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Tharmasothirajan A, Melcr J, Linney J, Gensch T, Krumbach K, Ernst KM, Brasnett C, Poggi P, Pitt AR, Goddard AD, Chatgilialoglu A, Marrink SJ, Marienhagen J. Membrane manipulation by free fatty acids improves microbial plant polyphenol synthesis. Nat Commun 2023; 14:5619. [PMID: 37699874 PMCID: PMC10497605 DOI: 10.1038/s41467-023-40947-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 08/16/2023] [Indexed: 09/14/2023] Open
Abstract
Microbial synthesis of nutraceutically and pharmaceutically interesting plant polyphenols represents a more environmentally friendly alternative to chemical synthesis or plant extraction. However, most polyphenols are cytotoxic for microorganisms as they are believed to negatively affect cell integrity and transport processes. To increase the production performance of engineered cell factories, strategies have to be developed to mitigate these detrimental effects. Here, we examine the accumulation of the stilbenoid resveratrol in the cell membrane and cell wall during its production using Corynebacterium glutamicum and uncover the membrane rigidifying effect of this stilbenoid experimentally and with molecular dynamics simulations. A screen of free fatty acid supplements identifies palmitelaidic acid and linoleic acid as suitable additives to attenuate resveratrol's cytotoxic effects resulting in a three-fold higher product titer. This cost-effective approach to counteract membrane-damaging effects of product accumulation is transferable to the microbial production of other polyphenols and may represent an engineering target for other membrane-active bioproducts.
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Affiliation(s)
- Apilaasha Tharmasothirajan
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425, Jülich, Germany
- Institute of Biotechnology, RWTH Aachen University, Worringer Weg 3, 52074, Aachen, Germany
| | - Josef Melcr
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - John Linney
- College of Health and Life Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Thomas Gensch
- Institute for Information Processing, IBI-1: Molecular and Cellular Physiology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Karin Krumbach
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Karla Marlen Ernst
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Christopher Brasnett
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Paola Poggi
- Remembrane Srl, via San Francesco 40, 40026, Imola, Italy
| | - Andrew R Pitt
- College of Health and Life Sciences, Aston University, Birmingham, B4 7ET, UK
- Manchester Institute of Biotechnology and Department of Chemistry, University of Manchester, Manchester, UK
| | - Alan D Goddard
- College of Health and Life Sciences, Aston University, Birmingham, B4 7ET, UK
| | | | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Jan Marienhagen
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, 52425, Jülich, Germany.
- Institute of Biotechnology, RWTH Aachen University, Worringer Weg 3, 52074, Aachen, Germany.
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Effect of organic solvents on asymmetric reduction of β-keto esters using cyanobacterium Synechocystis sp. PCC 6803. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2021.153249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Comparative Proteomics of Marinobacter sp. TT1 Reveals Corexit Impacts on Hydrocarbon Metabolism, Chemotactic Motility, and Biofilm Formation. Microorganisms 2020; 9:microorganisms9010003. [PMID: 33374976 PMCID: PMC7822026 DOI: 10.3390/microorganisms9010003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/19/2020] [Accepted: 12/19/2020] [Indexed: 12/12/2022] Open
Abstract
The application of chemical dispersants during marine oil spills can affect the community composition and activity of marine microorganisms. Several studies have indicated that certain marine hydrocarbon-degrading bacteria, such as Marinobacter spp., can be inhibited by chemical dispersants, resulting in lower abundances and/or reduced biodegradation rates. However, a major knowledge gap exists regarding the mechanisms underlying these physiological effects. Here, we performed comparative proteomics of the Deepwater Horizon isolate Marinobacter sp. TT1 grown under different conditions. Strain TT1 received different carbon sources (pyruvate vs. n-hexadecane) with and without added dispersant (Corexit EC9500A). Additional treatments contained crude oil in the form of a water-accommodated fraction (WAF) or chemically-enhanced WAF (CEWAF; with Corexit). For the first time, we identified the proteins associated with alkane metabolism and alginate biosynthesis in strain TT1, report on its potential for aromatic hydrocarbon biodegradation and present a protein-based proposed metabolism of Corexit components as carbon substrates. Our findings revealed that Corexit exposure affects hydrocarbon metabolism, chemotactic motility, biofilm formation, and induces solvent tolerance mechanisms, like efflux pumps, in strain TT1. This study provides novel insights into dispersant impacts on microbial hydrocarbon degraders that should be taken into consideration for future oil spill response actions.
