytic activities of MoS2. Fe and Mg are found to act like dopants in the MoS2 lattice forming respective doped MoS2 QDs, while Li formed an intercalated MoS2 QD. The efficacy and tunability of these luminescent doped QDs towards various electrocatalytic activities (hydrogen evolution reaction, oxygen evolution reaction and oxygen reduction action) are reported here.

  9. Single step, bulk synthesis of engineered MoS2 quantum dots for multifunctional electrocatalysis.

    PubMed

    Tadi, Kiran Kumar; Palve, Anil M; Pal, Shubhadeep; Sudeep, P M; Narayanan, Tharangattu N

    2016-07-01

    Bi- or tri- functional catalysts based on atomic layers are receiving tremendous scientific attention due to their importance in various energy technologies. Recent studies on molybdenum disulphide (MoS2) nanosheets revealed that controlling the edge states and doping/modifying with suitable elements are highly important in tuning the catalytic activities of MoS2. Here we report a bulk, single step method to synthesize metal modified MoS2 quantum dots (QDs). Three elements, namely Fe, Mg and Li, are chosen to study the effects of dopants in the catalytic activities of MoS2. Fe and Mg are found to act like dopants in the MoS2 lattice forming respective doped MoS2 QDs, while Li formed an intercalated MoS2 QD. The efficacy and tunability of these luminescent doped QDs towards various electrocatalytic activities (hydrogen evolution reaction, oxygen evolution reaction and oxygen reduction action) are reported here. PMID:27231837

  10. CuFeS2 Quantum Dots and Highly Luminescent CuFeS2 Based Core/Shell Structures: Synthesis, Tunability, and Photophysics.

    PubMed

    Bhattacharyya, Biswajit; Pandey, Anshu

    2016-08-17

    We report the synthesis of copper iron sulfide (CuFeS2) quantum dots (QDs). These materials exhibit a tunable band gap that spans the range 0.5-2 eV (600-2500 nm). Although the as-prepared material is nonemissive, CuFeS2/CdS core/shell structures are shown to exhibit quantum yields that exceed 80%. Like other members of the I-III-VI2 family QDs, CuFeS2 based nanoparticles exhibit a long-lived emission that is significantly red-shifted compared to the band gap. CuFeS2 QDs are unique in terms of their composition. In particular, these QDs are the only band-gap-tunable infrared chromophore composed entirely of elements with atomic numbers less than 30. PMID:27447297

  11. Measurement of absolute cross sections for excitation of the 2s(2) S-1 -> 2s2p P-1 degrees transition in O+4

    NASA Technical Reports Server (NTRS)

    Smith, S. J.; Djuric, N.; Lozano, J. A.; Berrington, K. A.; Chutjian, A.

    2005-01-01

    Experimental cross sections are reported for the 1s(2)2s(2) S-1 -> 1s(2)2s2p P-1(o) transition in O+4 located at 19.689 eV. Use is made of the electron energy-loss method, using a merged electron-ion beam geometry. The center-of-mass interaction energies for the measurements in the S-1 -> P-1(o) transition are in the range 18 eV ( below the threshold) to 30 eV. Data are compared with other previous electron energy-loss measurements and with results of a 26 term R-matrix calculation that includes fine structure explicitly via the Breit-Pauli Hamiltonian. Clear resonance enhancement is observed in all experimental and theoretical results near the threshold for this S-1 -> P-1(o) transition.

  12. Earth-Abundant Metal Pyrites (FeS2, CoS2, NiS2, and Their Alloys) for Highly Efficient Hydrogen Evolution and Polysulfide Reduction Electrocatalysis.

