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Gaur S, Kaur M, Kalra R, Rene ER, Goel M. Application of microbial resources in biorefineries: Current trend and future prospects. Heliyon 2024; 10:e28615. [PMID: 38628756 PMCID: PMC11019186 DOI: 10.1016/j.heliyon.2024.e28615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 04/19/2024] Open
Abstract
The recent growing interest in sustainable and alternative sources of energy and bio-based products has driven the paradigm shift to an integrated model termed "biorefinery." Biorefinery framework implements the concepts of novel eco-technologies and eco-efficient processes for the sustainable production of energy and value-added biomolecules. The utilization of microbial resources for the production of various value-added products has been documented in the literatures. However, the appointment of these microbial resources in integrated resource management requires a better understanding of their status. The main of aim of this review is to provide an overview on the defined positioning and overall contribution of the microbial resources, i.e., algae, fungi and bacteria, for various bioprocesses and generation of multiple products from a single biorefinery. By utilizing waste material as a feedstock, biofuels can be generated by microalgae while sequestering environmental carbon and producing value added compounds as by-products. In parallel, fungal biorefineries are prolific producers of lignocellulose degrading enzymes along with pharmaceutically important novel products. Conversely, bacterial biorefineries emerge as a preferred platform for the transformation of standard cells into proficient bio-factories, developing chassis and turbo cells for enhanced target compound production. This comprehensive review is poised to offer an intricate exploration of the current trends, obstacles, and prospective pathways of microbial biorefineries, for the development of future biorefineries.
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Affiliation(s)
- Suchitra Gaur
- Sustainable Agriculture Program, The Energy and Resources Institute, TERI-Gram, Gurugram, 122001, Haryana, India
| | - Mehak Kaur
- Sustainable Agriculture Program, The Energy and Resources Institute, TERI-Gram, Gurugram, 122001, Haryana, India
| | - Rishu Kalra
- Sustainable Agriculture Program, The Energy and Resources Institute, TERI-Gram, Gurugram, 122001, Haryana, India
| | - Eldon R. Rene
- Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft Institute for Water Education, Westvest 7, Delft, 2601DA, the Netherlands
| | - Mayurika Goel
- Sustainable Agriculture Program, The Energy and Resources Institute, TERI-Gram, Gurugram, 122001, Haryana, India
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Peng Q, Lin L, Tu Q, Wang X, Zhou Y, Chen J, Jiao N, Zhou J. Unraveling the roles of coastal bacterial consortia in degradation of various lignocellulosic substrates. mSystems 2023; 8:e0128322. [PMID: 37417747 PMCID: PMC10469889 DOI: 10.1128/msystems.01283-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 05/12/2023] [Indexed: 07/08/2023] Open
Abstract
Lignocellulose, as the most abundant natural organic carbon on earth, plays a key role in regulating the global carbon cycle, but there have been only few studies in marine ecosystems. Little information is available about the extant lignin-degrading bacteria in coastal wetlands, limiting our understanding of their ecological roles and traits in lignocellulose degradation. We utilized in situ lignocellulose enrichment experiments coupled with 16S rRNA amplicon and shotgun metagenomics sequencing to identify and characterize bacterial consortia attributed to different lignin/lignocellulosic substrates in the southern-east intertidal zone of East China Sea. We found the consortia enriched on woody lignocellulose showed higher diversity than those on herbaceous substrate. This also revealed substrate-dependent taxonomic groups. A time-dissimilarity pattern with increased alpha diversity over time was observed. Additionally, this study identified a comprehensive set of genes associated with lignin degradation potential, containing 23 gene families involved in lignin depolymerization, and 371 gene families involved in aerobic/anaerobic lignin-derived aromatic compound pathways, challenging the traditional view of lignin recalcitrance within marine ecosystems. In contrast to similar cellulase genes among the lignocellulose substrates, significantly different ligninolytic gene groups were observed between consortia under woody and herbaceous substrates. Importantly, we not only observed synergistic degradation of lignin and hemi-/cellulose, but also pinpointed the potential biological actors at the levels of taxa and functional genes, which indicated that the alternation of aerobic and anaerobic catabolism could facilitate lignocellulose degradation. Our study advances the understanding of coastal bacterial community assembly and metabolic potential for lignocellulose substrates. IMPORTANCE It is essential for the global carbon cycle that microorganisms drive lignocellulose transformation, due to its high abundance. Previous studies were primarily constrained to terrestrial ecosystems, with limited information about the role of microbes in marine ecosystems. Through in situ lignocellulose enrichment experiment coupled with high-throughput sequencing, this study demonstrated different impacts that substrates and exposure times had on long-term bacterial community assembly and pinpointed comprehensive, yet versatile, potential decomposers at the levels of taxa and functional genes in response to different lignocellulose substrates. Moreover, the links between ligninolytic functional traits and taxonomic groups of substrate-specific populations were revealed. It showed that the synergistic effect of lignin and hemi-/cellulose degradation could enhance lignocellulose degradation under alternation of aerobic and anaerobic conditions. This study provides valuable taxonomic and genomic insights into coastal bacterial consortia for lignocellulose degradation.
