Metabolic engineering最新文献

{"title":"Generation of a Vibrio-based platform for efficient conversion of raffinose through Adaptive Laboratory Evolution on a solid medium","authors":"Sunghwa Woo ,&nbsp;Yong Hee Han ,&nbsp;Hye Kyung Lee ,&nbsp;Dongyeop Baek ,&nbsp;Myung Hyun Noh ,&nbsp;Sukjae Han ,&nbsp;Hyun Gyu Lim ,&nbsp;Gyoo Yeol Jung ,&nbsp;Sang Woo Seo","doi":"10.1016/j.ymben.2024.11.001","DOIUrl":"10.1016/j.ymben.2024.11.001","url":null,"abstract":"<div><div>Raffinose, a trisaccharide abundantly found in soybeans, is a potential alternative carbon source for biorefineries. Nevertheless, residual intermediate di- or monosaccharides and low catabolic efficiency limit raffinose use through conventional microbial hosts. This study presents a <em>Vibrio</em>-based platform to convert raffinose efficiently. <em>Vibrio</em> sp. dhg was selected as the starting strain for the Adaptive Laboratory Evolution (ALE) strategy to leverage its significantly higher metabolic efficiency. We conducted ALE on a solid minimal medium supplemented with raffinose to prevent the enrichment of undesired phenotypes due to the shared effect of extracellular raffinose hydrolysis among multiple strains. As a result, we generated the VRA10 strain that efficiently utilizes raffinose without leaving behind degraded di- or monosaccharides, achieving a notable growth rate (0.40 h⁻¹) and raffinose consumption rate (1.2 g/g_dcw/h). Whole genome sequencing and reverse engineering identified that a missense mutation in the <em>melB</em> gene (encoding a melibiose/raffinose:sodium symporter) and the deletion of the two <em>galR</em> genes (encoding transcriptional repressors for galactose catabolism) facilitated rapid raffinose utilization. The further engineered strain produced 6.2 g/L of citramalate from 20 g/L of raffinose. This study will pave the way for the efficient utilization of diverse raffinose-rich byproducts and the expansion of alternative carbon streams in biorefinery applications.</div></div>","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"86 ","pages":"Pages 300-307"},"PeriodicalIF":6.8,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142569125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Engineering Halomonas bluephagenesis for synthesis of polyhydroxybutyrate (PHB) in the presence of high nitrogen containing media","authors":"Zhongnan Zhang ,&nbsp;Mingwei Shao ,&nbsp;Ge Zhang ,&nbsp;Simian Sun ,&nbsp;Xueqing Yi ,&nbsp;Zonghao Zhang ,&nbsp;Hongtao He ,&nbsp;Kang Wang ,&nbsp;Qitiao Hu ,&nbsp;Qiong Wu ,&nbsp;Guo-Qiang Chen","doi":"10.1016/j.ymben.2024.10.012","DOIUrl":"10.1016/j.ymben.2024.10.012","url":null,"abstract":"<div><div>The trade-offs exist between microbial growth and bioproduct synthesis including intracellular polyester polyhydroxybutyrate (PHB). Under nitrogen limitation, more carbon flux is directed to PHB synthesis while growth is inhibited with diminishing overall carbon utilization, similar to the suboptimal carbon utilization during glycolysis-derived pyruvate decarboxylation. This study reconfigured the central carbon network of <em>Halomonas blu</em><em>e</em><em>phagenesis</em> to improve PHB yield theoretically and practically. It was found that the downregulation of glutamine synthetase (GS) activity led to a synchronous improvement on PHB accumulation and cell growth under nitrogen non-limitation condition, increasing the PHB yield from glucose (g/g) to 85% of theoretical yield, PHB titer from 7.6 g/L to 12.9 g/L, and from 51 g/L to 65 g/L when grown in shake flasks containing a rich N-source, and grown in a fed-batch cultivation conducted in a 7-L bioreactor also containing a rich N-source, respectively. Results offer better metabolic balance between glucose conversion efficiency and microbial growth for economic PHB production.