1
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Seo H, Castro G, Trinh CT. Engineering a Synthetic Escherichia coli Coculture for Compartmentalized de novo Biosynthesis of Isobutyl Butyrate from Mixed Sugars. ACS Synth Biol 2024; 13:259-268. [PMID: 38091519 PMCID: PMC10804408 DOI: 10.1021/acssynbio.3c00493] [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: 08/11/2023] [Revised: 11/21/2023] [Accepted: 11/22/2023] [Indexed: 01/23/2024]
Abstract
Short-chain esters are versatile chemicals that can be used as flavors, fragrances, solvents, and fuels. The de novo ester biosynthesis consists of diverging and converging pathway submodules, which is challenging to engineer to achieve optimal metabolic fluxes and selective product synthesis. Compartmentalizing the pathway submodules into specialist cells that facilitate pathway modularization and labor division is a promising solution. Here, we engineered a synthetic Escherichia coli coculture with the compartmentalized sugar utilization and ester biosynthesis pathways to produce isobutyl butyrate from a mixture of glucose and xylose. To compartmentalize the sugar-utilizing pathway submodules, we engineered a xylose-utilizing E. coli specialist that selectively consumes xylose over glucose and bypasses carbon catabolite repression (CCR) while leveraging the native CCR machinery to activate a glucose-utilizing E. coli specialist. We found that the compartmentalization of sugar catabolism enabled simultaneous co-utilization of glucose and xylose by a coculture of the two E. coli specialists, improving the stability of the coculture population. Next, we modularized the isobutyl butyrate pathway into the isobutanol, butyl-CoA, and ester condensation submodules, where we distributed the isobutanol submodule to the glucose-utilizing specialist and the other submodules to the xylose-utilizing specialist. Upon compartmentalization of the isobutyl butyrate pathway submodules into these sugar-utilizing specialist cells, a robust synthetic coculture was engineered to selectively produce isobutyl butyrate, reduce the biosynthesis of unwanted ester byproducts, and improve the production titer as compared to the monoculture.
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Affiliation(s)
- Hyeongmin Seo
- Department
of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
- Center
of Bioenergy Innovation, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Gillian Castro
- Department
of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Cong T. Trinh
- Department
of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
- Center
of Bioenergy Innovation, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37830, United States
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2
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Seo H, Singh P, Wyman CE, Cai CM, Trinh CT. Rewiring metabolism of Clostridium thermocellum for consolidated bioprocessing of lignocellulosic biomass poplar to produce short-chain esters. BIORESOURCE TECHNOLOGY 2023:129263. [PMID: 37271458 DOI: 10.1016/j.biortech.2023.129263] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/06/2023]
Abstract
Consolidated bioprocessing (CBP) of lignocellulosic biomass uses cellulolytic microorganisms to enable enzyme production, saccharification, and fermentation to produce biofuels, biochemicals, and biomaterials in a single step. However, understanding and redirecting metabolisms of these microorganisms compatible with CBP are limited. Here, a cellulolytic thermophile Clostridium thermocellum was engineered and demonstrated to be compatible with CBP integrated with a Co-solvent Enhanced Lignocellulosic Fractionation (CELF) pretreatment for conversion of hardwood poplar into short-chain esters with industrial use as solvents, flavors, fragrances, and biofuels. The recombinant C. thermocellum engineered with deletion of carbohydrate esterases and stable overexpression of alcohol acetyltransferases improved ester production without compromised deacetylation activities. These esterases were discovered to exhibit promiscuous thioesterase activities and their deletion enhanced ester production by rerouting the electron and carbon metabolism. Ester production was further improved up to 80-fold and ester composition could be modulated by deleting lactate biosynthesis and using poplar with different pretreatment severity.
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Affiliation(s)
- Hyeongmin Seo
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Priyanka Singh
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Chemical and Environmental Engineering Department, University of California, Riverside, CA 92521, USA
| | - Charles E Wyman
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Chemical and Environmental Engineering Department, University of California, Riverside, CA 92521, USA
| | - Charles M Cai
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Chemical and Environmental Engineering Department, University of California, Riverside, CA 92521, USA
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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3
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Lv S, Zheng F, Wang Z, Dai L, Liu H, Hrynshpan D, Savitskaya T, Chen J. Effects of bamboo-charcoal modified by bimetallic Fe/Pd nanoparticles on n-hexane biodegradation by bacteria Pseudomonas mendocina NX-1. CHEMOSPHERE 2023; 318:137897. [PMID: 36657580 DOI: 10.1016/j.chemosphere.2023.137897] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/24/2022] [Accepted: 01/15/2023] [Indexed: 06/17/2023]
Abstract
The high hydrophobicity of n-hexane is the main reason why it is difficult to be removed biologically. In this study, the effects of bamboo-charcoal modified by bimetallic Fe/Pd (BBC) on n-hexane biodegradation by Pseudomonas mendocina NX-1 (PM) was investigated. The n-hexane removal efficiency was increased in the presence of BC. The highest n-hexane removal efficiency at 90.0% was achieved at 0.05 g L-1 BCE and 3 g L-1 NH4+ under pH 7.7 and 35 °C. Additionally, protein content (45.9 μg mL-1) and negative cell surface zeta potential (-26.4 mV) were increased during biodegradation process, with PM-BBC being 43.1 μg mL-1 and 19.1 mV. Bacterial growth was improved and maximum cell surface hydrophobicity was obtained after 20 h, which was 59.4% higher than the control with PM-BBC (37.7%) or PM (16.1%), showing biodegradation products of 1-butanol and acetic acid. The results indicate that BBC improved n-hexane biodegradation efficiency by promoting bacterial growth, reducing cell zeta potential, exposing hydrophobic proteins, and increasing cell surface hydrophobicity of bacterial strain NX-1. This investigation suggests that BBC-enhanced biodegradation can be promising to treat n-hexane-containing gas.