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Affiliation(s)
- Qiannan Peng
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Lu Lin
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Qichao Tu
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Xiaopeng Wang
- Key Laboratory of Applied Marine Biotechnology, Ministry of Education, Ningbo University, Ningbo, China
| | - Yueyue Zhou
- Key Laboratory of Applied Marine Biotechnology, Ministry of Education, Ningbo University, Ningbo, China
| | - Jiyu Chen
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Nianzhi Jiao
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
- Joint Lab for Ocean Research and Education at Shandong University, Xiamen University and Dalhousie University, Qingdao, China
| | - Jizhong Zhou
- Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA
- School of Civil Engineering and Environmental Sciences, University of Oklahoma, Norman, Oklahoma, USA
- School of Computer Science, University of Oklahoma, Norman, Oklahoma, USA
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Hocq R, Bottone S, Gautier A, Pflügl S. A fluorescent reporter system for anaerobic thermophiles. Front Bioeng Biotechnol 2023; 11:1226889. [PMID: 37476481 PMCID: PMC10355840 DOI: 10.3389/fbioe.2023.1226889] [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: 05/22/2023] [Accepted: 06/23/2023] [Indexed: 07/22/2023] Open
Abstract
Owing to their inherent capacity to make invisible biological processes visible and quantifiable, fluorescent reporter systems have numerous applications in biotechnology. For classical fluorescent protein systems (i.e., GFP and derivatives), chromophore maturation is O2-dependent, restricting their applications to aerobic organisms. In this work, we pioneered the use of the oxygen-independent system FAST (Fluorescence Activating and absorption Shifting tag) in the thermophilic anaerobe Thermoanaerobacter kivui. We developed a modular cloning system that was used to easily clone a library of FAST expression cassettes in an E. coli-Thermoanaerobacter shuttle plasmid. FAST-mediated fluorescence was then assessed in vivo in T. kivui, and we observed bright green and red fluorescence for cells grown at 55°C. Next, we took advantage of this functional reporter system to characterize a set of homologous and heterologous promoters by quantifying gene expression, expanding the T. kivui genetic toolbox. Low fluorescence at 66°C (Topt for T. kivui) was subsequently investigated at the single-cell level using flow cytometry and attributed to plasmid instability at higher temperatures. Adaptive laboratory evolution circumvented this issue and drastically enhanced fluorescence at 66°C. Whole plasmid sequencing revealed the evolved strain carried functional plasmids truncated at the Gram-positive origin of replication, that could however not be linked to the increased fluorescence displayed by the evolved strain. Collectively, our work demonstrates the applicability of the FAST fluorescent reporter systems to T. kivui, paving the way for further applications in thermophilic anaerobes.
