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Yin S, Li Y, Hou J. Expression of the two-component regulator StyS/StyR enhanced transcription of the styrene monooxygenase gene styAB and indigo biosynthesis in Escherichia coli. Enzyme Microb Technol 2024; 174:110381. [PMID: 38134734 DOI: 10.1016/j.enzmictec.2023.110381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 12/24/2023]
Abstract
Indigo, an economically important dye, could be biosynthesized from indole by catalysis of the styrene monooxygenase StyAB. To enhance indigo biosynthesis, the styAB gene and its transcription regulator gene styS/styR in styrene catabolism were cloned from Pseudomonas putida and coexpressed in Escherichia coli. The presence of the intact regulator gene styS/styR dramatically increased the transcriptional levels of styA and styB by approximately 120-fold in the recombinant strain SRAB2 with coexpression of styS/styR and styAB compared to the control strain ABST with solo expression of styAB. A yield of 67.6 mg/L indigo was detected in strain SRAB2 after 24 h of fermentation with 120 μg/mL indole, which was approximately 14-fold higher than that in the control strain ABST. The maximum yield of indigo was produced from 160 μg/mL indole in fermentation of strain SRAB2. However, the addition of styrene to the media significantly inhibited the transcription of styA and styB and consequent indigo biosynthesis in recombinant E. coli strains. Furthermore, the substitution of indole with tryptophan as the fermentation substrate remarkably boosted indigo production, and the maximal yield of 565.6 mg/L was detected in strain SRAB2 in fermentation with 1.2 mg/mL tryptophan. The results revealed that the regulation of styAB transcription by the two-component regulator StyS/StyR in styrene catabolism in P. putida was effective in E. coli, which provided a new strategy for the development of engineered E. coli strains with the capacity for highly efficient indigo production.
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Affiliation(s)
- Sheng Yin
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology & Business University, Beijing 100048, China; Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology & Business University, Beijing 100048, China; School of Food & Health, Beijing Technology & Business University, Beijing 100048, China.
| | - Yujie Li
- School of Food & Health, Beijing Technology & Business University, Beijing 100048, China
| | - Jialing Hou
- School of Food & Health, Beijing Technology & Business University, Beijing 100048, China
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García-Franco A, Godoy P, Duque E, Ramos JL. Engineering styrene biosynthesis: designing a functional trans-cinnamic acid decarboxylase in Pseudomonas. Microb Cell Fact 2024; 23:69. [PMID: 38419048 PMCID: PMC10903017 DOI: 10.1186/s12934-024-02341-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 02/17/2024] [Indexed: 03/02/2024] Open
Abstract
We are interested in converting second generation feedstocks into styrene, a valuable chemical compound, using the solvent-tolerant Pseudomonas putida DOT-T1E as a chassis. Styrene biosynthesis takes place from L-phenylalanine in two steps: firstly, L-phenylalanine is converted into trans-cinnamic acid (tCA) by PAL enzymes and secondly, a decarboxylase yields styrene. This study focuses on designing and synthesizing a functional trans-cinnamic acid decarboxylase in Pseudomonas putida. To achieve this, we utilized the "wholesale" method, involving deriving two consensus sequences from multi-alignments of homologous yeast ferulate decarboxylase FDC1 sequences with > 60% and > 50% identity, respectively. These consensus sequences were used to design Pseudomonas codon-optimized genes named psc1 and psd1 and assays were conducted to test the activity in P. putida. Our results show that the PSC1 enzyme effectively decarboxylates tCA into styrene, whilst the PSD1 enzyme does not. The optimal conditions for the PSC1 enzyme, including pH and temperature were determined. The L-phenylalanine DOT-T1E derivative Pseudomonas putida CM12-5 that overproduces L-phenylalanine was used as the host for expression of pal/psc1 genes to efficiently convert L-phenylalanine into tCA, and the aromatic carboxylic acid into styrene. The highest styrene production was achieved when the pal and psc1 genes were co-expressed as an operon in P. putida CM12-5. This construction yielded styrene production exceeding 220 mg L-1. This study serves as a successful demonstration of our strategy to tailor functional enzymes for novel host organisms, thereby broadening their metabolic capabilities. This breakthrough opens the doors to the synthesis of aromatic hydrocarbons using Pseudomonas putida as a versatile biofactory.
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Affiliation(s)
- Ana García-Franco
- Estación Experimental del Zaidín. Consejo Superior de Investigaciones Científicas, c/ Profesor Albareda 1, 18008, Granada, Spain
- Programa de Doctorado en Bioquímica y Biología Molecular, Universidad de Granada, Granada, Spain
| | - Patricia Godoy
- Estación Experimental del Zaidín. Consejo Superior de Investigaciones Científicas, c/ Profesor Albareda 1, 18008, Granada, Spain
| | - Estrella Duque
- Estación Experimental del Zaidín. Consejo Superior de Investigaciones Científicas, c/ Profesor Albareda 1, 18008, Granada, Spain
| | - Juan L Ramos
- Estación Experimental del Zaidín. Consejo Superior de Investigaciones Científicas, c/ Profesor Albareda 1, 18008, Granada, Spain.
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Paciello F, Pisani A, Rolesi R, Montuoro R, Mohamed-Hizam V, Boni G, Ripoli C, Galli J, Sisto R, Fetoni AR, Grassi C. Oxidative stress and inflammation cause auditory system damage via glial cell activation and dysregulated expression of gap junction proteins in an experimental model of styrene-induced oto/neurotoxicity. J Neuroinflammation 2024; 21:4. [PMID: 38178142 PMCID: PMC10765700 DOI: 10.1186/s12974-023-02996-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 12/13/2023] [Indexed: 01/06/2024] Open
Abstract
BACKGROUND Redox imbalance and inflammation have been proposed as the principal mechanisms of damage in the auditory system, resulting in functional alterations and hearing loss. Microglia and astrocytes play a crucial role in mediating oxidative/inflammatory injury in the central nervous system; however, the role of glial cells in the auditory damage is still elusive. OBJECTIVES Here we investigated glial-mediated responses to toxic injury in peripheral and central structures of the auditory pathway, i.e., the cochlea and the auditory cortex (ACx), in rats exposed to styrene, a volatile compound with well-known oto/neurotoxic properties. METHODS Male adult Wistar rats were treated with styrene (400 mg/kg daily for 3 weeks, 5/days a week). Electrophysiological, morphological, immunofluorescence and molecular analyses were performed in both the cochlea and the ACx to evaluate the mechanisms underlying styrene-induced oto/neurotoxicity in the auditory system. RESULTS We showed that the oto/neurotoxic insult induced by styrene increases oxidative stress in both cochlea and ACx. This was associated with macrophages and glial cell activation, increased expression of inflammatory markers (i.e., pro-inflammatory cytokines and chemokine receptors) and alterations in connexin (Cxs) and pannexin (Panx) expression, likely responsible for dysregulation of the microglia/astrocyte network. Specifically, we found downregulation of Cx26 and Cx30 in the cochlea, and high level of Cx43 and Panx1 in the ACx. CONCLUSIONS Collectively, our results provide novel evidence on the role of immune and glial cell activation in the oxidative/inflammatory damage induced by styrene in the auditory system at both peripheral and central levels, also involving alterations of gap junction networks. Our data suggest that targeting glial cells and connexin/pannexin expression might be useful to attenuate oxidative/inflammatory damage in the auditory system.
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Affiliation(s)
- Fabiola Paciello
- Department of Neuroscience, Università Cattolica del Sacro Cuore, 00168, Rome, Italy
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168, Rome, Italy
| | - Anna Pisani
- Department of Head and Neck Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Rolando Rolesi
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168, Rome, Italy
- Department of Head and Neck Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Raffaele Montuoro
- Department of Head and Neck Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | | | - Giammarco Boni
- Department of Neuroscience, Università Cattolica del Sacro Cuore, 00168, Rome, Italy
| | - Cristian Ripoli
- Department of Neuroscience, Università Cattolica del Sacro Cuore, 00168, Rome, Italy
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168, Rome, Italy
| | - Jacopo Galli
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168, Rome, Italy
- Department of Head and Neck Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Renata Sisto
- Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, Italian Workers' Compensation Authority (INAIL), Monte Porzio Catone, Rome, Italy
| | - Anna Rita Fetoni
- Department of Neuroscience, Unit of Audiology, Università Degli Studi di Napoli Federico II, Naples, Italy.
| | - Claudio Grassi
- Department of Neuroscience, Università Cattolica del Sacro Cuore, 00168, Rome, Italy
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168, Rome, Italy
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Asor R, Singaram SW, Levi-Kalisman Y, Hagan MF, Raviv U. Effect of ionic strength on the assembly of simian vacuolating virus capsid protein around poly(styrene sulfonate). Eur Phys J E Soft Matter 2023; 46:107. [PMID: 37917241 DOI: 10.1140/epje/s10189-023-00363-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 10/09/2023] [Indexed: 11/04/2023]
Abstract
Virus-like particles (VLPs) are noninfectious nanocapsules that can be used for drug delivery or vaccine applications. VLPs can be assembled from virus capsid proteins around a condensing agent, such as RNA, DNA, or a charged polymer. Electrostatic interactions play an important role in the assembly reaction. VLPs assemble from many copies of capsid protein, with a combinatorial number of intermediates. Hence, the mechanism of the reaction is poorly understood. In this paper, we combined solution small-angle X-ray scattering (SAXS), cryo-transmission electron microscopy (TEM), and computational modeling to determine the effect of ionic strength on the assembly of Simian Vacuolating Virus 40 (SV40)-like particles. We mixed poly(styrene sulfonate) with SV40 capsid protein pentamers at different ionic strengths. We then characterized the assembly product by SAXS and cryo-TEM. To analyze the data, we performed Langevin dynamics simulations using a coarse-grained model that revealed incomplete, asymmetric VLP structures consistent with the experimental data. We found that close to physiological ionic strength, [Formula: see text] VLPs coexisted with VP1 pentamers. At lower or higher ionic strengths, incomplete particles coexisted with pentamers and [Formula: see text] particles. Including the simulated structures was essential to explain the SAXS data in a manner that is consistent with the cryo-TEM images.
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Affiliation(s)
- Roi Asor
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 9190401, Jerusalem, Israel
| | - Surendra W Singaram
- Department of Physics, Brandeis University, 415 South Street, Waltham, 02453, MA, USA
| | - Yael Levi-Kalisman
- Institute of Life Sciences and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 9190401, Jerusalem, Israel
| | - Michael F Hagan
- Department of Physics, Brandeis University, 415 South Street, Waltham, 02453, MA, USA.
| | - Uri Raviv
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 9190401, Jerusalem, Israel.
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Tallandier V, Merlen L, Chalansonnet M, Boucard S, Thomas A, Venet T, Pouyatos B. Three-dimensional cultured ampullae from rats as a screening tool for vestibulotoxicity: Proof of concept using styrene. Toxicology 2023; 495:153600. [PMID: 37516305 DOI: 10.1016/j.tox.2023.153600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 07/24/2023] [Accepted: 07/26/2023] [Indexed: 07/31/2023]
Abstract
Numerous ototoxic drugs, such as some antibiotics and chemotherapeutics, are both cochleotoxic and vestibulotoxic (causing hearing loss and vestibular disorders). However, the impact of some industrial cochleotoxic compounds on the vestibular receptor, if any, remains unknown. As in vivo studies are long and expensive, there is considerable need for predictive and cost-effective in vitro models to test ototoxicity. Here, we present an organotypic model of cultured ampullae harvested from rat neonates. When cultured in a gelatinous matrix, ampulla explants form an enclosed compartment that progressively fills with a high-potassium (K+) endolymph-like fluid. Morphological analyses confirmed the presence of a number of cell types, sensory epithelium, secretory cells, and canalar cells. Treatments with inhibitors of potassium transporters demonstrated that the potassium homeostasis mechanisms were functional. To assess the potential of this model to reveal the toxic effects of chemicals, explants were exposed for either 2 or 72 h to styrene at a range of concentrations (0.5-1 mM). In the 2-h exposure condition, K+ concentration was significantly reduced, but ATP levels remained stable, and no histological damage was visible. After 72 h exposure, variations in K+ concentration were associated with histological damage and decreased ATP levels. This in vitro 3D neonatal rat ampulla model therefore represents a reliable and rapid means to assess the toxic properties of industrial compounds on this vestibular tissue, and can be used to investigate the specific underlying mechanisms.