    PubMed

    Faber, Matthew S; Lukowski, Mark A; Ding, Qi; Kaiser, Nicholas S; Jin, Song

    2014-09-18

    Many materials have been explored as potential hydrogen evolution reaction (HER) electrocatalysts to generate clean hydrogen fuel via water electrolysis, but none so far compete with the highly efficient and stable (but cost prohibitive) noble metals. Similarly, noble metals often excel as electrocatalytic counter electrode materials in regenerative liquid-junction photoelectrochemical solar cells, such as quantum dot-sensitized solar cells (QDSSCs) that employ the sulfide/polysulfide redox electrolyte as the hole mediator. Here, we systematically investigate thin films of the earth-abundant pyrite-phase transition metal disulfides (FeS2, CoS2, NiS2, and their alloys) as promising alternative electrocatalysts for both the HER and polysulfide reduction. Their electrocatalytic activity toward the HER is correlated to their composition and morphology. The emergent trends in their performance suggest that cobalt plays an important role in facilitating the HER, with CoS2 exhibiting highest overall performance. Additionally, we demonstrate the high activity of the transition metal pyrites toward polysulfide reduction and highlight the particularly high intrinsic activity of NiS2, which could enable improved QDSSC performance. Furthermore, structural disorder introduced by alloying different transition metal pyrites could increase their areal density of active sites for catalysis, leading to enhanced performance. PMID:25247028

  13. Earth-Abundant Metal Pyrites (FeS2, CoS2, NiS2, and Their Alloys) for Highly Efficient Hydrogen Evolution and Polysulfide Reduction Electrocatalysis.

    PubMed

    Faber, Matthew S; Lukowski, Mark A; Ding, Qi; Kaiser, Nicholas S; Jin, Song

    2014-09-18

    Many materials have been explored as potential hydrogen evolution reaction (HER) electrocatalysts to generate clean hydrogen fuel via water electrolysis, but none so far compete with the highly efficient and stable (but cost prohibitive) noble metals. Similarly, noble metals often excel as electrocatalytic counter electrode materials in regenerative liquid-junction photoelectrochemical solar cells, such as quantum dot-sensitized solar cells (QDSSCs) that employ the sulfide/polysulfide redox electrolyte as the hole mediator. Here, we systematically investigate thin films of the earth-abundant pyrite-phase transition metal disulfides (FeS2, CoS2, NiS2, and their alloys) as promising alternative electrocatalysts for both the HER and polysulfide reduction. Their electrocatalytic activity toward the HER is correlated to their composition and morphology. The emergent trends in their performance suggest that cobalt plays an important role in facilitating the HER, with CoS2 exhibiting highest overall performance. Additionally, we demonstrate the high activity of the transition metal pyrites toward polysulfide reduction and highlight the particularly high intrinsic activity of NiS2, which could enable improved QDSSC performance. Furthermore, structural disorder introduced by alloying different transition metal pyrites could increase their areal density of active sites for catalysis, leading to enhanced performance.

  14. Earth-Abundant Metal Pyrites (FeS2, CoS2, NiS2, and Their Alloys) for Highly Efficient Hydrogen Evolution and Polysulfide Reduction Electrocatalysis

    PubMed Central

    2015-01-01

    Many materials have been explored as potential hydrogen evolution reaction (HER) electrocatalysts to generate clean hydrogen fuel via water electrolysis, but none so far compete with the highly efficient and stable (but cost prohibitive) noble metals. Similarly, noble metals often excel as electrocatalytic counter electrode materials in regenerative liquid-junction photoelectrochemical solar cells, such as quantum dot-sensitized solar cells (QDSSCs) that employ the sulfide/polysulfide redox electrolyte as the hole mediator. Here, we systematically investigate thin films of the earth-abundant pyrite-phase transition metal disulfides (FeS2, CoS2, NiS2, and their alloys) as promising alternative electrocatalysts for both the HER and polysulfide reduction. Their electrocatalytic activity toward the HER is correlated to their composition and morphology. The emergent trends in their performance suggest that cobalt plays an important role in facilitating the HER, with CoS2 exhibiting highest overall performance. Additionally, we demonstrate the high activity of the transition metal pyrites toward polysulfide reduction and highlight the particularly high intrinsic activity of NiS2, which could enable improved QDSSC performance. Furthermore, structural disorder introduced by alloying different transition metal pyrites could increase their areal density of active sites for catalysis, leading to enhanced performance. PMID:25247028