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Affiliation(s)
- Rémi Hocq
- Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Vienna, Austria
- Christian Doppler Laboratory for Optimized Expression of Carbohydrate-Active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Vienna, Austria
| | - Sara Bottone
- Laboratoire des Biomolécules (LBM), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, École Normale Supérieure, Université PSL, Paris, France
- Institut Universitaire de France, Paris, France
| | - Arnaud Gautier
- Laboratoire des Biomolécules (LBM), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, École Normale Supérieure, Université PSL, Paris, France
- Institut Universitaire de France, Paris, France
| | - Stefan Pflügl
- Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Vienna, Austria
- Christian Doppler Laboratory for Optimized Expression of Carbohydrate-Active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Vienna, Austria
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Le Y, Sun J. CRISPR/Cas genome editing systems in thermophiles: Current status, associated challenges, and future perspectives. ADVANCES IN APPLIED MICROBIOLOGY 2022; 118:1-30. [PMID: 35461662 DOI: 10.1016/bs.aambs.2022.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Thermophiles, offering an attractive and unique platform for a broad range of applications in biofuels and environment protections, have received a significant attention and growing interest from academy and industry. However, the exploration and exploitation of thermophilic organisms have been hampered by the lack of a powerful genome manipulation tool to improve production efficiency. At current, the clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/CRISPR associated (Cas) system has been successfully exploited as a competent, simplistic, and powerful tool for genome engineering both in eukaryotes and prokaryotes. Indeed, with the significant efforts made in recent years, some thermostable Cas9 proteins have been well identified and characterized and further, some thermostable Cas9-based editing tools have been successfully established in some representative obligate thermophiles. In this regard, we reviewed the current status and its progress in CRISPR/Cas-based genome editing system towards a variety of thermophilic organisms. Despite the potentials of these progresses, multiple factors/barriers still have to be overcome and optimized for improving its editing efficiency in thermophiles. Some insights into the roles of thermostable CRISPR/Cas technologies for the metabolic engineering of thermophiles as a thermophilic microbial cell factory were also fully analyzed and discussed.
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Affiliation(s)
- Yilin Le
- Biofuels institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China.
| | - Jianzhong Sun
- Biofuels institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China.
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Abstract
Synthetic biology applications rely on a well-characterized set of microbial strains, with an established toolbox of molecular biology methods for their genetic manipulation. Since there are no thermophiles with such attributes, most biotechnology and synthetic biology studies use organisms that grow in the mesophilic temperature range. As a result, thermophiles, a heterogenous group of microbes that thrive at high (>50 °C) temperatures, are largely overlooked, with respect to their biotechnological potential, even though they share several favorable traits. Thermophilic bacteria tend to grow at higher rates compared to their mesophilic counterparts, while their growth has lower cooling requirements and is less prone to contamination. Over the last few years, there has been renewed interest in developing tools and methods for thermophile bioengineering. In this perspective, we explain why it is a good idea to invest time and effort into developing a thermophilic synthetic biology direction, which is the state of the art, and why we think that the implementation of a thermophilic synthetic biology platform—a thermochassis—will take synthetic biology to the extremes.
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Lin L. Bottom-up synthetic ecology study of microbial consortia to enhance lignocellulose bioconversion. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:14. [PMID: 35418100 PMCID: PMC8822760 DOI: 10.1186/s13068-022-02113-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 01/28/2022] [Indexed: 01/21/2023]
Abstract
Lignocellulose is the most abundant organic carbon polymer on the earth. Its decomposition and conversion greatly impact the global carbon cycle. Furthermore, it provides feedstock for sustainable fuel and other value-added products. However, it continues to be underutilized, due to its highly recalcitrant and heterogeneric structure. Microorganisms, which have evolved versatile pathways to convert lignocellulose, undoubtedly are at the heart of lignocellulose conversion. Numerous studies that have reported successful metabolic engineering of individual strains to improve biological lignin valorization. Meanwhile, the bottleneck of single strain modification is becoming increasingly urgent in the conversion of complex substrates. Alternatively, increased attention has been paid to microbial consortia, as they show advantages over pure cultures, e.g., high efficiency and robustness. Here, we first review recent developments in microbial communities for lignocellulose bioconversion. Furthermore, the emerging area of synthetic ecology, which is an integration of synthetic biology, ecology, and computational biology, provides an opportunity for the bottom-up construction of microbial consortia. Then, we review different modes of microbial interaction and their molecular mechanisms, and discuss considerations of how to employ these interactions to construct synthetic consortia via synthetic ecology, as well as highlight emerging trends in engineering microbial communities for lignocellulose bioconversion.
