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Aqif M, Shah MUH, Khan R, Umar M, SajjadHaider, Razak SIA, Wahit MU, Khan SUD, Sivapragasam M, Ullah S, Nawaz R. Glycolipids biosurfactants production using low-cost substrates for environmental remediation: progress, challenges, and future prospects. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:47475-47504. [PMID: 39017873 DOI: 10.1007/s11356-024-34248-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 07/02/2024] [Indexed: 07/18/2024]
Abstract
The production of renewable materials from alternative sources is becoming increasingly important to reduce the detrimental environmental effects of their non-renewable counterparts and natural resources, while making them more economical and sustainable. Chemical surfactants, which are highly toxic and non-biodegradable, are used in a wide range of industrial and environmental applications harming humans, animals, plants, and other entities. Chemical surfactants can be substituted with biosurfactants (BS), which are produced by microorganisms like bacteria, fungi, and yeast. They have excellent emulsifying, foaming, and dispersing properties, as well as excellent biodegradability, lower toxicity, and the ability to remain stable under severe conditions, making them useful for a variety of industrial and environmental applications. Despite these advantages, BS derived from conventional resources and precursors (such as edible oils and carbohydrates) are expensive, limiting large-scale production of BS. In addition, the use of unconventional substrates such as agro-industrial wastes lowers the BS productivity and drives up production costs. However, overcoming the barriers to commercial-scale production is critical to the widespread adoption of these products. Overcoming these challenges would not only promote the use of environmentally friendly surfactants but also contribute to sustainable waste management and reduce dependence on non-renewable resources. This study explores the efficient use of wastes and other low-cost substrates to produce glycolipids BS, identifies efficient substrates for commercial production, and recommends strategies to improve productivity and use BS in environmental remediation.
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Affiliation(s)
- Muhammad Aqif
- Faculty of Materials and Chemical Engineering, Department of Chemical Engineering, Ghulam Ishaq Khan Institute, Topi, Swabi, Khyber Pakhtunkhwa, 23460, Pakistan
- Chemical Engineering Department, College of Engineering, King Saud University, P.O. Box 800, 11421, Riyadh, Saudi Arabia
| | - Mansoor Ul Hassan Shah
- Department of Chemical Engineering, Faculty of Mechanical, Chemical and Industrial Engineering, University of Engineering and Technology, Peshawar, 25120, Pakistan
| | - Rawaiz Khan
- College of Dentistry, Engineer Abdullah Bugshan Research Chair for Dental and Oral Rehabilitation, King Saud University, 11545, Riyadh, Saudi Arabia.
| | - Muhammad Umar
- Faculty of Materials and Chemical Engineering, Department of Chemical Engineering, Ghulam Ishaq Khan Institute, Topi, Swabi, Khyber Pakhtunkhwa, 23460, Pakistan
| | - SajjadHaider
- Chemical Engineering Department, College of Engineering, King Saud University, P.O. Box 800, 11421, Riyadh, Saudi Arabia
| | - Saiful Izwan Abd Razak
- BioInspired Device and Tissue Engineering Research Group, School of Biomedical Engineering and Health Sciences, Faculty of Engineering, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia
- Sports Innovation & Technology Centre, Institute of Human Centred Engineering, Universiti Teknologi Malaysia, 81300, Skudai, Johor, Malaysia
| | - Mat Uzir Wahit
- Faculty of Chemical and Energy Engineering, UniversitiTeknologi Malaysia (UTM), 81310, Skudai, Johor Bahru, Johor, Malaysia
- Centre for Advanced Composite Materials (CACM), Universiti Teknologi Malaysia (UTM), 81310, Skudai, Johor, Malaysia
| | - Salah Ud-Din Khan
- College of Engineering, Sustainable Energy Center Technologies, King Saud University, P.O. Box 800, 11421, Riyadh, Saudi Arabia
| | - Magaret Sivapragasam
- Faculty of Integrated Life Sciences, School of Integrated Sciences (SIS), School of Postgraduate Studies, Research and Internationalization, Quest International University, 30250, Ipoh, Perak, Malaysia
| | - Shafi Ullah
- Institute of Soil and Environmental Sciences, PirMehr Ali Shah Arid Agriculture University Shamsabad, Murree Rd, Rawalpindi, 46300, Pakistan
| | - Rab Nawaz
- Institute of Soil and Environmental Sciences, PirMehr Ali Shah Arid Agriculture University Shamsabad, Murree Rd, Rawalpindi, 46300, Pakistan
- Department of Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600, Bangi, Selangor, Malaysia
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González‐Valdez A, Escalante A, Soberón‐Chávez G. Heterologous production of rhamnolipids in Pseudomonas chlororaphis subsp chlororaphis ATCC 9446 based on the endogenous production of N-acyl-homoserine lactones. Microb Biotechnol 2024; 17:e14377. [PMID: 38041625 PMCID: PMC10832566 DOI: 10.1111/1751-7915.14377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 11/08/2023] [Accepted: 11/10/2023] [Indexed: 12/03/2023] Open
Abstract