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Affiliation(s)
- Sini Lv
- College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Fengzhen Zheng
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou, 310015, China
| | - Zeyu Wang
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou, 310015, China
| | - Luyao Dai
- College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Huan Liu
- College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Dzmitry Hrynshpan
- Research Institute of Physical and Chemical Problems, Belarusian State University, Minsk, 220030, Belarus
| | - Tatsiana Savitskaya
- Research Institute of Physical and Chemical Problems, Belarusian State University, Minsk, 220030, Belarus
| | - Jun Chen
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou, 310015, China.
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4
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Seo H, Giannone RJ, Yang YH, Trinh CT. Proteome reallocation enables the selective de novo biosynthesis of non-linear, branched-chain acetate esters. Metab Eng 2022; 73:38-49. [PMID: 35561848 DOI: 10.1016/j.ymben.2022.05.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/21/2022] [Accepted: 05/06/2022] [Indexed: 10/25/2022]
Abstract
The one-carbon recursive ketoacid elongation pathway is responsible for making various branched-chain amino acids, aldehydes, alcohols, and acetate esters in living cells. Controlling selective microbial biosynthesis of these target molecules at high efficiency is challenging due to enzyme promiscuity, regulation, and metabolic burden. In this study, we present a systematic modular design approach to control proteome reallocation for selective microbial biosynthesis of branched-chain acetate esters. Through pathway modularization, we partitioned the branched-chain ester pathways into four submodules including keto-isovalerate submodule for converting pyruvate to keto-isovalerate, ketoacid elongation submodule for producing longer carbon-chain keto-acids, ketoacid decarboxylase submodule for converting ketoacids to alcohols, and alcohol acyltransferase submodule for producing branched-chain acetate esters by condensing alcohols and acetyl-CoA. By systematic manipulation of pathway gene replication and transcription, enzyme specificity of the first committed steps of these submodules, and downstream competing pathways, we demonstrated selective microbial production of isoamyl acetate over isobutyl acetate. We found that the optimized isoamyl acetate pathway globally redistributed the amino acid fractions in the proteomes and required up to 23-31% proteome reallocation at the expense of other cellular resources, such as those required to generate precursor metabolites and energy for growth and amino acid biosynthesis. From glucose fed-batch fermentation, the engineered strains produced isoamyl acetate up to a titer of 8.8 g/L (>0.25 g/L toxicity limit), a yield of 0.22 g/g (61% of maximal theoretical value), and 86% selectivity, achieving the highest titers, yields and selectivity of isoamyl acetate reported to date.
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Affiliation(s)
- Hyeongmin Seo
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Richard J Giannone
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Yung-Hun Yang
- Department of Biological Engineering, Konkuk University, Seoul, South Korea
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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5
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Ku JT, Chen AY, Lan EI. Metabolic engineering of Escherichia coli for efficient biosynthesis of butyl acetate. Microb Cell Fact 2022; 21:28. [PMID: 35193559 PMCID: PMC8864926 DOI: 10.1186/s12934-022-01755-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 02/07/2022] [Indexed: 11/30/2022] Open
Abstract
Background Butyl acetate is a versatile compound that is widely used in the chemical and food industry. The conventional butyl acetate synthesis via Fischer esterification of butanol and acetic acid using catalytic strong acids under high temperature is not environmentally benign. Alternative lipase-catalyzed ester formation requires a significant amount of organic solvent which also presents another environmental challenge. Therefore, a microbial cell factory capable of producing butyl acetate through fermentation of renewable resources would provide a greener approach to butyl acetate production. Result Here, we developed a metabolically engineered strain of Escherichia coli that efficiently converts glucose to butyl acetate. A modified Clostridium CoA-dependent butanol production pathway was used to synthesize butanol which was then condensed with acetyl-CoA through an alcohol acetyltransferase. Optimization of alcohol acetyltransferase expression and redox balance with auto-inducible fermentative controlled gene expression led to an effective titer of 22.8 ± 1.8 g/L butyl acetate produced in a bench-top bioreactor. Conclusion Building on the well-developed Clostridium CoA-dependent butanol biosynthetic pathway, expression of an alcohol acetyltransferase converts the butanol produced into butyl acetate. The results from this study provided a strain of E. coli capable of directly producing butyl acetate from renewable resources at ambient conditions. Supplementary Information The online version contains supplementary material available at 10.1186/s12934-022-01755-y.
