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Lee SG, Kim MK, Kim YS. The first experimental results from W divertor utilizing x-ray imaging crystal spectrometer on KSTAR. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:073515. [PMID: 39012178 DOI: 10.1063/5.0210736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 06/28/2024] [Indexed: 07/17/2024]
Abstract
The x-ray imaging crystal spectrometer (XICS) for Korea Superconducting Tokamak Advanced Research is applied to measure multiple atomic states, such as Ar16+, Ar17+, W43+, and W44+, with keeping the same spectrometer configuration because all spectra are well separated within the detector boundary. The first experimental results from the recently installed full W tiles in the lower divertor utilizing the XICS are discussed.
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Yun JH, Lee H, Nam JW, Ko M, Park J, Lee DH, Lee SG, Kim HS. Unlocking synergies: Harnessing the potential of biological methane sequestration through metabolic coupling between Methylomicrobium alcaliphilum 20Z and Chlorella sp. HS2. BIORESOURCE TECHNOLOGY 2024; 399:130607. [PMID: 38499203 DOI: 10.1016/j.biortech.2024.130607] [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: 01/24/2024] [Revised: 03/09/2024] [Accepted: 03/15/2024] [Indexed: 03/20/2024]
Abstract
A halotolerant consortium between microalgae and methanotrophic bacteria could effectively remediate in situ CH4 and CO2, particularly using saline wastewater sources. Herein, Methylomicrobium alcaliphilum 20Z was demonstrated to form a mutualistic association with Chlorella sp. HS2 at a salinity level above 3.0%. Co-culture significantly enhanced the growth of both microbes, independent of initial inoculum ratios. Additionally, increased methane provision in enclosed serum bottles led to saturated methane removal. Subsequent analyses suggested nearly an order of magnitude increase in the amount of carbon sequestered in biomass in methane-fed co-cultures, conditions that also maintained a suitable cultural pH suitable for methanotrophic growth. Collectively, these results suggest a robust metabolic coupling between the two microbes and the influence of the factors other than gaseous exchange on the assembled consortium. Therefore, multi-faceted investigations are needed to harness the significant methane removal potential of the identified halotolerant consortium under conditions relevant to real-world operation scenarios.
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Kim TH, Ju K, Kim SK, Woo SG, Lee JS, Lee CH, Rha E, Shin J, Kwon KK, Lee H, Kim H, Lee SG, Lee DH. Novel Signal Peptides and Episomal Plasmid System for Enhanced Protein Secretion in Engineered Bacteroides Species. ACS Synth Biol 2024; 13:648-657. [PMID: 38224571 DOI: 10.1021/acssynbio.3c00649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
The genus Bacteroides, a predominant group in the human gut microbiome, presents significant potential for microbiome engineering and the development of live biotherapeutics aimed at treating gut diseases. Despite its promising capabilities, tools for effectively engineering Bacteroides species have been limited. In our study, we have made a breakthrough by identifying novel signal peptides in Bacteroides thetaiotaomicron and Akkermansia muciniphila. These peptides facilitate efficient protein transport across cellular membranes in Bacteroides, a critical step for therapeutic applications. Additionally, we have developed an advanced episomal plasmid system. This system demonstrates superior protein secretion capabilities compared to traditional chromosomal integration plasmids, making it a vital tool for enhancing the delivery of therapeutic proteins in Bacteroides species. Initially, the stability of this episomal plasmid posed a challenge; however, we have overcome this by incorporating an essential gene-based selection system. This novel strategy not only ensures plasmid stability but also aligns with the growing need for antibiotic-free selection methods in clinical settings. Our work, therefore, not only provides a more robust secretion system for Bacteroides but also sets a new standard for the development of live biotherapeutics.
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Emelianov G, Song DU, Jang N, Ko M, Kim SK, Rha E, Shin J, Kwon KK, Kim H, Lee DH, Lee H, Lee SG. Engineered Methylococcus capsulatus Bath for efficient methane conversion to isoprene. BIORESOURCE TECHNOLOGY 2024; 393:130098. [PMID: 38040299 DOI: 10.1016/j.biortech.2023.130098] [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: 10/20/2023] [Revised: 11/22/2023] [Accepted: 11/22/2023] [Indexed: 12/03/2023]
Abstract
Isoprene has numerous industrial applications, including rubber polymer and potential biofuel. Microbial methane-based isoprene production could be a cost-effective and environmentally benign process, owing to a reduced carbon footprint and economical utilization of methane. In this study, Methylococcus capsulatus Bath was engineered to produce isoprene from methane by introducing the exogenous mevalonate (MVA) pathway. Overexpression of MVA pathway enzymes and isoprene synthase from Populus trichocarpa under the control of a phenol-inducible promoter substantially improved isoprene production. M. capsulatus Bath was further engineered using a CRISPR-base editor to disrupt the expression of soluble methane monooxygenase (sMMO), which oxidizes isoprene to cause toxicity. Additionally, optimization of the metabolic flux in the MVA pathway and culture conditions increased isoprene production to 228.1 mg/L, the highest known titer for methanotroph-based isoprene production. The developed methanotroph could facilitate the efficient conversion of methane to isoprene, resulting in the sustainable production of value-added chemicals.