Rhamnolipids (RL) are biosurfactants naturally produced by the opportunistic pathogen Pseudomonas aeruginosa. Currently, RL are commercialized for various applications and produced by Pseudomonas putida due to the health risks associated with their large-scale production by P. aeruginosa. In this work, we show that RL containing one or two rhamnose moieties (mono-RL or di-RL, respectively) can be produced by the innocuous soil-bacterium Pseudomonas chlororaphis subsp chlororaphis ATCC 9446 at titres up to 66 mg/L (about 86% of the production of P. aeruginosa PAO1 in the same culture conditions). The production of RL depends on the expression of P. aeruginosa PAO1 genes encoding the enzymes RhlA, RhlB and RhlC. These genes were introduced in a plasmid, together with a transcriptional regulator (rhlR) forming part of the same operon, with and without RhlC. We show that the activation of rhlAB by RhlR depends on its interaction with P. chlororaphis endogenous acyl-homoserine lactones, which are synthetized by either PhzI or CsaI autoinducer synthases (producing 3-hydroxy-hexanoyl homoserine lactone, 3OH-C6-HSL, or 3-oxo-hexanoyl homoserine lactone, 3O-C6-HSL, respectively). P. chlororaphis transcriptional regulator couple with 3OH-C6-HSL is the primary activator of gene expression for phenazine-1-carboxylic acid (PCA) and phenazine-1-carboxamide (PCN) production in this soil bacterium. We show that RhlR coupled with 3OH-C6-HSL or 3O-C6-HSL promotes RL production and increases the production of PCA in P. chlororaphis. However, PhzR/3OH-C6-HSL or CsaR/3O-C6-HSL cannot activate the expression of the rhlAB operon to produce mono-RL. These results reveal a complex regulatory interaction between RhlR and P. chlororaphis quorum-sensing signals and highlight the biotechnology potential of P. chlororaphis ATCC 9446 expressing P. aeruginosa rhlAB-R or rhlAB-R-C for the industrial production of RL.
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Affiliation(s)
- Abigail González‐Valdez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones BiomédicasUniversidad Nacional Autónoma de MéxicoCoyoacanMexico
| | - Adelfo Escalante
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoCuernavacaMexico
| | - Gloria Soberón‐Chávez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones BiomédicasUniversidad Nacional Autónoma de MéxicoCoyoacanMexico
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Lipphardt A, Karmainski T, Blank LM, Hayen H, Tiso T. Identification and quantification of biosurfactants produced by the marine bacterium Alcanivorax borkumensis by hyphenated techniques. Anal Bioanal Chem 2023; 415:7067-7084. [PMID: 37819435 PMCID: PMC10684412 DOI: 10.1007/s00216-023-04972-5] [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: 07/26/2023] [Revised: 09/19/2023] [Accepted: 09/21/2023] [Indexed: 10/13/2023]
Abstract
A novel biosurfactant was discovered to be synthesized by the marine bacterium Alcanivorax borkumensis in 1992. This bacterium is abundant in marine environments affected by oil spills, where it helps to degrade alkanes and, under such conditions, produces a glycine-glucolipid biosurfactant. The biosurfactant enhances the bacterium's attachment to oil droplets and facilitates the uptake of hydrocarbons. Due to its useful properties expected, there is interest in the biotechnological production of this biosurfactant. To support this effort analytically, a method combining reversed-phase high-performance liquid chromatography (HPLC) with high-resolution mass spectrometry (HRMS) was developed, allowing the separation and identification of glycine-glucolipid congeners. Accurate mass, retention time, and characteristic fragmentation pattern were utilized for species assignment. In addition, charged-aerosol detection (CAD) was employed to enable absolute quantification without authentic standards. The methodology was used to investigate the glycine-glucolipid production by A. borkumensis SK2 using different carbon sources. Mass spectrometry allowed us to identify congeners with varying chain lengths (C6-C12) and degrees of unsaturation (0-1 double bonds) in the incorporated 3-hydroxy-alkanoic acids, some previously unknown. Quantification using CAD revealed that the titer was approximately twice as high when grown with hexadecane as with pyruvate (49 mg/L versus 22 mg/L). The main congener for both carbon sources was glc-40:0-gly, accounting for 64% with pyruvate and 85% with hexadecane as sole carbon source. With the here presented analytical suit, complex and varying glycolipids can be identified, characterized, and quantified, as here exemplarily shown for the interesting glycine-glucolipid of A. borkumensis.
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Affiliation(s)
- Anna Lipphardt
- Institute of Inorganic and Analytical Chemistry, University of Münster, Münster, Germany
| | - Tobias Karmainski
- Institute of Applied Microbiology, RWTH Aachen University, Aachen, Germany
| | - Lars M Blank
- Institute of Applied Microbiology, RWTH Aachen University, Aachen, Germany
| | - Heiko Hayen
- Institute of Inorganic and Analytical Chemistry, University of Münster, Münster, Germany
| | - Till Tiso
- Institute of Applied Microbiology, RWTH Aachen University, Aachen, Germany.