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Affiliation(s)
- V Tallandier
- French Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Toxicology and Biomonitoring Division, Vandoeuvre les Nancy, France; DevAH EA 3450 - Développement, Adaptation et Handicap. Régulations cardio-respiratoires et de la motricité-Université de Lorraine, F-54500 Vandœuvre, France
| | - L Merlen
- French Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Toxicology and Biomonitoring Division, Vandoeuvre les Nancy, France
| | - M Chalansonnet
- French Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Toxicology and Biomonitoring Division, Vandoeuvre les Nancy, France.
| | - S Boucard
- French Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Toxicology and Biomonitoring Division, Vandoeuvre les Nancy, France
| | - A Thomas
- French Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Toxicology and Biomonitoring Division, Vandoeuvre les Nancy, France
| | - T Venet
- French Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Toxicology and Biomonitoring Division, Vandoeuvre les Nancy, France; DevAH EA 3450 - Développement, Adaptation et Handicap. Régulations cardio-respiratoires et de la motricité-Université de Lorraine, F-54500 Vandœuvre, France
| | - B Pouyatos
- French Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Toxicology and Biomonitoring Division, Vandoeuvre les Nancy, France; DevAH EA 3450 - Développement, Adaptation et Handicap. Régulations cardio-respiratoires et de la motricité-Université de Lorraine, F-54500 Vandœuvre, France
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Zhou R, Zhang S, Nguyen HT, Ding H, Gaffney A, Kappes JC, Smith AB, Sodroski JG. Conformations of Human Immunodeficiency Virus Envelope Glycoproteins in Detergents and Styrene-Maleic Acid Lipid Particles. J Virol 2023; 97:e0032723. [PMID: 37255444 PMCID: PMC10308955 DOI: 10.1128/jvi.00327-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 05/10/2023] [Indexed: 06/01/2023] Open
Abstract
The mature human immunodeficiency virus (HIV) envelope glycoprotein (Env) trimer, which consists of noncovalently associated gp120 exterior and gp41 transmembrane subunits, mediates virus entry into cells. The pretriggered (State-1) Env conformation is the major target for broadly neutralizing antibodies (bNAbs), whereas receptor-induced downstream Env conformations elicit immunodominant, poorly neutralizing antibody (pNAb) responses. To examine the contribution of membrane anchorage to the maintenance of the metastable pretriggered Env conformation, we compared wild-type and State-1-stabilized Envs solubilized in detergents or in styrene-maleic acid (SMA) copolymers. SMA directly incorporates membrane lipids and resident membrane proteins into lipid nanoparticles (styrene-maleic acid lipid particles [SMALPs]). The integrity of the Env trimer in SMALPs was maintained at both 4°C and room temperature. In contrast, Envs solubilized in Cymal-5, a nonionic detergent, were unstable at room temperature, although their stability was improved at 4°C and/or after incubation with the entry inhibitor BMS-806. Envs solubilized in ionic detergents were relatively unstable at either temperature. Comparison of Envs solubilized in Cymal-5 and SMA at 4°C revealed subtle differences in bNAb binding to the gp41 membrane-proximal external region, consistent with these distinct modes of Env solubilization. Otherwise, the antigenicity of the Cymal-5- and SMA-solubilized Envs was remarkably similar, both in the absence and in the presence of BMS-806. However, both solubilized Envs were recognized differently from the mature membrane Env by specific bNAbs and pNAbs. Thus, detergent-based and detergent-free solubilization at 4°C alters the pretriggered membrane Env conformation in consistent ways, suggesting that Env assumes default conformations when its association with the membrane is disrupted. IMPORTANCE The human immunodeficiency virus (HIV) envelope glycoproteins (Envs) in the viral membrane mediate virus entry into the host cell and are targeted by neutralizing antibodies elicited by natural infection or vaccines. Detailed studies of membrane proteins rely on purification procedures that allow the proteins to maintain their natural conformation. In this study, we show that a styrene-maleic acid (SMA) copolymer can extract HIV-1 Env from a membrane without the use of detergents. The Env in SMA is more stable at room temperature than Env in detergents. The purified Env in SMA maintains many but not all of the characteristics expected of the natural membrane Env. Our results underscore the importance of the membrane environment to the native conformation of HIV-1 Env. Purification methods that bypass the need for detergents could be useful tools for future studies of HIV-1 Env structure and its interaction with receptors and antibodies.
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Affiliation(s)
- Rong Zhou
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Shijian Zhang
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Hanh T. Nguyen
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Haitao Ding
- Department of Medicine, University of Alabama at Birmingham, Alabama, USA
- Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, Alabama, USA
| | - Althea Gaffney
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - John C. Kappes
- Department of Medicine, University of Alabama at Birmingham, Alabama, USA
- Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, Alabama, USA
| | - Amos B. Smith
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Joseph G. Sodroski
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
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Zimmerling J, Oelschlägel M, Großmann C, Voitel M, Schlömann M, Tischler D. Biochemical Characterization of Phenylacetaldehyde Dehydrogenases from Styrene-degrading Soil Bacteria. Appl Biochem Biotechnol 2021; 193:650-667. [PMID: 33106986 PMCID: PMC7910268 DOI: 10.1007/s12010-020-03421-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 09/11/2020] [Indexed: 10/24/2022]
Abstract
Four phenylacetaldehyde dehydrogenases (designated as FeaB or StyD) originating from styrene-degrading soil bacteria were biochemically investigated. In this study, we focused on the Michaelis-Menten kinetics towards the presumed native substrate phenylacetaldehyde and the obviously preferred co-substrate NAD+. Furthermore, the substrate specificity on four substituted phenylacetaldehydes and the co-substrate preference were studied. Moreover, these enzymes were characterized with respect to their temperature as well as long-term stability. Since aldehyde dehydrogenases are known to show often dehydrogenase as well as esterase activity, we tested this capacity, too. Almost all results showed clearly different characteristics between the FeaB and StyD enzymes. Furthermore, FeaB from Sphingopyxis fribergensis Kp5.2 turned out to be the most active enzyme with an apparent specific activity of 17.8 ± 2.1 U mg-1. Compared with that, both StyDs showed only activities less than 0.2 U mg-1 except the overwhelming esterase activity of StyD-CWB2 (1.4 ± 0.1 U mg-1). The clustering of both FeaB and StyD enzymes with respect to their characteristics could also be mirrored in the phylogenetic analysis of twelve dehydrogenases originating from different soil bacteria.
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Affiliation(s)
- Juliane Zimmerling
- Interdisciplinary Ecological Center, Environmental Microbiology Group, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany.
| | - Michel Oelschlägel
- Interdisciplinary Ecological Center, Environmental Microbiology Group, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany
| | - Carolin Großmann
- Interdisciplinary Ecological Center, Environmental Microbiology Group, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany
| | - Matthias Voitel
- Interdisciplinary Ecological Center, Environmental Microbiology Group, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany
| | - Michael Schlömann
- Interdisciplinary Ecological Center, Environmental Microbiology Group, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany
| | - Dirk Tischler
- Interdisciplinary Ecological Center, Environmental Microbiology Group, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany.
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
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Zhu C, Miller M, Lusskin N, Bergk Pinto B, Maccario L, Häggblom M, Vogel T, Larose C, Bromberg Y. Snow microbiome functional analyses reveal novel aspects of microbial metabolism of complex organic compounds. Microbiologyopen 2020; 9:e1100. [PMID: 32762019 PMCID: PMC7520998 DOI: 10.1002/mbo3.1100] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/19/2020] [Accepted: 05/29/2020] [Indexed: 12/17/2022] Open
Abstract
Microbes active in extreme cold are not as well explored as those of other extreme environments. Studies have revealed a substantial microbial diversity and identified cold-specific microbiome molecular functions. We analyzed the metagenomes and metatranscriptomes of 20 snow samples collected in early and late spring in Svalbard, Norway using mi-faser, our read-based computational microbiome function annotation tool. Our results reveal a more diverse microbiome functional capacity and activity in the early- vs. late-spring samples. We also find that functional dissimilarity between the same-sample metagenomes and metatranscriptomes is significantly higher in early than late spring samples. These findings suggest that early spring samples may contain a larger fraction of DNA of dormant (or dead) organisms, while late spring samples reflect a new, metabolically active community. We further show that the abundance of sequencing reads mapping to the fatty acid synthesis-related microbial pathways in late spring metagenomes and metatranscriptomes is significantly correlated with the organic acid levels measured in these samples. Similarly, the organic acid levels correlate with the pathway read abundances of geraniol degradation and inversely correlate with those of styrene degradation, suggesting a possible nutrient change. Our study thus highlights the activity of microbial degradation pathways of complex organic compounds previously unreported at low temperatures.
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Affiliation(s)
- Chengsheng Zhu
- Department of Biochemistry and MicrobiologyRutgers UniversityNew BrunswickNJUSA
| | - Maximilian Miller
- Department of Biochemistry and MicrobiologyRutgers UniversityNew BrunswickNJUSA
| | - Nicholas Lusskin
- Department of Biochemistry and MicrobiologyRutgers UniversityNew BrunswickNJUSA
| | - Benoît Bergk Pinto
- Environmental Microbial GenomicsLaboratoire AmpereEcole Centrale de LyonCNRS UMR 5005Université de LyonEcullyFrance
| | - Lorrie Maccario
- Environmental Microbial GenomicsLaboratoire AmpereEcole Centrale de LyonCNRS UMR 5005Université de LyonEcullyFrance
- Section of MicrobiologyCopenhagen UniversityCopenhagen ØDenmark
| | - Max Häggblom
- Department of Biochemistry and MicrobiologyRutgers UniversityNew BrunswickNJUSA
| | - Timothy Vogel
- Environmental Microbial GenomicsLaboratoire AmpereEcole Centrale de LyonCNRS UMR 5005Université de LyonEcullyFrance
| | - Catherine Larose
- Environmental Microbial GenomicsLaboratoire AmpereEcole Centrale de LyonCNRS UMR 5005Université de LyonEcullyFrance
| | - Yana Bromberg
- Department of Biochemistry and MicrobiologyRutgers UniversityNew BrunswickNJUSA
- Department of GeneticsHuman Genetics InstituteRutgers UniversityPiscatawayNJUSA
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Khabiri B, Ferdowsi M, Buelna G, Jones JP, Heitz M. Simultaneous biodegradation of methane and styrene in biofilters packed with inorganic supports: Experimental and macrokinetic study. Chemosphere 2020; 252:126492. [PMID: 32443260 DOI: 10.1016/j.chemosphere.2020.126492] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 01/23/2020] [Accepted: 03/12/2020] [Indexed: 06/11/2023]
Abstract
Four upflow 0.018 m3 biofilters (3 beds), B-ME, B-200, B-500 and B-700, all packed with inorganic materials, were operated at a constant air flow rate of 0.18 m3 h-1 to eliminate methane (CH4), a harmful greenhouse gas (GHG), and styrene (C8H8), a carcinogenic volatile organic compound (VOC). The biofilters were irrigated with 0.001 m3 of recycled nutrient solution (NS) every day (flow rate of 60 × 10-3 m3 h-1). Styrene inlet load (IL) was kept constant in each biofilter. Different CH4-ILs varying in the range of 7-60 gCH4 m-3 h-1 were examined in B-ME (IL of 0 gC8H8 m-3 h-1), B-200 (IL of 9 gC8H8 m-3 h-1), B-500 (IL of 22 gC8H8 m-3 h-1) and B-700 (IL of 32 gC8H8 m-3 h-1). Finally, the effect of C8H8 on the macrokinetic parameters of CH4 biofiltration was studied based on the Michaelis-Menten model. Average C8H8 removal efficiencies (RE) varying between 64 and 100% were obtained at CH4-ILs increasing from 7 to 60 gCH4 m-3 h-1 and for C8H8-ILs range of 0-32 gC8H8 m-3 h-1. More than 90% of C8H8 was removed in the bottom and middle beds of the biofilters. By increasing C8H8-IL from 0 to 32 gC8H8 m-3 h-1, maximal EC in Michaelis-Menten model and macrokinetic saturation constant declined from 311 to 39 g m-3 h-1 and from 19 to 2.3 g m-3, respectively, which confirmed that an uncompetitive inhibition occurred during CH4 biofiltration in the presence of C8H8.
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Affiliation(s)
- Bahman Khabiri
- Department of Chemical Engineering and Biotechnological Engineering, Faculty of Engineering, 2500 boulevard de l'Université, Université de Sherbrooke, Sherbrooke, J1K 2R1, Quebec, Canada
| | - Milad Ferdowsi
- Department of Chemical Engineering and Biotechnological Engineering, Faculty of Engineering, 2500 boulevard de l'Université, Université de Sherbrooke, Sherbrooke, J1K 2R1, Quebec, Canada
| | - Gerardo Buelna
- Department of Chemical Engineering and Biotechnological Engineering, Faculty of Engineering, 2500 boulevard de l'Université, Université de Sherbrooke, Sherbrooke, J1K 2R1, Quebec, Canada
| | - J Peter Jones
- Department of Chemical Engineering and Biotechnological Engineering, Faculty of Engineering, 2500 boulevard de l'Université, Université de Sherbrooke, Sherbrooke, J1K 2R1, Quebec, Canada
| | - Michèle Heitz
- Department of Chemical Engineering and Biotechnological Engineering, Faculty of Engineering, 2500 boulevard de l'Université, Université de Sherbrooke, Sherbrooke, J1K 2R1, Quebec, Canada.
