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Singh B, Kumar A, Saini AK, Saini RV, Thakur R, Mohammed SA, Tuli HS, Gupta VK, Areeshi MY, Faidah H, Jalal NA, Haque S. Strengthening microbial cell factories for efficient production of bioactive molecules. Biotechnol Genet Eng Rev 2023:1-34. [PMID: 36809927 DOI: 10.1080/02648725.2023.2177039] [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: 08/11/2022] [Accepted: 01/21/2023] [Indexed: 02/24/2023]
Abstract
High demand of bioactive molecules (food additives, antibiotics, plant growth enhancers, cosmetics, pigments and other commercial products) is the prime need for the betterment of human life where the applicability of the synthetic chemical product is on the saturation due to associated toxicity and ornamentations. It has been noticed that the discovery and productivity of such molecules in natural scenarios are limited due to low cellular yields as well as less optimized conventional methods. In this respect, microbial cell factories timely fulfilling the requirement of synthesizing bioactive molecules by improving production yield and screening more promising structural homologues of the native molecule. Where the robustness of the microbial host can be potentially achieved by taking advantage of cell engineering approaches such as tuning functional and adjustable factors, metabolic balancing, adapting cellular transcription machinery, applying high throughput OMICs tools, stability of genotype/phenotype, organelle optimizations, genome editing (CRISPER/Cas mediated system) and also by developing accurate model systems via machine-learning tools. In this article, we provide an overview from traditional to recent trends and the application of newly developed technologies, for strengthening the systemic approaches and providing future directions for enhancing the robustness of microbial cell factories to speed up the production of biomolecules for commercial purposes.
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Affiliation(s)
- Bharat Singh
- Department of Biotechnology and Central Research Cell, MMEC, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala, India
| | - Ankit Kumar
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gurugram, India
| | - Adesh Kumar Saini
- Department of Biotechnology and Central Research Cell, MMEC, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala, India
| | - Reena Vohra Saini
- Department of Biotechnology and Central Research Cell, MMEC, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala, India
| | - Rahul Thakur
- Department of Biotechnology and Central Research Cell, MMEC, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala, India
| | - Shakeel A Mohammed
- Department of Biotechnology and Central Research Cell, MMEC, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala, India
| | - Hardeep Singh Tuli
- Department of Biotechnology and Central Research Cell, MMEC, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala, India
| | - Vijai Kumar Gupta
- Biorefining and Advanced Materials Research Centre, Scotland's Rural College (SRUC), Edinburgh, UK
| | - Mohammed Y Areeshi
- Medical Laboratory Technology Department, College of Applied Medical Sciences, Jazan University, Jazan, Saudi Arabia
- Research and Scientific Studies Unit, College of Nursing and Allied Health Sciences, Jazan University, Jazan, Saudi Arabia
| | - Hani Faidah
- Department of Microbiology, Faculty of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Naif A Jalal
- Department of Microbiology, Faculty of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Shafiul Haque
- Research and Scientific Studies Unit, College of Nursing and Allied Health Sciences, Jazan University, Jazan, Saudi Arabia
- Gilbert and Rose-Marie Chagoury School of Medicine, Lebanese American University, Beirut, Lebanon
- Centre of Medical and Bio-Allied Health Sciences Research, Ajman University, Ajman, United Arab Emirates
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Chen C, Zheng P. Effects of down-regulation of ackA expression by CRISPR-dCpf1 on succinic acid production in Actinobacillus succinogenes. AMB Express 2023; 13:12. [PMID: 36700989 PMCID: PMC9880102 DOI: 10.1186/s13568-023-01518-x] [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: 01/12/2023] [Accepted: 01/19/2023] [Indexed: 01/27/2023] Open
Abstract
Succinic acid (SA), a key intermediate in the cellular tricarboxylic acid cycle (TCA), is a 4-carbon dicarboxylic acid of great industrial value. Actinobacillus succinogenes can ferment various carbon sources and accumulate relatively high concentrations of SA, but few reliable genetic engineering tools exist for A. succinogenes and this has hindered strain improvement to increase SA production for industrial application. Two different repressors, endonuclease-deactivated Cas9 (dCas9) from Streptococcus pyogenes and Cpf1 (dCpf1) from Francisella tularensis, were applied to construct a CRISPRi system in A. succinogenes. Codon-optimized Cas9 and native Cpf1 were successfully expressed in A. succinogenes, and the corresponding sgRNA and crRNA expression elements, promoted by the fumarate reductase promoter, frd, were introduced into the CRISPRi plasmid. The highest repression of the ackA gene (encoding acetate kinase) and thereby acetic acid production (~ eightfold) was achieved by the dCpf1-based CRISPRi system, in which the mutation site, E1006A acted at the start of the coding region of ackA, the gene which regulates acetic acid biosynthesis. Compared with the ackA gene knockout mutant, cell growth was moderately improved and SA production increased by 6.3%. Further, the SA titer and productivity in a 3 L fermenter reached 57.06 g/L and 1.87 g/L/h, and there was less acetic acid production. A dCpf1-based CRISPRi-mediated gene repression system was successfully established for the first time, providing a simple and effective tool for studying functional genomics in A. succinogenes and optimizing SA production.