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de Vrije T, Nagtegaal RM, Veloo RM, Kappen FHJ, de Wolf FA. Medium chain length polyhydroxyalkanoate produced from ethanol by Pseudomonas putida grown in liquid obtained from acidogenic digestion of organic municipal solid waste. BIORESOURCE TECHNOLOGY 2023; 375:128825. [PMID: 36878376 DOI: 10.1016/j.biortech.2023.128825] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/27/2023] [Accepted: 03/01/2023] [Indexed: 06/18/2023]
Abstract
Production of medium chain length polyhydroxyalkanoate (mcl-PHA) up to about 6 g.L-1 was obtained by feeding ethanol to Pseudomonas putida growing in liquid obtained from acidogenic digestion of organic municipal solid waste. Washing the wet, heat-inactivated Pseudomonas cells at the end of the fermentation with ethanol obviated the need of drying the biomass and enabled the removal of contaminating lipids before solvent-mediated extraction of PHA. Using 'green' solvents, 90 to near 100% of the mcl-PHA was extracted and purities of 71-78% mcl-PHA were reached already by centrifugation and decantation without further filtration for biomass removal. The mcl-PHA produced in this way consists of 10-18% C8, 72-78% C10 and 8-12% C12 chains (entirely medium chain length), has a crystallinity and melting temperature of ∼13% and ∼49 °C, respectively, and is a stiff rubberlike, colourless material at room temperature.
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Affiliation(s)
- Truus de Vrije
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands.
| | - Ricardo M Nagtegaal
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands
| | - Ruud M Veloo
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands
| | - Frans H J Kappen
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands
| | - Frits A de Wolf
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands
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Rhamnolipid Self-Aggregation in Aqueous Media: A Long Journey toward the Definition of Structure–Property Relationships. Int J Mol Sci 2023; 24:ijms24065395. [PMID: 36982468 PMCID: PMC10048978 DOI: 10.3390/ijms24065395] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/06/2023] [Accepted: 03/07/2023] [Indexed: 03/16/2023] Open
Abstract
The need to protect human and environmental health and avoid the widespread use of substances obtained from nonrenewable sources is steering research toward the discovery and development of new molecules characterized by high biocompatibility and biodegradability. Due to their very widespread use, a class of substances for which this need is particularly urgent is that of surfactants. In this respect, an attractive and promising alternative to commonly used synthetic surfactants is represented by so-called biosurfactants, amphiphiles naturally derived from microorganisms. One of the best-known families of biosurfactants is that of rhamnolipids, which are glycolipids with a headgroup formed by one or two rhamnose units. Great scientific and technological effort has been devoted to optimization of their production processes, as well as their physicochemical characterization. However, a conclusive structure–function relationship is far from being defined. In this review, we aim to move a step forward in this direction, by presenting a comprehensive and unified discussion of physicochemical properties of rhamnolipids as a function of solution conditions and rhamnolipid structure. We also discuss still unresolved issues that deserve further investigation in the future, to allow the replacement of conventional surfactants with rhamnolipids.
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Ziegler AL, Grütering C, Poduschnick L, Mitsos A, Blank LM. Co-feeding enhances the yield of methyl ketones. J Ind Microbiol Biotechnol 2023; 50:kuad029. [PMID: 37704397 PMCID: PMC10521942 DOI: 10.1093/jimb/kuad029] [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: 04/12/2023] [Accepted: 09/11/2023] [Indexed: 09/15/2023]
Abstract
The biotechnological production of methyl ketones is a sustainable alternative to fossil-derived chemical production. To date, the best host for microbial production of methyl ketones is a genetically engineered Pseudomonas taiwanensis VLB120 ∆6 pProd strain, achieving yields of 101 mgg-1 on glucose in batch cultivations. For competitiveness with the petrochemical production pathway, however, higher yields are necessary. Co-feeding can improve the yield by fitting the carbon-to-energy ratio to the organism and the target product. In this work, we developed co-feeding strategies for P. taiwanensis VLB120 ∆6 pProd by combined metabolic modeling and experimental work. In a first step, we conducted flux balance analysis with an expanded genome-scale metabolic model of iJN1463 and found ethanol as the most promising among five cosubstrates. Next, we performed cultivations with ethanol and found the highest reported yield in batch production of methyl ketones with P. taiwanensis VLB120 to date, namely, 154 mg g-1 methyl ketones. However, ethanol is toxic to the cell, which reflects in a lower substrate consumption and lower product concentrations when compared to production on glucose. Hence, we propose cofeeding ethanol with glucose and find that, indeed, higher concentrations than in ethanol-fed cultivation (0.84 g Laq-1 with glucose and ethanol as opposed to 0.48 g Laq-1 with only ethanol) were achieved, with a yield of 85 mg g-1. In a last step, comparing experimental with computational results suggested the potential for improving the methyl ketone yield by fed-batch cultivation, in which cell growth and methyl ketone production are separated into two phases employing optimal ethanol to glucose ratios. ONE-SENTENCE SUMMARY By combining computational and experimental work, we demonstrate that feeding ethanol in addition to glucose improves the yield of biotechnologically produced methyl ketones.