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10
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Portune KJ, Pérez MC, Álvarez-Hornos J, Gabaldón C. Contribution of bacterial biodiversity on the operational performance of a styrene biotrickling filter. Chemosphere 2020; 247:125800. [PMID: 31927182 DOI: 10.1016/j.chemosphere.2019.125800] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/10/2019] [Accepted: 12/30/2019] [Indexed: 06/10/2023]
Abstract
Long-term operational stability of biotrickling filters (BTFs) degrading volatile organic compounds (VOCs) is dependent on both physicochemical as well as biological properties. Effects of increasingly stressful levels of air pollutants on the microbial structure of biofilms within BTFs are not well understood, especially for VOCs such as styrene. To investigate the relationship between biofilm biodiversity and operational stability, the temporal dynamics of a biofilm from a biotrickling filter subjected to stepwise increasing levels of air polluted with styrene was investigated using 16S rDNA pyrosequencing and PCR-denaturing gradient gel electrophoresis (PCR-DGGE). As styrene contaminant loads were increased, microbial community composition was distinctly altered and diversity was initially reduced in early stages but gradually stabilized and increased diversity in later stages, suggesting a recovery and acclimatization period within the microbial community during incremental exposure of the pollutant. Although temporary reductions in known styrene-degrading bacterial genera (Pseudomonas and Rhodococcus) occurred under increased styrene loads, stable BTF performance was maintained due to functional redundancy. New candidate genera for styrene degradation (Azoarcus, Dokdonella) were identified in conditions of high styrene loads, and may have supported the observed stable BTF performance throughout the experiment. Styrene inlet load was found to be important modulator of community composition and may have been partly responsible for the observed temporary reductions of Pseudomonas. Notable differences between dominant genera detected via pyrosequencing compared to species detected by PCR-DGGE suggests that simultaneous implementation of both techniques is valuable for fully characterizing dynamic microbial communities.
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Affiliation(s)
- Kevin J Portune
- Research Group GI(2)AM, Department of Chemical Engineering, Universitat de València, Burjassot, Spain
| | - M Carmen Pérez
- Research Group GI(2)AM, Department of Chemical Engineering, Universitat de València, Burjassot, Spain
| | - Javier Álvarez-Hornos
- Research Group GI(2)AM, Department of Chemical Engineering, Universitat de València, Burjassot, Spain
| | - Carmen Gabaldón
- Research Group GI(2)AM, Department of Chemical Engineering, Universitat de València, Burjassot, Spain.
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11
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Rezaei M, Moussavi G, Naddafi K, Johnson MS. Enhanced biodegradation of styrene vapors in the biotrickling filter inoculated with biosurfactant-generating bacteria under H 2O 2 stimulation. Sci Total Environ 2020; 704:135325. [PMID: 31839317 DOI: 10.1016/j.scitotenv.2019.135325] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 10/21/2019] [Accepted: 10/30/2019] [Indexed: 06/10/2023]
Abstract
Biotrickling filters (BTFs) applied to hydrophobic volatile organic compounds (VOCs) suffer from limited mass transfer. Phase transfer kinetic and equilibrium effects limit the biodegradation of hydrophobic VOCs especially at high concentrations. This study evaluates two strategies for overcoming the problem. First, a natural process was used to enhance the aqueous availability of styrene, a hydrophobic VOC model, by inoculating the BTF with a mixture of biosurfactant-generating bacteria. This method achieved a maximum elimination capacity (ECmax) of 139 g m-3h-1 in the BTF at an empty bed residence time (EBRT) of 60s. The highest concentrations of the biosurfactants surfactin and rhamnolipid were 205 and 86 mg L-1, respectively, in this step. Sequencing 16S rRNA confirmed the presence of biosurfactant-producing bacteria capable of biodegrading styrene in the BTF including Bacillus sonorensis, Bacillus subtilis, Lysinibacillus sphaericus, Lysinibacillus fusiformis, Alcaligenes feacalis, Arthrobacter creatinolyticus, and Kocuria rosea. Second, the effect of adding H2O2 to the recycle liquid on the BTF performance was determined. The biodegradation and mineralization of styrene in the BTF operated at a loading rate of 266 g m-3h-1 and H2O2/styrene molar ratio of 0.05 with EBRT as short as 15 s were 94% and 53%, respectively, with the EC of 250 g m-3h-1. High concentrations of antioxidant enzymes (peroxidase and catalase: 56 and 7 U gbiomass-1, respectively) were produced and biosurfactant generation was increased in this step, contributing to enhanced styrene biodegradation and mineralization. The styrene biodegradation and mineralization values in the BTF in the last day operated under similar conditions but without H2O2 were 11.4% and 5.3%, respectively. The bacterial population had no considerable change in the BTF after adding H2O2. Accordingly, stimulating the BTF inoculated with biosurfactant-generating bacteria with H2O2 is a promising strategy for improving the biodegradation of hydrophobic VOCs.
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Affiliation(s)
- Mohsen Rezaei
- Department of Environmental Health Engineering, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Gholamreza Moussavi
- Department of Environmental Health Engineering, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
| | - Kazem Naddafi
- Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Matthew S Johnson
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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12
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Li K, Zhou J, Wang L, Mao Z, Xu R. The styrene purification performance of biotrickling filter with toluene-styrene acclimatization under acidic conditions. J Air Waste Manag Assoc 2019; 69:944-955. [PMID: 30973304 DOI: 10.1080/10962247.2019.1604450] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 03/28/2019] [Accepted: 04/02/2019] [Indexed: 06/09/2023]
Abstract
The obvious disadvantages of biotrickling filters (BTFs) are the long start-up time and low removal efficiency (RE) when treating refractory hydrophobic volatile organic compounds (VOCs), which limits its industrial application. It is worthwhile to investigate how to reduce the start-up period of the BTF for treating hydrophobic VOCs. Here, we present the first study to evaluate the strategy of toluene induction combined with toluene-styrene synchronous acclimatization during start-up in a laboratory-scale BTF inoculated with activated sludge for styrene removal, as well as the effects of styrene inlet concentration (0.279 to 2.659 g·m-3), empty bed residence time (EBRT) (i.e., 136, 90, 68, 45, 34 sec), humidity (7.7% to 88.9%), and pH (i.e., 4, 3, 2.5, 2) on the performance of the BTF system. The experiments were carried out under acidic conditions (pH 4.5) to make fungi dominant in the BTF. The start-up period for styrene in the BTF was shortened to about 28 days. A maximum elimination capacity (ECmax) of 126 g·m-3·hr-1 with an RE of 80% was attained when styrene inlet loading rate (ILR) was below 180 g·m-3·hr-1. The highest styrene RE(s) [of BTF] that could be achieved were 95% and 93.4%, respectively, for humidity of 7.7% and at pH 2. A single dominant fungal strain was isolated and identified as Candida palmioleophila strain MA-M11 based on the 26S ribosomal RNA gene. Overall, the styrene induction with the toluene-styrene synchronous acclimatization could markedly reduce the start-up period and enhance the RE of styrene. The BTF dominated by fungi exhibited good performance under low pH and humidity and great potential in treating styrene with higher inlet concentrations. Implications: The application of the toluene induction combined with toluene-styrene synchronous acclimatization demonstrated to be a promising approach for the highly efficient removal of styrene. The toluene induction can accelerate biofilm formation, and the adaptability of microorganisms to styrene can be improved rapidly by the toluene-styrene synchronous acclimatization. The integrated application of two technologies can shorten the start-up period of biotrickling filters markedly and promote its industrial application.
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Affiliation(s)
- Kang Li
- a School of Environment Science and Spatial Informatics, China University of Mining and Technology , Xuzhou, Jiangsu, People's Republic of China
| | - Jiazhen Zhou
- b College of Environmental Science and Engineering, Tongji University , Shanghai , People's Republic of China
| | - Liping Wang
- a School of Environment Science and Spatial Informatics, China University of Mining and Technology , Xuzhou, Jiangsu, People's Republic of China
| | - Zhen Mao
- a School of Environment Science and Spatial Informatics, China University of Mining and Technology , Xuzhou, Jiangsu, People's Republic of China
| | - Ruiwei Xu
- c College of Environmental Sciences and Engineering, Peking University , Beijing , People's Republic of China
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13
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Abstract
PURPOSE Oxidative stress in the auditory system contributes to acquired sensorineural hearing loss. Systemic oxidative stress, which may predict auditory oxidative stress, can be assessed by measuring volatile organic compound metabolite concentrations in urine. The purpose of this retrospective study was to determine if hearing decreased in those with higher concentrations of urinary volatile organic compound metabolites. MATERIALS AND METHODS Audiometric, demographic, and metabolite concentration data were downloaded from the 2011-2012 cycle of the U.S. National Health and Nutritional Examination Survey. Participants were first grouped by reported noise exposure. For each metabolite, an analysis of covariance was used to look for differences in age-adjusted hearing loss among urinary volatile organic compound metabolite concentration groups. Participants were grouped into quartiles based on concentration for each metabolite separately because many individuals were at the lower limit of concentration detection for several metabolites, leading to a non-normal distribution. RESULTS Age-adjusted high-frequency pure-tone thresholds were significantly (FDR < 0.05) increased by about 3 to 4 dB in high concentration quartile groups for five metabolites. All five metabolites were glutathione-dependent mercapturic acids. The parent compounds of these metabolites included acrylonitrile, 1,3 butadiene, styrene, acrylamide, and N,N-dimethylformamide. Significant associations were only found in those with no reported noise exposure. CONCLUSIONS Urinary metabolites may help to explain susceptibility to oxidative stress-induced hearing loss.
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Affiliation(s)
- Charles Pudrith
- Department of Allied Health and Communicative Disorders, Northern Illinois University, IL, United States of America.
| | - William N Dudley
- Department of Public Health Education, University of North Carolina at Greensboro, NC, United States of America.
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14
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Kim HW, Lee SM, Seo JA, Kim YS. Effects of pH and Cultivation Time on the Formation of Styrene and Volatile Compounds by Penicillium expansum. Molecules 2019; 24:molecules24071333. [PMID: 30987370 PMCID: PMC6479942 DOI: 10.3390/molecules24071333] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 03/29/2019] [Accepted: 03/29/2019] [Indexed: 11/16/2022] Open
Abstract
Styrene can be formed by the microbial metabolism of bacteria and fungi. In our previous study, styrene was determined as a spoilage marker of Fuji apples decayed by Penicillium expansum, which is responsible for postharvest diseases. In the present study, P. expansum was cultivated in potato dextrose broth added with phenylalanine—which is a precursor of styrene—using different initial pH values and cultivation times. Volatile compounds were extracted and analyzed using gas chromatography-mass spectrometry (GC-MS) combined with stir-bar sorptive extraction. The 76 detected volatile compounds included 3-methylbutan-1-ol, 3-methyl butanal, oct-1-en-3-ol, geosmin, nonanal, hexanal, and γ-decalactone. In particular, the formation of 10 volatile compounds derived from phenylalanine (including styrene and 2-phenylethanol) showed different patterns according to pH and the cultivation time. Partial least square-discriminant analysis (PLS-DA) plots indicated that the volatile compounds were affected more by pH than by the cultivation time. These results indicated that an acidic pH enhances the formation of styrene and that pH could be a critical factor in the production of styrene by P. expansum. This is the first study to analyze volatile compounds produced by P. expansum according to pH and cultivation time and to determine their effects on the formation of styrene.
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Affiliation(s)
- Hye Won Kim
- Department of Food Science and Engineering, Ewha Womans University, Seoul 120-750, Korea.
| | - Sang Mi Lee
- Department of Food Science and Engineering, Ewha Womans University, Seoul 120-750, Korea.
| | - Jeong-Ah Seo
- School of Systems Biomedical Science, Soongsil University 369 Sangdo-ro, Dongjak-gu, Seoul 06978, Korea.
| | - Young-Suk Kim
- Department of Food Science and Engineering, Ewha Womans University, Seoul 120-750, Korea.
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15
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Heine T, Zimmerling J, Ballmann A, Kleeberg SB, Rückert C, Busche T, Winkler A, Kalinowski J, Poetsch A, Scholtissek A, Oelschlägel M, Schmidt G, Tischler D. On the Enigma of Glutathione-Dependent Styrene Degradation in Gordonia rubripertincta CWB2. Appl Environ Microbiol 2018; 84:e00154-18. [PMID: 29475871 PMCID: PMC5930330 DOI: 10.1128/aem.00154-18] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 02/19/2018] [Indexed: 02/05/2023] Open
Abstract
Among bacteria, only a single styrene-specific degradation pathway has been reported so far. It comprises the activity of styrene monooxygenase, styrene oxide isomerase, and phenylacetaldehyde dehydrogenase, yielding phenylacetic acid as the central metabolite. The alternative route comprises ring-hydroxylating enzymes and yields vinyl catechol as central metabolite, which undergoes meta-cleavage. This was reported to be unspecific and also allows the degradation of benzene derivatives. However, some bacteria had been described to degrade styrene but do not employ one of those routes or only parts of them. Here, we describe a novel "hybrid" degradation pathway for styrene located on a plasmid of foreign origin. As putatively also unspecific, it allows metabolizing chemically analogous compounds (e.g., halogenated and/or alkylated styrene derivatives). Gordonia rubripertincta CWB2 was isolated with styrene as the sole source of carbon and energy. It employs an assembled route of the styrene side-chain degradation and isoprene degradation pathways that also funnels into phenylacetic acid as the central metabolite. Metabolites, enzyme activity, genome, transcriptome, and proteome data reinforce this observation and allow us to understand this biotechnologically relevant pathway, which can be used for the production of ibuprofen.IMPORTANCE The degradation of xenobiotics by bacteria is not only important for bioremediation but also because the involved enzymes are potential catalysts in biotechnological applications. This study reveals a novel degradation pathway for the hazardous organic compound styrene in Gordonia rubripertincta CWB2. This study provides an impressive illustration of horizontal gene transfer, which enables novel metabolic capabilities. This study presents glutathione-dependent styrene metabolization in an (actino-)bacterium. Further, the genomic background of the ability of strain CWB2 to produce ibuprofen is demonstrated.