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Affiliation(s)
- Lu Lin
- Institute of Marine Science and Technology, Shandong University, Qingdao, 266237, Shandong, China.
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Chacuttayapong W, Enoki H, Nabetani Y, Matsui M, Oguchi T, Motohashi R. Transformation of Jatropha curcas L. for production of larger seeds and increased amount of biodiesel. PLANT BIOTECHNOLOGY (TOKYO, JAPAN) 2021; 38:247-256. [PMID: 34393603 PMCID: PMC8329273 DOI: 10.5511/plantbiotechnology.21.0422b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 04/22/2021] [Indexed: 06/13/2023]
Abstract
The development of green energy is important to mitigate global warming. Jatropha (Jatropha curcas L.) is a promising candidate for the production of alternative biofuel, which could reduce the burden on the Earth's resources. Jatropha seeds contain a large quantity of lipids that can be used to produce biofuel, and the rest of the plant has many other uses. Currently, techniques for plant genetic transformation are extensively employed to study, create, and improve the specific characteristics of the target plant. Successful transformation involves the alteration of plants and their genetic materials. The aim of this study was to generate Jatropha plants that can support biofuel production by increasing their seed size using genes found via the rice FOX-hunting system. The present study improved previous protocols, enabling the production of transgenic Jatropha in two steps: the first step involved using auxins and dark incubation to promote root formation in excised shoots and the second step involved delaying the timing of antibiotic selection in the cultivation medium. Transgenic plants were subjected to PCR analysis; the transferred gene expression was confirmed via RT-PCR and the ploidy level was investigated. The results suggest that the genes associated with larger seed size in Arabidopsis thaliana, which were found using the rice FOX-hunting system, produce larger seeds in Jatropha.
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Affiliation(s)
- Wiluk Chacuttayapong
- Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, Shizuoka 422-8529, Japan
| | - Harumi Enoki
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, Shizuoka 422-8529, Japan
| | - Yusei Nabetani
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, Shizuoka 422-8529, Japan
| | - Minami Matsui
- Synthetic Genomics Research group, RIKEN, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Taichi Oguchi
- Tsukuba Plant‐Innovation Research Center, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8572, Japan
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8572, Japan
| | - Reiko Motohashi
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, Shizuoka 422-8529, Japan
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, Shizuoka 422-8529, Japan
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Gallo G, Puopolo R, Carbonaro M, Maresca E, Fiorentino G. Extremophiles, a Nifty Tool to Face Environmental Pollution: From Exploitation of Metabolism to Genome Engineering. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:5228. [PMID: 34069056 PMCID: PMC8157027 DOI: 10.3390/ijerph18105228] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/06/2021] [Accepted: 05/09/2021] [Indexed: 12/13/2022]
Abstract
Extremophiles are microorganisms that populate habitats considered inhospitable from an anthropocentric point of view and are able to tolerate harsh conditions such as high temperatures, extreme pHs, high concentrations of salts, toxic organic substances, and/or heavy metals. These microorganisms have been broadly studied in the last 30 years and represent precious sources of biomolecules and bioprocesses for many biotechnological applications; in this context, scientific efforts have been focused on the employment of extremophilic microbes and their metabolic pathways to develop biomonitoring and bioremediation strategies to face environmental pollution, as well as to improve biorefineries for the conversion of biomasses into various chemical compounds. This review gives an overview on the peculiar metabolic features of certain extremophilic microorganisms, with a main focus on thermophiles, which make them attractive for biotechnological applications in the field of environmental remediation; moreover, it sheds light on updated genetic systems (also those based on the CRISPR-Cas tool), which expand the potentialities of these microorganisms to be genetically manipulated for various biotechnological purposes.