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Affiliation(s)
- Anita L Ziegler
- Process Systems Engineering (AVT.SVT), RWTH Aachen University, 52074 Aachen, Germany
| | - Carolin Grütering
- Institute of Applied Microbiology (iAMB), RWTH Aachen University, 52074 Aachen, Germany
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Leon Poduschnick
- Process Systems Engineering (AVT.SVT), RWTH Aachen University, 52074 Aachen, Germany
- Institute of Applied Microbiology (iAMB), RWTH Aachen University, 52074 Aachen, Germany
| | - Alexander Mitsos
- JARA-ENERGY, 52056 Aachen, Germany
- Process Systems Engineering (AVT.SVT), RWTH Aachen University, 52074 Aachen, Germany
- Institute of Energy and Climate Research: Energy Systems Engineering (IEK-10), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Lars M Blank
- Institute of Applied Microbiology (iAMB), RWTH Aachen University, 52074 Aachen, Germany
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The Glycine-Glucolipid of Alcanivorax borkumensis Is Resident to the Bacterial Cell Wall. Appl Environ Microbiol 2022; 88:e0112622. [PMID: 35938787 PMCID: PMC9397105 DOI: 10.1128/aem.01126-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The marine bacterium Alcanivorax borkumensis produces a surface-active glycine-glucolipid during growth with long-chain alkanes. A high-performance liquid chromatography (HPLC) method was developed for absolute quantification. This method is based on the conversion of the glycine-glucolipid to phenacyl esters with subsequent measurement by HPLC with diode array detection (HPLC-DAD). Different molecular species were separated by HPLC and identified as glucosyl-tetra(3-hydroxy-acyl)-glycine with varying numbers of 3-hydroxy-decanoic acid or 3-hydroxy-octanoic acid groups via mass spectrometry. The growth rate of A. borkumensis cells with pyruvate as the sole carbon source was elevated compared to hexadecane as recorded by the increase in cell density as well as oxygen/carbon dioxide transfer rates. The amount of the glycine-glucolipid produced per cell during growth on hexadecane was higher compared with growth on pyruvate. The glycine-glucolipid from pyruvate-grown cells contained considerable amounts of 3-hydroxy-octanoic acid, in contrast to hexadecane-grown cells, which almost exclusively incorporated 3-hydroxy-decanoic acid into the glycine-glucolipid. The predominant proportion of the glycine-glucolipid was found in the cell pellet, while only minute amounts were present in the cell-free supernatant. The glycine-glucolipid isolated from the bacterial cell broth, cell pellet, or cell-free supernatant showed the same structure containing a glycine residue, in contrast to previous reports, which suggested that a glycine-free form of the glucolipid exists which is secreted into the supernatant. In conclusion, the glycine-glucolipid of A. borkumensis is resident to the cell wall and enables the bacterium to bind and solubilize alkanes at the lipid-water interface. IMPORTANCE Alcanivorax borkumensis is one of the most abundant marine bacteria found in areas of oil spills, where it degrades alkanes. The production of a glycine-glucolipid is considered an essential element for alkane degradation. We developed a quantitative method and determined the structure of the A. borkumensis glycine-glucolipid in different fractions of the cultures after growth in various media. Our results show that the amount of the glycine-glucolipid in the cells by far exceeds the amount measured in the supernatant, confirming the proposed cell wall localization. These results support the scenario that the surface hydrophobicity of A. borkumensis cells increases by producing the glycine-glucolipid, allowing the cells to attach to the alkane-water interface and form a biofilm. We found no evidence for a glycine-free form of the glucolipid.
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Blunt W, Blanchard C, Morley K. Effects of environmental parameters on microbial rhamnolipid biosynthesis and bioreactor strategies for enhanced productivity. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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9
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Sarwar A, Nguyen LT, Lee EY. Bio-upgrading of ethanol to fatty acid ethyl esters by metabolic engineering of Pseudomonas putida KT2440. BIORESOURCE TECHNOLOGY 2022; 350:126899. [PMID: 35217159 DOI: 10.1016/j.biortech.2022.126899] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 02/19/2022] [Accepted: 02/21/2022] [Indexed: 06/14/2023]
Abstract
Fatty acid ethyl esters (FAEEs) have gained increasing attention as a replacement for traditional fossil fuels in the recent years. Here, we report the efficient upgrading of ethanol to FAEEs from Pseudomonas putida KT2440, using ethanol as the sole carbon source. First, the wax synthase (WS) encoded by the atfA gene from Acinetobacter baylyi ADP1 was expressed in P. putida KT2440. Second, the flux from ethanol towards acetyl-CoA was increased by expression of the acetaldehyde dehydrogenase (ada) from Dickeya zeae. By using dodecane overlay to capture FAEEs, 1.2 g/L of FAEEs with a yield of 152.09 mg FAEEs/g ethanol were produced. Culture optimization enhanced the FAEEs contents up to 1.6 g/L in shake flask and 4.3 g/L in a fed-batch fermenter. In summary, our study provides a basis for combining the bioethanol production process with the efficient upgrading of ethanol to biodiesel.
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Affiliation(s)
- Arslan Sarwar
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Linh Thanh Nguyen
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Eun Yeol Lee
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea.