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Affiliation(s)
- Thomas Heine
- Institute of Biosciences, TU Bergakademie Freiberg, Freiberg, Germany
| | | | - Anne Ballmann
- Institute of Biosciences, TU Bergakademie Freiberg, Freiberg, Germany
| | | | - Christian Rückert
- Technologieplattform Genomik, Centrum für Biotechnologie (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Tobias Busche
- Technologieplattform Genomik, Centrum für Biotechnologie (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Anika Winkler
- Technologieplattform Genomik, Centrum für Biotechnologie (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Jörn Kalinowski
- Technologieplattform Genomik, Centrum für Biotechnologie (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Ansgar Poetsch
- Plant Biochemistry, Ruhr University Bochum, Bochum, Germany
- School of Biomedical and Healthcare Sciences, Plymouth University, Plymouth, United Kingdom
| | - Anika Scholtissek
- Institute of Biosciences, TU Bergakademie Freiberg, Freiberg, Germany
| | | | - Gert Schmidt
- Institut für Keramik, Glas- und Baustofftechnik, TU Bergakademie Freiberg, Freiberg, Germany
| | - Dirk Tischler
- Institute of Biosciences, TU Bergakademie Freiberg, Freiberg, Germany
- Microbial Biotechnology, Ruhr University Bochum, Bochum, Germany
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16
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Parnian P, Zamir SM, Shojaosadati SA. Effect of operating temperature on styrene mass transfer characteristics in a biotrickling filter. Environ Technol 2017; 38:1324-1332. [PMID: 27586791 DOI: 10.1080/09593330.2016.1226960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 08/12/2016] [Indexed: 06/06/2023]
Abstract
To study the effect of operating temperature on styrene mass transfer from gas to liquid phase in biotrickling filters (BTFs), overall mass transfer coefficient (KL a) was calculated through fitting test data to a general mass balance model under abiotic conditions. Styrene was used as the volatile organic compound and the BTF was packed with a mixture of pall rings and pumice. Operating temperature was set at 30°C and 50°C for mesophilic and thermophilic conditions, respectively. KL a values increased from 54 to 70 h-1 at 30°C and from 60 to 90 h-1 at 50°C, respectively, depending on the countercurrent gas to liquid flow ratio that varied in the range of 7.5-32. Evaluation of styrene mass transfer capacity (MTC) showed that liquid-phase mass transfer resistance decreased as the flow ratio increased at constant temperature. MTC also decreased with an increase in operating temperature. Both gas-liquid partition coefficient and KL a increased with increasing temperature; however the effect on gas-liquid partition coefficient was more significant and served to increase mass transfer limitations. Thermophilic biofiltration on the one hand increases mass transfer limitations, but on the other hand may enhance the biodegradation rate in favor of enhancing BTFs' performance.
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Affiliation(s)
- Parham Parnian
- a Biotechnology Group, Faculty of Chemical Engineering , Tarbiat Modares University , Tehran , Iran
| | - Seyed Morteza Zamir
- a Biotechnology Group, Faculty of Chemical Engineering , Tarbiat Modares University , Tehran , Iran
| | - Seyed Abbas Shojaosadati
- a Biotechnology Group, Faculty of Chemical Engineering , Tarbiat Modares University , Tehran , Iran
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17
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Montagnolli RN, Lopes PRM, Cruz JM, Claro MT, Quiterio GM, Bidoia ED. Metabolical shifts towards alternative BTEX biodegradation intermediates induced by perfluorinated compounds in firefighting foams. Chemosphere 2017; 173:49-60. [PMID: 28107715 DOI: 10.1016/j.chemosphere.2016.12.144] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/27/2016] [Accepted: 12/28/2016] [Indexed: 06/06/2023]
Abstract
The type and concentration of perfluorinated compounds (PFCs) can induce different types of enzymes and promote alternate patterns of BTEX transformation. However, it is not known how the presence of active fluorocarbon-degrading microbial populations affects the transformation of BTEX. In addition to chemical analysis at the molecular level, our research approached the aqueous film forming fire-fighting foams (AFFF) and BTEX co-contamination at a large-scale with respirometers to quantify the total microbial metabolism of soil via CO2 output levels. The intended outcome of this research was to obtain and characterize shifts in BTEX degradation at a set realistic environmental condition while measuring byproducts and CO2 production. Both methodologies complimentarily provided an in-depth knowledge of the environmental behavior of fire-fighting foams. The biodegradation was monitored using headspace sampling and two types of gas chromatography: thermal conductivity detector and flame ionization detector. Headspace samples were periodically withdrawn for BTEX biodegradation and CO2 production analysis. Our research suggests the discovery of an altered metabolic pathway in aromatic hydrocarbons biodegradation that is directly affected by fluorinated substances. The fluorinated compounds affected the BTEX biodegradation kinetics, as PFCs may contribute to a shift in styrene and catechol concentrations in co-contamination scenarios. A faster production of styrene and catechol was detected. Catechol is also rapidly consumed, thus undergoing further metabolic stages earlier under the presence of PFCs. The release of AFFF compounds not only changes byproducts output but also drastically disturbs the soil microbiota according to the highly variable CO2 yields. Therefore, we observed a high sensitivity of microbial consortia due to PFCs in the AFFF formulation, therefore shifting their BTEX degradation routes in terms of intermediate products concentration.
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Affiliation(s)
- Renato Nallin Montagnolli
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, UNESP - São Paulo State University, Avenida 24 A, 1515 - Bela Vista, 13506-900, Rio Claro, SP, Brazil
| | - Paulo Renato Matos Lopes
- Faculdade de Ciências Agrárias e Tecnológicas, UNESP - São Paulo State University, Rodovia Comandante João Ribeiro de Barros (SP 294), Km 651, 17900-000, Dracena, SP, Brazil
| | - Jaqueline Matos Cruz
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, UNESP - São Paulo State University, Avenida 24 A, 1515 - Bela Vista, 13506-900, Rio Claro, SP, Brazil
| | - Marina Turini Claro
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, UNESP - São Paulo State University, Avenida 24 A, 1515 - Bela Vista, 13506-900, Rio Claro, SP, Brazil
| | - Gabriela Mercuri Quiterio
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, UNESP - São Paulo State University, Avenida 24 A, 1515 - Bela Vista, 13506-900, Rio Claro, SP, Brazil
| | - Ederio Dino Bidoia
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, UNESP - São Paulo State University, Avenida 24 A, 1515 - Bela Vista, 13506-900, Rio Claro, SP, Brazil.
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18
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Abstract
Cytochrome P450 BM-3 variant 139-3 is highly active in the hydroxylation of alkanes and fatty acids (AGlieder, ET Farinas, and FH Arnold, Nature Biotech 2002;20:1135-1139); it also epoxidizes various alkenes, including styrene. Here the authors describe a colorimetric, high-throughput assay suitable for optimizing this latter activity by directed evolution. The product of styrene oxidation by 139-3, styrene oxide, reacts with the nucleophile γ-(4-nitrobenzyl)pyridine (NBP) to form a purple-colored precursor dye, which can be monitored spectrophotometrically in cell lysates. The sensitivity limit of this assay is 50-100 μ Mof product, and the detection limit for P450 BM-3 139-3 is ~0.2 μ Mof enzyme. To validate the assay, activities in a small library of random mutants were compared to those determined using an NADPH depletion assay for initial turnover rates. ( Journal of Biomolecular Screening 2004:141-146)
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Affiliation(s)
- Miguel Alcalde
- Departamento de Biocatalisis, Instituto de Catalisis y Petroleoquimica (CSIC), Campus Universidad Autonoma de Madrid, Cantoblanco, Madrid, Spain
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Hong S, Lee J, Lee C, Yoon SJ, Jeon S, Kwon BO, Lee JH, Giesy JP, Khim JS. Are styrene oligomers in coastal sediments of an industrial area aryl hydrocarbon-receptor agonists? Environ Pollut 2016; 213:913-921. [PMID: 27043777 DOI: 10.1016/j.envpol.2016.03.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/09/2016] [Accepted: 03/09/2016] [Indexed: 06/05/2023]
Abstract
Effect-directed analysis (EDA) was performed to identify the major aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area (Lake Shihwa, Korea). Great AhR-mediated potencies were found in fractions containing aromatic compounds with log Kow values of 5-8, and relatively great concentrations of styrene oligomers (SOs) and polycyclic aromatic hydrocarbons (PAHs) were detected in those fractions. Until now, there was little information on occurrences and toxic relative potencies (RePs) of SOs in coastal environments. In the present study; i) distributions and compositions, ii) AhR binding affinities, and iii) contributions of SOs to total AhR-mediated potencies were determined in coastal sediments. Elevated concentrations of 10 SOs were detected in sediments of inland creeks ranging from 61 to 740 ng g(-1) dry mass (dm), while lesser concentrations were found in inner (mean = 33 ng g(-1) dm) and outer regions (mean = 25 ng g(-1) dm) of the lake. Concentrations of PAHs in sediments were comparable to those of SOs. 2,4-diphenyl-1-butene (SD3) was the predominant SO analogue in sediments. SOs and PAHs were accumulated in sediments near sources, and could not be transported to remote regions due to their hydrophobicity. RePs of 3 SOs could be derived, which were 1000- to 10,000-fold less than that of one representative potent AhR active PAH, benzo[a]pyrene. Although concentrations of SOs in sediments were comparable to those of PAHs, the collective contribution of SOs to total AhR-mediated potencies were rather small (<1%), primarily due to their smaller RePs. Overall, the present study provides information on distributions and AhR binding affinities for SOs as baseline data for degradation products of polystyrene plastic in the coastal environment.
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Affiliation(s)
- Seongjin Hong
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea
| | - Junghyun Lee
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea
| | - Changkeun Lee
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea
| | - Seo Joon Yoon
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea
| | - Seungyeon Jeon
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea
| | - Bong-Oh Kwon
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea
| | - Jong-Hyeon Lee
- Institute of Environmental Protection and Safety, NeoEnBiz Co., Bucheon, Republic of Korea
| | - John P Giesy
- Department of Veterinary Biomedical Sciences & Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada; Department of Zoology & Center for Integrative Toxicology, Michigan State University, East Lansing, MI, USA; School of Biological Sciences, University of Hong Kong, Hong Kong, China; State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China
| | - Jong Seong Khim
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea.
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20
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Wallace S, Balskus EP. Designer Micelles Accelerate Flux Through Engineered Metabolism in E. coli and Support Biocompatible Chemistry. Angew Chem Int Ed Engl 2016; 55:6023-7. [PMID: 27061024 PMCID: PMC4973394 DOI: 10.1002/anie.201600966] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/17/2016] [Indexed: 01/04/2023]
Abstract
Synthetic biology has enabled the production of many value-added chemicals via microbial fermentation. However, the problem of low product titers from recombinant pathways has limited the utility of this approach. Methods to increase metabolic flux are therefore critical to the success of metabolic engineering. Here we demonstrate that vitamin E-derived designer micelles, originally developed for use in synthetic chemistry, are biocompatible and accelerate flux through a styrene production pathway in Escherichia coli. We show that these micelles associate non-covalently with the bacterial outer-membrane and that this interaction increases membrane permeability. In addition, these micelles also accommodate both heterogeneous and organic-soluble transition metal catalysts and accelerate biocompatible cyclopropanation in vivo. Overall, this work demonstrates that these surfactants hold great promise for further application in the field of synthetic biotechnology, and for expanding the types of molecules that can be readily accessed from renewable resources via the combination of microbial fermentation and biocompatible chemistry.
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Affiliation(s)
- Stephen Wallace
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA.
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Langos D, Granvogl M. Studies on the Simultaneous Formation of Aroma-Active and Toxicologically Relevant Vinyl Aromatics from Free Phenolic Acids during Wheat Beer Brewing. J Agric Food Chem 2016; 64:2325-2332. [PMID: 26800353 DOI: 10.1021/acs.jafc.5b05606] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
During the brewing process of wheat beer, the desired aroma-active vinyl aromatics 2-methoxy-4-vinylphenol and 4-vinylphenol as well as the undesired and toxicologically relevant styrene are formed from their respective precursors, free ferulic acid, p-coumaric acid, and cinnamic acid, deriving from the malts. Analysis of eight commercial wheat beers revealed high concentrations of 2-methoxy-4-vinylphenol and 4-vinylphenol always in parallel with high concentrations of styrene or low concentrations of the odorants in parallel with low styrene concentrations, suggesting a similar pathway. To better understand the formation of these vinyl aromatics, each process step of wheat beer brewing and the use of different strains of Saccharomyces cerevisiae were evaluated. During wort boiling, only a moderate decarboxylation of free phenolic acids and formation of desired and undesired vinyl aromatics were monitored due to the thermal treatment. In contrast, this reaction mainly occurred enzymatically catalyzed during fermentation with S. cerevisiae strain W68 with normal Pof(+) activity (phenolic off-flavor) resulting in a wheat beer eliciting the typical aroma requested by consumers due to high concentrations of 2-methoxy-4-vinylphenol (1790 μg/L) and 4-vinylphenol (937 μg/L). Unfortunately, also a high concentration of undesired styrene (28.3 μg/L) was observed. Using a special S. cerevisiae strain without Pof(+) activity resulted in a significant styrene reduction (<LoQ), but also in low amounts of 2-methoxy-4-vinylphenol (158 μg/L) and 4-vinylphenol (46.7 μg/L), resulting in a less pronounced wheat beer aroma.