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Affiliation(s)
- Giovanni Gallo
- Department of Biology, University of Naples Federico II, Via Cinthia 21, 80126 Napoli, Italy; (G.G.); (R.P.); (M.C.); (E.M.)
- Consiglio Nazionale delle Ricerche CNR, Institute of Polymers, Composites and Biomaterials (IPCB), Via Campi Flegrei, 34, 80078 Pozzuoli, Italy
| | - Rosanna Puopolo
- Department of Biology, University of Naples Federico II, Via Cinthia 21, 80126 Napoli, Italy; (G.G.); (R.P.); (M.C.); (E.M.)
| | - Miriam Carbonaro
- Department of Biology, University of Naples Federico II, Via Cinthia 21, 80126 Napoli, Italy; (G.G.); (R.P.); (M.C.); (E.M.)
| | - Emanuela Maresca
- Department of Biology, University of Naples Federico II, Via Cinthia 21, 80126 Napoli, Italy; (G.G.); (R.P.); (M.C.); (E.M.)
| | - Gabriella Fiorentino
- Department of Biology, University of Naples Federico II, Via Cinthia 21, 80126 Napoli, Italy; (G.G.); (R.P.); (M.C.); (E.M.)
- Consiglio Nazionale delle Ricerche CNR, Institute of Polymers, Composites and Biomaterials (IPCB), Via Campi Flegrei, 34, 80078 Pozzuoli, Italy
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Genome Editing of the Anaerobic Thermophile Thermoanaerobacter ethanolicus Using Thermostable Cas9. Appl Environ Microbiol 2020; 87:AEM.01773-20. [PMID: 33067194 DOI: 10.1128/aem.01773-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/04/2020] [Indexed: 12/11/2022] Open
Abstract
Thermoanaerobacter ethanolicus can produce acetate, lactate, hydrogen, and ethanol from sugars resulting from plant carbohydrate polymer degradation at temperatures above 65°C. T. ethanolicus is a promising candidate for thermophilic ethanol fermentations due to the utilization of both pentose and hexose. Although an ethanol balance model in T. ethanolicus has been developed, only a few physiological or biochemical experiments regarding the function of important enzymes in ethanol formation have been carried out. To address this issue, we developed a thermostable Cas9-based system for genome editing of T. ethanolicus As a proof of principle, three genes, including the thymidine kinase gene (tdk), acetaldehyde-alcohol dehydrogenase gene (adhE), and redox sensing protein gene (rsp), were chosen as editing targets, and these genes were edited successfully. As a genetic tool, we tested the gene knockout and a small DNA fragment knock-in. After optimization of the transformation strategies, 77% genome-editing efficiency was observed. Furthermore, our in vivo results revealed that redox sensing protein (RSP) plays a more important role in regulation of energy metabolism, including hydrogen production and ethanol formation. The genetic system provides us with an effective strategy to identify genes involved in biosynthesis and energy metabolism.IMPORTANCE Interest in thermophilic microorganisms as emerging metabolic engineering platforms to produce biofuels and chemicals has surged. Thermophilic microbes for biofuels have attracted great attention, due to their tolerance of high temperature and wide range of substrate utilization. On the basis of the biochemical experiments of previous investigation, the formation of ethanol was controlled via transcriptional regulation and influenced by the relevant properties of specific enzymes in T. ethanolicus Thus, there is an urgent need to understand the physiological function of these key enzymes, which requires genetic manipulations such as deletion or overexpression of genes encoding putative key enzymes. Here, we developed a thermostable Cas9-based engineering tool for gene editing in T. ethanolicus The thermostable Cas9-based genome-editing tool may further be applied to metabolically engineer T. ethanolicus to produce biofuels. This genetic system represents an important expansion of the genetic tool box of anaerobic thermophile T. ethanolicus strains.
