Metabolic Engineering Communications最新文献

{"title":"Rewiring Saccharomyces cerevisiae metabolism for optimised Taxol® precursors production","authors":"Behnaz Nowrouzi ,&nbsp;Pablo Torres-Montero ,&nbsp;Eduard J. Kerkhoven ,&nbsp;José L. Martínez ,&nbsp;Leonardo Rios-Solis","doi":"10.1016/j.mec.2023.e00229","DOIUrl":"https://doi.org/10.1016/j.mec.2023.e00229","url":null,"abstract":"<div><p><em>Saccharomyces cerevisiae</em> has been conveniently used to produce Taxol® anticancer drug early precursors. However, the harmful impact of oxidative stress by the first cytochrome P450-reductase enzymes (CYP725A4-POR) of Taxol® pathway has hampered sufficient progress in yeast. Here, we evolved an oxidative stress-resistant yeast strain with three-fold higher titre of their substrate, taxadiene. The performance of the evolved and parent strains were then evaluated in galactose-limited chemostats before and under the oxidative stress by an oxidising agent. The interaction of evolution and oxidative stress was comprehensively evaluated through transcriptomics and metabolite profiles integration in yeast enzyme-constrained genome scale model. Overall, the evolved strain showed improved respiration, reduced overflow metabolites production and oxidative stress re-induction tolerance. The cross-protection mechanism also potentially contributed to better heme, flavin and NADPH availability, essential for CYP725A4 and POR optimal activity in yeast. The results imply that the evolved strain is a robust cell factory for future efforts towards Taxol© production.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"18 ","pages":"Article e00229"},"PeriodicalIF":5.2,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214030123000123/pdfft?md5=f48e8c4c1f2c289451094a6c748a04e0&pid=1-s2.0-S2214030123000123-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138467346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Engineering Yarrowia lipolytica for the biosynthesis of geraniol","authors":"Ayushi Agrawal ,&nbsp;Zhiliang Yang ,&nbsp;Mark Blenner","doi":"10.1016/j.mec.2023.e00228","DOIUrl":"https://doi.org/10.1016/j.mec.2023.e00228","url":null,"abstract":"<div><p>Geraniol is a monoterpene with wide applications in the food, cosmetics, and pharmaceutical industries. Microbial production has largely used model organisms lacking favorable properties for monoterpene production. In this work, we produced geraniol in metabolically engineered <em>Yarrowia lipolytica</em>. First, two plant-derived geraniol synthases (GES) from <em>Catharanthus roseus</em> (Cr) and <em>Valeriana officinalis</em> (Vo) were tested based on previous reports of activity. Both wild type and truncated mutants of GES (without signal peptide targeting chloroplast) were examined by co-expressing with MVA pathway enzymes tHMG1 and IDI1. Truncated CrGES (tCrGES) produced the most geraniol and thus was used for further experimentation. The initial strain was obtained by overexpression of the truncated HMG1, IDI and tCrGES. The acetyl-CoA precursor pool was enhanced by overexpressing mevalonate pathway genes such as ERG10, HMGS or MVK, PMK. The final strain overexpressing 3 copies of tCrGES and single copies of ERG10, HMGS, tHMG1, IDI produced approximately 1 g/L in shake-flask fermentation. This is the first demonstration of geraniol production in <em>Yarrowia lipolytica</em> and the highest de novo titer reported to date in yeast.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"17 ","pages":"Article e00228"},"PeriodicalIF":5.2,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214030123000111/pdfft?md5=f08729130a21ca40f8b22486294fafb5&pid=1-s2.0-S2214030123000111-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91685392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Have you tried turning it off and on again? Oscillating selection to enhance fitness-landscape traversal in adaptive laboratory evolution experiments","authors":"Alexander C. Carpenter ,&nbsp;Adam M. Feist ,&nbsp;Fergus S.M. Harrison ,&nbsp;Ian T. Paulsen ,&nbsp;Thomas C. Williams","doi":"10.1016/j.mec.2023.e00227","DOIUrl":"10.1016/j.mec.2023.e00227","url":null,"abstract":"<div><p>Adaptive Laboratory Evolution (ALE) is a powerful tool for engineering and understanding microbial physiology. ALE relies on the selection and enrichment of mutations that enable survival or faster growth under a selective condition imposed by the experimental setup. Phenotypic fitness landscapes are