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Affiliation(s)
- Jason T Ku
- Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, 1001 Daxue Road, Hsinchu City, 300, Taiwan.,Institute of Molecular Medicine and Bioengineering, National Yang Ming Chiao Tung University, 1001 Daxue Road, Hsinchu City, 300, Taiwan
| | - Arvin Y Chen
- Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, 1001 Daxue Road, Hsinchu City, 300, Taiwan.,Institute of Molecular Medicine and Bioengineering, National Yang Ming Chiao Tung University, 1001 Daxue Road, Hsinchu City, 300, Taiwan
| | - Ethan I Lan
- Department of Biological Science and Technology, National Chiao Tung University, 1001 Daxue Road, Hsinchu City, 300, Taiwan. .,Department of Biological Science and Technology, National Yang Ming Chiao Tung University, 1001 Daxue Road, Hsinchu City, 300, Taiwan.
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6
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Controlling selectivity of modular microbial biosynthesis of butyryl-CoA-derived designer esters. Metab Eng 2021; 69:262-274. [PMID: 34883244 DOI: 10.1016/j.ymben.2021.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/21/2021] [Accepted: 12/01/2021] [Indexed: 02/02/2023]
Abstract
Short-chain esters have broad utility as flavors, fragrances, solvents, and biofuels. Controlling selectivity of ester microbial biosynthesis has been an outstanding metabolic engineering problem. In this study, we enabled the de novo fermentative microbial biosynthesis of butyryl-CoA-derived designer esters (e.g., butyl acetate, ethyl butyrate, butyl butyrate) in Escherichia coli with controllable selectivity. Using the modular design principles, we generated the butyryl-CoA-derived ester pathways as exchangeable production modules compatible with an engineered chassis cell for anaerobic production of designer esters. We designed these modules derived from an acyl-CoA submodule (e.g., acetyl-CoA, butyryl-CoA), an alcohol submodule (e.g., ethanol, butanol), a cofactor regeneration submodule (e.g., NADH), and an alcohol acetyltransferase (AAT) submodule (e.g., ATF1, SAAT) for rapid module construction and optimization by manipulating replication (e.g., plasmid copy number), transcription (e.g., promoters), translation (e.g., codon optimization), pathway enzymes, and pathway induction conditions. To further enhance production of designer esters with high selectivity, we systematically screened various strategies of protein solubilization using protein fusion tags and chaperones to improve the soluble expression of multiple pathway enzymes. Finally, our engineered ester-producing strains could achieve 19-fold increase in butyl acetate production (0.64 g/L, 96% selectivity), 6-fold increase in ethyl butyrate production (0.41 g/L, 86% selectivity), and 13-fold increase in butyl butyrate production (0.45 g/L, 54% selectivity) as compared to the initial strains. Overall, this study presented a generalizable framework to engineer modular microbial platforms for anaerobic production of butyryl-CoA-derived designer esters from renewable feedstocks.
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7
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Heath RS, Ruscoe RE, Turner NJ. The beauty of biocatalysis: sustainable synthesis of ingredients in cosmetics. Nat Prod Rep 2021; 39:335-388. [PMID: 34879125 DOI: 10.1039/d1np00027f] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Covering: 2015 up to July 2021The market for cosmetics is consumer driven and the desire for green, sustainable and natural ingredients is increasing. The use of isolated enzymes and whole-cell organisms to synthesise these products is congruent with these values, especially when combined with the use of renewable, recyclable or waste feedstocks. The literature of biocatalysis for the synthesis of ingredients in cosmetics in the past five years is herein reviewed.
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Affiliation(s)
- Rachel S Heath
- Manchester Institute of Biotechnology, Department of Chemistry, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
| | - Rebecca E Ruscoe
- Manchester Institute of Biotechnology, Department of Chemistry, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
| | - Nicholas J Turner
- Manchester Institute of Biotechnology, Department of Chemistry, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
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8
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Lee JW, Seo H, Young C, Trinh CT. Probing specificities of alcohol acyltransferases for designer ester biosynthesis with a high-throughput microbial screening platform. Biotechnol Bioeng 2021; 118:4655-4667. [PMID: 34436763 DOI: 10.1002/bit.27926] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 08/13/2021] [Accepted: 08/22/2021] [Indexed: 11/07/2022]
Abstract
Alcohol acyltransferases (AATs) enables microbial biosynthesis of a large space of esters by condensing an alcohol and an acyl-CoA. However, substrate promiscuity of AATs prevents microbial biosynthesis of designer esters with high selectivity. Here, we developed a high-throughput microbial screening platform that facilitates rapid identification of AATs for designer ester biosynthesis. First, we established a microplate-based culturing technique with in situ fermentation and extraction of esters. We validated its capability in rapid profiling of the alcohol substrate specificity of 20 chloramphenicol acetyltransferase variants derived from Staphylococcus aureus (CATSa ) for microbial biosynthesis of acetate esters with various exogeneous alcohol supply. By coupling the microplate-based culturing technique with a previously established colorimetric assay, we developed a high-throughput microbial screening platform for AATs. We demonstrated that this platform could not only probe the alcohol substrate specificity of both native and engineered AATs but also identify the beneficial mutations in engineered AATs for enhanced ester synthesis. We anticipate the high-throughput microbial screening platform provides a useful tool to identify novel wildtype and engineered AATs that have important roles in nature and industrial biocatalysis for designer bioester production.