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Lu AT, Fei Z, Haghani A, Robeck TR, Zoller JA, Li CZ, Lowe R, Yan Q, Zhang J, Vu H, Ablaeva J, Acosta-Rodriguez VA, Adams DM, Almunia J, Aloysius A, Ardehali R, Arneson A, Baker CS, Banks G, Belov K, Bennett NC, Black P, Blumstein DT, Bors EK, Breeze CE, Brooke RT, Brown JL, Carter GG, Caulton A, Cavin JM, Chakrabarti L, Chatzistamou I, Chen H, Cheng K, Chiavellini P, Choi OW, Clarke SM, Cooper LN, Cossette ML, Day J, DeYoung J, DiRocco S, Dold C, Ehmke EE, Emmons CK, Emmrich S, Erbay E, Erlacher-Reid C, Faulkes CG, Ferguson SH, Finno CJ, Flower JE, Gaillard JM, Garde E, Gerber L, Gladyshev VN, Gorbunova V, Goya RG, Grant MJ, Green CB, Hales EN, Hanson MB, Hart DW, Haulena M, Herrick K, Hogan AN, Hogg CJ, Hore TA, Huang T, Izpisua Belmonte JC, Jasinska AJ, Jones G, Jourdain E, Kashpur O, Katcher H, Katsumata E, Kaza V, Kiaris H, Kobor MS, Kordowitzki P, Koski WR, Krützen M, Kwon SB, Larison B, Lee SG, Lehmann M, Lemaitre JF, Levine AJ, Li C, Li X, Lim AR, Lin DTS, Lindemann DM, Little TJ, Macoretta N, Maddox D, Matkin CO, Mattison JA, McClure M, Mergl J, Meudt JJ, Montano GA, Mozhui K, Munshi-South J, Naderi A, Nagy M, Narayan P, Nathanielsz PW, Nguyen NB, Niehrs C, O'Brien JK, O'Tierney Ginn P, Odom DT, Ophir AG, Osborn S, Ostrander EA, Parsons KM, Paul KC, Pellegrini M, Peters KJ, Pedersen AB, Petersen JL, Pietersen DW, Pinho GM, Plassais J, Poganik JR, Prado NA, Reddy P, Rey B, Ritz BR, Robbins J, Rodriguez M, Russell J, Rydkina E, Sailer LL, Salmon AB, Sanghavi A, Schachtschneider KM, Schmitt D, Schmitt T, Schomacher L, Schook LB, Sears KE, Seifert AW, Seluanov A, Shafer ABA, Shanmuganayagam D, Shindyapina AV, Simmons M, Singh K, Sinha I, Slone J, Snell RG, Soltanmaohammadi E, Spangler ML, Spriggs MC, Staggs L, Stedman N, Steinman KJ, Stewart DT, Sugrue VJ, Szladovits B, Takahashi JS, Takasugi M, Teeling EC, Thompson MJ, Van Bonn B, Vernes SC, Villar D, Vinters HV, Wallingford MC, Wang N, Wayne RK, Wilkinson GS, Williams CK, Williams RW, Yang XW, Yao M, Young BG, Zhang B, Zhang Z, Zhao P, Zhao Y, Zhou W, Zimmermann J, Ernst J, Raj K, Horvath S. Author Correction: Universal DNA methylation age across mammalian tissues. NATURE AGING 2023; 3:1462. [PMID: 37674040 PMCID: PMC10645586 DOI: 10.1038/s43587-023-00499-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
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Lu AT, Fei Z, Haghani A, Robeck TR, Zoller JA, Li CZ, Lowe R, Yan Q, Zhang J, Vu H, Ablaeva J, Acosta-Rodriguez VA, Adams DM, Almunia J, Aloysius A, Ardehali R, Arneson A, Baker CS, Banks G, Belov K, Bennett NC, Black P, Blumstein DT, Bors EK, Breeze CE, Brooke RT, Brown JL, Carter GG, Caulton A, Cavin JM, Chakrabarti L, Chatzistamou I, Chen H, Cheng K, Chiavellini P, Choi OW, Clarke SM, Cooper LN, Cossette ML, Day J, DeYoung J, DiRocco S, Dold C, Ehmke EE, Emmons CK, Emmrich S, Erbay E, Erlacher-Reid C, Faulkes CG, Ferguson SH, Finno CJ, Flower JE, Gaillard JM, Garde E, Gerber L, Gladyshev VN, Gorbunova V, Goya RG, Grant MJ, Green CB, Hales EN, Hanson MB, Hart DW, Haulena M, Herrick K, Hogan AN, Hogg