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Affiliation(s)
- Chunmei Chen
- grid.258151.a0000 0001 0708 1323The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 China
| | - Pu Zheng
- grid.258151.a0000 0001 0708 1323The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 China
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Zhou S, Zhang M, Zhu L, Zhao X, Chen J, Chen W, Chang C. Hydrolysis of lignocellulose to succinic acid: a review of treatment methods and succinic acid applications. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:1. [PMID: 36593503 PMCID: PMC9806916 DOI: 10.1186/s13068-022-02244-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 12/08/2022] [Indexed: 01/03/2023]
Abstract
Succinic acid (SA) is an intermediate product of the tricarboxylic acid cycle (TCA) and is one of the most significant platform chemicals for the production of various derivatives with high added value. Due to the depletion of fossil raw materials and the demand for eco-friendly energy sources, SA biosynthesis from renewable energy sources is gaining attention for its environmental friendliness. This review comprehensively analyzes strategies for the bioconversion of lignocellulose to SA based on the lignocellulose pretreatment processes and cellulose hydrolysis and fermentation principles and highlights the research progress on acid production and SA utilization under different microbial culture conditions. In addition, the fermentation efficiency of different microbial strains for the production of SA and the main challenges were analyzed. The future application directions of SA derivatives were pointed out. It is expected that this research will provide a reference for the optimization of SA production from lignocellulose.
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Affiliation(s)
- Shuzhen Zhou
- grid.207374.50000 0001 2189 3846College of Chemical Engineering, Zhengzhou University, Zhengzhou, China
| | - Miaomiao Zhang
- grid.207374.50000 0001 2189 3846College of Chemical Engineering, Zhengzhou University, Zhengzhou, China
| | - Linying Zhu
- grid.207374.50000 0001 2189 3846College of Management Engineering, Zhengzhou University, Zhengzhou, China
| | - Xiaoling Zhao
- grid.207374.50000 0001 2189 3846College of Chemical Engineering, Zhengzhou University, Zhengzhou, China ,grid.454889.cState Key Laboratory of Motor Vehicle Biofuel Technology, Nanyang, China ,Henan Center for Outstanding Overseas Scientists, Zhengzhou, China
| | - Junying Chen
- grid.207374.50000 0001 2189 3846College of Chemical Engineering, Zhengzhou University, Zhengzhou, China ,grid.454889.cState Key Laboratory of Motor Vehicle Biofuel Technology, Nanyang, China ,Henan Center for Outstanding Overseas Scientists, Zhengzhou, China
| | - Wei Chen
- Henan Key Laboratory of Green Manufacturing of Biobased Chemicals, Puyang, China
| | - Chun Chang
- grid.207374.50000 0001 2189 3846College of Chemical Engineering, Zhengzhou University, Zhengzhou, China ,grid.454889.cState Key Laboratory of Motor Vehicle Biofuel Technology, Nanyang, China ,Henan Center for Outstanding Overseas Scientists, Zhengzhou, China
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Tian W, Qin J, Lian C, Yao Q, Wang X. Identification of a major facilitator superfamily protein that is beneficial to L-lactic acid production by Bacillus coagulans at low pH. BMC Microbiol 2022; 22:310. [PMID: 36536285 PMCID: PMC9764580 DOI: 10.1186/s12866-022-02736-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Product inhibition is one of the major problems in lactic acid (LA) fermentation. Our previous study revealed that Bacillus coagulans 2-6 was an efficient producer of high-optical-purity L-LA. Its mutant strain B. coagulans Na-2 has better resistance to sodium lactate stress but the resistance mechanism has not been understood. RESULTS In this study, the whole-genome sequencing of B. coagulans Na-2 was performed and one mutant gene mfs coding for the major facilitator superfamily (MFS) protein was revealed by comparative genome analysis. Ten mutation sites were identified between the wild (MFS-2-6) and mutant (MFS-Na-2) proteins, among which T127A and N154T were