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Affiliation(s)
- Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Hyeongmin Seo
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, USA
| | - Caleb Young
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, USA
| | - Cong T Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, USA
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9
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Sinumvayo JP, Li Y, Zhang Y. Microbial production of butyl butyrate: from single strain to cognate consortium. BIORESOUR BIOPROCESS 2021; 8:50. [PMID: 38650250 PMCID: PMC10992917 DOI: 10.1186/s40643-021-00403-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/07/2021] [Indexed: 11/10/2022] Open
Abstract
Butyl butyrate (BB) is an important chemical with versatile applications in beverage, food and cosmetics industries. Since chemical synthesis of BB may cause adverse impacts on the environment, biotechnology is an emerging alternative approach for microbial esters biosynthesis. BB can be synthesized by using a single Clostridium strain natively producing butanol or butyrate, with exogenously supplemented butyrate or butanol, in the presence of lipase. Recently, E. coli strains have been engineered to produce BB, but the titer and yield remained very low. This review highlighted a new trend of developing cognate microbial consortium for BB production and associated challenges, and end up with new prospects for further improvement for microbial BB biosynthesis.
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Affiliation(s)
- Jean Paul Sinumvayo
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yin Li
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Yanping Zhang
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
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10
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Poudel S, Cope AL, O'Dell KB, Guss AM, Seo H, Trinh CT, Hettich RL. Identification and characterization of proteins of unknown function (PUFs) in Clostridium thermocellum DSM 1313 strains as potential genetic engineering targets. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:116. [PMID: 33971924 PMCID: PMC8112048 DOI: 10.1186/s13068-021-01964-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 04/26/2021] [Indexed: 05/13/2023]
Abstract
BACKGROUND Mass spectrometry-based proteomics can identify and quantify thousands of proteins from individual microbial species, but a significant percentage of these proteins are unannotated and hence classified as proteins of unknown function (PUFs). Due to the difficulty in extracting meaningful metabolic information, PUFs are often overlooked or discarded during data analysis, even though they might be critically important in functional activities, in particular for metabolic engineering research. RESULTS We optimized and employed a pipeline integrating various "guilt-by-association" (GBA) metrics, including differential expression and co-expression analyses of high-throughput mass spectrometry proteome data and phylogenetic coevolution analysis, and sequence homology-based approaches to determine putative functions for PUFs in Clostridium thermocellum. Our various analyses provided putative functional information for over 95% of the PUFs detected by mass spectrometry in a wild-type and/or an engineered strain of C. thermocellum. In particular, we validated a predicted acyltransferase PUF (WP_003519433.1) with functional activity towards 2-phenylethyl alcohol, consistent with our GBA and sequence homology-based predictions. CONCLUSIONS This work demonstrates the value of leveraging sequence homology-based annotations with empirical evidence based on the concept of GBA to broadly predict putative functions for PUFs, opening avenues to further interrogation via targeted experiments.
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Affiliation(s)
- Suresh Poudel
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- The Center for Bioenergy Innovation at Oak Ridge National Laboratory, Oak Ridge, TN, USA
- The Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
| | - Alexander L Cope
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- The Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
| | - Kaela B O'Dell
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- The Center for Bioenergy Innovation at Oak Ridge National Laboratory, Oak Ridge, TN, USA
- The Bredesen Center, University of Tennessee, Knoxville, TN, USA
| | - Adam M Guss
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- The Bredesen Center, University of Tennessee, Knoxville, TN, USA
| | - Hyeongmin Seo
- The Center for Bioenergy Innovation at Oak Ridge National Laboratory, Oak Ridge, TN, USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA
| | - Cong T Trinh
- The Center for Bioenergy Innovation at Oak Ridge National Laboratory, Oak Ridge, TN, USA
- The Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
- The Bredesen Center, University of Tennessee, Knoxville, TN, USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA
| | - Robert L Hettich
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
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11
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Seo H, Lee JW, Giannone RJ, Dunlap NJ, Trinh CT. Engineering promiscuity of chloramphenicol acetyltransferase for microbial designer ester biosynthesis. Metab Eng 2021; 66:179-190. [PMID: 33872779 DOI: 10.1016/j.ymben.2021.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/06/2021] [Accepted: 04/11/2021] [Indexed: 02/07/2023]
Abstract
Robust and efficient enzymes are essential modules for metabolic engineering and synthetic biology strategies across biological systems to engineer whole-cell biocatalysts. By condensing an acyl-CoA and an alcohol, alcohol acyltransferases (AATs) can serve as interchangeable metabolic modules for microbial biosynthesis of a diverse class of ester molecules with broad applications as flavors, fragrances, solvents, and drop-in biofuels. However, the current lack of robust and efficient AATs significantly limits their compatibility with heterologous precursor pathways and microbial hosts. Through bioprospecting and rational protein engineering, we identified and engineered promiscuity of chloramphenicol acetyltransferases (CATs) from mesophilic prokaryotes to function as robust and efficient AATs compatible with at least 21 alcohol and 8 acyl-CoA substrates for microbial biosynthesis of linear, branched, saturated, unsaturated and/or aromatic esters. By plugging the best engineered CAT (CATec3 Y20F) into the gram-negative mesophilic bacterium Escherichia coli, we demonstrated that the recombinant strain could effectively convert various alcohols into desirable esters, for instance, achieving a titer of 13.9 g/L isoamyl acetate with 95% conversion by fed-batch fermentation. The recombinant E. coli was also capable of simulating the ester profile of roses with high conversion (>97%) and titer (>1 g/L) from fermentable sugars at 37 °C. Likewise, a recombinant gram-positive, cellulolytic, thermophilic bacterium Clostridium thermocellum harboring CATec3 Y20F could produce many of these esters from recalcitrant cellulosic biomass at elevated temperatures (>50 °C) due to the engineered enzyme's remarkable thermostability. Overall, the engineered CATs can serve as a robust and efficient platform for designer ester biosynthesis from renewable and sustainable feedstocks.