CJ, Hore TA, Huang T, Izpisua Belmonte JC, Jasinska AJ, Jones G, Jourdain E, Kashpur O, Katcher H, Katsumata E, Kaza V, Kiaris H, Kobor MS, Kordowitzki P, Koski WR, Krützen M, Kwon SB, Larison B, Lee SG, Lehmann M, Lemaitre JF, Levine AJ, Li C, Li X, Lim AR, Lin DTS, Lindemann DM, Little TJ, Macoretta N, Maddox D, Matkin CO, Mattison JA, McClure M, Mergl J, Meudt JJ, Montano GA, Mozhui K, Munshi-South J, Naderi A, Nagy M, Narayan P, Nathanielsz PW, Nguyen NB, Niehrs C, O'Brien JK, O'Tierney Ginn P, Odom DT, Ophir AG, Osborn S, Ostrander EA, Parsons KM, Paul KC, Pellegrini M, Peters KJ, Pedersen AB, Petersen JL, Pietersen DW, Pinho GM, Plassais J, Poganik JR, Prado NA, Reddy P, Rey B, Ritz BR, Robbins J, Rodriguez M, Russell J, Rydkina E, Sailer LL, Salmon AB, Sanghavi A, Schachtschneider KM, Schmitt D, Schmitt T, Schomacher L, Schook LB, Sears KE, Seifert AW, Seluanov A, Shafer ABA, Shanmuganayagam D, Shindyapina AV, Simmons M, Singh K, Sinha I, Slone J, Snell RG, Soltanmaohammadi E, Spangler ML, Spriggs MC, Staggs L, Stedman N, Steinman KJ, Stewart DT, Sugrue VJ, Szladovits B, Takahashi JS, Takasugi M, Teeling EC, Thompson MJ, Van Bonn B, Vernes SC, Villar D, Vinters HV, Wallingford MC, Wang N, Wayne RK, Wilkinson GS, Williams CK, Williams RW, Yang XW, Yao M, Young BG, Zhang B, Zhang Z, Zhao P, Zhao Y, Zhou W, Zimmermann J, Ernst J, Raj K, Horvath S. Universal DNA methylation age across mammalian tissues. NATURE AGING 2023; 3:1144-1166. [PMID: 37563227 PMCID: PMC10501909 DOI: 10.1038/s43587-023-00462-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 06/21/2023] [Indexed: 08/12/2023]
Abstract
Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.
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Jang N, Jeong J, Ko M, Song DU, Emelianov G, Kim SK, Rha E, Kwon KK, Kim H, Lee DH, Lee H, Lee SG. High Cell-Density Cultivation of Methylococcus capsulatus Bath for Efficient Methane-Derived Mevalonate Production. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:4924-4931. [PMID: 36931885 DOI: 10.1021/acs.jafc.3c00286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The engineered Methylococcus capsulatus Bath presents a promising approach for converting methane, a potent greenhouse gas, into valuable chemicals. High cell-density culture (HCDC) is necessary for high-titer growth-associated bioproducts, but it often requires time-consuming and labor-intensive optimization processes. In this study, we aimed to achieve efficient HCDC of M. capsulatus Bath by measuring the residual nutrient levels during bioreactor operations and analyzing the specific uptake of each medium component. By controlling the concentrations of nutrients, particularly calcium and phosphorus via intermittent feeding, we achieved a high cell density of 28.2 g DCW/L and a significantly elevated production of mevalonate at a concentration of 1.8 g/L from methane. Our findings demonstrate that the methanotroph HCDC approach presented herein offers a promising strategy for promoting sustainable development, with an exceptional g-scale production titer for value-added synthetic biochemicals.