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Affiliation(s)
- Daniel Langos
- Deutsche Forschungsanstalt für Lebensmittelchemie , Lise-Meitner-Straße 34, D-85354 Freising, Germany
| | - Michael Granvogl
- Lehrstuhl für Lebensmittelchemie, Department für Chemie, Technische Universität München , Lise-Meitner-Straße 34, D-85354 Freising, Germany
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Jiang L, Zhu R, Mao Y, Chen J, Zhang L. Conversion characteristics and production evaluation of styrene/o-xylene mixtures removed by DBD pretreatment. Int J Environ Res Public Health 2015; 12:1334-50. [PMID: 25629961 PMCID: PMC4344669 DOI: 10.3390/ijerph120201334] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 11/26/2014] [Accepted: 12/30/2014] [Indexed: 11/16/2022]
Abstract
The combination of chemical oxidation methods with biotechnology to removal recalcitrant VOCs is a promising technology. In this paper, the aim was to identify the role of key process parameters and biodegradability of the degradation products using a dielectric barrier discharge (DBD) reactor, which provided the fundamental data to evaluate the possibilities of the combined system. Effects of various technologic parameters like initial concentration of mixtures, residence time and relative humidity on the decomposition and the degradation products were examined and discussed. It was found that the removal efficiency of mixed VOCs decreased with increasing initial concentration. The removal efficiency reached the maximum value as relative humidity was approximately 40%-60%. Increasing the residence time resulted in increasing the removal efficiency and the order of destruction efficiency of VOCs followed the order styrene > o-xylene. Compared with the single compounds, the removal efficiency of styrene and o-xylene in the mixtures of VOCs decreased significantly and o-xylene decreased more rapidly. The degradation products were analyzed by gas chromatography and gas chromatography-mass spectrometry, and the main compounds detected were O3, COx and benzene ring derivatives. The biodegradability of mixed VOCs was improved and the products had positive effect on biomass during plasma application, and furthermore typical results indicated that the biodegradability and biotoxicity of gaseous pollutant were quite depending on the specific input energy (SIE).
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Affiliation(s)
- Liying Jiang
- College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
| | - Runye Zhu
- College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
| | - Yubo Mao
- College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
| | - Jianmeng Chen
- College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
| | - Liang Zhang
- College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
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Portune KJ, Pérez MC, Álvarez-Hornos FJ, Gabaldón C. Investigating bacterial populations in styrene-degrading biofilters by 16S rDNA tag pyrosequencing. Appl Microbiol Biotechnol 2015; 99:3-18. [PMID: 24950754 PMCID: PMC4286631 DOI: 10.1007/s00253-014-5868-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 05/29/2014] [Accepted: 05/31/2014] [Indexed: 11/29/2022]
Abstract
Microbial biofilms are essential components in the elimination of pollutants within biofilters, yet still little is known regarding the complex relationships between microbial community structure and biodegradation function within these engineered ecosystems. To further explore this relationship, 16S rDNA tag pyrosequencing was applied to samples taken at four time points from a styrene-degrading biofilter undergoing variable operating conditions. Changes in microbial structure were observed between different stages of biofilter operation, and the level of styrene concentration was revealed to be a critical factor affecting these changes. Bacterial genera Azoarcus and Pseudomonas were among the dominant classified genera in the biofilter. Canonical correspondence analysis (CCA) and correlation analysis revealed that the genera Brevundimonas, Hydrogenophaga, and Achromobacter may play important roles in styrene degradation under increasing styrene concentrations. No significant correlations (P > 0.05) could be detected between biofilter operational/functional parameters and biodiversity measurements, although biological heterogeneity within biofilms and/or technical variability within pyrosequencing may have considerably affected these results. Percentages of selected bacterial taxonomic groups detected by fluorescence in situ hybridization (FISH) were compared to results from pyrosequencing in order to assess the effectiveness and limitations of each method for identifying each microbial taxon. Comparison of results revealed discrepancies between the two methods in the detected percentages of numerous taxonomic groups. Biases and technical limitations of both FISH and pyrosequencing, such as the binding of FISH probes to non-target microbial groups and lack of classification of sequences for defined taxonomic groups from pyrosequencing, may partially explain some differences between the two methods.
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Affiliation(s)
- Kevin J Portune
- Research Group GI2AM, Department of Chemical Engineering, Universitat de València, Av. de la Universidad s/n, 46100, Burjassot, Spain,
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McKenna R, Thompson B, Pugh S, Nielsen DR. Rational and combinatorial approaches to engineering styrene production by Saccharomyces cerevisiae. Microb Cell Fact 2014; 13:123. [PMID: 25162943 PMCID: PMC4145238 DOI: 10.1186/s12934-014-0123-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 08/14/2014] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Styrene is an important building-block petrochemical and monomer used to produce numerous plastics. Whereas styrene bioproduction by Escherichia coli was previously reported, the long-term potential of this approach will ultimately rely on the use of hosts with improved industrial phenotypes, such as the yeast Saccharomyces cerevisiae. RESULTS Classical metabolic evolution was first applied to isolate a mutant capable of phenylalanine over-production to 357 mg/L. Transcription analysis revealed up-regulation of several phenylalanine biosynthesis pathway genes including ARO3, encoding the bottleneck enzyme DAHP synthase. To catalyze the first pathway step, phenylalanine ammonia lyase encoded by PAL2 from A. thaliana was constitutively expressed from a high copy plasmid. The final pathway step, phenylacrylate decarboxylase, was catalyzed by the native FDC1. Expression of FDC1 was naturally induced by trans-cinnamate, the pathway intermediate and its substrate, at levels sufficient for ensuring flux through the pathway. Deletion of ARO10 to eliminate the competing Ehrlich pathway and expression of a feedback-resistant DAHP synthase encoded by ARO4K229L preserved and promoted the endogenous availability precursor phenylalanine, leading to improved pathway flux and styrene production. These systematic improvements allowed styrene titers to ultimately reach 29 mg/L at a glucose yield of 1.44 mg/g, a 60% improvement over the initial strain. CONCLUSIONS The potential of S. cerevisiae as a host for renewable styrene production has been demonstrated. Significant strain improvements, however, will ultimately be needed to achieve economical production levels.
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Affiliation(s)
- Rebekah McKenna
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, PO Box 876106, Tempe, AZ 85287-6106 USA
| | - Brian Thompson
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, PO Box 876106, Tempe, AZ 85287-6106 USA
| | - Shawn Pugh
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, PO Box 876106, Tempe, AZ 85287-6106 USA
| | - David R Nielsen
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, PO Box 876106, Tempe, AZ 85287-6106 USA
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25
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Shen S, Li L, Ding X, Zheng J. Metabolism of styrene to styrene oxide and vinylphenols in cytochrome P450 2F2- and P450 2E1-knockout mouse liver and lung microsomes. Chem Res Toxicol 2014; 27:27-33. [PMID: 24320693 PMCID: PMC4041473 DOI: 10.1021/tx400305w] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pulmonary toxicity of styrene is initiated by cytochromes P450-dependent metabolic activation. P450 2E1 and P450 2F2 are considered to be two main cytochrome P450 enzymes responsible for styrene metabolism in mice. The objective of the current study was to determine the correlation between the formation of styrene metabolites (i.e., styrene oxide and 4-vinylphenol) and pulmonary toxicity of styrene, using Cyp2e1- and Cyp2f2-null mouse models. A dramatic decrease in the formation of styrene glycol and 4-vinylphenol was found in Cyp2f2-null mouse lung microsomes relative to that in the wild-type mouse lung microsomes; however, no significant difference in the production of the styrene metabolites was observed between lung microsomes obtained from Cyp2e1-null and the wild-type mice. The knockout and wild-type mice were treated with styrene (6.0 mmol/kg, ip), and cell counts and LDH activity in bronchoalveolar lavage fluids were monitored to evaluate the pulmonary toxicity induced by styrene. Cyp2e1-null mice displayed a susceptibility to lung toxicity of styrene similar to that of the wild-type animals; however, Cyp2f2-null mice were resistant to styrene-induced pulmonary toxicity. In conclusion, both P450 2E1 and P450 2F2 are responsible for the metabolic activation of styrene. The latter enzyme plays an important role in styrene-induced pulmonary toxicity. Both styrene oxide and 4-vinylphenol are suggested to participate in the development of lung injury induced by styrene.
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Affiliation(s)
- Shuijie Shen
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington 98101
| | - Lei Li
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, Albany, New York 12201
| | - Xinxin Ding
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, Albany, New York 12201
| | - Jiang Zheng
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington 98101
- Division of Gastroenterology and Hepatology, Department of Pediatrics, University of Washington, Seattle, Washington 98105
- Shenyang Pharmaceutical University, Shenyang, 110016, P. R. China
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Azeem M, Borg-Karlson AK, Rajarao GK. Sustainable bio-production of styrene from forest waste. Bioresour Technol 2013; 144:684-688. [PMID: 23899574 DOI: 10.1016/j.biortech.2013.07.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 07/03/2013] [Accepted: 07/09/2013] [Indexed: 06/02/2023]
Abstract
A strain of Penicillium expansum was studied for the production of styrene using forest waste biomass as a feeding substrate. The fungal strain was cultivated on bark of various trees supplemented with yeast extract and the volatiles produced were collected on Tenax TA and analyzed by gas chromatography-mass spectrometry. Fungus cultured on grated soft bark of pine (Pinus sylvestris) stems (GPB) and mature bark of oak (Quercus robur) supplemented with yeast extract produced relatively the highest amounts of styrene. The maximum styrene production rate was 52.5 μg/h, 41 μg/h and 27 μg/h from fungus cultivated on 50 mL liquid media with 10 g GPB or mature bark of oak and potato dextrose broth respectively. These promising results suggest that the fungal strain could be used to produce "green" styrene plastics using renewable forest waste biomass.
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Affiliation(s)
- Muhammad Azeem
- KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Ecological Chemistry Group, Stockholm, Sweden.
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27
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Abstract
We are the first to report allosterism during styrene oxidation by recombinant CYP2E1 and human liver microsomes. At low styrene concentrations, oxidation is inefficient because of weak binding to CYP2E1 (K(s) = 830 μM). A second styrene molecule then binds CYP2E1 with higher affinity (K(ss) = 110 μM) and significantly improves oxidation to achieve a k(cat) of 6.3 nmol · min(-1) · nmol CYP2E1(-1). The transition between these metabolic cycles coincides with reported styrene concentrations in blood from exposed workers; thus, this CYP2E1 mechanism may be relevant in vivo. Scaled modeling of the in vitro-positive allosteric mechanism for styrene metabolism to its in vivo clearance led to significant deviations from the traditional model based on Michaelis-Menten kinetics. Low styrene levels were notably much less toxic than generally assumed. We interrogated the allosteric mechanism using the CYP2E1-specific inhibitor and drug 4-methylpyrazole, which we have shown binds two CYP2E1 sites. From the current studies, styrene was a positive allosteric effector on 4-methylpyrazole binding, based on a 10-fold increase in 4-methylpyrazole binding affinity from K(i) 0.51 to K(si) 0.043 μM. The inhibitor was a negative allosteric effector on styrene oxidation, because k(cat) decreased 6-fold to 0.98 nmol · min(-1) · nmol CYP2E1(-1). Consequently, mixtures of styrene and other molecules can induce allosteric effects on binding and metabolism by CYP2E1 and thus mitigate the efficiency of their metabolism and corresponding effects on human health. Taken together, our elucidation of mechanisms for these allosteric reactions provides a powerful tool for further investigating the complexities of CYP2E1 metabolism of drugs and pollutants.
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Affiliation(s)
- Jessica H Hartman
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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28
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Kolstad HA, Ebbehøj N, Bonde JP, Lynge E, Albin M. [Health effects following occupational styrene exposure in the reinforced plastics industry]. Ugeskr Laeger 2012; 174:267-270. [PMID: 22293073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This is a summary of the health risks of occupational styrene exposure based on recent reviews. We conclude about the exposure levels that there is strong evidence that styrene causes acute irritation of eyes and respiratory tract above 25 ppm, genotoxic effects above 10 ppm, and persistent nervous system effects with for instance reduced psychological performance, colour discrimination and hearing level following long-term styrene exposure above 10 ppm. There is moderate evidence of a causal association with cancer, but data are not sufficient to allow us to pinpoint specific cancers at risk or relevant exposure levels. We recommend reconsideration of the current Danish threshold limit value of 25 ppm, biological monitoring of styrene exposed workers, and epidemiological analyses of styrene exposure levels and long-term health effects among employees of the Danish reinforced plastics industry.