</div></div>","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"86 ","pages":"Pages 242-249"},"PeriodicalIF":6.8,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Not all cytochrome b5s are created equal: How a specific CytB5 boosts forskolin biosynthesis in Saccharomyces cerevisiae","authors":"Victor Forman ,&nbsp;Dan Luo ,&nbsp;Sotirios C. Kampranis ,&nbsp;Dan Stærk ,&nbsp;Birger Lindberg Møller ,&nbsp;Irini Pateraki","doi":"10.1016/j.ymben.2024.10.008","DOIUrl":"10.1016/j.ymben.2024.10.008","url":null,"abstract":"<div><div>Cytochrome B5s, or CytB5s, are small heme-binding proteins, ubiquitous across all kingdoms of life that serve mainly as electron donors to enzymes engaged in oxidative reactions. They often function as redox partners of the cytochrome P450s (CYPs), a superfamily of enzymes participating in multiple biochemical processes. In plants, CYPs catalyze key reactions in the biosynthesis of plant specialized metabolites with their activity dependent on electron donation often from cytochrome P450 oxidoreductases (CPRs or PORs). In eukaryotic microsomal CYPs, CytB5s frequently participate in the electron transfer process although their exact role remains understudied, especially in plant systems. In this study, we assess the role of CytB5s in the heterologous biotechnological production of plant specialized metabolites in yeast. For this, we used as a case-study the biosynthesis of forskolin - a bioactive diterpenoid produced exclusively from the plant <em>Coleus forskohlii</em>. The complete biosynthetic pathway for forskolin is known and includes three CYP enzymes. We reconstructed the entire forskolin pathway in the yeast <em>Saccharomyces cerevisiae,</em> and upon co-expression of the three CytB5s - identified in <em>C. forskohlii</em> transcriptomes - alleviation of a CYP-related bottleneck step was noticed only when a specific CytB5, <em>Cf</em>CytB5A, was used. Co-expression of <em>Cf</em>CytB5A in yeast, in combination with forskolin pathway engineering, resulted in forskolin production at titers of 1.81 g/L in a bioreactor. Our findings demonstrate that CytB5s not only play an important role in plant specialized metabolism but also, they can interact with precision with specific CYPs, indicating that the properties of CytB5s are far from understood. Moreover, our work highlights how CytB5s may act as indispensable components in the sustainable microbial production of plant metabolites, when their biosynthetic pathways involve CYP enzymes.</div></div>","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"86 ","pages":"Pages 288-299"},"PeriodicalIF":6.8,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142503498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptive laboratory evolution and metabolic engineering of Cupriavidus necator for improved catabolism of volatile fatty acids","authors":"Eric C. Holmes,&nbsp;Alissa C. Bleem,&nbsp;Christopher W. Johnson,&nbsp;Gregg T. Beckham","doi":"10.1016/j.ymben.2024.10.011","DOIUrl":"10.1016/j.ymben.2024.10.011","url":null,"abstract":"<div><div>Bioconversion of high-volume waste streams into value-added products will be an integral component of the growing bioeconomy. Volatile fatty acids (VFAs) (e.g., butyrate, valerate, and hexanoate) are an emerging and promising waste-derived feedstock for microbial carbon upcycling. <em>Cupriavidus necator</em> H16 is a favorable host for conversion of VFAs into various bioproducts due to its diverse carbon metabolism, ease of metabolic engineering, and use at industrial scales. Here, we report that a common strategy to improve product titers in <em>C. necator</em>, deletion of the polyhydroxybutyrate (PHB) biosynthetic operon, results in a significant growth defect on VFA substrates. Using adaptive laboratory evolution, we identify mutations to the regulator gene <em>phaR</em>, the two-component response regulator-histidine kinase pair encoded by <em>H16_A1372</em>/<em>H16_A1373</em>, and the tripartite transporter assembly encoded by <em>H16_A2296</em>-<em>A2298</em> as causative for improved growth on VFA substrates. Deletion of <em>phaR</em> and <em>H16_A1373</em> led to significantly reduced NADH abundance accompanied by large changes to expression of genes involved in carbon metabolism, balance of electron carriers, and oxidative stress tolerance that may be responsible for improved growth of these engineered strains. These results provide insight into the role of PHB biosynthesis in carbon and energy metabolism and highlight a key role for the regulator PhaR in global regulatory networks. By combining mutations, we generated platform strains with significant growth improvements on VFAs, which can enable improved conversion of waste-derived VFA substrates to target bioproducts.