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Kim TH, Woo SG, Kim SK, Yoo BH, Shin J, Rha E, Kim SJ, Kwon KK, Lee H, Kim H, Kim HT, Sung BH, Lee SG, Lee DH. A Genetically Encoded Biosensor for the Detection of Levulinic Acid. J Microbiol Biotechnol 2023; 33:552-558. [PMID: 36775859 PMCID: PMC10164729 DOI: 10.4014/jmb.2301.01021] [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: 01/13/2023] [Revised: 01/20/2023] [Accepted: 01/20/2023] [Indexed: 02/14/2023]
Abstract
Levulinic acid (LA) is a valuable chemical used in fuel additives, fragrances, and polymers. In this study, we proposed possible biosynthetic pathways for LA production from lignin and poly(ethylene terephthalate). We also created a genetically encoded biosensor responsive to LA, which can be used for screening and evolving the LA biosynthesis pathway genes, by employing an LvaR transcriptional regulator of Pseudomonas putida KT2440 to express a fluorescent reporter gene. The LvaR regulator senses LA as a cognate ligand. The LA biosensor was first examined in an Escherichia coli strain and was found to be non-functional. When the host of the LA biosensor was switched from E. coli to P. putida KT2440, the LA biosensor showed a linear correlation between fluorescence intensity and LA concentration in the range of 0.156-10 mM LA. In addition, we determined that 0.156 mM LA was the limit of LA detection in P. putida KT2440 harboring an LA-responsive biosensor. The maximal fluorescence increase was 12.3-fold in the presence of 10 mM LA compared to that in the absence of LA. The individual cell responses to LA concentrations reflected the populationaveraged responses, which enabled high-throughput screening of enzymes and metabolic pathways involved in LA biosynthesis and sustainable production of LA in engineered microbes.
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Kim SK, Kim H, Woo SG, Kim TH, Rha E, Kwon KK, Lee H, Lee SG, Lee DH. CRISPRi-based programmable logic inverter cascade for antibiotic-free selection and maintenance of multiple plasmids. Nucleic Acids Res 2022; 50:13155-13171. [PMID: 36511859 PMCID: PMC9825151 DOI: 10.1093/nar/gkac1104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 10/27/2022] [Accepted: 11/03/2022] [Indexed: 12/14/2022] Open
Abstract
Antibiotics have been widely used for plasmid-mediated cell engineering. However, continued use of antibiotics increases the metabolic burden, horizontal gene transfer risks, and biomanufacturing costs. There are limited approaches to maintaining multiple plasmids without antibiotics. Herein, we developed an inverter cascade using CRISPRi by building a plasmid containing a single guide RNA (sgRNA) landing pad (pSLiP); this inhibited host cell growth by repressing an essential cellular gene. Anti-sgRNAs on separate plasmids restored cell growth by blocking the expression of growth-inhibitory sgRNAs in pSLiP. We maintained three plasmids in Escherichia coli with a single antibiotic selective marker. To completely avoid antibiotic use and maintain the CRISPRi-based logic inverter cascade, we created a novel d-glutamate auxotrophic E. coli. This enabled the stable maintenance of the plasmid without antibiotics, enhanced the production of the terpenoid, (-)-α-bisabolol, and generation of an antibiotic-resistance gene-free plasmid. CRISPRi is therefore widely applicable in genetic circuits and may allow for antibiotic-free biomanufacturing.
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Bak SK, Seong W, Rha E, Lee H, Kim SK, Kwon KK, Kim H, Lee SG. Novel High-Throughput DNA Part Characterization Technique for Synthetic Biology. J Microbiol Biotechnol 2022; 32:1026-1033. [PMID: 35879270 PMCID: PMC9628936 DOI: 10.4014/jmb.2207.07013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/19/2022] [Accepted: 07/19/2022] [Indexed: 12/15/2022]
Abstract
This study presents a novel DNA part characterization technique that increases throughput by combinatorial DNA part assembly, solid plate-based quantitative fluorescence assay for phenotyping, and barcode tagging-based long-read sequencing for genotyping. We confirmed that the fluorescence intensities of colonies on plates were comparable to fluorescence at the single-cell level from a high-end, flow-cytometry device and developed a high-throughput image analysis pipeline. The barcode tagging-based long-read sequencing technique enabled rapid identification of all DNA parts and their combinations with a single sequencing experiment. Using our techniques, forty-four DNA parts (21 promoters and 23 RBSs) were successfully characterized in 72 h without any automated equipment. We anticipate that this high-throughput and easy-to-use part characterization technique will contribute to increasing part diversity and be useful for building genetic circuits and metabolic pathways in synthetic biology.
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Lee SG. Experimental results from x-ray imaging crystal spectrometer utilizing double crystal assembly in Korea Superconducting Tokamak Advanced Research (KSTAR). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:083508. [PMID: 36050113 DOI: 10.1063/5.0098520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 07/16/2022] [Indexed: 06/15/2023]
Abstract
A double crystal assembly (DCA) for multiple atomic spectra measurements, including helium-like Ar and hydrogen-like Ar, and other impurity lines are applied for the x-ray imaging crystal spectrometer in Korea Superconducting Tokamak Advanced Research. The DCA expands measurable wavelengths much wider so that cross comparisons of the ion temperature and toroidal rotation between two different atomic states are possible. The recent experimental comparison studies for the ion temperature and toroidal rotation of helium-like Ar and hydrogen-like Ar from the DCA are reported.