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Affiliation(s)
- Henrik Albert Kolstad
- Arbejdsmedicinsk Klinik, Aarhus Universitetshospital, Nørrebrogade 44, 8000 Aarhus C, Denmark.
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29
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Babaei R, Bonakdarpour B, Nasernejad B, Fallah N. Kinetics of styrene biodegradation in synthetic wastewaters using an industrial activated sludge. J Hazard Mater 2010; 184:111-117. [PMID: 20828926 DOI: 10.1016/j.jhazmat.2010.08.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 07/20/2010] [Accepted: 08/05/2010] [Indexed: 05/29/2023]
Abstract
Kinetics of styrene biodegradation in synthetic wastewaters, containing either styrene or styrene together with ethanol, by an industrial activated sludge obtained from the wastewater treatment unit of a petrochemical complex was studied. The kinetic data could be fitted using the Haldane kinetic model. This model was previously used to predict kinetic data for biodegradation of styrene by pure or mixed microbial cultures isolated from biofilters, but the values of the model parameters reported in these studies was substantially different from that obtained for the industrial activated sludge. The presence of ethanol did not affect the kinetics of styrene biodegradation by the industrial activated sludge; however, it increased the rates of styrene biodegradation due to the resulting higher microbial growth rates. Styrene concentration was found to affect the specific growth rate in a manner similar to its effect on the styrene degradation rate. No lag phase was observed in styrene biodegradation by industrial activated sludge for styrene concentrations up to 100mg/L. Lag phase was observed for municipal activated sludge even at 50mg/L styrene concentration but the rate of styrene biodegradation after the lag phase was similar to that achieved by the industrial activated sludge.
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Affiliation(s)
- R Babaei
- Chemical Engineering Department, Amirkabir University of Technology, 424 Hafez Ave., Tehran, Iran
| | - B Bonakdarpour
- Chemical Engineering Department, Amirkabir University of Technology, 424 Hafez Ave., Tehran, Iran; Food Process Engineering and Biotechnology Research Centre, Amirkabir University of Technology, 424 Hafez Ave., Tehran, Iran.
| | - B Nasernejad
- Chemical Engineering Department, Amirkabir University of Technology, 424 Hafez Ave., Tehran, Iran
| | - N Fallah
- Chemical Engineering Department, Amirkabir University of Technology, 424 Hafez Ave., Tehran, Iran
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30
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Terre'Blanche G, Heyer N, Bergh JJ, Mienie LJ, van der Schyf CJ, Harvey BH. The styrene metabolite, phenylglyoxylic acid, induces striatal-motor toxicity in the rat: influence of dose escalation/reduction over time. Neurotox Res 2010; 20:97-101. [PMID: 20931367 PMCID: PMC3089729 DOI: 10.1007/s12640-010-9222-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 09/16/2010] [Accepted: 09/20/2010] [Indexed: 12/21/2022]
Abstract
Exposure to the industrial solvent, styrene, induces locomotor and cognitive dysfunction in rats, and parkinsonian-like manifestations in man. The antipsychotic, haloperidol (HP), well known to induce striatal toxicity in man and animals, and styrene share a common metabolic pathway yielding p-fluoro phenylglyoxylic acid and phenylglyoxylic acid (PGA), respectively. Using an exposure period of 30 days and the vacous chewing movement (VCM) model as an expression of striatal-motor toxicity, we found that incremental PGA dosing (220–400 mg/kg) significantly increased VCMs up to day 25, but decreased to control levels shortly after reaching maximum dose. However, a diminishing dose of PGA (400–200 mg/kg) did not evoke an immediate worsening of VCMs but precipitated a significant increase in VCMs following dosage reduction to 200 mg/kg on day 22. PGA exposure, therefore, compromises striatal-motor function that is especially sensitive to changes in exposure dose. Longer alternating dose exposure studies are needed to establish whether motor dysfunction is progressive in severity or longevity. These findings are of significance for the environmental toxicology of styrene in the chemical industry.
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Affiliation(s)
- Gisella Terre'Blanche
- Pharmaceutical Chemistry, Unit for Drug Research and Development, School of Pharmacy, North-West University, Private Bag X6001, Box 304, Potchefstroom 2520, South Africa.
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31
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Yuan W, Jin H, Chung JK, Zheng J. Evidence for cellular protein covalent binding derived from styrene metabolite. Chem Biol Interact 2010; 186:323-30. [PMID: 20470765 PMCID: PMC3463232 DOI: 10.1016/j.cbi.2010.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 05/06/2010] [Accepted: 05/06/2010] [Indexed: 12/13/2022]
Abstract
Styrene is one of the most important industrial intermediates consumed in the world. Human exposure to styrene occurs mainly in the reinforced plastics industry, particularly in developing countries. Styrene has been found to be hepatotoxic and pneumotoxic in humans and animals. The biochemical mechanisms of styrene-induced toxicities remain unknown. Albumin and hemoglobin adduction derived from styrene oxide, a major reactive metabolite of styrene, has been reported in blood samples obtained from styrene-exposed workers. The objectives of the current study focused on cellular protein covalent binding of styrene metabolite and its correlation with cytotoxicity induced by styrene. We found that radioactivity was bound to cellular proteins obtained from mouse airway trees after incubation with (14)C-styrene. Microsomal incubation studies showed that the observed protein covalent binding required the metabolic activation of styrene. The observed radioactivity binding in protein samples obtained from the cultured airways and microsomal incubations was significantly suppressed by co-incubation with disulfiram, a CYP2E1 inhibitor, although disulfiram apparently did not show a protective effect against the cytotoxicity of styrene. A 2-fold increase in radioactivity bound to cellular proteins was detected in cells stably transfected with CYP2E1 compared to the wild-type cells after (14)C-styrene exposure. With the polyclonal antibody developed in our lab, we detected cellular protein adduction derived from styrene oxide at cysteinyl residues in cells treated with styrene. Competitive immunoblot studies confirmed the modification of cysteine residues by styrene oxide. Cell culture studies showed that the styrene-induced protein modification and cell death increased with the increasing concentration of styrene exposure. In conclusion, we detected cellular protein covalent modification by styrene oxide in microsomal incubations, cultured cells, and mouse airways after exposure to styrene and found a good correlation between styrene-induced cytotoxicity and styrene oxide-derived cellular protein adduction.
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Affiliation(s)
- Wei Yuan
- Department of Medicine, University of Washington, Seattle, WA 98195
| | - Hua Jin
- Center for Developmental Therapeutics, Seattle Children’s Research Institute, Division of Gastroenterology, Department of Pediatrics, University of Washington, Seattle, WA 98101
| | - Jou-Ku Chung
- Department of Drug Metabolism and Pharmacokinetics, Archemix Corp., Cambridge, MA 02142
| | - Jiang Zheng
- Center for Developmental Therapeutics, Seattle Children’s Research Institute, Division of Gastroenterology, Department of Pediatrics, University of Washington, Seattle, WA 98101
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32
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Rene ER, López ME, Veiga MC, Kennes C. Performance of a fungal monolith bioreactor for the removal of styrene from polluted air. Bioresour Technol 2010; 101:2608-2615. [PMID: 19944600 DOI: 10.1016/j.biortech.2009.10.060] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 10/13/2009] [Accepted: 10/19/2009] [Indexed: 05/28/2023]
Abstract
Gas-phase styrene removal using the fungus, Sporothrix variecibatus was evaluated in a novel monolith bioreactor, receiving a continuous supply of nutrients from the trickling liquid phase. During the start-up process, the monolith reactor was operated for 22 days with relatively low styrene concentrations in the gas-phase (<0.4 g m(-3)). Afterwards, continuous experiments were carried out at different inlet styrene concentrations, ranging between 0.06 and 2.5 g m(-3), and at two different flow rates corresponding to empty bed residence times (EBRTs) of 77 and 19 s, respectively. A maximum elimination capacity of 67.4 g m(-3) h(-1) was observed at an inlet styrene load of 73.5 g m(-3) h(-1). However, it was observed that the critical loading rates to the monolith bioreactor were a strong function of the gas residence time. The critical load, with greater than 95% styrene removal was 74 g m(-3) h(-1) at an EBRT of 77 s, while it was only 37.2 g m(-3) h(-1) for an EBRT of 19 s. After 92 days of continuous operation, due to excess biomass growth on the surface of the monolith, the biodegradation efficiency decreased significantly. To ascertain the instantaneous response of the attached fungus, to withstand fluctuations in loading conditions, two dynamic shock loads were conducted, at EBRTs of 77 and 19 s, respectively. It was observed that, the performance of the monolith bioreactor decreased significantly at low residence times, when subjected to high shock loads. The recovery times for high performance, in both cases, did not exceed more than 1 h.
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Affiliation(s)
- Eldon R Rene
- Chemical Engineering Laboratory, Faculty of Sciences, University of La Coruña, Rua Alejandro de la Sota, 1, E-15008, La Coruña, Spain
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33
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Rene ER, Veiga MC, Kennes C. Biodegradation of gas-phase styrene using the fungus Sporothrix variecibatus: impact of pollutant load and transient operation. Chemosphere 2010; 79:221-227. [PMID: 20149411 DOI: 10.1016/j.chemosphere.2010.01.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 01/18/2010] [Accepted: 01/19/2010] [Indexed: 05/28/2023]
Abstract
Biofiltration of gas-phase styrene was studied using a newly isolated fungus Sporothrix variecibatus, in a perlite biofilter, at inlet concentrations and gas-flow rates ranging from 0.13 to 14 g m(-3) and 0.075 to 0.34 m(3) h(-1), respectively, corresponding to empty bed residence times (EBRT) ranging between 91 and 20s. Styrene loading rates were varied between 50 and 845 g m(-3) h(-1)and a maximum elimination capacity of 336 g m(-3) h(-1) was attained with nearly 65% styrene removal. On the other hand, the critical inlet loads to achieve more than 90% removal were 301, 240 and 92 g m(-3) h(-1) for EBRT of 91, 40, and 20s, respectively. In order to test the stability and shock bearing capacity of the fungal biofilter, short-term tests were conducted by suddenly increasing the gas-phase styrene concentration, while maintaining the gas-flow rate constant. The response, a restoration in the removal performance to previous high values, after subjecting the biofilter to shock loads proves the resilient nature of the attached Sporothrix sp. and its suitability for biofiltration under non-steady state conditions.
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Affiliation(s)
- Eldon R Rene
- Chemical Engineering Laboratory, Faculty of Sciences, University of La Coruña, Rua Alejandro de la Sota, 1, E-15008 La Coruña, Spain
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Abstract
Styrene, which is widely used in manufacturing, is both acutely and chronically toxic to mice. Styrene is metabolized by cytochromes P-450 to the toxic metabolite styrene oxide, which is detoxified via hydrolysis with microsomal epoxide hydrolase (mEH) playing a major role. The purpose of these studies was to characterize the importance of this pathway by determining the hepatotoxicity and pneumotoxicity of styrene in wild-type and mEH-deficient (mEH(-/-)) mice. While the mEH(-/-) mice metabolized styrene to styrene oxide at the same rate as the wild-type mice, as expected there was minimal metabolism of styrene oxide to glycol. mEH(-/-) mice were more susceptible to the lethal effects of styrene. Twenty-four hours following the administration of 200 mg/kg ip styrene, mice demonstrated a greater hepatotoxic response due to styrene, as measured by increased serum sorbitol dehydrogenase activity and greater pneumotoxicity as shown by increased protein levels, cell numbers, and lactate dehydrogenase activity in bronchioalveolar lavage fluid. mEH(-/-) mice were also more susceptible to styrene-induced oxidative stress, as indicated by greater decreases in hepatic glutathione levels 3 h after styrene. Styrene oxide at a dose of 150 mg/kg did not produce hepatotoxicity in either wild-type or mEH(-/-) mice. However, styrene oxide produced pneumotoxicity that was similar in the two strains. Thus, mEH plays an important role in the detoxification of styrene but not for exogenously administered styrene oxide.
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Affiliation(s)
- Gary P Carlson
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA.
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Cemeli E, Mirkova E, Chiuchiarelli G, Alexandrova E, Anderson D. Investigation on the mechanisms of genotoxicity of butadiene, styrene and their combination in human lymphocytes using the Comet assay. Mutat Res 2009; 664:69-76. [PMID: 19428383 DOI: 10.1016/j.mrfmmm.2009.02.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 02/10/2009] [Accepted: 02/13/2009] [Indexed: 05/27/2023]
Abstract
The toxicity of butadiene and styrene is exerted by their metabolites. Such metabolites have been extensively scrutinized at the in vitro level demonstrating evident genotoxic properties. In monitoring, a diverse range of outcomes has been produced. Additionally, epidemiological studies in rubber workers face difficulties of data interpretation due to the changeability and multiple exposures of the workers as well as to confounding factors inherent to the cohorts. Nevertheless, toxicity has been associated with a significant trend of increasing the risk of leukaemia in employees at the styrene-butadiene rubber industry. Thus, further effort must be made to distinguish the exposures to each chemical over time and to characterize their interrelationships. The present investigation focuses on the effects and mechanisms of damage of the mixture styrene-butadiene by examining its metabolites: styrene oxide (SO), butadiene monoepoxide (BME) and butadiene diepoxide (BDE) respectively. The in vitro Comet assay on frozen lymphocytes has been employed to ascertain the DNA damage patterns for the styrene-butadiene metabolites combined and on their own. Different patterns were observed for the mixture and each of its components. This study has also led to determining the mechanism of damage of the mixture and the compounds. With regard to the presence of reactive oxygen species (ROS), co-treatment with catalase does not modulate the genotoxicity of the mixture but it does modulate its components. The outcomes also indicate that the mixture induces cross-links and this is due to the influence of BDE in the mixture, being more evident as the concentration of BDE increases. An investigation on the sensitivity of lymphocytes from occupationally un/exposed subjects to in vitro exposure of the mixture and its components revealed that occupationally exposed subjects had a substantially higher background of DNA damage and a lower sensitivity to the metabolites of styrene, 1,3-butadiene and its mixture.