predicted locating in the center of the transmembrane transport channel. The MFS-2-6 and MFS-Na-2 were expressed separately in a genetically operable strain, B. coagulans DSM1, using the genes' native promoter. The expression of the two MFS proteins had no effect and a negative effect on L-LA production when the pH was controlled at 6.0 and 7.0 by sodium hydroxide, respectively. However, 4.2 and 4.6-fold of L-LA concentrations were obtained at pH 5.0 by the strains expressing MFS-2-6 and MFS-Na-2 than that by the control strain, respectively. The intracellular pH values of the strains expressing MFS-2-6 and MFS-Na-2 were approximately 0.69 and 0.45 higher than that of the control strain during pH-controlled fermentation at 5.0. Results suggest that the expression of MFS-2-6 and MFS-Na-2 were both conducive to L-LA production at low pH, while the better performance of the latter was probably due to the more appropriate intracellular pH during the whole fermentation process. CONCLUSIONS The MFS protein identified here can improve the ability of B. coagulans to resist acidic environments and produce more L-LA at low pH. The MFS protein has an application potential in environment-friendly L-LA production.
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Affiliation(s)
- Wenzhe Tian
- grid.440653.00000 0000 9588 091XCollege of Pharmacy, Binzhou Medical University, Yantai, 264003 China
| | - Jiayang Qin
- grid.440653.00000 0000 9588 091XCollege of Pharmacy, Binzhou Medical University, Yantai, 264003 China
| | - Congcong Lian
- grid.440653.00000 0000 9588 091XCollege of Pharmacy, Binzhou Medical University, Yantai, 264003 China
| | - Qingshou Yao
- grid.440653.00000 0000 9588 091XCollege of Pharmacy, Binzhou Medical University, Yantai, 264003 China
| | - Xiuwen Wang
- grid.440653.00000 0000 9588 091XCollege of Pharmacy, Binzhou Medical University, Yantai, 264003 China
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Narisetty V, Okibe MC, Amulya K, Jokodola EO, Coulon F, Tyagi VK, Lens PNL, Parameswaran B, Kumar V. Technological advancements in valorization of second generation (2G) feedstocks for bio-based succinic acid production. BIORESOURCE TECHNOLOGY 2022; 360:127513. [PMID: 35772717 DOI: 10.1016/j.biortech.2022.127513] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 06/15/2023]
Abstract
Succinic acid (SA) is used as a commodity chemical and as a precursor in chemical industry to produce other derivatives such as 1,4-butaneidol, tetrahydrofuran, fumaric acid, and bio-polyesters. The production of bio-based SA from renewable feedstocks has always been in the limelight owing to the advantages of renewability, abundance and reducing climate change by CO2 capture. Considering this, the current review focuses on various 2G feedstocks such as lignocellulosic biomass, crude glycerol, and food waste for cost-effective SA production. It also highlights the importance of producing SA via separate enzymatic hydrolysis and fermentation, simultaneous saccharification and fermentation, and consolidated bioprocessing. Furthermore, recent advances in genetic engineering, and downstream SA processing are thoroughly discussed. It also elaborates on the techno-economic analysis and life cycle assessment (LCA) studies carried out to understand the economics and environmental effects of bio-based SA synthesis.
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Affiliation(s)
- Vivek Narisetty
- School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK
| | | | - K Amulya
- National University of Ireland Galway, University Road, H91TK33 Galway, Ireland
| | | | - Frederic Coulon
- School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK
| | - Vinay Kumar Tyagi
- Environmental Hydrology Division, National Institute of Hydrology (NIH), Roorkee 247667, Uttarakhand, India
| | - Piet N L Lens
- National University of Ireland Galway, University Road, H91TK33 Galway, Ireland
| | - Binod Parameswaran
- Microbial Processes and Technology Division, CSIR - National Institute for Interdisciplinary Science and Technology, Trivandrum, Kerala 695019, India
| | - Vinod Kumar
- School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK.