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Choe D, Kim K, Kang M, Lee SG, Cho S, Palsson B, Cho BK. Synthetic 3'-UTR valves for optimal metabolic flux control in Escherichia coli. Nucleic Acids Res 2022; 50:4171-4186. [PMID: 35357499 PMCID: PMC9023263 DOI: 10.1093/nar/gkac206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 03/12/2022] [Accepted: 03/29/2022] [Indexed: 11/15/2022] Open
Abstract
As the design of genetic circuitry for synthetic biology becomes more sophisticated, diverse regulatory bioparts are required. Despite their importance, well-characterized 3′-untranslated region (3′-UTR) bioparts are limited. Thus, transcript 3′-ends require further investigation to understand the underlying regulatory role and applications of the 3′-UTR. Here, we revisited the use of Term-Seq in the Escherichia coli strain K-12 MG1655 to enhance our understanding of 3′-UTR regulatory functions and to provide a diverse collection of tunable 3′-UTR bioparts with a wide termination strength range. Comprehensive analysis of 1,629 transcript 3′-end positions revealed multiple 3′-termini classes generated through transcription termination and RNA processing. The examination of individual Rho-independent terminators revealed a reduction in downstream gene expression over a wide range, which led to the design of novel synthetic metabolic valves that control metabolic fluxes in branched pathways. These synthetic metabolic valves determine the optimal balance of heterologous pathways for maximum target biochemical productivity. The regulatory strategy using 3′-UTR bioparts is advantageous over promoter- or 5′-UTR-based transcriptional control as it modulates gene expression at transcription levels without trans-acting element requirements (e.g. transcription factors). Our results provide a foundational platform for 3′-UTR engineering in synthetic biology applications.
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Yeom SJ, Kwon KK, An JU, Park SH, Lee JY, Rha E, Lee H, Kim H, Lee DH, Lee SG. Single-Cell-Based Screening and Engineering of d-Amino Acid Amidohydrolases Using Artificial Amidophenol Substrates and Microbial Biosensors. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:1203-1211. [PMID: 34994555 DOI: 10.1021/acs.jafc.1c05834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Enantiomerically pure d-amino acids are important intermediates as chiral building blocks for peptidomimetics and semisynthetic antibiotics. Here, a transcriptional factor-based screening strategy was used for the rapid screening of d-stereospecific amino acid amidase via an enzyme-specific amidophenol substrate. We used a d-threonine amidophenyl derivative to produce 2-aminophenol that serves as a putative enzyme indicator in the presence of d-threonine amidases. Comparative analyses of known bacterial species indicated that several Bacillus strains produce amidase and form putative indicators in culture media. The estimated amidase was cloned and subjected to rapid directed evolution through biosensor cells. Consequently, we characterized the F119A mutation that significantly improved the catalytic activity toward d-alanine, d-threonine, and d-glutamate. Its beneficial effects were confirmed by higher conversions and recurrent applications of the mutant enzyme, compared to the wild-type. This study showed that rapid directed evolution with biosensors coupled to designed substrates is useful to develop biocatalytic processes.
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Shin J, Noh JR, Choe D, Lee N, Song Y, Cho S, Kang EJ, Go MJ, Ha SK, Chang DH, Kim JH, Kim YH, Kim KS, Jung H, Kim MH, Sung BH, Lee SG, Lee DH, Kim BC, Lee CH, Cho BK. Ageing and rejuvenation models reveal changes in key microbial communities associated with healthy ageing. MICROBIOME 2021; 9:240. [PMID: 34906228 PMCID: PMC8672520 DOI: 10.1186/s40168-021-01189-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 11/04/2021] [Indexed: 05/17/2023]
Abstract
BACKGROUND The gut microbiota is associated with diverse age-related disorders. Several rejuvenation methods, such as probiotic administration and faecal microbiota transplantation, have been applied to alter the gut microbiome and promote healthy ageing. Nevertheless, prolongation of the health span of aged mice by remodelling the gut microbiome remains challenging. RESULTS Here, we report the changes in gut microbial communities and their functions in mouse models during ageing and three rejuvenation procedures including co-housing, serum-injection and parabiosis. Our results showed that the compositional structure and gene abundance of the intestinal microbiota changed dynamically during the ageing process. Through the three rejuvenation procedures, we observed that the microbial community and intestinal immunity of aged mice were comparable to those of young mice. The results of metagenomic data analysis underscore the importance of the high abundance of Akkermansia and the butyrate biosynthesis pathway in the rejuvenated mouse group. Furthermore, oral administration of Akkermansia sufficiently ameliorated the senescence-related phenotype in the intestinal systems in aged mice and extended the health span, as evidenced by the frailty index and restoration of muscle atrophy. CONCLUSIONS In conclusion, the changes in key microbial communities and their functions during ageing and three rejuvenation procedures, and the increase in the healthy lifespan of aged mice by oral administration of Akkermansia. Our results provide a rationale for developing therapeutic strategies to achieve healthy active ageing. Video abstract.