</div></div>","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"86 ","pages":"Pages 262-273"},"PeriodicalIF":6.8,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coordinated reprogramming of ATP metabolism strongly enhances adipic acid production in Escherichia coli","authors":"Soo Young Moon ,&nbsp;Nan Yeong An ,&nbsp;Seung Soo Oh ,&nbsp;Ju Young Lee","doi":"10.1016/j.ymben.2024.10.010","DOIUrl":"10.1016/j.ymben.2024.10.010","url":null,"abstract":"<div><div>Maintaining a delicate balance of adenosine-5′-triphosphate (ATP) is crucial not only for optimal cellular functions but also for improved metabolite production, indicating the need for careful regulation of ATP demands in metabolic engineering. This study explored the modification of ATP metabolism to enhance adipic acid production in <em>Escherichia coli</em>, focusing on the reverse adipate degradation pathway (RADP), and ATP-consuming cycles were fine-tuned by controlling the overexpression of genes (<em>panK</em> and <em>acs</em>) to balance ATP consumption and adipic acid production. As a result, we successfully achieved a significant increase (19.5-fold) in adipic acid production, reaching 1093.11 mg/L in a shake flask, compared to that in the control strain (wild-type <em>E. coli</em> harboring the RADP). Our transcriptomic analysis indicated that modulation of ATP metabolism, along with a balanced supply of pathway precursors, affects metabolic fluxes, enhancing adipic acid biosynthesis in <em>E. coli</em>. This study suggests the potential of metabolic reprogramming of ATP to meet biosynthetic demands, which may improve the production of adipic acid and other ATP-derived chemicals.</div></div>","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"86 ","pages":"Pages 234-241"},"PeriodicalIF":6.8,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142503497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution-assisted engineering of E. coli enables growth on formic acid at ambient CO2 via the Serine Threonine Cycle.","authors":"Sebastian Wenk,Vittorio Rainaldi,Karin Schann,Hai He,Madeleine Bouzon,Volker Döring,Steffen N Lindner,Arren Bar-Even","doi":"10.1016/j.ymben.2024.10.007","DOIUrl":"https://doi.org/10.1016/j.ymben.2024.10.007","url":null,"abstract":"Atmospheric CO2 poses a major threat to life on Earth by causing global warming and climate change. On the other hand, it can be considered as a resource that is scalable enough to establish a circular carbon economy. Accordingly, technologies to capture and convert CO2 into reduced one-carbon (C1) compounds (e.g. formic acid) are developing and improving fast. Driven by the idea of creating sustainable bioproduction platforms, natural and synthetic C1-utilization pathways are engineered into industrially relevant microbes. The realization of synthetic C1-assimilation cycles in living organisms is a promising but challenging endeavour. Here, we engineer the Serine Threonine Cycle, a synthetic C1-assimilation cycle in Escherichia coli to achieve growth on formic acid. Our stepwise engineering approach in tailored selection strains combined with adaptive laboratory evolution experiments enabled formatotrophic growth of the organism. Whole genome sequencing and reverse engineering allowed us to determine the key mutations linked to pathway activity. The Serine Threonine Cycle strains created in this work use formic acid as a carbon and energy source and can grow at ambient CO2 cultivation conditions. This work sets an example for the engineering of complex C1-assimilation cycles in heterotrophic microbes.","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"96 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142490609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AI-based automated construction of high-precision Geobacillus thermoglucosidasius enzyme constraint model.","authors":"Minghao Zhang,Haijiao Shi,Xiaohong Wang,Yanan Zhu,Zilong Li,Linna Tu,Yu Zheng,Menglei Xia,Weishan Wang,Min Wang","doi":"10.1016/j.ymben.2024.10.006","DOIUrl":"https://doi.org/10.1016/j.ymben.2024.10.006","url":null,"abstract":"Geobacillus thermoglucosidasius NCIMB 11955 possesses advantages, such as high-temperature tolerance, rapid growth rate, and low contamination risk. Additionally, it features efficient gene editing tools, making it one of the most promising next-generation cell factories. However, as a non-model microorganism, a lack of metabolic information significantly hampers the construction of high-precision metabolic flux models. Here, we propose a BioIntelliModel (BIM) strategy based on artificial intelligence technology for the automated construction of enzyme-constrained models. 1) . BIM utilises the Contrastive Learning Enabled Enzyme Annotation (CLEAN) prediction tool to analyse the entire genome sequence of G. thermoglucosidasius NCIMB 11955, uncovering potential functional proteins in non-model strains. 