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Oh YR, Jang YA, Hong SH, Han JJ, Eom GT. Efficient production of lactobionic acid using genetically engineered Pseudomonas taetrolens as a whole-cell biocatalyst. Enzyme Microb Technol 2020; 141:109668. [DOI: 10.1016/j.enzmictec.2020.109668] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/07/2020] [Accepted: 09/09/2020] [Indexed: 12/15/2022]
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Luo G, Fujino M, Nakano S, Hida A, Tajima T, Kato J. Accelerating itaconic acid production by increasing membrane permeability of whole-cell biocatalyst based on a psychrophilic bacterium Shewanella livingstonensis Ac10. J Biotechnol 2020; 312:56-62. [DOI: 10.1016/j.jbiotec.2020.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/21/2020] [Accepted: 03/05/2020] [Indexed: 12/27/2022]
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Yue T, Chen R, Chen D, Liu J, Xie K, Dai J. Enzymatic Synthesis of Bioactive O-Glucuronides Using Plant Glucuronosyltransferases. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:6275-6284. [PMID: 31083910 DOI: 10.1021/acs.jafc.9b01769] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Many O-glucuronides exhibiting various pharmacological activities have been found in nature and in drug metabolism. The glucuronidation of bioactive natural products or drugs to generate glucuronides with better activity and druggability is important in drug discovery and research. In this study, by using two uridine diphosphate (UDP)-dependent glucuronosyltransferases (GATs, UGT88D4 and UGT88D7) from plants, we developed two glucuronidation approaches, pure enzyme catalysis in vitro and recombinant whole-cell catalysis in vivo, to efficiently synthesize bioactive O-glucuronides by the glucuronidation of natural products. In total, 14 O-glucuronides with different structures, including flavonoids, anthraquinones, coumarins, and lignans, were obtained, 7 of which were new compounds. Furthermore, one of the biosynthesized O-glucuronides, kaempferol-7- O-β-d-glucuronide (3a), potently inhibited protein tyrosine phosphatase (PTP) 1B with an IC50 value of 8.02 × 10-6 M. Some of the biosynthesized O-glucuronides also exhibited significant antioxidant activities.
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Reddy PV, Karegoudar TB, Nayak AS. Enhanced utilization of fluorene by Paenibacillus sp. PRNK-6: Effect of rhamnolipid biosurfactant and synthetic surfactants. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 151:206-211. [PMID: 29407558 DOI: 10.1016/j.ecoenv.2018.01.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 01/08/2018] [Accepted: 01/10/2018] [Indexed: 06/07/2023]
Abstract
The present investigation was to study the effect of different non-ionic surfactants (Tween-80, Tween-60, Tween-40, Tween-20, Triton X-100) and a rhamnolipid biosurfactant on the degradation of fluorene by Paenibacillus sp. PRNK-6. An enhancement in the growth, as well as fluorene utilization by this strain were observed in the presence of biosurfactant and non-ionic surfactants except Tween-20 and Triton X-100. Triton X-100 and Tween-20 were toxic to this bacterium. The strain PRNK-6 utilized 75% of fluorene (280mg/L) in 24h in an unamended condition. On the other hand, the complete utilization of higher concentration fluorene (320mg/L) by this strain was noticed when the medium was amended with Tween-80 (1.5% v/v) within 24h of incubation. Whereas, 90.6%, 96.5% and 96.7% of fluorene (280mg/L) was utilized when amended with Tween-60 (3.5% v/v), Tween-40 (3% v/v) and biosurfactant (25mg/L) respectively. Biosurfactant promoted the fluorene degradation potential of PRNK-6 as 96.2% of 320mg/L fluorene was degraded within 24h. Further, the added tween series surfactants and a biosurfactant have increased the cell surface hydrophobicity of the PRNK-6. Thus correlating with the enhanced degradation of the fluorene.
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Affiliation(s)
- Pooja V Reddy
- Department of Biochemistry, Gulbarga University, Kalaburagi 585106, Karnataka, India
| | - T B Karegoudar
- Department of Biochemistry, Gulbarga University, Kalaburagi 585106, Karnataka, India
| | - Anand S Nayak
- Department of Biochemistry, Gulbarga University, Kalaburagi 585106, Karnataka, India.