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Huang C, Wang C, Luo Y. Research progress of pathway and genome evolution in microbes. Synth Syst Biotechnol 2022; 7:648-656. [PMID: 35224232 PMCID: PMC8857405 DOI: 10.1016/j.synbio.2022.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/23/2021] [Accepted: 01/06/2022] [Indexed: 12/16/2022] Open
Abstract
Microbes can produce valuable natural products widely applied in medicine, food and other important fields. Nevertheless, it is usually challenging to achieve ideal industrial yields due to low production rate and poor toxicity tolerance. Evolution is a constant mutation and adaptation process used to improve strain performance. Generally speaking, the synthesis of natural products in microbes is often intricate, involving multiple enzymes or multiple pathways. Individual evolution of a certain enzyme often fails to achieve the desired results, and may lead to new rate-limiting nodes that affect the growth of microbes. Therefore, it is inevitable to evolve the biosynthetic pathways or the whole genome. Here, we reviewed the pathway-level evolution including multi-enzyme evolution, regulatory elements engineering, and computer-aided engineering, as well as the genome-level evolution based on several tools, such as genome shuffling and CRISPR/Cas systems. Finally, we also discussed the major challenges faced by in vivo evolution strategies and proposed some potential solutions.
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Affiliation(s)
- Chaoqun Huang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Chang Wang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Yunzi Luo
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
- Georgia Tech Shenzhen Institute, Tianjin University, Tangxing Road 133, Nanshan District, Shenzhen, 518071, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, 300072, China
- Corresponding author. Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
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Liu J, Liu J, Guo L, Liu J, Chen X, Liu L, Gao C. Advances in microbial synthesis of bioplastic monomers. ADVANCES IN APPLIED MICROBIOLOGY 2022; 119:35-81. [DOI: 10.1016/bs.aambs.2022.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Gao H, Wang J, Wu H, Xin F, Zhang W, Jiang M, Fang Y. Biofilm-Integrated Glycosylated Membrane for Biosuccinic Acid Production. ACS APPLIED BIO MATERIALS 2021; 4:7517-7523. [PMID: 35006701 DOI: 10.1021/acsabm.1c00764] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Biofilm-based cell-immobilized fermentation technology is regarded as the technique with the most potential for biobased product (chemicals, biofuelss materials, etc.) production in industry. Glycosylated membrane can mimic natural extracellular matrix (ECM) and improve cell adhesion and biofilm formation based on carbohydrate-microbial lectin interaction. Here, we applied glycosylated membrane with rhamnose modified surface for constructing Actinobacillus succinogenes biofilm and producing biosuccinic acid. Polymer hollow fiber (PHF) membrane surface was first modified by glycosylation based on physical adsorption approach. The approach is simple, green, and suitable for scale-amplification. Then, the microbial biofilm formed dramatically on the modified membrane surface. And for subsequent biosuccinic acid production, the maximum titer of succinic acid reached 67.3 g/L, and the yield was 0.82 g/g. Compared with free cell fermentation, the titer and yield increased by 18% and 9% in this biofilm-based cell-immobilized fermentation system, respectively. Importantly, the production efficiency of biosuccinic acid increased obviously for subsequent biofilm-based cell-immobilized fermentation. In addition, the biofilm-integrated glycosylated membrane showed high reusability for succinic acid production. This result is important for developing biofilms for a wide range of applications in bioproduct (chemicals, biofuels, materials, etc.) production.