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Affiliation(s)
- Hyeongmin Seo
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Richard J Giannone
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Noah J Dunlap
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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12
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Duber A, Zagrodnik R, Chwialkowska J, Juzwa W, Oleskowicz-Popiel P. Evaluation of the feed composition for an effective medium chain carboxylic acid production in an open culture fermentation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 728:138814. [PMID: 32361117 DOI: 10.1016/j.scitotenv.2020.138814] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 03/29/2020] [Accepted: 04/17/2020] [Indexed: 06/11/2023]
Abstract
The objective of this study was to investigate the effect of substrate composition on chain elongation pathways and on shaping reactor microbiome during open culture fermentation (OCF). The process was performed in a continuous mode in an upflow anaerobic sludge blanket (UASB) reactor fed with either fresh acid whey (AW) or AW at controlled stage of prefermentation (with controlled content of electron donors). Dosing AW with an increasing ethanol loading rate led to ethanol oxidation and short chain carboxylic acids (SCCAs) generation. Change of the feedstock composition (higher lactate and lactose content and ethanol cut off) shifted the process outcome towards medium chain carboxylic acids (MCCAs) production, with caproate as the main product. The MCCAs production rate has grown from 0.7 ± 0 to 4.12 ± 1 g/L/day (38.3 ± 5 to 212.6 ± 60 mmol C/L/day) and reached specificity of 48 ± 18% mol C. The differentiation between microbiome samples confirmed the reactor microbiome shaped according to the feed composition. The only known caproic acid producers were represented by Caproiciproducens ssp., that reached a relative OTU abundance between 3 and 7%. The developed method enables to substitute the use of fossil resources with products from the OCF of waste and wastewater. Thus, it contributes to reduce the carbon footprint and enhance the sustainability of the chemical industry.
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Affiliation(s)
- Anna Duber
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland
| | - Roman Zagrodnik
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznanskiego 8, 61-614 Poznan, Poland
| | - Joanna Chwialkowska
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland
| | - Wojciech Juzwa
- Department of Biotechnology and Food Microbiology, Poznan University of Life Sciences, Wojska Polskiego 48, 60-627 Poznan, Poland
| | - Piotr Oleskowicz-Popiel
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland.
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13
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Sharma A, Sharma P, Singh J, Singh S, Nain L. Prospecting the Potential of Agroresidues as Substrate for Microbial Flavor Production. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2020. [DOI: 10.3389/fsufs.2020.00018] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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14
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Lee JW, Trinh CT. Towards renewable flavors, fragrances, and beyond. Curr Opin Biotechnol 2020; 61:168-180. [PMID: 31986468 DOI: 10.1016/j.copbio.2019.12.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 12/01/2019] [Accepted: 12/17/2019] [Indexed: 02/08/2023]
Abstract
Esters constitute a large space of unique molecules with broad range of applications as flavors, fragrances, pharmaceuticals, cosmetics, green solvents, and advanced biofuels. Global demand of natural esters in food, household cleaner, personal care, and perfume industries is increasing while the ester supply from natural sources has been limited. Development of novel microbial cell factories for ester production from renewable feedstocks can potentially provide an alternative and sustainable source of natural esters and hence help fulfill growing demand. Here, we highlight recent advances in microbial production of esters and provide perspectives for improving its economic feasibility. As the field matures, microbial ester production platforms will enable renewable and sustainable production of flavors and fragrances, and open new market opportunities beyond what nature can offer.