  15. A Facile Way to Fabricate High-Performance Solution-Processed n-MoS2/p-MoS2 Bilayer Photodetectors

    NASA Astrophysics Data System (ADS)

    Ye, Jian; Li, Xueliang; Zhao, Jianjun; Mei, Xuelan; Li, Qian

    2015-11-01

    Two-dimensional (2D) material has many advantages including high carrier mobilities and conductivity, high optical transparency, excellent mechanical flexibility, and chemical stability, which made 2D material an ideal material for various optoelectronic devices. Here, we developed a facile method of preparing MoS2 nanosheets followed by a facile liquid exfoliation method via ethyl cellulose-assisted doping and utilizing a plasma-induced p-doping approach to generate t effectively the partially oxided MoS2 (p-MoS2) nanosheets from the pristine n-type nanosheets. Moreover, an n-p junction type MoS2 photodetector device with the built-in potentials to separate the photogenerated charges is able to significantly improved visible light response. We have fabricated photodetector devices consisting of a vertically stacked indium tin oxide (ITO)/pristine n-type MoS2 nanosheets/p-MoS2/Ag structure, which exhibit reasonably good performance illumination, as well as high current values in the range of visible wavelength from 350 to 600 nm. We believe that this work provides important scientific insights for photoelectric response properties of emerging atomically layered 2D materials for photovoltaic and other optoelectronic applications.

  16. Confocal absorption spectral imaging of MoS2: optical transitions depending on the atomic thickness of intrinsic and chemically doped MoS2.

    PubMed

    Dhakal, Krishna P; Duong, Dinh Loc; Lee, Jubok; Nam, Honggi; Kim, Minsu; Kan, Min; Lee, Young Hee; Kim, Jeongyong

    2014-11-01

    We performed a nanoscale confocal absorption spectral imaging to obtain the full absorption spectra (over the range 1.5-3.2 eV) within regions having different numbers of layers and studied the variation of optical transition depending on the atomic thickness of the MoS2 film. Three distinct absorption bands corresponding to A and B excitons and a high-energy background (BG) peak at 2.84 eV displayed a gradual redshift as the MoS2 film thickness increased from the monolayer, to the bilayer, to the bulk MoS2 and this shift was attributed to the reduction of the gap energy in the Brillouin zone at the K-point as the atomic thickness increased. We also performed n-type chemical doping of MoS2 films using reduced benzyl viologen (BV) and the confocal absorption spectra modified by the doping showed a strong dependence on the atomic thickness: A and B exciton peaks were greatly quenched in the monolayer MoS2 while much less effect was shown in larger thickness and the BG peak either showed very small quenching for 1 L MoS2 or remained constant for larger thicknesses. Our results indicate that confocal absorption spectral imaging can provide comprehensive information on optical transitions of microscopic size intrinsic and doped two-dimensional layered materials.

  17. A Facile Way to Fabricate High-Performance Solution-Processed n-MoS2/p-MoS2 Bilayer Photodetectors.

    PubMed

    Ye, Jian; Li, Xueliang; Zhao, Jianjun; Mei, Xuelan; Li, Qian

    2015-12-01

    Two-dimensional (2D) material has many advantages including high carrier mobilities and conductivity, high optical transparency, excellent mechanical flexibility, and chemical stability, which made 2D material an ideal material for various optoelectronic devices. Here, we developed a facile method of preparing MoS2 nanosheets followed by a facile liquid exfoliation method via ethyl cellulose-assisted doping and utilizing a plasma-induced p-doping approach to generate t effectively the partially oxided MoS2 (p-MoS2) nanosheets from the pristine n-type nanosheets. Moreover, an n-p junction type MoS2 photodetector device with the built-in potentials to separate the photogenerated charges is able to significantly improved visible light response. We have fabricated photodetector devices consisting of a vertically stacked indium tin oxide (ITO)/pristine n-type MoS2 nanosheets/p-MoS2/Ag structure, which exhibit reasonably good performance illumination, as well as high current values in the range of visible wavelength from 350 to 600 nm. We believe that this work provides important scientific insights for photoelectric response properties of emerging atomically layered 2D materials for photovoltaic and other optoelectronic applications.