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Sałek K, Euston SR, Janek T. Phase Behaviour, Functionality, and Physicochemical Characteristics of Glycolipid Surfactants of Microbial Origin. Front Bioeng Biotechnol 2022; 10:816613. [PMID: 35155390 PMCID: PMC8830654 DOI: 10.3389/fbioe.2022.816613] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/10/2022] [Indexed: 01/14/2023] Open
Abstract
Growing demand for biosurfactants as environmentally friendly counterparts of chemically derived surfactants enhances the extensive search for surface-active compounds of biological (microbial) origin. The understanding of the physicochemical properties of biosurfactants such as surface tension reduction, dispersion, emulsifying, foaming or micelle formation is essential for the successful application of biosurfactants in many branches of industry. Glycolipids, which belong to the class of low molecular weight surfactants are currently gaining a lot of interest for industrial applications. For this reason, we focus mainly on this class of biosurfactants with particular emphasis on rhamnolipids and sophorolipids, the most studied of the glycolipids.
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Affiliation(s)
- Karina Sałek
- Institute for Life and Earth Sciences, School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh, United Kingdom
- *Correspondence: Karina Sałek,
| | - Stephen R. Euston
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, United Kingdom
| | - Tomasz Janek
- Department of Biotechnology and Food Microbiology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
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Demling P, Ankenbauer A, Klein B, Noack S, Tiso T, Takors R, Blank LM. Pseudomonas putida KT2440 endures temporary oxygen limitations. Biotechnol Bioeng 2021; 118:4735-4750. [PMID: 34506651 DOI: 10.1002/bit.27938] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 01/26/2023]
Abstract
The obligate aerobic nature of Pseudomonas putida, one of the most prominent whole-cell biocatalysts emerging for industrial bioprocesses, questions its ability to be cultivated in large-scale bioreactors, which exhibit zones of low dissolved oxygen tension. P. putida KT2440 was repeatedly subjected to temporary oxygen limitations in scale-down approaches to assess the effect on growth and an exemplary production of rhamnolipids. At those conditions, the growth and production of P. putida KT2440 were decelerated compared to well-aerated reference cultivations, but remarkably, final biomass and rhamnolipid titers were similar. The robust growth behavior was confirmed across different cultivation systems, media compositions, and laboratories, even when P. putida KT2440 was repeatedly exposed to dual carbon and oxygen starvation. Quantification of the nucleotides ATP, ADP, and AMP revealed a decrease of intracellular ATP concentrations with increasing duration of oxygen starvation, which can, however, be restored when re-supplied with oxygen. Only small changes in the proteome were detected when cells encountered oscillations in dissolved oxygen tensions. Concluding, P. putida KT2440 appears to be able to cope with repeated oxygen limitations as they occur in large-scale bioreactors, affirming its outstanding suitability as a whole-cell biocatalyst for industrial-scale bioprocesses.
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Affiliation(s)
- Philipp Demling
- Institute of Applied Microbiology (iAMB), Aachen Biology and Biotechnology (ABBt), RWTH Aachen University, Aachen, Germany
| | - Andreas Ankenbauer
- Institute of Biochemical Engineering, University of Stuttgart, Stuttgart, Germany
| | - Bianca Klein
- Institute of Bio- and Geosciences (IBG-1): Biotechnology, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Stephan Noack
- Institute of Bio- and Geosciences (IBG-1): Biotechnology, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Till Tiso
- Institute of Applied Microbiology (iAMB), Aachen Biology and Biotechnology (ABBt), RWTH Aachen University, Aachen, Germany
| | - Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart, Stuttgart, Germany
| | - Lars M Blank
- Institute of Applied Microbiology (iAMB), Aachen Biology and Biotechnology (ABBt), RWTH Aachen University, Aachen, Germany
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Henson WR, Meyers AW, Jayakody LN, DeCapite A, Black BA, Michener WE, Johnson CW, Beckham GT. Biological upgrading of pyrolysis-derived wastewater: Engineering Pseudomonas putida for alkylphenol, furfural, and acetone catabolism and (methyl)muconic acid production. Metab Eng 2021; 68:14-25. [PMID: 34438073 DOI: 10.1016/j.ymben.2021.08.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 08/18/2021] [Accepted: 08/22/2021] [Indexed: 10/20/2022]
Abstract
While biomass-derived carbohydrates have been predominant substrates for biological production of renewable fuels, chemicals, and materials, organic waste streams are growing in prominence as potential alternative feedstocks to improve the sustainability of manufacturing processes. Catalytic fast pyrolysis (CFP) is a promising approach to generate biofuels from lignocellulosic biomass, but it generates a complex, carbon-rich, and toxic wastewater stream that is challenging to process catalytically but could be biologically upgraded to valuable co-products. In this work, we implemented modular, heterologous catabolic pathways in the Pseudomonas putida KT2440-derived EM42 strain along with the overexpression of native toxicity tolerance machinery to enable utilization of 89% (w/w) of carbon in CFP wastewater. The dmp monooxygenase and meta-cleavage pathway from Pseudomonas putida CF600 were constitutively expressed to enable utilization of phenol, cresols, 2- and 3-ethyl phenol, and methyl catechols, and the native chaperones clpB, groES, and groEL were overexpressed to improve toxicity tolerance to diverse aromatic substrates. Next, heterologous furfural and acetone utilization pathways were incorporated, and a native alcohol dehydrogenase was overexpressed to improve methanol utilization, generating reducing equivalents. All pathways (encoded by genes totaling ~30 kilobases of DNA) were combined into a single strain that can catabolize a mock CFP wastewater stream as a sole carbon source. Further engineering enabled conversion of all aromatic compounds in the mock wastewater stream to (methyl)muconates with a ~90% (mol/mol) yield. Biological upgrading of CFP wastewater as outlined in this work provides a roadmap for future applications in valorizing other heterogeneous waste streams.