often underpinned by complex genotypes involving multiple genes, with combinatorial positive and negative effects on fitness. Such genotype relationships result in mutational fitness landscapes with multiple local fitness maxima and valleys. Traversing local maxima to find a global maximum often requires an individual or sub-population of cells to traverse fitness valleys. Traversing involves gaining mutations that are not adaptive for a given local maximum but are necessary to ‘peak shift’ to another local maximum, or eventually a global maximum. Despite these relatively well understood evolutionary principles, and the combinatorial genotypes that underlie most metabolic phenotypes, the majority of applied ALE experiments are conducted using constant selection pressures. The use of constant pressure can result in populations becoming trapped within local maxima, and often precludes the attainment of optimum phenotypes associated with global maxima. Here, we argue that oscillating selection pressures is an easily accessible mechanism for traversing fitness landscapes in ALE experiments, and provide theoretical and practical frameworks for implementation.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"17 ","pages":"Article e00227"},"PeriodicalIF":5.2,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10393799/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10295679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Engineered ketocarotenoid biosynthesis in the polyextremophilic red microalga Cyanidioschyzon merolae 10D","authors":"Mark Seger ,&nbsp;Fakhriyya Mammadova ,&nbsp;Melany Villegas-Valencia ,&nbsp;Bárbara Bastos de Freitas ,&nbsp;Clarissa Chang ,&nbsp;Iona Isachsen ,&nbsp;Haley Hemstreet ,&nbsp;Fatimah Abualsaud ,&nbsp;Malia Boring ,&nbsp;Peter J. Lammers ,&nbsp;Kyle J. Lauersen","doi":"10.1016/j.mec.2023.e00226","DOIUrl":"https://doi.org/10.1016/j.mec.2023.e00226","url":null,"abstract":"<div><p>The polyextremophilic Cyanidiophyceae are eukaryotic red microalgae with promising biotechnological properties arising from their low pH and elevated temperature requirements which can minimize culture contamination at scale. <em>Cyanidioschyzon merolae</em> 10D is a cell wall deficient species with a fully sequenced genome that is amenable to nuclear transgene integration by targeted homologous recombination. <em>C. merolae</em> maintains a minimal carotenoid profile and here, we sought to determine its capacity for ketocarotenoid accumulation mediated by heterologous expression of a green algal β-carotene ketolase (BKT) and hydroxylase (CHYB). To achieve this, a synthetic transgene expression cassette system was built to integrate and express <em>Chlamydomonas reinhardtii</em> (Cr) sourced enzymes by fusing native <em>C. merolae</em> transcription, translation and chloroplast targeting signals to codon-optimized coding sequences. Chloramphenicol resistance was used to select for the integration of synthetic linear DNAs into a neutral site within the host genome. <em>Cr</em>BKT expression caused accumulation of canthaxanthin and adonirubin as major carotenoids while co-expression of <em>Cr</em>BKT with <em>Cr</em>CHYB generated astaxanthin as the major carotenoid in <em>C. merolae</em>. Unlike green algae and plants, ketocarotenoid accumulation in <em>C. merolae</em> did not reduce total carotenoid contents, but chlorophyll <em>a</em> reduction was observed. Light intensity affected global ratios of all pigments but not individual pigment compositions and phycocyanin contents were not markedly different between parental strain and transformants. Continuous illumination was found to encourage biomass accumulation and all strains could be cultivated in simulated summer conditions from two different extreme desert environments. Our findings present the first example of carotenoid metabolic engineering in a red eukaryotic microalga and open the possibility for use of <em>C. merolae</em> 10D for simultaneous production of phycocyanin and ketocarotenoid pigments.