  18. Magnetism by interfacial hybridization and p-type doping of MoS(2) in Fe(4)N/MoS(2) superlattices: a first-principles study.

    PubMed

    Feng, Nan; Mi, Wenbo; Cheng, Yingchun; Guo, Zaibing; Schwingenschlögl, Udo; Bai, Haili

    2014-03-26

    Magnetic and electronic properties of Fe4N(111)/MoS2(√3 × √3) superlattices are investigated by first-principles calculations, considering two models: (I) Fe(I)Fe(II)-S and (II) N-S interfaces, each with six stacking configurations. In model I, strong interfacial hybridization between Fe(I)/Fe(II) and S results in magnetism of monolayer MoS2, with a magnetic moment of 0.33 μB for Mo located on top of Fe(I). For model II, no magnetism is induced due to weak N-S interfacial bonding, and the semiconducting nature of monolayer MoS2 is preserved. Charge transfer between MoS2 and N results in p-type MoS2 with Schottky barrier heights of 0.5-0.6 eV. Our results demonstrate that the interfacial geometry and hybridization can be used to tune the magnetism and doping in Fe4N(111)/MoS2(√3 × √3) superlattices.

  19. Interface Engineering of MoS2 /Ni3 S2 Heterostructures for Highly Enhanced Electrochemical Overall-Water-Splitting Activity.

    PubMed

    Zhang, Jian; Wang, Tao; Pohl, Darius; Rellinghaus, Bernd; Dong, Renhao; Liu, Shaohua; Zhuang, Xiaodong; Feng, Xinliang

    2016-06-01

    To achieve sustainable production of H2 fuel through water splitting, low-cost electrocatalysts for the hydrogen-evolution reaction (HER) and the oxygen-evolution reaction (OER) are required to replace Pt and IrO2 catalysts. Herein, for the first time, we present the interface engineering of novel MoS2 /Ni3 S2 heterostructures, in which abundant interfaces are formed. For OER, such MoS2 /Ni3 S2 heterostructures show an extremely low overpotential of ca. 218 mV at 10 mA cm(-2) , which is superior to that of the state-of-the-art OER electrocatalysts. Using MoS2 /Ni3 S2 heterostructures as bifunctional electrocatalysts, an alkali electrolyzer delivers a current density of 10 mA cm(-2) at a very low cell voltage of ca. 1.56 V. In combination with DFT calculations, this study demonstrates that the constructed interfaces synergistically favor the chemisorption of hydrogen and oxygen-containing intermediates, thus accelerating the overall electrochemical water splitting.

  20. Stability and Electronic Properties of Hydrogenated MoS2 Monolayer: A First-Principles Study.

    PubMed

    Zhang, Weibin; Zhang, Zhijun; Yang, Woochul

    2015-10-01

    First-principles total energy studies are used to investigate the stability of hydrogenated MoS2 monolayer (MoS2-Hx) (x = 1-8), which is a compound with different numbers of H atoms adsorbed on the MoS2 surface. Energetically, the S-top side of the MoS2 is found to be the most favorable for H-adsorption. H2S and graphene are well-known to be stable, and MoS2-Hx is predicted to be even more stable because its binding energy is lower than that of H2S and its formation energy and adsorption energy are lower than those of graphene. The analysis of the electronic density distribution and the orbital hybrid also shows that MoS2-Hx forms stable structures. In addition, the influence of the number of the adsorbed H-atoms in the MoS2-Hx on the electronic structure of the compound is also investigated. The MoS2-Hx band structure exhibits a dispersion and the MoS2-Hx band gap gradually decreases from 1.72 eV to 0 eV as the number of adsorbed H atoms increases. The corresponding work function increases as a result of the strengthening of the dipole moment formed between the H atoms that are adsorbed and the hydrogenated MoS2.