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Affiliation(s)
- William R Henson
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Alex W Meyers
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Lahiru N Jayakody
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Annette DeCapite
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Brenna A Black
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - William E Michener
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Christopher W Johnson
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA.
| | - Gregg T Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA.
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13
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Noll P, Treinen C, Müller S, Lilge L, Hausmann R, Henkel M. Exploiting RNA thermometer-driven molecular bioprocess control as a concept for heterologous rhamnolipid production. Sci Rep 2021; 11:14802. [PMID: 34285304 PMCID: PMC8292423 DOI: 10.1038/s41598-021-94400-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/09/2021] [Indexed: 11/23/2022] Open
Abstract
A key challenge to advance the efficiency of bioprocesses is the uncoupling of biomass from product formation, as biomass represents a by-product that is in most cases difficult to recycle efficiently. Using the example of rhamnolipid biosurfactants, a temperature-sensitive heterologous production system under translation control of a fourU RNA thermometer from Salmonella was established to allow separating phases of preferred growth from product formation. Rhamnolipids as bulk chemicals represent a model system for future processes of industrial biotechnology and are therefore tied to the efficiency requirements in competition with the chemical industry. Experimental data confirms function of the RNA thermometer and suggests a major effect of temperature on specific rhamnolipid production rates with an increase of the average production rate by a factor of 11 between 25 and 38 °C, while the major part of this increase is attributable to the regulatory effect of the RNA thermometer rather than an unspecific overall increase in bacterial metabolism. The production capacity of the developed temperature sensitive-system was evaluated in a simple batch process driven by a temperature switch. Product formation was evaluated by efficiency parameters and yields, confirming increased product formation rates and product-per-biomass yields compared to a high titer heterologous rhamnolipid production process from literature.
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Affiliation(s)
- Philipp Noll
- Institute of Food Science and Biotechnology, Department of Bioprocess Engineering (150K), University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany
| | - Chantal Treinen
- Institute of Food Science and Biotechnology, Department of Bioprocess Engineering (150K), University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany
| | - Sven Müller
- Institute of Food Science and Biotechnology, Department of Bioprocess Engineering (150K), University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany
| | - Lars Lilge
- Institute of Food Science and Biotechnology, Department of Bioprocess Engineering (150K), University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany
| | - Rudolf Hausmann
- Institute of Food Science and Biotechnology, Department of Bioprocess Engineering (150K), University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany
| | - Marius Henkel
- Institute of Food Science and Biotechnology, Department of Bioprocess Engineering (150K), University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany.
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14
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Welsing G, Wolter B, Hintzen HMT, Tiso T, Blank LM. Upcycling of hydrolyzed PET by microbial conversion to a fatty acid derivative. Methods Enzymol 2021; 648:391-421. [PMID: 33579413 DOI: 10.1016/bs.mie.2020.12.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The enzymatic degradation of polyethylene terephthalate (PET) results in a hydrolysate consisting almost exclusively of its two monomers, ethylene glycol and terephthalate. To biologically valorize the PET hydrolysate, microbial upcycling into high-value products is proposed. Fatty acid derivatives hydroxyalkanoyloxy alkanoates (HAAs) represent such valuable target molecules. HAAs exhibit surface-active properties and can be exploited in the catalytical conversion to drop-in biofuels as well as in the polymerization to bio-based poly(amide urethane). This chapter presents the genetic engineering methods of pseudomonads for the metabolization of PET monomers and the biosynthesis of HAAs with detailed protocols concerning product purification.
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Affiliation(s)
- Gina Welsing
- iAMB-Institute of Applied Microbiology, ABBt-Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Birger Wolter
- iAMB-Institute of Applied Microbiology, ABBt-Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Henric M T Hintzen
- iAMB-Institute of Applied Microbiology, ABBt-Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Till Tiso
- iAMB-Institute of Applied Microbiology, ABBt-Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Lars M Blank
- iAMB-Institute of Applied Microbiology, ABBt-Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany.
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15
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Coupling an Electroactive Pseudomonas putida KT2440 with Bioelectrochemical Rhamnolipid Production. Microorganisms 2020; 8:microorganisms8121959. [PMID: 33322018 PMCID: PMC7763313 DOI: 10.3390/microorganisms8121959] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 12/16/2022] Open
Abstract
Sufficient supply of oxygen is a major bottleneck in industrial biotechnological synthesis. One example is the heterologous production of rhamnolipids using Pseudomonas putida KT2440. Typically, the synthesis is accompanied by strong foam formation in the reactor vessel hampering the process. It is caused by the extensive bubbling needed to sustain the high respirative oxygen demand in the presence of the produced surfactants. One way to reduce the oxygen requirement is to enable the cells to use the anode of a bioelectrochemical system (BES) as an alternative sink for their metabolically derived electrons. We here used a P. putida KT2440 strain that interacts with the anode using mediated extracellular electron transfer via intrinsically produced phenazines, to perform heterologous rhamnolipid production under oxygen limitation. The strain P. putida RL-PCA successfully produced 30.4 ± 4.7 mg/L mono-rhamnolipids together with 11.2 ± 0.8 mg/L of phenazine-1-carboxylic acid (PCA) in 500-mL benchtop BES reactors and 30.5 ± 0.5 mg/L rhamnolipids accompanied by 25.7 ± 8.0 mg/L PCA in electrode containing standard 1-L bioreactors. Hence, this study marks a first proof of concept to produce glycolipid surfactants in oxygen-limited BES with an industrially relevant strain.