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Ohashi T, Hasegawa Y, Misaki R, Fujiyama K. Substrate preference of citrus naringenin rhamnosyltransferases and their application to flavonoid glycoside production in fission yeast. Appl Microbiol Biotechnol 2015; 100:687-96. [DOI: 10.1007/s00253-015-6982-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Revised: 08/21/2015] [Accepted: 09/02/2015] [Indexed: 01/01/2023]
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9
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Sim DH, Shin KC, Oh DK. 13-Hydroxy-9Z,11E-Octadecadienoic Acid Production by Recombinant Cells Expressing Burkholderia thailandensis 13-Lipoxygenase. J AM OIL CHEM SOC 2015. [DOI: 10.1007/s11746-015-2694-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Comparative study of the bioconversion process using R-(+)- and S-(–)-limonene as substrates for Fusarium oxysporum 152B. Food Chem 2015; 174:606-13. [DOI: 10.1016/j.foodchem.2014.11.059] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Revised: 10/27/2014] [Accepted: 11/10/2014] [Indexed: 01/11/2023]
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11
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Bustamante M, Rubilar O, Diez MC. Effect of Soya Lecithin on Solubilization and Biodegradation of Pentachlorophenol by <i>Anthracophyllum discolor</i>. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ajac.2014.51005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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12
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Yao Z, Zhang C, Zhao J, Lu F, Bie X, Lu Z. Acetaldehyde detoxification using resting cells of recombinant Escherichia coli overexpressing acetaldehyde dehydrogenase. Appl Biochem Biotechnol 2013; 172:2030-40. [PMID: 24326678 DOI: 10.1007/s12010-013-0632-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 10/30/2013] [Indexed: 11/25/2022]
Abstract
Acetaldehyde dehydrogenase (E.C. 1.2.1.10) plays a key role in the acetaldehyde detoxification. The recombinant Escherichia coli cells producing acetaldehyde dehydrogenase (ist-ALDH) were applied as whole-cell biocatalysts for biodegradation of acetaldehyde. Response surface methodology (RSM) was employed to enhance the production of recombinant ist-ALDH. Under the optimum culture conditions containing 20.68 h post-induction time, 126.75 mL medium volume and 3 % (v/v) inoculum level, the maximum ist-ALDH activity reached 496.65 ± 0.81 U/mL, resulting in 12.5-fold increment after optimization. Furthermore, the optimum temperature and pH for the catalytic activity of wet cells were 40 °C and pH 9.5, respectively. The biocatalytic activity was improved 80 % by permeabilizing the recombinant cells with 0.075 % (v/v) Triton X-100. When using 2 mmol/L NAD(+) as coenzyme, the permeabilized cells could catalyze 98 % of acetaldehyde within 15 min. The results indicated that the recombinant E. coli with high productivity of ist-ALDH might be highly efficient and easy-to-make biocatalysts for acetaldehyde detoxification.
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Affiliation(s)
- Zhengying Yao
- College of Food Science and Technology, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, People's Republic of China
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Zhang D, Zhu L, Li F. Influences and mechanisms of surfactants on pyrene biodegradation based on interactions of surfactant with a Klebsiella oxytoca strain. BIORESOURCE TECHNOLOGY 2013; 142:454-61. [PMID: 23751486 DOI: 10.1016/j.biortech.2013.05.077] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 05/19/2013] [Accepted: 05/20/2013] [Indexed: 05/22/2023]
Abstract
Surfactant-enhanced bioremediation has been proposed as a promising technology for the treatment of organic polluted soils; however its application has been hindered by the controversial influences and mechanisms of surfactants on the biodegradation of hydrophobic organic compounds. To address this problem, effects of five surfactants on the sorption and biodegradation of pyrene by Klebsiella oxytoca PYR-1, as well as their interactions with bacterial cell surface and membrane lipids were investigated. We found that surfactants enhanced or inhibited pyrene biodegradation depending on their effects on the sorption of pyrene onto bacterial cell, which occurred mainly through modifying cell surface hydrophobicity (such as Tween series surfactants) or disrupting bacterial membrane (such as Triton X-100), respectively. A relatively high positive correlation (P<0.0001) was observed between biodegradation promotion (Bs/B0) and enhancement of sorption coefficients (Kd,s(∗)/Kd,0(∗)) for pyrene in the presence of surfactant, indicating that surfactant-induced sorption played the dominant role during pyrene biodegradation.