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Affiliation(s)
- Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Cong T Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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15
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Sulzbach M, Kunjapur AM. The Pathway Less Traveled: Engineering Biosynthesis of Nonstandard Functional Groups. Trends Biotechnol 2020; 38:532-545. [PMID: 31954529 DOI: 10.1016/j.tibtech.2019.12.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/02/2019] [Accepted: 12/06/2019] [Indexed: 12/12/2022]
Abstract
The field of metabolic engineering has achieved biochemical routes for conversion of renewable inputs to structurally diverse chemicals, but these products contain a limited number of chemical functional groups. In this review, we provide an overview of the progression of uncommon or 'nonstandard' functional groups from the elucidation of their biosynthetic machinery to the pathway optimization framework of metabolic engineering. We highlight exemplary efforts from primarily the last 5 years for biosynthesis of aldehyde, ester, terminal alkyne, terminal alkene, fluoro, epoxide, nitro, nitroso, nitrile, and hydrazine functional groups. These representative nonstandard functional groups vary in development stage and showcase the pipeline of chemical diversity that could soon appear within customized, biologically produced molecules.
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Affiliation(s)
- Morgan Sulzbach
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19711, USA
| | - Aditya M Kunjapur
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19711, USA.
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16
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Kruis AJ, Bohnenkamp AC, Patinios C, van Nuland YM, Levisson M, Mars AE, van den Berg C, Kengen SW, Weusthuis RA. Microbial production of short and medium chain esters: Enzymes, pathways, and applications. Biotechnol Adv 2019; 37:107407. [DOI: 10.1016/j.biotechadv.2019.06.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/24/2019] [Accepted: 06/09/2019] [Indexed: 12/12/2022]
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17
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Lee JW, Trinh CT. Microbial biosynthesis of lactate esters. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:226. [PMID: 31548868 PMCID: PMC6753613 DOI: 10.1186/s13068-019-1563-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 09/07/2019] [Indexed: 05/18/2023]
Abstract
BACKGROUND Green organic solvents such as lactate esters have broad industrial applications and favorable environmental profiles. Thus, manufacturing and use of these biodegradable solvents from renewable feedstocks help benefit the environment. However, to date, the direct microbial biosynthesis of lactate esters from fermentable sugars has not yet been demonstrated. RESULTS In this study, we present a microbial conversion platform for direct biosynthesis of lactate esters from fermentable sugars. First, we designed a pyruvate-to-lactate ester module, consisting of a lactate dehydrogenase (ldhA) to convert pyruvate to lactate, a propionate CoA-transferase (pct) to convert lactate to lactyl-CoA, and an alcohol acyltransferase (AAT) to condense lactyl-CoA and alcohol(s) to make lactate ester(s). By generating a library of five pyruvate-to-lactate ester modules with divergent AATs, we screened for the best module(s) capable of producing a wide range of linear, branched, and aromatic lactate esters with an external alcohol supply. By co-introducing a pyruvate-to-lactate ester module and an alcohol (i.e., ethanol, isobutanol) module into a modular Escherichia coli (chassis) cell, we demonstrated for the first time the microbial biosynthesis of ethyl and isobutyl lactate esters directly from glucose. In an attempt to enhance ethyl lactate production as a proof-of-study, we re-modularized the pathway into (1) the upstream module to generate the ethanol and lactate precursors and (2) the downstream module to generate lactyl-CoA and condense it with ethanol to produce the target ethyl lactate. By manipulating the metabolic fluxes of the upstream and downstream modules through plasmid copy numbers, promoters, ribosome binding sites, and environmental perturbation, we were able to probe and alleviate the metabolic bottlenecks by improving ethyl lactate production by 4.96-fold. We found that AAT is the most rate-limiting step in biosynthesis of lactate esters likely due to its low activity and specificity toward the non-natural substrate lactyl-CoA and alcohols. CONCLUSIONS We have successfully established the biosynthesis pathway of lactate esters from fermentable sugars and demonstrated for the first time the direct fermentative production of lactate esters from glucose using an E. coli modular cell. This study defines a cornerstone for the microbial production of lactate esters as green solvents from renewable resources with novel industrial applications.
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Affiliation(s)
- Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Cong T. Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Dr., DO#432, Knoxville, TN 37996 USA
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18
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Xin F, Zhang W, Jiang M. Bioprocessing Butanol into More Valuable Butyl Butyrate. Trends Biotechnol 2019; 37:923-926. [DOI: 10.1016/j.tibtech.2019.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/11/2019] [Accepted: 03/19/2019] [Indexed: 10/27/2022]
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Comparison of Multi-Objective Evolutionary Algorithms to Solve the Modular Cell Design Problem for Novel Biocatalysis. Processes (Basel) 2019. [DOI: 10.3390/pr7060361] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A large space of chemicals with broad industrial and consumer applications could be synthesized by engineered microbial biocatalysts. However, the current strain optimization process is prohibitively laborious and costly to produce one target chemical and often requires new engineering efforts to produce new molecules. To tackle this challenge, modular cell design based on a chassis strain that can be combined with different product synthesis pathway modules has recently been proposed. This approach seeks to minimize unexpected failure and avoid task repetition, leading to a more robust and faster strain engineering process. In our previous study, we mathematically formulated the modular cell design problem based on the multi-objective optimization framework. In this study, we evaluated a library of state-of-the-art multi-objective evolutionary algorithms (MOEAs) to identify the most effective method to solve the modular cell design problem. Using the best MOEA, we found better solutions for modular cells compatible with many product synthesis modules. Furthermore, the best performing algorithm could provide better and more diverse design options that might help increase the likelihood of successful experimental implementation. We identified key parameter configurations to overcome the difficulty associated with multi-objective optimization problems with many competing design objectives. Interestingly, we found that MOEA performance with a real application problem, e.g., the modular strain design problem, does not always correlate with artificial benchmarks. Overall, MOEAs provide powerful tools to solve the modular cell design problem for novel biocatalysis.