2). The MetaPatchM module of BIM automates the repair of the metabolic network model. 3). The Tianjin University of Science and Technology-kcat (TUST-kcat) module predicts the kcat values of enzymes within the model. 4). The Enzyme-insert procedure constructs an enzyme-constrained model and performs a global scan to address overconstraint issues. Enzymatic data were automatically integrated into the metabolic flux model, creating an enzyme-constrained model, ec_G-ther11955. To validate model accuracy, we used both the p-thermo and ec_G-ther11955 models to predict riboflavin production strategies. The ec_G-ther11955 model demonstrated significantly higher accuracy. To further verify its efficacy, we employed ec_G-ther11955 to guide the rational design of L-valine-producing strains. Using the Optimisation Procedure for Identifying All Genetic Manipulations Leading to Targeted Overproductions (OptForce), Predictive Knockout Targeting (PKT), and Flux Scanning based on Enforced Objective Flux (FSEOF) algorithms, we identified 24 knockout and overexpression targets, achieving an accuracy rate of 87.5%. Ultimately, this led to an increase of 664.04% in L-valine titre. This study provides a novel strategy for rapidly constructing non-model strain models and demonstrates the tremendous potential of artificial intelligence in metabolic engineering.","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"33 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142486335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AI-based automated construction of high-precision Geobacillus thermoglucosidasius enzyme constraint model","authors":"Minghao Zhang ,&nbsp;Haijiao Shi ,&nbsp;Xiaohong Wang ,&nbsp;Yanan Zhu ,&nbsp;Zilong Li ,&nbsp;Linna Tu ,&nbsp;Yu Zheng ,&nbsp;Menglei Xia ,&nbsp;Weishan Wang ,&nbsp;Min Wang","doi":"10.1016/j.ymben.2024.10.006","DOIUrl":"10.1016/j.ymben.2024.10.006","url":null,"abstract":"<div><div><em>Geobacillus thermoglucosidasius</em> NCIMB 11955 possesses advantages, such as high-temperature tolerance, rapid growth rate, and low contamination risk. Additionally, it features efficient gene editing tools, making it one of the most promising next-generation cell factories. However, as a non-model microorganism, a lack of metabolic information significantly hampers the construction of high-precision metabolic flux models. Here, we propose a BioIntelliModel (BIM) strategy based on artificial intelligence technology for the automated construction of enzyme-constrained models. 1). BIM utilises the Contrastive Learning Enabled Enzyme Annotation (CLEAN) prediction tool to analyse the entire genome sequence of <em>G. thermoglucosidasius</em> NCIMB 11955, uncovering potential functional proteins in non-model strains. 2). The MetaPatchM module of BIM automates the repair of the metabolic network model. 3). The Tianjin University of Science and Technology-<em>k</em>_cat (TUST-<em>k</em>_cat) module predicts the <em>k</em>_cat values of enzymes within the model. 4). The Enzyme-insert procedure constructs an enzyme-constrained model and performs a global scan to address overconstraint issues. Enzymatic data were automatically integrated into the metabolic flux model, creating an enzyme-constrained model, ec_G-ther11955. To validate model accuracy, we used both the <em>p-thermo</em> and ec_G-ther11955 models to predict riboflavin production strategies. The ec_G-ther11955 model demonstrated significantly higher accuracy. To further verify its efficacy, we employed ec_G-ther11955 to guide the rational design of L-valine-producing strains. Using the Optimisation Procedure for Identifying All Genetic Manipulations Leading to Targeted Overproductions (OptForce), Predictive Knockout Targeting (PKT), and Flux Scanning based on Enforced Objective Flux (FSEOF) algorithms, we identified 24 knockout and overexpression targets, achieving an accuracy rate of 87.5%. Ultimately, this led to an increase of 664.04% in L-valine titre. This study provides a novel strategy for rapidly constructing non-model strain models and demonstrates the tremendous potential of artificial intelligence in metabolic engineering.</div></div>","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"86 ","pages":"Pages 208-233"},"PeriodicalIF":6.