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Affiliation(s)
- Hao Gao
- College of Biotechnology and Pharmaceutical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, P.R. China
| | - Jie Wang
- College of Biotechnology and Pharmaceutical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, P.R. China
| | - Hao Wu
- College of Biotechnology and Pharmaceutical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, P.R. China
| | - Fengxue Xin
- College of Biotechnology and Pharmaceutical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, P.R. China
| | - Wenming Zhang
- College of Biotechnology and Pharmaceutical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, P.R. China
| | - Min Jiang
- College of Biotechnology and Pharmaceutical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, P.R. China
| | - Yan Fang
- College of Biotechnology and Pharmaceutical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, P.R. China
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Tran VG, Zhao H. Engineering robust microorganisms for organic acid production. J Ind Microbiol Biotechnol 2021; 49:6373449. [PMID: 34549297 PMCID: PMC9118992 DOI: 10.1093/jimb/kuab067] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 09/11/2021] [Indexed: 11/24/2022]
Abstract
Organic acids are an important class of compounds that can be produced by microbial conversion of renewable feedstocks and have huge demands and broad applications in food, chemical, and pharmaceutical industries. An economically viable fermentation process for production of organic acids requires robust microbial cell factories with excellent tolerance to low pH conditions, high concentrations of organic acids, and lignocellulosic inhibitors. In this review, we summarize various strategies to engineer robust microorganisms for organic acid production and highlight their applications in a few recent examples.
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Affiliation(s)
- Vinh G Tran
- Department of Chemical and Biomolecular Engineering, U.S. Department of Energy Center for Bioenergy and Bioproducts Innovation (CABBI), Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, U.S. Department of Energy Center for Bioenergy and Bioproducts Innovation (CABBI), Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States.,Departments of Chemistry, Biochemistry, and Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
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Applications and research advance of genome shuffling for industrial microbial strains improvement. World J Microbiol Biotechnol 2020; 36:158. [PMID: 32968940 DOI: 10.1007/s11274-020-02936-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 09/15/2020] [Indexed: 12/25/2022]
Abstract
Genome shuffling, an efficient and practical strain improvement technology via recursive protoplasts fusion, can break through the limits of species even genus to accelerate the directed evolution of microbial strains, without requiring the comprehensively cognized genetic background and operable genetic system. Hence this technology has been widely used for many important strains to obtain the desirable industrial phenotypes. In this review, we introduce the procedure of genome shuffling, discuss the new aid strategies of genome shuffling, summarize the applications of genome shuffling for increasing metabolite yield, improving strain tolerance, enhancing substrate utilization, and put forward the outlook to the future development of this technology.
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Recent advances in improving metabolic robustness of microbial cell factories. Curr Opin Biotechnol 2020; 66:69-77. [PMID: 32683192 DOI: 10.1016/j.copbio.2020.06.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 06/12/2020] [Accepted: 06/17/2020] [Indexed: 12/20/2022]
Abstract
Engineering microbial cell factories has been widely applied to produce compounds spanning from intricate natural products to bulk commodities. In each case, host robustness is essential to ensure the reliable and sustainable production of targeted metabolites. However, it can be negatively affected by metabolic burden, pathway toxicity, and harsh environment, resulting in a decreased titer and productivity. Enhanced robustness enables host to have better production performance under complicated growth circumstances. Here, we review current strategies for boosting host robustness, including metabolic balancing, genetic and phenotype stability enhancement, and tolerance engineering. In addition, we discuss the challenges and future perspectives on microbial host engineering for increased robustness.
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Engineering salt tolerance of photosynthetic cyanobacteria for seawater utilization. Biotechnol Adv 2020; 43:107578. [PMID: 32553809 DOI: 10.1016/j.biotechadv.2020.107578] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/17/2020] [Accepted: 06/05/2020] [Indexed: 02/04/2023]
Abstract
Photosynthetic cyanobacteria are capable of utilizing sunlight and CO2 as sole energy and carbon sources, respectively. With genetically modified cyanobacteria being used as a promising chassis to produce various biofuels and chemicals in recent years, future large-scale cultivation of cyanobacteria would have to be performed in seawater, since freshwater supplies of the earth are very limiting. However, high concentration of salt is known to inhibit the growth of cyanobacteria. This review aims at comparing the mechanisms that different cyanobacteria respond to salt stress, and then summarizing various strategies of developing salt-tolerant cyanobacteria for seawater cultivation, including the utilization of halotolerant cyanobacteria and the engineering of salt-tolerant freshwater cyanobacteria. In addition, the challenges and potential strategies related to further improving salt tolerance in cyanobacteria are also discussed.
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Genome Shuffling of Bacillus velezensis for Enhanced Surfactin Production and Variation Analysis. Curr Microbiol 2019; 77:71-78. [DOI: 10.1007/s00284-019-01807-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 10/31/2019] [Indexed: 10/25/2022]
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