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Kim K, Hou CY, Choe D, Kang M, Cho S, Sung BH, Lee DH, Lee SG, Kang TJ, Cho BK. Adaptive laboratory evolution of Escherichia coli W enhances gamma-aminobutyric acid production using glycerol as the carbon source. Metab Eng 2021; 69:59-72. [PMID: 34775076 DOI: 10.1016/j.ymben.2021.11.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 10/19/2021] [Accepted: 11/06/2021] [Indexed: 11/25/2022]
Abstract
The microbial conversion of glycerol into value-added commodity products has emerged as an attractive means to meet the demands of biosustainability. However, glycerol is a non-preferential carbon source for productive fermentation because of its low energy density. We employed evolutionary and metabolic engineering in tandem to construct an Escherichia coli strain with improved GABA production using glycerol as the feedstock carbon. Adaptive evolution of E. coli W under glycerol-limited conditions for 1300 generations harnessed an adapted strain with a metabolic system optimized for glycerol utilization. Mutation profiling, enzyme kinetic assays, and transcriptome analysis of the adapted strain allowed us to decipher the basis of glycerol adaptation at the molecular level. Importantly, increased substrate influx mediated by the mutant glpK and modulation of intracellular cAMP levels were the key drivers of improved fitness in the glycerol-limited condition. Leveraging the enhanced capability of glycerol utilization in the strain, we constructed a GABA-producing E. coli W-derivative with superior GABA production compared to the wild-type. Furthermore, rationally designed inactivation of the non-essential metabolic genes, including ackA, mgsA, and gabT, in the glycerol-adapted strain improved the final GABA titer and specific productivity by 3.9- and 4.3-fold, respectively, compared with the wild-type.
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Kim K, Choe D, Song Y, Kang M, Lee SG, Lee DH, Cho BK. Engineering Bacteroides thetaiotaomicron to produce non-native butyrate based on a genome-scale metabolic model-guided design. Metab Eng 2021; 68:174-186. [PMID: 34655791 DOI: 10.1016/j.ymben.2021.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 10/04/2021] [Accepted: 10/09/2021] [Indexed: 12/29/2022]
Abstract
Bacteroides thetaiotaomicron represents a major symbiont of the human gut microbiome that is increasingly viewed as a promising candidate strain for microbial therapeutics. Here, we engineer B. thetaiotaomicron for heterologous production of non-native butyrate as a proof-of-concept biochemical at therapeutically relevant concentrations. Since B. thetaiotaomicron is not a natural producer of butyrate, we heterologously expressed a butyrate biosynthetic pathway in the strain, which led to the production of butyrate at the final concentration of 12 mg/L in a rich medium. Further optimization of butyrate production was achieved by a round of metabolic engineering guided by an expanded genome-scale metabolic model (GEM) of B. thetaiotaomicron. The in silico knock-out simulation of the expanded model showed that pta and ldhD were the potent knock-out targets to enhance butyrate production. The maximum titer and specific productivity of butyrate in the pta-ldhD double knockout mutant increased by nearly 3.4 and 4.8 folds, respectively. To our knowledge, this is the first engineering attempt that enabled butyrate production from a non-butyrate producing commensal B. thetaiotaomicron. The study also highlights that B. thetaiotaomicron can serve as an effective strain for live microbial therapeutics in human.
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Lim HS, Kim SK, Woo SG, Kim TH, Yeom SJ, Yong W, Ko YJ, Kim SJ, Lee SG, Lee DH. (-)-α-Bisabolol Production in Engineered Escherichia coli Expressing a Novel (-)-α-Bisabolol Synthase from the Globe Artichoke Cynara cardunculus var. Scolymus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:8492-8503. [PMID: 34282904 DOI: 10.1021/acs.jafc.1c02759] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
(-)-α-Bisabolol is a functional ingredient in various health and cosmetic products and has antibacterial, anti-inflammatory, and wound healing properties. (-)-α-Bisabolol is chemically synthesized and produced by steam distillation of essential oils extracted from Brazilian Candeia (Eremanthus erythropappus). To sustainably produce pure (-)-α-bisabolol, we previously engineered Escherichia coli to produce 9.1 g/L (-)-α-bisabolol via heterologous mevalonate pathways and (-)-α-bisabolol synthase (BOS) from German chamomile, Matricaria recutita (MrBOS). BOS has only been reported in MrBOS and Brazilian Candeia (EeBOS). The limited availability of BOS has made it difficult to achieve high titer and yield and large-scale (-)-α-bisabolol production. We identified a novel BOS in globe artichoke (CcBOS) and examined its functionality in vitro and in vivo. CcBOS showed higher catalytic efficiency and (-)-α-bisabolol production rates than those from MrBOS or EeBOS. In fed-batch fermentation, CcBOS generated the highest reported (-)-α-bisabolol titer to date (23.4 g/L). These results may facilitate economically viable industrial (-)-α-bisabolol production.