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142469629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Butyrate as a growth factor of Clostridium acetobutylicum","authors":"Hyeongmin Seo,&nbsp;Sofia H. Capece,&nbsp;John D. Hill,&nbsp;Jonathan K. Otten,&nbsp;Eleftherios T. Papoutsakis","doi":"10.1016/j.ymben.2024.10.005","DOIUrl":"10.1016/j.ymben.2024.10.005","url":null,"abstract":"<div><div>The butyrate biosynthetic pathway not only contributes to electron management and energy generation in butyrate forming bacteria, but also confers evolutionary advantages to the host by inhibiting the growth of surrounding butyrate-sensitive microbes. While high butyrate levels induce toxic stress, effects of non-toxic levels on cell growth, health, metabolism, and sporulation remain unclear. Here, we show that butyrate stimulates cellular processes of <em>Clostridium acetobutylicum</em>, a model butyrate forming Firmicute. First, we deleted the 3-hydroxybutyryl-CoA dehydrogenase gene (<em>hbd</em>) from the <em>C. acetobutylicum</em> chromosome to eliminate the butyrate synthetic pathway and thus butyrate formation. A xylose inducible Cas9 cassette was chromosomally integrated and utilized for the one-step markerless gene deletions. Non-toxic butyrate levels significantly affected growth, health, and sporulation of <em>C. acetobutylicum</em>. After deleting <em>spo0A</em>, the gene encoding the master regulator of sporulation, Spo0A, and conducting butyrate addition experiments, we conclude that butyrate affects cellular metabolism through both Spo0A-dependent and independent mechanisms. We also deleted the <em>hbd</em> gene from the chromosome of the asporogenous <em>C. acetobutylicum</em> M5 strain lacking the pSOL1 plasmid to examine the potential involvement of pSOL1 genes on the observed butyrate effects. Addition of crotonate, the precursor of butyrate biosynthesis, to the <em>hbd</em> deficient M5 strain was used to probe the role of butyrate biosynthesis pathway in electron and metabolic fluxes. Finally, we found that butyrate addition can enhance the growth of the non-butyrate forming <em>Clostridium saccharolyticum</em>. Our data suggest that butyrate functions as a stimulator of cellular processes, like a growth factor, in <em>C. acetobutylicum</em> and potentially evolutionarily related <em>Clostridium</em> organisms.</div></div>","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"86 ","pages":"Pages 194-207"},"PeriodicalIF":6.8,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142469630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Growth-coupled production of L-isoleucine in Escherichia coli via metabolic engineering","authors":"Nan Lu ,&nbsp;Minhua Wei ,&nbsp;Xuejing Yang ,&nbsp;Yingzi Li ,&nbsp;Hao Sun ,&nbsp;Qianyu Yan ,&nbsp;Haibin Zhang ,&nbsp;Jilong He ,&nbsp;Jie Ma ,&nbsp;Menglei Xia ,&nbsp;Chenglin Zhang","doi":"10.1016/j.ymben.2024.10.004","DOIUrl":"10.1016/j.ymben.2024.10.004","url":null,"abstract":"<div><div>L-isoleucine, an essential amino acid, is widely used in the pharmaceutical and food industries. However, the current production efficiency is insufficient to meet the increasing demands. In this study, we aimed to develop an efficient L-isoleucine-producing strain of <em>Escherichia coli</em>. First, accumulation of L-isoleucine was achieved by employing feedback-resistant enzymes. Next, a growth-coupled L-isoleucine synthetic pathway was established by introducing the <em>metA</em>-<em>metB</em>-based α-ketobutyrate-generating bypass, which significantly increased L-isoleucine production to 7.4 g/L. Upon employing an activity-improved cystathionine γ-synthase mutant obtained from adaptive laboratory evolution, L-isoleucine production further increased to 8.5 g/L. Subsequently, the redox flux was improved by bypassing the NADPH-dependent aspartate aminotransferase pathway and employing the NADH-dependent pathway and transhydrogenase. Finally, L-isoleucine efflux was enhanced by modifying the transport system. After fed-batch fermentation for 48 h, the resultant strain, ISO-12, reached an L-isoleucine production titer of 51.5 g/L and yield of 0.29 g/g glucose. The strains developed in this study achieved a higher L-isoleucine production efficiency than those reported previously. These strategies will aid in the development of cell factories that produce L-isoleucine and related products.</div></div>","PeriodicalId":18483,"journal":{"name":"Metabolic engineering","volume":"86 ","pages":"Pages 181-193"},"PeriodicalIF":6.8,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142447953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}