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"17 ","pages":"Article e00226"},"PeriodicalIF":5.2,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50172341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Engineering of increased L-Threonine production in bacteria by combinatorial cloning and machine learning","authors":"Paul Hanke ,&nbsp;Bruce Parrello ,&nbsp;Olga Vasieva ,&nbsp;Chase Akins ,&nbsp;Philippe Chlenski ,&nbsp;Gyorgy Babnigg ,&nbsp;Chris Henry ,&nbsp;Fatima Foflonker ,&nbsp;Thomas Brettin ,&nbsp;Dionysios Antonopoulos ,&nbsp;Rick Stevens ,&nbsp;Michael Fonstein","doi":"10.1016/j.mec.2023.e00225","DOIUrl":"10.1016/j.mec.2023.e00225","url":null,"abstract":"<div><p>The goal of this study is to develop a general strategy for bacterial engineering using an integrated synthetic biology and machine learning (ML) approach. This strategy was developed in the context of increasing L-threonine production in <em>Escherichia coli</em> ATCC 21277. A set of 16 genes was initially selected based on metabolic pathway relevance to threonine biosynthesis and used for combinatorial cloning to construct a set of 385 strains to generate training data (i.e., a range of L-threonine titers linked to each of the specific gene combinations). Hybrid (regression/classification) deep learning (DL) models were developed and used to predict additional gene combinations in subsequent rounds of combinatorial cloning for increased L-threonine production based on the training data. As a result, <em>E. coli</em> strains built after just three rounds of iterative combinatorial cloning and model prediction generated higher L-threonine titers (from 2.7 g/L to 8.4 g/L) than those of patented L-threonine strains being used as controls (4–5 g/L). Interesting combinations of genes in L-threonine production included deletions of the <em>tdh</em>, <em>metL</em>, <em>dapA</em>, and <em>dhaM</em> genes as well as overexpression of the <em>pntAB</em>, <em>ppc</em>, and <em>aspC</em> genes. Mechanistic analysis of the metabolic system constraints for the best performing constructs offers ways to improve the models by adjusting weights for specific gene combinations. Graph theory analysis of pairwise gene modifications and corresponding levels of L-threonine production also suggests additional rules that can be incorporated into future ML models.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"17 ","pages":"Article e00225"},"PeriodicalIF":5.2,"publicationDate":"2023-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/31/d3/main.PMC10331477.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9812416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of a hybrid bacterial/Arabidopsis thaliana fatty acid synthase system II in Saccharomyces cerevisiae","authors":"Tatiana A. Pozdniakova ,&nbsp;João P. Cruz ,&nbsp;Paulo César Silva ,&nbsp;Flávio Azevedo ,&nbsp;Pier Parpot ,&nbsp;Maria Rosario Domingues ,&nbsp;Magnus Carlquist ,&nbsp;Björn Johansson","doi":"10.1016/j.mec.2023.e00224","DOIUrl":"https://doi.org/10.1016/j.mec.2023.e00224","url":null,"abstract":"<div><p>Fatty acids are produced by eukaryotes like baker's yeast <em>Saccharomyces cerevisiae</em> mainly using a large multifunctional type I fatty acid synthase (FASI) where seven catalytic steps and a carrier domain are shared between one or two protein subunits. While this system may offer efficiency in catalysis, only a narrow range of fatty acids are produced. Prokaryotes, chloroplasts and mitochondria rely instead on a FAS type II (FASII) where each catalytic step is carried out by a monofunctional enzyme encoded by a separate gene. FASII is more flexible and capable of producing a wider range of fatty acid structures, such as the direct production of unsaturated fatty acids. An efficient FASII in the preferred industrial organism <em>S. cerevisiae</em> could provide a platform for developing sustainable production of specialized fatty acids. We functionally replaced either yeast FASI genes (<em>FAS1</em> or <em>FAS2</em>) with a FASII consisting of nine genes from <em>Escherichia coli</em> (<em>acpP</em>, <em>acpS</em> and <em>fab</em> -<em>A</em>, -<em>B</em>, -<em>D</em>, -<em>F</em>, -<em>G</em>, -<em>H</em>, -<em>Z</em>) as well as three from <em>Arabidopsis thaliana</em> (<em>MOD1</em>, <em>FATA1</em> and <em>FATB</em>). The genes were expressed from an autonomously replicating multicopy vector assembled using the Yeast Pathway Kit for <em>in-vivo</em> assembly in yeast. Two rounds of adaptation led to a strain with a maximum growth rate (μmax) of 0.19 h⁻¹ without exogenous fatty acids, twice the growth rate previously reported for a comparable strain. Additional copies of the <em>MOD1</em> or <em>fabH</em> genes resulted in cultures with higher final cell densities and three times higher lipid content compared to the control.