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Affiliation(s)
- Eduardo Cemeli
- University of Bradford, Division of Biomedical Sciences, Richmond Road, Bradford, West Yorkshire BD7 1DP, United Kingdom
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Paca J, Halecky M, Fitch M. Steady-state performance of an activated carbon biofilter degrading styrene: effects of residence time and inlet concentration. J Air Waste Manag Assoc 2009; 59:45-51. [PMID: 19216187 DOI: 10.3155/1047-3289.59.1.45] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A granular-activated-carbon-packed biofilter receiving a constant loading rate of styrene was subjected to changes in residence time and concentration, and the effects on performance characteristics and the composition of biofilm along the bed height in the biofilter were studied. This study was carried out during the last 3 months of the entire biofilter operation of 16 months. The total bed height of the biofilter was physically divided into four individual reactor stages in series. This configuration permitted measurement of the leachate pH in each stage. Also, between-stage mixing of the culture was minimized. Each reactor stage was loaded in an upflow mode. The shortest residence time tested, 1.05 min, resulted in a decrease of removal efficiency to 95% (from 100% achieved at longer residence times). The shorter residence time nonetheless resulted in a higher elimination capacity in the higher stages of the filter bed. In the first two stages, the leachate pH values were 6.4 and 6.6, slightly lower than in higher stages (pH 7). A decrease of the styrene concentration along the bed height significantly affected the total cell number of immobilized cells whereas the number of degraders, Pseudomonads, and eukaryotes changed only a little. Microbial analysis of the mixed culture showed the presence of four bacterial strains and three fungi.
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Affiliation(s)
- Jan Paca
- Department of Fermentation Chemistry and Bioengineering, Institute of Chemical Technology, Prague, Czech Republic.
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Beck JJ, Merrill GB, Palumbo JD, O'Keeffe TL. Strain of Fusarium oxysporum isolated from almond hulls produces styrene and 7-methyl-1,3,5-cyclooctatriene as the principal volatile components. J Agric Food Chem 2008; 56:11392-11398. [PMID: 18998704 DOI: 10.1021/jf802570w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
An isolated strain of Fusarium oxysporum from the hulls of Prunus dulcis (sweet almond) was found to produce relatively large quantities of the hydrocarbons styrene and two isomers of 7-methyl-1,3,5- cyclooctatriene (MCOT). Production of styrene and MCOT was reproduced on a small scale using potato dextrose agar as a growth medium and scaled up using 1 L of inoculated potato dextrose broth. The compounds were trapped as volatile organic compounds (VOCs) onto solid-phase microextraction (SPME) for small scale and Tenax for large scale and then isolated using standard high-performance liquid chromatography (HPLC) methods. Styrene was authenticated by a comparison to the retention times, fragmentation patterns, and calculated retention indices of a commercially available sample. The identity of MCOT was verified by a short chemical synthesis and a comparison of spectroscopic data to the isolated sample. A biosynthetic scheme of styrene is proposed on the basis of a (13)C-labeling study. This is the first report of MCOT isolated as a natural product.
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Affiliation(s)
- John J Beck
- Western Regional Research Center, U.S. Department of Agriculture, Albany, California 94710, USA.
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Santini F, Mantovani A, Cristaudo A, Rago T, Marsili A, Buselli R, Mignani A, Ceccarini G, Bastillo R, Taddei D, Ricco I, Vitti P, Pinchera A. Thyroid function and exposure to styrene. Thyroid 2008; 18:1065-9. [PMID: 18816178 DOI: 10.1089/thy.2008.0003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Many natural substances and drugs have long been known to cause goiter or thyroid dysfunction. More recently, several environmental pollutants, such as pesticides and industrial compounds, have been investigated for their thyroid-disrupting activity and related adverse effects on human health. The aim of this study was to evaluate the effects of styrene on the thyroid axis in occupationally exposed workers. METHODS Thirty-eight exposed (E) and 123 nonexposed (NE) male workers (controls) were assessed. Serum concentrations of thyrotropin (TSH; basal and after thyrotropin-releasing hormone [TRH] administration.), free thyroxine (FT(4)), free triiodothyronine (FT(3)), anti-thyroglobulin, thyroid peroxidase antibody, and calcitonin were measured. Thyroid ultrasound examination was also performed. In E workers, urinary creatinine, mandelic acid (MA), and phenylglyoxylic acid (PGA) were also measured. RESULTS No significant differences between E and NE workers were demonstrated, as far as thyroid volume, nodularity, serum thyroid antibodies, and calcitonin were analyzed. However, in the E group a positive correlation between duration of exposure and thyroid volume was detected. After exclusion of subjects with nodular or autoimmune thyroid diseases, serum concentrations of FT(4), FT(3), and TSH did not differ between the two groups. In E workers there was a positive correlation between the urinary concentrations of styrene metabolites (MA plus PGA) and FT(4) or FT(4)/FT(3) ratio (p < 0.05; r = 0.45 and p < 0.005; r = 0.61, respectively), while no correlation was observed between urinary concentrations of MA plus PGA and serum TSH (either basal and stimulated). CONCLUSIONS Chronic exposure to styrene is not associated with an increase in nodular or autoimmune thyroid diseases. However, styrene could interfere with peripheral metabolism of thyroid hormones by inhibiting T(4) to T(3) conversion. Whether this is a direct effect on iodothyronine deiodinases or a consequence of a general distress, such as in nonthyroidal illnesses, remains to be established. Further studies in a larger population of exposed workers are needed to confirm these preliminary observations.
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Affiliation(s)
- Ferruccio Santini
- Department of Endocrinology and Kidney, University Hospital of Pisa, Pisa, Italy.
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Abstract
To determine the cytochrome P450 (CYP) primarily expressed after styrene exposure, seven forms of hepatic CYP mRNA in rats treated with 600 mg kg(-1) styrene were examined. CYP1A2, CYP2B1/2, CYP2E1 and CYP3A2 mRNA were observed using real-time LightCycler PCR. The amount of CYP2B1 mRNA was significantly increased, 47-fold compared with controls, suggesting that this CYP is the primary cytochrome P450 in rats exposed to styrene. Significant increases in the amount of CYP2E1, CYP1A2 and CYP2B2 mRNA were also observed after styrene exposure, and their increase levels were 3.1-, 1.7- and 1.7-fold higher than controls, respectively. Western blot analysis also indicated that the protein levels of CYP2B1, CYP2B2, CYP2E1 and CYP1A2 showed clear increases after styrene treatment, corresponding to their mRNA expression. CYP2C11 mRNA decreased significantly in rats after styrene exposure. CYP1A1 was detected at the mRNA level in rat liver, but it was not detected at the protein level. The expression of epoxide hydrolase (EH), involved in Phase I drug metabolism, was also examined. EH mRNA increased 2-fold compared with controls after styrene exposure. Styrene thus appears to be a chemical compound that induces multiple CYPs. The results demonstrate that CYP2B1 is the primarily induced CYP form by styrene treatment to rats at acute toxic level.
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Affiliation(s)
- F Hirasawa
- Department of Biochemistry, Akita University School of Medicine, Japan
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Abstract
The performance of biocatalytic reactions is often hampered by product and/or substrate toxicity and short-term reaction times due to instable biocatalysts. Microbes in biofilms show a remarkable resistance against biocides and form stable communities. In nature, especially in environments characterized by harsh conditions such as heavily contaminated sites, cells grow pre-dominantly in biofilms, which enable them to cope with physiological stress. This robustness was utilized to design a bioprocess concept based on catalytic biofilms for stable long-term transformations of toxic reactants. Sixty-nine bacterial strains have been screened to find organisms suitable for biofilm-based biotransformations. This included host strains important for recombinant enzyme expression and strains isolated from biofilters or contaminated soils. Nearly all organisms with bioremediation potential showed good biofilm forming capacities. Pseudomonas sp. strain VLB120DeltaC was chosen as a model organism due to its excellent biofilm forming capacity and its well-studied capability of catalyzing asymmetric epoxidations. A tubular reactor was used for the biotransformation of styrene to (S)-styrene oxide as a model reaction. The process was stable for at least 55 days at a maximal volumetric productivity of 16 g/(L(aq) day) and a yield of 9 mol%. In situ product extraction prevented product inhibition of the catalyst. Biofilm physiology and dynamics are characterized during the biotransformation and limitations and advantages of this reaction concept are discussed.
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Affiliation(s)
- Rainer Gross
- Department of Biochemical and Chemical Engineering, University of Dortmund, Emil-Figge-Str. 66, 44221 Dortmund, Germany
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Rihs HP, Triebig G, Werner P, Rabstein S, Heinze E, Pesch B, Bruning T. Association between genetic polymorphisms in styrene-metabolizing enzymes and biomarkers in styrene-exposed workers. J Toxicol Environ Health A 2008; 71:866-873. [PMID: 18569587 DOI: 10.1080/15287390801987998] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Single-nucleotide polymorphisms (SNP) in genes of styrene-metabolizing enzymes could modulate biomarker concentrations in blood or urine after exposure to styrene. Ten SNP were analyzed to study their influence on styrene-specific biomarkers in 89 workers of a fiber-reinforced plastic boat building factory. The internal styrene body burden was analyzed in post-shift blood and urine samples. External styrene exposure was measured by passive samplers. Spearman rank correlations between styrene exposure and biomarkers were calculated and distributions of biomarkers were checked for lognormality. Mixed linear models were applied to analyze the influence of genotypes and styrene exposure, on styrene in blood (Monday and Thursday post-shift) and on phenyglyoxylic acid (PGA; adjusted for day of measurement, Monday to Thursday) due to a lognormal distribution, smoking (current, not current), and use of respirators. Stratified analyzes for workers without and with different types of respirators were also performed. The models of both the subgroups revealed a significant influence dependent on the respirator type that workers used for inhalation protection. An influence of the external styrene concentration on the urinary PGA concentration was not observed. After implementation of the SNP into the model significant lower adjusted means of urinary PGA concentrations were found for GSTP1 105IleVal and CYP2E1 -71TT. For styrene levels in blood no significant effect was observed. A significant influence on styrene levels in blood was correlated with external styrene concentration only in workers without use of respirators. The effects of two SNP on urinary PGA decrease indicated a limited modulating SNP effect. The most effective prevention for styrene exposure was obtained with the wearing of respirators.
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Affiliation(s)
- Hans-Peter Rihs
- BGFA-Research Institute of Occupational Medicine, German Social Accident Insurance, Ruhr-University Bochum, Germany
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Goff M, Ward PG, O'Connor KE. Improvement of the conversion of polystyrene to polyhydroxyalkanoate through the manipulation of the microbial aspect of the process: A nitrogen feeding strategy for bacterial cells in a stirred tank reactor. J Biotechnol 2007; 132:283-6. [PMID: 17559958 DOI: 10.1016/j.jbiotec.2007.03.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 03/06/2007] [Accepted: 03/15/2007] [Indexed: 10/23/2022]
Abstract
Pseudomonas putida CA-3 has been shown to accumulate the biodegradable plastic polyhydroxyalkanoate (PHA) when fed styrene or polystyrene pyrolysis oil as the sole carbon and energy source under nitrogen limiting growth conditions (67 mg nitrogen per litre at time 0). Batch fermentation of P. putida CA-3 grown on styrene or polystyrene pyrolysis oil in a stirred tank reactor yields PHA at 30% of the cell dry weight (CDW). The feeding of nitrogen at a rate of 1mg N/l/h resulted in a 1.1-fold increase in the percentage of CDW accumulated as PHA. An increase in the rate of nitrogen feeding up to 1.5mg N/l/h resulted in further increases in the percentage of the cell dry weight composed of PHA. However, feeding rates of 1.75 and 2mg N/l/h resulted in dramatic decreases in the percentage of cell dry weight composed of PHA. Interestingly nitrogen was not detectable in the growth medium after 16 h, in any of the growth conditions tested. A higher cell density was observed in cells supplied with nitrogen and thus further increases in the overall production of PHA were observed through nitrogen feeding. The highest yield of PHA was 0.28 g PHA per g styrene supplied with a nitrogen feeding rate of 1.5mg/l/h.