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Zhu D, Adebisi WA, Ahmad F, Sethupathy S, Danso B, Sun J. Recent Development of Extremophilic Bacteria and Their Application in Biorefinery. Front Bioeng Biotechnol 2020; 8:483. [PMID: 32596215 PMCID: PMC7303364 DOI: 10.3389/fbioe.2020.00483] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/27/2020] [Indexed: 12/22/2022] Open
Abstract
The biorefining technology for biofuels and chemicals from lignocellulosic biomass has made great progress in the world. However, mobilization of laboratory research toward industrial setup needs to meet a series of criteria, including the selection of appropriate pretreatment technology, breakthrough in enzyme screening, pathway optimization, and production technology, etc. Extremophiles play an important role in biorefinery by providing novel metabolic pathways and catalytically stable/robust enzymes that are able to act as biocatalysts under harsh industrial conditions on their own. This review summarizes the potential application of thermophilic, psychrophilic alkaliphilic, acidophilic, and halophilic bacteria and extremozymes in the pretreatment, saccharification, fermentation, and lignin valorization process. Besides, the latest studies on the engineering bacteria of extremophiles using metabolic engineering and synthetic biology technologies for high-efficiency biofuel production are also introduced. Furthermore, this review explores the comprehensive application potential of extremophiles and extremozymes in biorefinery, which is partly due to their specificity and efficiency, and points out the necessity of accelerating the commercialization of extremozymes.
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Affiliation(s)
- Daochen Zhu
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Wasiu Adewale Adebisi
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
| | - Fiaz Ahmad
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
| | - Sivasamy Sethupathy
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
| | - Blessing Danso
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
| | - Jianzhong Sun
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
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Abstract
Thermophilic microbes are an attractive bioproduction platform due to their inherently lower contamination risk and their ability to perform thermostable enzymatic processes which may be required for biomass processing and other industrial applications. The engineering of microbes for industrial scale processes requires a suite of genetic engineering tools to optimize existing biological systems as well as to design and incorporate new metabolic pathways within strains. Yet, such tools are often lacking and/or inadequate for novel microbes, especially thermophiles. This chapter focuses on genetic tool development and engineering strategies, in addition to challenges, for thermophilic microbes. We provide detailed instructions and techniques for tool development for an anaerobic thermophile, Caldanaerobacter subterraneus subsp. tengcongensis, including culturing, plasmid construction, transformation, and selection. This establishes a foundation for advanced genetic tool development necessary for the metabolic engineering of this microbe and potentially other thermophilic organisms.
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Sahoo K, Sahoo RK, Gaur M, Subudhi E. Cellulolytic thermophilic microorganisms in white biotechnology: a review. Folia Microbiol (Praha) 2019; 65:25-43. [DOI: 10.1007/s12223-019-00710-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 04/15/2019] [Indexed: 10/26/2022]
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Improvement of stress tolerance and riboflavin production of Bacillus subtilis by introduction of heat shock proteins from thermophilic bacillus strains. Appl Microbiol Biotechnol 2019; 103:4455-4465. [PMID: 30968162 DOI: 10.1007/s00253-019-09788-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/12/2019] [Accepted: 03/19/2019] [Indexed: 10/27/2022]
Abstract
In this study, stress tolerance devices consisting of heat shock protein (HSP) genes from thermophiles Geobacillus and Parageobacillus were introduced into riboflavin-producing strain Bacillus subtilis 446 to improve its stress tolerance and riboflavin production. The 12 HSP homologs were selected from 28 Geobacillus and Parageobacillus genomes according to their sequence clustering and phylogenetically analysis which represents the diversity of HSPs from thermophilic bacillus. The 12 HSP genes and 2 combinations of them (PtdnaK-PtdnaJ-PtgrpE and PtgroeL-PtgroeS) were heterologously expressed in B. subtilis 446 under the control of a strong constitutive promoter P43. Most of the 14 engineered strains showed increased cell density at 44 to 48 °C and less cell death at 50 °C compared with the control strains. Among them, strains B.s446-HSP20-3, B.s446-HSP20-2, and B.s446-PtDnaK-PtDnaJ-PtGrpE increased their cell densities over 25% at 44 to 48 °C. They also showed 5-, 4-, and 4-fold improved cell survivals after the 10-h heat shock treatment at 50 °C, respectively. These three strains also showed reduced cell death rates under osmotic stress of 10% NaCl, indicating that the introduction of HSPs improved not only the heat tolerance of B. subtilis 446 but also its osmotic tolerance. Fermentation of these three strains at higher temperatures of 39 and 43 °C showed 23-66% improved riboflavin titers, as well as 24-h shortened fermentation period. These results indicated that implanting HSPs from thermophiles to B. subtilis 446 would be an efficient approach to improve its stress tolerance and riboflavin production.