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Noh HJ, Lee SY, Jang YS. Microbial production of butyl butyrate, a flavor and fragrance compound. Appl Microbiol Biotechnol 2019; 103:2079-2086. [PMID: 30659333 DOI: 10.1007/s00253-018-09603-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 12/26/2018] [Accepted: 12/27/2018] [Indexed: 12/11/2022]
Abstract
Butyl butyrate (BB) has been widely used as a flavor and fragrance compound in the beverage, food, perfume, and cosmetic industries. Currently, BB is produced through two-step processes; butanol and butyrate are first produced and are used as precursors for the esterification reactions to yield BB in the next step. Recently, an alternative process to the current process has been developed by using microorganisms for the one-pot BB production. In the one-pot BB process, alcohol acyl transferases (AATs) and lipases play roles in the esterification of butanol together with their co-substrates butyryl-CoA and butyrate, respectively. In this paper, we review the characteristics of two enzymes including AAT and lipase in the esterification reaction. Also, we review the one-pot processes for BB production by employing the wild-type and engineered Clostridium species and the engineered Escherichia coli strains, with the combination of AATs and lipases.
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Affiliation(s)
- Hyeon Ji Noh
- Department of Agricultural Chemistry and Food Science Technology, Division of Applied Life Science (BK21 Plus Program), Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju, Republic of Korea
| | - Sang Yup Lee
- Department of Chemical and Biomolecular Engineering (BK21 Plus Program), BioProcess Engineering Research Center, Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea.
| | - Yu-Sin Jang
- Department of Agricultural Chemistry and Food Science Technology, Division of Applied Life Science (BK21 Plus Program), Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju, Republic of Korea.
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21
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Multiobjective strain design: A framework for modular cell engineering. Metab Eng 2019; 51:110-120. [DOI: 10.1016/j.ymben.2018.09.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 09/05/2018] [Accepted: 09/05/2018] [Indexed: 01/28/2023]
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Seo H, Lee JW, Garcia S, Trinh CT. Single mutation at a highly conserved region of chloramphenicol acetyltransferase enables isobutyl acetate production directly from cellulose by Clostridium thermocellum at elevated temperatures. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:245. [PMID: 31636704 PMCID: PMC6792240 DOI: 10.1186/s13068-019-1583-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/01/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND Esters are versatile chemicals and potential drop-in biofuels. To develop a sustainable production platform, microbial ester biosynthesis using alcohol acetyltransferases (AATs) has been studied for decades. Volatility of esters endows high-temperature fermentation with advantageous downstream product separation. However, due to the limited thermostability of AATs known, the ester biosynthesis has largely relied on use of mesophilic microbes. Therefore, developing thermostable AATs is important for ester production directly from lignocellulosic biomass by the thermophilic consolidated bioprocessing (CBP) microbes, e.g., Clostridium thermocellum. RESULTS In this study, we engineered a thermostable chloramphenicol acetyltransferase from Staphylococcus aureus (CATSa) for enhanced isobutyl acetate production at elevated temperatures. We first analyzed the broad alcohol substrate range of CATSa. Then, we targeted a highly conserved region in the binding pocket of CATSa for mutagenesis. The mutagenesis revealed that F97W significantly increased conversion of isobutanol to isobutyl acetate. Using CATSa F97W, we demonstrated direct conversion of cellulose into isobutyl acetate by an engineered C. thermocellum at elevated temperatures. CONCLUSIONS This study highlights that CAT is a potential thermostable AAT that can be harnessed to develop the thermophilic CBP microbial platform for biosynthesis of designer bioesters directly from lignocellulosic biomass.
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Affiliation(s)
- Hyeongmin Seo
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN USA
- Center for Bioenergy Innovation (CBI), Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN USA
- Center for Bioenergy Innovation (CBI), Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Sergio Garcia
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN USA
- Center for Bioenergy Innovation (CBI), Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Cong T. Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN USA
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN USA
- Center for Bioenergy Innovation (CBI), Oak Ridge National Laboratory, Oak Ridge, TN USA
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Noh HJ, Woo JE, Lee SY, Jang YS. Metabolic engineering of Clostridium acetobutylicum for the production of butyl butyrate. Appl Microbiol Biotechnol 2018; 102:8319-8327. [PMID: 30076425 DOI: 10.1007/s00253-018-9267-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 05/31/2018] [Accepted: 07/19/2018] [Indexed: 10/28/2022]
Abstract
Butyl butyrate is widely used as a fragrance additive for foods and beverages. The first step in the currently used process is the production of precursors, including butanol and butyrate, from petroleum using chemical catalysts, followed by the conversion of precursors to butyl butyrate by immobilized lipase. In this work, we engineered Clostridium acetobutylicum for the selective, one-step production of butyl butyrate from glucose. C. acetobutylicum ATCC 824, possessing a strong carbon flux that yields butanol and butyryl-CoA, was selected as a host and was engineered by introducing alcohol acyltransferases (AATs) from Fragaria x ananassa (strawberry) or Malus sp. (apple). Batch culture of the engineered C. acetobutylicum strain CaSAAT expressing the strawberry SAAT gene produced 50.07 mg/L of butyl butyrate with a selectivity of 84.8% of total esters produced. Also, the engineered C. acetobutylicum strain CaAAAT expressing the apple AAAT gene produced 40.60 mg/L of butyl butyrate with a selectivity of 87.4%. This study demonstrated the feasibility of the one-step fermentation of butyl butyrate from glucose in the engineered C. acetobutylicum, as a proof of concept.