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16
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Wittgens A, Rosenau F. Heterologous Rhamnolipid Biosynthesis: Advantages, Challenges, and the Opportunity to Produce Tailor-Made Rhamnolipids. Front Bioeng Biotechnol 2020; 8:594010. [PMID: 33195161 PMCID: PMC7642724 DOI: 10.3389/fbioe.2020.594010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 10/07/2020] [Indexed: 12/18/2022] Open
Abstract
The first heterologous expression of genes responsible for the production of rhamnolipids was already implemented in the mid-1990s during the functional identification of the rhlAB operon. This was the starting shot for multiple approaches to establish the rhamnolipid biosynthesis in different host organisms. Since most of the native rhamnolipid producing organisms are human or plant pathogens, the intention for these ventures was the establishment of non-pathogenic organisms as heterologous host for the production of rhamnolipids. The pathogenicity of producing organisms is one of the bottlenecks for applications of rhamnolipids in many industrial products especially foods and cosmetics. The further advantage of heterologous rhamnolipid production is the circumvention of the complex regulatory network, which regulates the rhamnolipid biosynthesis in wild type production strains. Furthermore, a suitable host with an optimal genetic background to provide sufficient amounts of educts allows the production of tailor-made rhamnolipids each with its specific physico-chemical properties depending on the contained numbers of rhamnose sugar residues and the numbers, chain length and saturation degree of 3-hydroxyfatty acids. The heterologous expression of rhl genes can also enable the utilization of unusual carbon sources for the production of rhamnolipids depending on the host organism.
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Affiliation(s)
- Andreas Wittgens
- Institute of Pharmaceutical Biotechnology, Ulm University, Ulm, Germany.,Ulm Center for Peptide Pharmaceuticals (U-PEP), Ulm University, Ulm, Germany
| | - Frank Rosenau
- Institute of Pharmaceutical Biotechnology, Ulm University, Ulm, Germany.,Ulm Center for Peptide Pharmaceuticals (U-PEP), Ulm University, Ulm, Germany.,Department Synthesis of Macromolecules, Max-Planck-Institute for Polymer Research Mainz, Mainz, Germany
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17
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Thompson MG, Incha MR, Pearson AN, Schmidt M, Sharpless WA, Eiben CB, Cruz-Morales P, Blake-Hedges JM, Liu Y, Adams CA, Haushalter RW, Krishna RN, Lichtner P, Blank LM, Mukhopadhyay A, Deutschbauer AM, Shih PM, Keasling JD. Fatty Acid and Alcohol Metabolism in Pseudomonas putida: Functional Analysis Using Random Barcode Transposon Sequencing. Appl Environ Microbiol 2020; 86:e01665-20. [PMID: 32826213 PMCID: PMC7580535 DOI: 10.1128/aem.01665-20] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 08/12/2020] [Indexed: 12/13/2022] Open
Abstract
With its ability to catabolize a wide variety of carbon sources and a growing engineering toolkit, Pseudomonas putida KT2440 is emerging as an important chassis organism for metabolic engineering. Despite advances in our understanding of the organism, many gaps remain in our knowledge of the genetic basis of its metabolic capabilities. The gaps are particularly noticeable in our understanding of both fatty acid and alcohol catabolism, where many paralogs putatively coding for similar enzymes coexist, making biochemical assignment via sequence homology difficult. To rapidly assign function to the enzymes responsible for these metabolisms, we leveraged random barcode transposon sequencing (RB-Tn-Seq). Global fitness analyses of transposon libraries grown on 13 fatty acids and 10 alcohols produced strong phenotypes for hundreds of genes. Fitness data from mutant pools grown on fatty acids of varying chain lengths indicated specific enzyme substrate preferences and enabled us to hypothesize that DUF1302/DUF1329 family proteins potentially function as esterases. From the data, we also postulate catabolic routes for the two biogasoline molecules isoprenol and isopentanol, which are catabolized via leucine metabolism after initial oxidation and activation with coenzyme A (CoA). Because fatty acids and alcohols may serve as both feedstocks and final products of metabolic-engineering efforts, the fitness data presented here will help guide future genomic modifications toward higher titers, rates, and yields.IMPORTANCE To engineer novel metabolic pathways into P. putida, a comprehensive understanding of the genetic basis of its versatile metabolism is essential. Here, we provide functional evidence for the putative roles of hundreds of genes involved in the fatty acid and alcohol metabolism of the bacterium. These data provide a framework facilitating precise genetic changes to prevent product degradation and to channel the flux of specific pathway intermediates as desired.