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"17 ","pages":"Article e00224"},"PeriodicalIF":5.2,"publicationDate":"2023-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50172342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cell-free metabolic engineering enables selective biotransformation of fatty acids to value-added chemicals","authors":"Yushi Liu ,&nbsp;Wan-Qiu Liu ,&nbsp;Shuhui Huang ,&nbsp;Huiling Xu ,&nbsp;Haofan Lu ,&nbsp;Changzhu Wu ,&nbsp;Jian Li","doi":"10.1016/j.mec.2022.e00217","DOIUrl":"10.1016/j.mec.2022.e00217","url":null,"abstract":"<div><p>Fatty acid-derived products such as alkanes, fatty aldehydes, and fatty alcohols have many applications in the chemical industry. These products are predominately produced from fossil resources, but their production processes are often not environmentally friendly. While microbes like <em>Escherichia coli</em> have been engineered to convert fatty acids to corresponding products, the design and optimization of metabolic pathways in cells for high productivity is challenging due to low mass transfer, heavy metabolic burden, and intermediate/product toxicity. Here, we describe an <em>E. coli</em>-based cell-free protein synthesis (CFPS) platform for <em>in vitro</em> conversion of long-chain fatty acids to value-added chemicals with product selectivity, which can also avoid the above issues when using microbial production systems. We achieve the selective biotransformation by cell-free expression of different enzymes and the use of different conditions (e.g., light and heating) to drive the biocatalysis toward different final products. Specifically, in response to blue light, cell-free expressed fatty acid photodecarboxylase (CvFAP, a photoenzyme) was able to convert fatty acids to alkanes with approximately 90% conversion. When the expressed enzyme was switched to carboxylic acid reductase (CAR), fatty acids were reduced to corresponding fatty aldehydes, which, however, could be further reduced to fatty alcohols by endogenous reductases in the cell-free system. By using a thermostable CAR and a heating treatment, the endogenous reductases were deactivated and fatty aldehydes could be selectively accumulated (&gt;97% in the product mixture) without over-reduction to alcohols. Overall, our cell-free platform provides a new strategy to convert fatty acids to valuable chemicals with notable properties of operation flexibility, reaction controllability, and product selectivity.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"16 ","pages":"Article e00217"},"PeriodicalIF":5.2,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/f3/36/main.PMC9791597.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10509847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Engineered production of isoprene from the model green microalga Chlamydomonas reinhardtii","authors":"Razan Z. Yahya,&nbsp;Gordon B. Wellman,&nbsp;Sebastian Overmans,&nbsp;Kyle J. Lauersen","doi":"10.1016/j.mec.2023.e00221","DOIUrl":"https://doi.org/10.1016/j.mec.2023.e00221","url":null,"abstract":"<div><p>Isoprene is a clear, colorless, volatile 5-carbon hydrocarbon that is one monomer of all cellular isoprenoids and a platform chemical with multiple applications in industry. Many plants have evolved isoprene synthases (IspSs) with the capacity to liberate isoprene from dimethylallyl diphosphate (DMADP) as part of cellular thermotolerance mechanisms. Isoprene is hydrophobic and volatile, rapidly leaves plant tissues and is one of the main carbon emission sources from vegetation globally. The universality of isoprenoid metabolism allows volatile isoprene production from microbes expressing heterologous IspSs. Here, we compared heterologous overexpression from the nuclear genome and localization into the plastid of four plant terpene synthases (TPs) in the green microalga <em>Chlamydomonas reinhardtii</em>. Using sealed vial mixotrophic cultivation, direct quantification of isoprene production was achieved from the headspace of living cultures, with the highest isoprene production observed in algae expressing the <em>Ipomoea batatas</em> IspS. Perturbations of the downstream carotenoid pathway through keto carotenoid biosynthesis enhanced isoprene titers, which could be further enhanced by increasing flux towards DMADP through heterologous co-expression of a yeast isopentenyl-DP delta isomerase. Multiplexed controlled-environment testing revealed that cultivation temperature, rather than illumination intensity, was the main factor affecting isoprene yield from the engineered alga. This is the first report of heterologous isoprene production from a eukaryotic alga and sets a foundation for further exploration of carbon conversion to this commodity chemical.