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Affiliation(s)
- Hyeon Ji Noh
- Institute of Agriculture & Life Science (IALS), Department of Agricultural Chemistry and Food Science Technology, Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju, Republic of Korea
| | - Ji Eun Woo
- Institute of Agriculture & Life Science (IALS), Department of Agricultural Chemistry and Food Science Technology, Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju, Republic of Korea
| | - Sang Yup Lee
- Department of Chemical and Biomolecular Engineering (BK21 Plus Program), BioProcess Engineering Research Center, Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea.
| | - Yu-Sin Jang
- Institute of Agriculture & Life Science (IALS), Department of Agricultural Chemistry and Food Science Technology, Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju, Republic of Korea.
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Abstract
When aiming to produce a target chemical at high yield, titer, and productivity, various combinations of genetic parts available to build the target pathway can generate a large number of strains for characterization. This engineering approach will become increasingly laborious and expensive when seeking to develop desirable strains for optimal production of a large space of biochemicals due to extensive screening. Our recent theoretical development of modular cell (MODCELL) design principles can offer a promising solution for rapid generation of optimal strains by coupling a modular cell with exchangeable production modules in a plug-and-play fashion. In this study, we experimentally validated some design properties of MODCELL by demonstrating the following: (i) a modular (chassis) cell is required to couple with a production module, a heterologous ethanol pathway, as a testbed, (ii) degree of coupling between the modular cell and production modules can be modulated to enhance growth and product synthesis, (iii) a modular cell can be used as a host to select an optimal pyruvate decarboxylase (PDC) of the ethanol production module and to help identify a hypothetical PDC protein, and (iv) adaptive laboratory evolution based on growth selection of the modular cell can enhance growth and product synthesis rates. We envision that the MODCELL design provides a powerful prototype for modular cell engineering to rapidly create optimal strains for synthesis of a large space of biochemicals.
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Affiliation(s)
- Brandon Wilbanks
- Department of Chemical and
Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Donovan S. Layton
- Department of Chemical and
Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Sergio Garcia
- Department of Chemical and
Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Cong T. Trinh
- Department of Chemical and
Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
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Wilbanks B, Trinh CT. Comprehensive characterization of toxicity of fermentative metabolites on microbial growth. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:262. [PMID: 29213315 PMCID: PMC5707818 DOI: 10.1186/s13068-017-0952-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/02/2017] [Indexed: 05/08/2023]
Abstract
BACKGROUND Volatile carboxylic acids, alcohols, and esters are natural fermentative products, typically derived from anaerobic digestion. These metabolites have important functional roles to regulate cellular metabolisms and broad use as food supplements, flavors and fragrances, solvents, and fuels. Comprehensive characterization of toxic effects of these metabolites on microbial growth under similar conditions is very limited. RESULTS We characterized a comprehensive list of thirty-two short-chain carboxylic acids, alcohols, and esters on microbial growth of Escherichia coli MG1655 under anaerobic conditions. We analyzed toxic effects of these metabolites on E. coli health, quantified by growth rate and cell mass, as a function of metabolite types, concentrations, and physiochemical properties including carbon number, chemical functional group, chain branching feature, energy density, total surface area, and hydrophobicity. Strain characterization revealed that these metabolites exert distinct toxic effects on E. coli health. We found that higher concentrations and/or carbon numbers of metabolites cause more severe growth inhibition. For the same carbon numbers and metabolite concentrations, we discovered that branched chain metabolites are less toxic than the linear chain ones. Remarkably, shorter alkyl esters (e.g., ethyl butyrate) appear less toxic than longer alkyl esters (e.g., butyl acetate). Regardless of metabolites, hydrophobicity of a metabolite, governed by its physiochemical properties, strongly correlates with the metabolite's toxic effect on E. coli health. CONCLUSIONS Short-chain alcohols, acids, and esters exhibit distinctive toxic effects on E. coli health. Hydrophobicity is a quantitative predictor to evaluate the toxic effect of a metabolite. This study sheds light on degrees of toxicity of fermentative metabolites on microbial health and further helps in the selection of desirable metabolites and hosts for industrial fermentation to overproduce them.
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Affiliation(s)
- Brandon Wilbanks
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Drive, Knoxville, TN 37996 USA
| | - Cong T. Trinh
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Drive, Knoxville, TN 37996 USA
- Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, USA
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