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Affiliation(s)
- Mitchell G Thompson
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Department of Plant Biology, University of California, Davis, California, USA
| | - Matthew R Incha
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
| | - Allison N Pearson
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
| | - Matthias Schmidt
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Institute of Applied Microbiology (iAMB), Aachen Biology and Biotechnology (ABBt), RWTH Aachen University, Aachen, Germany
| | - William A Sharpless
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Christopher B Eiben
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Joint Program in Bioengineering, University of California, Berkeley, California, USA
| | - Pablo Cruz-Morales
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Centro de Biotecnología FEMSA, Instituto Tecnológico y de Estudios Superiores de Monterrey, Monterrey, México
| | - Jacquelyn M Blake-Hedges
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Department of Chemistry, University of California, Berkeley, California, USA
| | - Yuzhong Liu
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Catharine A Adams
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Robert W Haushalter
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Rohith N Krishna
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Patrick Lichtner
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Lars M Blank
- Institute of Applied Microbiology (iAMB), Aachen Biology and Biotechnology (ABBt), RWTH Aachen University, Aachen, Germany
| | - Aindrila Mukhopadhyay
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Adam M Deutschbauer
- Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Patrick M Shih
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Department of Plant Biology, University of California, Davis, California, USA
- Environmental and Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Jay D Keasling
- Joint BioEnergy Institute, Emeryville, California, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Joint Program in Bioengineering, University of California, Berkeley, California, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California, USA
- Institute for Quantitative Biosciences, University of California, Berkeley, California, USA
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
- Center for Synthetic Biochemistry, Institute for Synthetic Biology, Shenzhen Institutes for Advanced Technologies, Shenzhen, China
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18
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Tiso T, Ihling N, Kubicki S, Biselli A, Schonhoff A, Bator I, Thies S, Karmainski T, Kruth S, Willenbrink AL, Loeschcke A, Zapp P, Jupke A, Jaeger KE, Büchs J, Blank LM. Integration of Genetic and Process Engineering for Optimized Rhamnolipid Production Using Pseudomonas putida. Front Bioeng Biotechnol 2020; 8:976. [PMID: 32974309 PMCID: PMC7468518 DOI: 10.3389/fbioe.2020.00976] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/27/2020] [Indexed: 12/27/2022] Open
Abstract
Rhamnolipids are biosurfactants produced by microorganisms with the potential to replace synthetic compounds with petrochemical origin. To promote industrial use of rhamnolipids, recombinant rhamnolipid production from sugars needs to be intensified. Since this remains challenging, the aim of the presented research is to utilize a multidisciplinary approach to take a step toward developing a sustainable rhamnolipid production process. Here, we developed expression cassettes for stable integration of the rhamnolipid biosynthesis genes into the genome outperformed plasmid-based expression systems. Furthermore, the genetic stability of the production strain was improved by using an inducible promoter. To enhance rhamnolipid synthesis, energy- and/or carbon-consuming traits were removed: mutants negative for the synthesis of the flagellar machinery or the storage polymer PHA showed increased production by 50%. Variation of time of induction resulted in an 18% increase in titers. A scale-up from shake flasks was carried out using a 1-L bioreactor. By recycling of the foam, biomass loss could be minimized and a rhamnolipid titer of up to 1.5 g/L was achieved without using mechanical foam destroyers or antifoaming agents. Subsequent liquid-liquid extraction was optimized by using a suitable minimal medium during fermentation to reduce undesired interphase formation. A technical-scale production process was designed and evaluated by a life-cycle assessment (LCA). Different process chains and their specific environmental impact were examined. It was found that next to biomass supply, the fermentation had the biggest environmental impact. The present work underlines the need for multidisciplinary approaches to address the challenges associated with achieving sustainable production of microbial secondary metabolites. The results are discussed in the context of the challenges of microbial biosurfactant production using hydrophilic substrates on an industrial scale.
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Affiliation(s)
- Till Tiso
- iAMB – Institute of Applied Microbiology, ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Nina Ihling
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Chair of Biochemical Engineering (AVT.BioVT), RWTH Aachen University, Aachen, Germany
| | - Sonja Kubicki
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Andreas Biselli
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Fluid Process Engineering (AVT.FVT), RWTH Aachen University, Aachen, Germany
| | - Andreas Schonhoff
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Institute of Energy and Climate Research – Systems Analysis and Technology Evaluation (IEK-STE), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Isabel Bator
- iAMB – Institute of Applied Microbiology, ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Stephan Thies
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Tobias Karmainski
- iAMB – Institute of Applied Microbiology, ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Sebastian Kruth
- iAMB – Institute of Applied Microbiology, ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Anna-Lena Willenbrink
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Fluid Process Engineering (AVT.FVT), RWTH Aachen University, Aachen, Germany
| | - Anita Loeschcke
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Petra Zapp
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Institute of Energy and Climate Research – Systems Analysis and Technology Evaluation (IEK-STE), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Andreas Jupke
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Fluid Process Engineering (AVT.FVT), RWTH Aachen University, Aachen, Germany
| | - Karl-Erich Jaeger
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
- Institute of Bio- and Geosciences IBG 1: Biotechnology, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Jochen Büchs
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
- Chair of Biochemical Engineering (AVT.BioVT), RWTH Aachen University, Aachen, Germany
| | - Lars M. Blank
- iAMB – Institute of Applied Microbiology, ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Aachen, Germany
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
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