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Lee H, Baek JI, Lee JY, Jeong J, Kim H, Lee DH, Kim DM, Lee SG. Syntrophic co-culture of a methanotroph and heterotroph for the efficient conversion of methane to mevalonate. Metab Eng 2021; 67:285-292. [PMID: 34298134 DOI: 10.1016/j.ymben.2021.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/07/2021] [Accepted: 07/18/2021] [Indexed: 10/20/2022]
Abstract
As the bioconversion of methane becomes increasingly important for bio-industrial and environmental applications, methanotrophs have received much attention for their ability to convert methane under ambient conditions. This includes the extensive reporting of methanotroph engineering for the conversion of methane to biochemicals. To further increase methane usability, we demonstrated a highly flexible and efficient modular approach based on a synthetic consortium of methanotrophs and heterotrophs mimicking the natural methane ecosystem to produce mevalonate (MVA) from methane. In the methane-conversion module, we used Methylococcus capsulatus Bath as a highly efficient methane biocatalyst and optimized the culture conditions for the production of high amounts of organic acids. In the MVA-synthesis module, we used Escherichia coli SBA01, an evolved strain with high organic acid tolerance and utilization ability, to convert organic acids to MVA. Using recombinant E. coli SBA01 possessing genes for the MVA pathway, 61 mg/L (0.4 mM) of MVA was successfully produced in 48 h without any addition of nutrients except methane. Our platform exhibited high stability and reproducibility with regard to cell growth and MVA production. We believe that this versatile system can be easily extended to many other value-added processes and has a variety of potential applications.
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Park SH, Seo H, Seok J, Kim H, Kwon KK, Yeom SJ, Lee SG, Kim KJ. Cβ-Selective Aldol Addition of d-Threonine Aldolase by Spatial Constraint of Aldehyde Binding. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bak MG, Won JS, Koo SW, Oh A, Lee HK, Kim DS, Lee SG. Migration Behavior of Lubricants in Polypropylene Composites under Accelerated Thermal Aging. Polymers (Basel) 2021; 13:polym13111723. [PMID: 34070231 PMCID: PMC8197380 DOI: 10.3390/polym13111723] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 11/26/2022] Open
Abstract
The surface migration of lubricants degrades the quality of thermoplastic polymer composites. In this study, the surface migration of lubricants in polypropylene composites were studied to improve the quality of the composites. Polypropylene (PP)/lubricant composites were manufactured using a co-rotating twin-screw extruder and injection molding, and the migration phenomena of the lubricant in the PP/lubricant composites were investigated under accelerated aging conditions with temperatures in the range of 20 to 90 °C and humidity of 100% for 72 h. The interrelation between the surface migration properties of PP/lubricant composites were investigated by considering their microstructural and morphological features, which were influenced by the thermal aging conditions. Further, the microstructural and morphological features were examined by contact angle, surface energy, attenuated total reflectance Fourier-transform infrared spectrometry, X-ray photoelectron spectroscopy, close-up digital imaging, and atomic force microscopy analyses. The polypropylene composites containing the magnesium stearate as the lubricant were found to exhibit a more stable migration behavior than the polypropylene composites containing a calcium stearate lubricant. This is attributed to multiple synergistic factors, such as interfacial tension and work of adhesion between PP and the lubricant. The findings of this study can be utilized to effectively manufacture high-quality thermoplastic composites for the fourth industrial revolution.
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Chung JM, Lee SG, Nam JS, Ha JG, Chung JH, Cho HJ, Kim CH, Lee SN, Lee H, Yoon JH. Compressive stress induces collective migration through cytoskeletal remodelling in nasal polyp epithelium. Rhinology 2021; 59:49-58. [PMID: 32666957 DOI: 10.4193/rhin19.268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Nasal polyps in the nasal cavity and mucous discharge inside the maxillary sinus exhibit compressive stress on the nasal mucosal epithelium. However, there have been only a few studies on how compressive stress impacts the human nasal mucosal epithelium. METHODOLOGY We investigated the effect of compressive stress on collective migration, junctional proteins, transepithelial electri- cal resistance, epithelial permeability, and gene expression in well-differentiated normal human nasal epithelial (NHNE) cells and human nasal polyp epithelial (HNPE) cells. RESULTS NHNE cells barely showed collective migration at compressive stress up to 150 mmH20. However, HNPE cells showed much greater degree of collective migration at a lower compressive stress of 100 mmH20. The cell migration of HNPE cells sub- jected to 100 mmH2O compression was significantly decreased at day 3 and was recovered to the status prior to the compressive stress by day 7, indicating that HNPE cells are relatively more sensitive to mechanical pressure than NHNE cells. Compressive stress also increased transepithelial electrical resistance and decreased epithelial permeability, indicating that the compressive stress disturbed the structural organization rather than physical interactions between cells. In addition, we found that compressive stress induced gene expressions relevant to airway inflammation and tissue remodelling in HNPE cells. CONCLUSION Taken together, these findings demonstrate that compressive stress on nasal polyp epithelium is capable of inducing collective migration and induce increased expression of genes related to airway inflammation, innate immunity, and polyp remo- delling, even in the absence of inflammatory mediators.