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Affiliation(s)
- Miriam Goff
- Centre for Synthesis and Chemical Biology, Conway Institute for Biomolecular and Biomedical Research, National University of Ireland, University College Dublin, Belfield, Dublin 4, Ireland
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Pinches SE, Apps P. Production in food of 1,3-pentadiene and styrene by Trichoderma species. Int J Food Microbiol 2007; 116:182-5. [PMID: 17360064 DOI: 10.1016/j.ijfoodmicro.2006.12.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 11/30/2006] [Accepted: 12/06/2006] [Indexed: 09/30/2022]
Abstract
The ability of two strains of Trichoderma, isolated from food, to produce the Volatile Organic Compounds 1,3-pentadiene and styrene was investigated. One of the strains had been implicated in a case of food spoilage involving the production of both compounds. In vitro in potato dextrose broth, the strains produced both 1,3-pentadiene and styrene within 5 days in the presence of sorbic acid and cinnamic acid. The taints were produced only in the presence of sorbic acid and cinnamic acid and were not synthesised de novo under the test conditions. Neither the conversion of cinnamic acid to styrene, nor the conversion of sorbic acid to 1,3-pentadiene by Trichoderma strains in foods has been previously reported. The range of organisms implicated in these types of spoilage is thus extended.
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Affiliation(s)
- S E Pinches
- Biosciences, Council for Scientific and Industrial Research (CSIR), PO Box 395, Pretoria 0001, South Africa.
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Di Gennaro P, Ferrara S, Ronco I, Galli E, Sello G, Papacchini M, Bestetti G. Styrene lower catabolic pathway in Pseudomonas fluorescens ST: identification and characterization of genes for phenylacetic acid degradation. Arch Microbiol 2007; 188:117-25. [PMID: 17377771 DOI: 10.1007/s00203-007-0226-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Revised: 01/15/2007] [Accepted: 02/14/2007] [Indexed: 11/24/2022]
Abstract
Pseudomonas fluorescens ST is a styrene degrading microorganism that, by the sequential oxidation of the vinyl side chain, converts styrene to phenylacetic acid. The cluster of styrene upper pathway catabolic genes (sty genes) has been previously localized on a chromosomal region. This report describes the isolation, sequencing and analysis of a new chromosomal fragment deriving from the ST strain genomic bank that contains the styrene lower degradative pathway genes (paa genes), involved in the metabolism of phenylacetic acid. Analysis of the paa gene cluster led to the description of 14 putative genes: a gene encoding a phenylacetyl-CoA ligase (paaF), the enzyme required for the activation of phenylacetic acid; five ORFs encoding the subunits of a ring hydroxylation multienzymatic system (paaGHIJK); the gene paaW encoding a membrane protein of unknown function; five genes for a beta-oxidation-like system (paaABCDE), involved in the steps following the aromatic ring cleavage; a gene encoding a putative permease (paaL) and a gene (paaN) probably involved in the aromatic ring cleavage. The function of some of the isolated genes has been proved by means of biotransformation experiments.
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Affiliation(s)
- Patrizia Di Gennaro
- Department of Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 1, 20126, Milan, Italy
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Pagot Y, Belin JM, Husson F, Spinnler HE. Metabolism of phenylalanine and biosynthesis of styrene in Penicillium camemberti. J DAIRY RES 2007; 74:180-5. [PMID: 17291386 DOI: 10.1017/s0022029906002251] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Accepted: 09/28/2006] [Indexed: 11/06/2022]
Abstract
The occurrence of styrene in food may be an important aroma defect (celluloid odour), even at very low concentrations (Miltz et al. 1980) causing consumer rejection and is therefore a problem for the food industry. We examined the biosynthetic pathway leading to styrene formation by Penicillium camemberti using labelled compounds. As styrene is strongly hydrophobic and volatile, we first had to develop a continuous extraction process. Using resins XAD2 it was reasonable to suspect phenylalanine (Phe) as the precursor. The addition of Phe marked with 13C on the ring provokes the accumulation of labelled styrene. The enzyme activities involved were also tentatively measured. Styrene appears to be synthesized from phenylalanine by phenylalanine ammonia-lyase activity followed by a decarboxylation catalysed by a cinnamic acid decarboxylase.
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Affiliation(s)
- Yves Pagot
- UMR de Microbiologie et Génétique Moléculaire, Institut National Agronomique Paris-Grignon, UMR INRA 537, URA CNRS 1925, F-78850 Thiverval-Grignon France.
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Abstract
To determine the effect of styrene on the male reproductive function of rats, male Wistar rats received a daily intraperitoneal (ip) injection of the xenobiotic at a dose of 600 mg/kg body weight. Serum testosterone (T) level was measured in duplicate by radioimmunoassay (RIA). Blood luteinizing hormone (LH) and follicle stimulating hormone (FSH) concentrations were determined using enzyme-linked immunosorbent assay (ELISA). After 10 days of treatment, an increase of the relative weight of the testis occurred, but that of the seminal vesicles and prostate remained unchanged compared to controls injected with an equivalent volume of the vehicle (corn oil). Serum T concentration dropped, while serum hypophyse hormone levels increased. Testicular histological observations revealed a pronounced morphological alteration, with enlarged intracellular spaces, loosening of tissue, and dramatic loss of gametes in the lumen of the seminiferous tubules. Spermatogenesis damage was also confirmed by the decrease in motility and the number of epididymal spermatozoa of treated rats. According to these results, with regard to the lack of a dose response relationship in this study, we may conclude that the testis, precisely the germinal and Sertoli cells, are the major targets for styrene toxicity.
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Affiliation(s)
- Naoufel Chamkhia
- Laboratoire de Physiologie Intégrée, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia
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Park JB, Bühler B, Habicher T, Hauer B, Panke S, Witholt B, Schmid A. The efficiency of recombinant Escherichia coli as biocatalyst for stereospecific epoxidation. Biotechnol Bioeng 2006; 95:501-12. [PMID: 16767777 DOI: 10.1002/bit.21037] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Styrene is efficiently converted into (S)-styrene oxide by growing Escherichia coli expressing the styrene monooxygenase genes styAB of Pseudomonas sp. strain VLB120 in an organic/aqueous emulsion. Now, we investigated factors influencing the epoxidation activity of recombinant E. coli with the aim to improve the process in terms of product concentration and volumetric productivity. The catalytic activity of recombinant E. coli was not stable and decreased with reaction time. Kinetic analyses and the independence of the whole-cell activity on substrate and biocatalyst concentrations indicated that the maximal specific biocatalyst activity was not exploited under process conditions and that substrate mass transfer and enzyme inhibition did not limit bioconversion performance. Elevated styrene oxide concentrations, however, were shown to promote acetic acid formation, membrane permeabilization, and cell lysis, and to reduce growth rate and colony-forming activity. During biotransformations, when cell viability was additionally reduced by styAB overexpression, such effects coincided with decreasing specific epoxidation rates and metabolic activity. This clearly indicated that biocatalyst performance was reduced as a result of product toxicity. The results point to a product toxicity-induced biological energy shortage reducing the biocatalyst activity under process conditions. By reducing exposure time of the biocatalyst to the product and increasing biocatalyst concentrations, volumetric productivities were increased up to 1,800 micromol/min/liter aqueous phase (with an average of 8.4 g/L(aq) x h). This represents the highest productivity reported for oxygenase-based whole-cell biocatalysis involving toxic products.
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Affiliation(s)
- Jin-Byung Park
- Institute of Biotechnology, ETH Zurich, Zurich, Switzerland
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Harvilchuck JA, Carlson GP. Comparison of styrene and its metabolites styrene oxide and 4-vinylphenol on cytotoxicity and glutathione depletion in Clara cells of mice and rats. Toxicology 2006; 227:165-72. [PMID: 16956708 DOI: 10.1016/j.tox.2006.08.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Revised: 07/21/2006] [Accepted: 08/02/2006] [Indexed: 11/17/2022]
Abstract
Styrene is a widely used compound in the manufacturing industry. In mice and rats, it is both hepatotoxic and pneumotoxic. It causes lung tumors in mice, but not in rats. The Clara cell is the main target for the toxicity of styrene and its metabolites, and it also has the greatest activity for styrene metabolism. Therefore, Clara cells isolated from CD-1 mice and Sprague-Dawley rats were used to compare the cytotoxicities induced by styrene and its metabolites. The cytotoxicity of styrene was greater in vitro than that of its metabolites styrene oxide (racemic, R- and S-) and 4-vinylphenol in contrast with what has been observed in vivo in previous studies on hepatotoxicity and pneumotoxicity. Susceptibility of rats to styrene and its metabolites are 4-fold less than that observed with mice. Glutathione levels were also measured in mice following addition of the chemicals in vitro and treatment of the CD-1 mice in vivo. Decreases in glutathione concentrations were seen even at doses which did not cause the death of mouse Clara cells. Significant decreases in glutathione were observed 3h after treatment with racemic SO and R-SO. At 12h, rebound effects were seen for all compounds, with all but R-SO rebounding above controls. These studies suggest that in vitro cytotoxicity of styrene and its metabolites does not strictly follow in vivo effects and that decreases in mouse glutathione levels may be related to oxidative stress.
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Affiliation(s)
- Jill A Harvilchuck
- School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, USA
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Chung JK, Yuan W, Liu G, Zheng J. Investigation of bioactivation and toxicity of styrene in CYP2E1 transgenic cells. Toxicology 2006; 226:99-106. [PMID: 16872732 DOI: 10.1016/j.tox.2006.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 05/17/2006] [Accepted: 06/03/2006] [Indexed: 10/24/2022]
Abstract
Styrene has been found to be toxic to the respiratory system, and the toxicity of styrene is metabolism-dependent. CYP2E1 is suggested to be one of the cytochrome P450 enzymes responsible for the bioactivation of styrene. Our work focused on the roles of CYP2E1 and epoxide, a metabolite of styrene epoxidation, in the cytotoxicity of styrene. Styrene was found to be more toxic to h2E1 cells than to the wild type, while there was no difference found when styrene oxide was administered. Both soluble and microsomal epoxide hydrolase inhibitors dramatically enhanced styrene toxicity. Glutathione and glutathione ethyl ester showed protection against styrene cytotoxicity. Cytotoxicity of a selection of styrene analogues, such as ethylbenzene, vinylcyclohexane, and ethylcyclohexane, was assessed to determine if unsaturation is required for styrene toxicity. Ethylbenzene and vinylcyclohexane were found to be as toxic as styrene to h2E1 cells, whereas little toxicity of ethylcyclohexane to h2E1 cells was observed. This indicates the importance of vinyl group of styrene in its cytotoxicity, but saturation of the vinyl group does not necessarily eliminate styrene toxicity. An N-acetylcysteine conjugate derived from styrene oxide was identified by LC/MS/MS in the sample obtained from the incubation of h2E1 cell lysate with styrene in the presence of N-acetylcysteine. Formation of the N-acetylcysteine conjugate was found to be NADPH-dependent. These studies provided strong evidence in support of toxic role of styrene epoxide metabolite in styrene toxicity.
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Affiliation(s)
- Jou-Ku Chung
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA
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del Peso-Santos T, Bartolomé-Martín D, Fernández C, Alonso S, García JL, Díaz E, Shingler V, Perera J. Coregulation by phenylacetyl-coenzyme A-responsive PaaX integrates control of the upper and lower pathways for catabolism of styrene by Pseudomonas sp. strain Y2. J Bacteriol 2006; 188:4812-21. [PMID: 16788190 PMCID: PMC1483010 DOI: 10.1128/jb.00176-06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The P(styA) promoter of Pseudomonas sp. strain Y2 controls expression of the styABCD genes, which are required for the conversion of styrene to phenylacetate, which is further catabolized by the products of two paa gene clusters. Two PaaX repressor proteins (PaaX1 and PaaX2) regulate transcription of the paa gene clusters of this strain. In silico analysis of the P(styA) promoter region revealed a sequence located just within styA that is similar to the reported PaaX binding sites of Escherichia coli and the proposed PaaX binding sites of the paa genes of Pseudomonas species. Here we show that protein extracts from some Pseudomonas strains that have paaX genes, but not from a paaX mutant strain, can bind and retard the migration of a P(styA) specific probe. Purified maltose-binding protein (MBP)-PaaX1 fusion protein specifically binds the P(styA) promoter proximal PaaX site, and this binding is eliminated by the addition of phenylacetyl-coenzyme A. The sequence protected by MBP-PaaX1 binding was defined by DNase I footprinting. Moreover, MBP-PaaX1 represses transcription from the P(styA) promoter in a phenylacetyl-coenzyme A-dependent manner in vitro. Finally, the inactivation of both paaX gene copies of Pseudomonas sp. strain Y2 leads to a higher level of transcription from the P(styA) promoter, while heterologous expression of the PaaX1 in E. coli greatly decreases transcription from the P(styA) promoter. These findings reveal a control mechanism that integrates regulation of styrene catabolism by coordinating the expression of the styrene upper catabolic operon to that of the paa-encoded central pathway and support a role for PaaX as a major regulatory protein in the phenylacetyl-coenzyme A catabolon through its response to the levels of this central metabolite.
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Affiliation(s)
- Teresa del Peso-Santos
- Department of Biochemistry and Molecular Biology, I, Facultad de Ciencias Biológicas, Universidad Complutense, 28040 Madrid, Spain
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