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Affiliation(s)
- Dong Zhang
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
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Kaehne F, Buchhaupt M, Schrader J. A recombinant α-dioxygenase from rice to produce fatty aldehydes using E. coli. Appl Microbiol Biotechnol 2011; 90:989-95. [PMID: 21347727 DOI: 10.1007/s00253-011-3165-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 01/31/2011] [Accepted: 01/31/2011] [Indexed: 11/30/2022]
Abstract
Fatty aldehydes are an important group of fragrance and flavor compounds that are found in different fruits and flowers. A biotechnological synthesis of fatty aldehydes based on Escherichia coli cells expressing an α-dioxygenase (αDOX) from Oryza sativa (rice) is presented. α-Dioxygenases are the initial enzymes of α-oxidation in plants and oxidize long and medium-chain C(n) fatty acids to 2-hydroperoxy fatty acids. The latter are converted to C(n-1) fatty aldehydes by spontaneous decarboxylation. Successful expression of αDOX in E. coli was proven by an in vitro luciferase assay. Using resting cells of this recombinant E. coli strain, conversion of different fatty acids to the respective fatty aldehydes shortened by one carbon atom was demonstrated. The usage of Triton X 100 improves the conversion rate up to 1 g aldehyde per liter per hour. Easy reuse of the cells was demonstrated by performing a second biotransformation without any loss of biocatalytic activity.
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Affiliation(s)
- Fenja Kaehne
- DECHEMA e.V. Karl-Winnacker-Institut, Biochemical Engineering, Theodor-Heuss-Allee 25, 60486 Frankfurt/Main, Germany
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Heyland J, Antweiler N, Lutz J, Heck T, Geueke B, Kohler HPE, Blank LM, Schmid A. Simple enzymatic procedure for L-carnosine synthesis: whole-cell biocatalysis and efficient biocatalyst recycling. Microb Biotechnol 2009; 3:74-83. [PMID: 21255308 PMCID: PMC3815949 DOI: 10.1111/j.1751-7915.2009.00143.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
β-Peptides and their derivates are usually stable to proteolysis and have an increased half-life compared with α-peptides. Recently, β-aminopeptidases were described as a new enzyme class that enabled the enzymatic degradation and formation of β-peptides. As an alternative to the existing chemical synthesis routes, the aim of the present work was to develop a whole-cell biocatalyst for the synthesis and production of β-peptides using this enzymatic activity. For the optimization of the reaction system we chose the commercially relevant β,α-dipeptide L-carnosine (β-alanine-L-histidine) as model product. We were able to show that different recombinant yeast and bacteria strains, which overexpress a β-peptidase, could be used directly as whole-cell biocatalysts for the synthesis of L-carnosine. By optimizing relevant reaction conditions for the best-performing recombinant Escherichia coli strain, such as pH and substrate concentrations, we obtained high l-carnosine yields of up to 71%. Long-time as well as biocatalyst recycling experiments indicated a high stability of the developed biocatalyst for at least five repeated batches. Application of the recombinant E. coli in a fed-batch process enabled the accumulation of l-carnosine to a concentration of 3.7 g l(-1).
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Affiliation(s)
- Jan Heyland
- Laboratory of Chemical Biotechnology, TU Dortmund, 44221 Dortmund, Germany
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Michielsen MJF, Frielink C, Meijer EA, van der Werf MJ, Wijffels RH, Tramper J, Beeftink HH. Stabilization of Maleate-Hydratase Activity of PermeabilizedPseudomonas Pseudoalcaligenes. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.3109/10242429909015227] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
Polycyclic aromatic hydrocarbons (PAHs) are toxic environmental pollutants that are known or suspected carcinogens or mutagens. Bioremediation has been used as a general way to eliminate them from the contaminated sites or aquifers, but their biodegradation is rather limited due to their low bioavailability because of their sparingly soluble nature. Surfactant-mediated biodegradation is a promising alternative. The presence of surfactants can increase the solubility of PAHs and hence potentially increase their bioavailability. However, inconclusive results have been reported on the effects of surfactant on the biodegradation of PAHs. In this work, surfactant-mediated biodegradation of PAHs is reviewed.