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Lee SG, Kim MK, Kim YS. Progress of x-ray imaging crystal spectrometer utilizing double crystal assembly on KSTAR. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:023501. [PMID: 33648144 DOI: 10.1063/5.0041202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
The x-ray imaging crystal spectrometer (XICS) for Korea Superconducting Tokamak Advanced Research (KSTAR) has been upgraded to increase its performance including measurement capabilities and stable operation. A dual crystal assembly for simultaneous measurements of the helium-like and hydrogen-like Ar spectra is successfully installed for improving measurement capabilities. Using a safety viewing port with an illuminator and removing the XICS control system from the harsh KSTAR tokamak hall for a stable operation are newly performed. The experimental results from the improved XICS are investigated.
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Kwon KK, Kim H, Yeom SJ, Rha E, Lee J, Lee H, Lee DH, Lee SG. Antagonistic Control of Genetic Circuit Performance for Rapid Analysis of Targeted Enzyme Activity in Living Cells. Front Mol Biosci 2021; 7:599878. [PMID: 33511156 PMCID: PMC7835892 DOI: 10.3389/fmolb.2020.599878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/07/2020] [Indexed: 11/13/2022] Open
Abstract
Genetic circuits have been developed for quantitative measurement of enzyme activity, metabolic engineering of strain development, and dynamic regulation of microbial cells. A genetic circuit consists of several bio-elements, including enzymes and regulatory cassettes, that can generate the desired output signal, which is then used as a precise criterion for enzyme screening and engineering. Antagonists and inhibitors are small molecules with inhibitory effects on regulators and enzymes, respectively. In this study, an antagonist and an inhibitor were applied to a genetic circuit for a dynamic detection range. We developed a genetic circuit relying on regulators and enzymes, allowing for straightforward control of its output signal without additional genetic modification. We used para-nitrophenol and alanine as an antagonist of DmpR and inhibitor of tyrosine phenol-lyase, respectively. We show that the antagonist resets the detection range of the genetic circuit similarly to a resistor in an electrical logic circuit. These biological resistors in genetic circuits can be used as a rapid and precise controller of variable outputs with minimal circuit configuration.
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Kim H, Seong W, Rha E, Lee H, Kim SK, Kwon KK, Park KH, Lee DH, Lee SG. Machine learning linked evolutionary biosensor array for highly sensitive and specific molecular identification. Biosens Bioelectron 2020; 170:112670. [DOI: 10.1016/j.bios.2020.112670] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/26/2020] [Accepted: 09/30/2020] [Indexed: 10/23/2022]
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Woo SG, Kim SK, Oh BR, Lee SG, Lee DH. Genetically Encoded Biosensor-Based Screening for Directed Bacteriophage T4 Lysozyme Evolution. Int J Mol Sci 2020; 21:ijms21228668. [PMID: 33212940 PMCID: PMC7698408 DOI: 10.3390/ijms21228668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/05/2020] [Accepted: 11/16/2020] [Indexed: 11/16/2022] Open
Abstract
Lysozyme is widely used as a model protein in studies of structure–function relationships. Recently, lysozyme has gained attention for use in accelerating the degradation of secondary sludge, which mainly consists of bacteria. However, a high-throughput screening system for lysozyme engineering has not been reported. Here, we present a lysozyme screening system using a genetically encoded biosensor. We first cloned bacteriophage T4 lysozyme (T4L) into a plasmid under control of the araBAD promoter. The plasmid was expressed in Escherichia coli with no toxic effects on growth. Next, we observed that increased soluble T4L expression decreased the fluorescence produced by the genetic enzyme screening system. To investigate T4L evolution based on this finding, we generated a T4L random mutation library, which was screened using the genetic enzyme screening system. Finally, we identified two T4L variants showing 1.4-fold enhanced lytic activity compared to native T4L. To our knowledge, this is the first report describing the use of a genetically encoded biosensor to investigate bacteriophage T4L evolution. Our approach can be used to investigate the evolution of other lysozymes, which will expand the applications of lysozyme.
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