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"16 ","pages":"Article e00221"},"PeriodicalIF":5.2,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50170513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved protein glycosylation enabled heterologous biosynthesis of monoterpenoid indole alkaloids and their unnatural derivatives in yeast","authors":"Mohammadamin Shahsavarani ,&nbsp;Joseph Christian Utomo ,&nbsp;Rahul Kumar ,&nbsp;Melina Paz-Galeano ,&nbsp;Jorge Jonathan Oswaldo Garza-García ,&nbsp;Zhan Mai ,&nbsp;Dae-Kyun Ro ,&nbsp;Yang Qu","doi":"10.1016/j.mec.2022.e00215","DOIUrl":"10.1016/j.mec.2022.e00215","url":null,"abstract":"<div><p>With over 3000 reported structures, monoterpenoid indole alkaloids (MIAs) constitute one of the largest alkaloid groups in nature, including the clinically important anticancer drug vinblastine and its semi-synthetic derivatives from <em>Catharanthus roseus</em> (Madagascar’s periwinkle). With the elucidation of the complete 28-step biosynthesis for anhydrovinblastine, it is possible to investigate the heterologous production of vinblastine and other medicinal MIAs. In this study, we successfully expressed the flavoenzyme <em>O</em>-acetylstemmadenine oxidase in <em>Saccharomyces cerevisiae</em> (baker’s yeast) by signal peptide modification, which is a vinblastine biosynthetic gene that has not been functionally expressed in this system. We also reported the simultaneous integration of ∼18 kb MIA biosynthetic gene cassettes as single copies into four genomic loci of baker’s yeast by CRISPR-Cas9, which enabled the biosynthesis of vinblastine precursors catharanthine and tabersonine from the feedstocks secologanin and tryptamine. We further demonstrated the biosynthesis of fluorinated and hydroxylated catharanthine and tabersonine derivatives using our yeasts, which showed that the MIA biosynthesis accommodates unnatural substrates, and the system can be further explored to produce other complex MIAs.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"16 ","pages":"Article e00215"},"PeriodicalIF":5.2,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/b6/12/main.PMC9772838.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10804046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metabolic engineering of low-pH-tolerant non-model yeast, Issatchenkia orientalis, for production of citramalate","authors":"Zong-Yen Wu ,&nbsp;Wan Sun ,&nbsp;Yihui Shen ,&nbsp;Jimmy Pratas ,&nbsp;Patrick F. Suthers ,&nbsp;Ping-Hung Hsieh ,&nbsp;Sudharsan Dwaraknath ,&nbsp;Joshua D. Rabinowitz ,&nbsp;Costas D. Maranas ,&nbsp;Zengyi Shao ,&nbsp;Yasuo Yoshikuni","doi":"10.1016/j.mec.2023.e00220","DOIUrl":"https://doi.org/10.1016/j.mec.2023.e00220","url":null,"abstract":"<div><p>Methyl methacrylate (MMA) is an important petrochemical with many applications. However, its manufacture has a large environmental footprint. Combined biological and chemical synthesis (semisynthesis) may be a promising alternative to reduce both cost and environmental impact, but strains that can produce the MMA precursor (citramalate) at low pH are required. A non-conventional yeast, <em>Issatchenkia orientalis</em>, may prove ideal, as it can survive extremely low pH. Here, we demonstrate the engineering of <em>I. orientalis</em> for citramalate production. Using sequence similarity network analysis and subsequent DNA synthesis, we selected a more active citramalate synthase gene (<em>cimA</em>) variant for expression in <em>I. orientalis</em>. We then adapted a piggyBac transposon system for <em>I. orientalis</em> that allowed us to simultaneously explore the effects of different <em>cimA</em> gene copy numbers and integration locations. A batch fermentation showed the genome-integrated-<em>cimA</em> strains produced 2.0 g/L citramalate in 48 h and a yield of up to 7% mol citramalate/mol consumed glucose. These results demonstrate the potential of <em>I. orientalis</em> as a chassis for citramalate production.</p></div>","PeriodicalId":18695,"journal":{"name":"Metabolic Engineering Communications","volume":"16 ","pages":"Article e00220"},"PeriodicalIF":5.2,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50170512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}