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Villa F, Cappitelli F, Principi P, Polo A, Sorlini C. Permeabilization method forin-situinvestigation of fungal conidia on surfaces. Lett Appl Microbiol 2009; 48:234-40. [DOI: 10.1111/j.1472-765x.2008.02520.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Chen RR. Permeability issues in whole-cell bioprocesses and cellular membrane engineering. Appl Microbiol Biotechnol 2007; 74:730-8. [PMID: 17221194 DOI: 10.1007/s00253-006-0811-x] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 12/14/2006] [Accepted: 12/17/2006] [Indexed: 10/23/2022]
Abstract
Nutrient uptake and waste excretion are among the many important functions of the cellular membrane. While permitting nutrients into the cell, the cellular membrane system evolves to guide against noxious agents present in the environment from entering the intracellular milieu. The semipermeable nature of the membrane is at odds with biomolecular engineers in their endeavor of using microbes as cell factory. The cellular membrane often retards the entry of substrate into the cellular systems and prevents the product from being released from the cellular system for an easy recovery. Consequently, productivities of whole-cell bioprocesses such as biocatalysis, fermentation, and bioremediations are severely compromised. For example, the rate of whole-cell biocatalysis is usually 1-2 orders of magnitude slower than that of the isolated enzymes. When product export cannot keep pace with the production rate, intracellular product accumulation quickly leads to a halt of production due to product inhibition. While permeabilization via chemical or physical treatment of cell membrane is effective in small-scale process, large-scale implementation is problematic. Molecular engineering approach recently emerged as a much better alternative. Armed with increasingly sophisticated tools, biomolecular engineers are following nature's ingenuity to derive satisfactory solutions to the permeability problem. This review highlights these exciting molecular engineering achievements.
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Affiliation(s)
- Rachel Ruizhen Chen
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0100, USA.
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Jang SA, Lee DS, Lee MW, Woo SH. Toxicity of phenanthrene dissolved in nonionic surfactant solutions to Pseudomonas putida P2. FEMS Microbiol Lett 2006; 267:194-9. [PMID: 17156121 DOI: 10.1111/j.1574-6968.2006.00546.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The fraction in which direct contact occurs between micellar-phase phenanthrene and the bacterial cell surface was estimated by measuring the toxicity of nonionic surfactant (Tween 80 and Triton X-100) solutions to the phenanthrene-degrading bacterium, Pseudomonas putida P2. Cell viability of completely dissolved phenanthrene decreased by 30% at concentrations greater than 0.3 mg L(-1), which is equal to approximately one third of its solubility. Both nonionic surfactants had no effect on cell viability up to 5 g L(-1). Cell viability increased with increasing surfactant concentration at a fixed phenanthrene concentration, due to the decreased concentration of aqueous-pseudophase phenanthrene and the reduced fraction of direct contact. The fraction of direct contact was c. 20% or more below 3 g L(-1) of Triton X-100. The fraction of direct contact for Tween 80 was estimated to be lower than Triton X-100.
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Affiliation(s)
- Soon A Jang
- Department of Food and Nutrition, Chungnam National University, Yuseong-Gu, Daejeon, Republic of Korea
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Ni Y, Chen RR. Accelerating whole-cell biocatalysis by reducing outer membrane permeability barrier. Biotechnol Bioeng 2005; 87:804-11. [PMID: 15329939 DOI: 10.1002/bit.20202] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Whole-cell biocatalysts are preferred in many biocatalysis applications. However, due to permeability barriers imposed by cell envelopes, whole-cell catalyzed reactions are reportedly 10-100-fold slower than reactions catalyzed by free enzymes. In this study, we accelerated whole-cell biocatalysis by reducing the membrane permeability barrier using molecular engineering approaches. Escherichia coli cells with genetically altered outer membrane structures were used. Specifically, a lipopolysaccarides mutant SM101 and a Braun's lipoprotein mutant E609L were used along with two model substrates that differ substantially in size and hydrophobicity, nitrocefin, and a tetrapeptide N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide. The reduction of the outer membrane permeability by genetic methods led to significant increases (up to 380%) in reaction rates of whole-cell catalyzed reactions. The magnitude of increase in biocatalysis rates was dependent on the substrates and on the nature of mutations introduced in the outer membrane structure. Notably, mutations in outer membrane can render the outer membrane completely permeable to one substrate, a barrierless condition that maximizes the reaction rate. The impact of the mutations introduced on the permeability barrier of the membranes was compared to the impact of polymixin B nonapeptide, a known potent permeabilizer acting on lipopolysaccharides. Our results suggest that genetic modifications to enhance the permeability of hydrophilic molecules should target the Lipid A region. However, strategies other than reduction of Lipid A synthesis should be considered. As we have demonstrated with tetrapeptide, membrane engineering can be much more effective in reducing a permeability barrier than are exogenous permeabilizers. This work, to our knowledge, is the first use of a molecular membrane engineering approach to address substrate permeability limitations encountered in biocatalysis applications.
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Affiliation(s)
- Ye Ni
- Chemical Engineering Department, Virginia Commonwealth University, 601 W. Main St., Richmond 23284-3028, USA
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