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Extremophilic exopolysaccharides: A review and new perspectives on engineering strategies and applications. Carbohydr Polym 2019; 205:8-26. [DOI: 10.1016/j.carbpol.2018.10.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/20/2018] [Accepted: 10/04/2018] [Indexed: 12/16/2022]
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Dong Z, Chen X, Cai K, Shen P, Tian K, Jin P, Liu X, Wang Z. Overexpression of the Bacillus licheniformis GroES enhances thermotolerance of Bacillus subtilis WB600. BIOTECHNOL BIOTEC EQ 2018. [DOI: 10.1080/13102818.2018.1517029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Affiliation(s)
- Zixing Dong
- Department of Biochemical Engineering, College of Chemical Engineering and Materials Science, Tianjin University of Science & Technology, Tianjin, PR China
| | - Xiaoling Chen
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, PR China
| | - Ke Cai
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, PR China
| | - Peili Shen
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, PR China
| | - Kangming Tian
- Department of Biochemical Engineering, College of Chemical Engineering and Materials Science, Tianjin University of Science & Technology, Tianjin, PR China
| | - Peng Jin
- Department of Biochemical Engineering, College of Chemical Engineering and Materials Science, Tianjin University of Science & Technology, Tianjin, PR China
| | - Xiaoguang Liu
- Department of Biochemical Engineering, College of Chemical Engineering and Materials Science, Tianjin University of Science & Technology, Tianjin, PR China
| | - Zhengxiang Wang
- Department of Biochemical Engineering, College of Chemical Engineering and Materials Science, Tianjin University of Science & Technology, Tianjin, PR China
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, PR China
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16
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Simultaneous Improvements of Pseudomonas Cell Growth and Polyhydroxyalkanoate Production from a Lignin Derivative for Lignin-Consolidated Bioprocessing. Appl Environ Microbiol 2018; 84:AEM.01469-18. [PMID: 30030226 DOI: 10.1128/aem.01469-18] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 07/05/2018] [Indexed: 11/20/2022] Open
Abstract
Cell growth and polyhydroxyalkanoate (PHA) biosynthesis are two key traits in PHA production from lignin or its derivatives. However, the links between them remain poorly understood. Here, the transcription levels of key genes involved in PHA biosynthesis were tracked in Pseudomonas putida strain A514 grown on vanillic acid as the sole carbon source under different levels of nutrient availability. First, enoyl-coenzyme A (CoA) hydratase (encoded by phaJ4) is stress induced and likely to contribute to PHA synthesis under nitrogen starvation conditions. Second, much higher expression levels of 3-hydroxyacyl-acyl carrier protein (ACP) thioesterase (encoded by phaG) and long-chain fatty acid-CoA ligase (encoded by alkK) under both high and low nitrogen (N) led to the hypothesis that they likely not only have a role in PHA biosynthesis but are also essential to cell growth. Third, 40 mg/liter PHA was synthesized by strain AphaJ4C1 (overexpression of phaJ4 and phaC1 in strain A514) under low-N conditions, in contrast to 23 mg/liter PHA synthesized under high-N conditions. Under high-N conditions, strain AalkKphaGC1 (overexpression of phaG, alkK, and phaC1 in A514) produced 90 mg/liter PHA with a cell dry weight of 667 mg/liter, experimentally validating our hypothesis. Finally, further enhancement in cell growth (714 mg/liter) and PHA titer (246 mg/liter) was achieved in strain Axyl_alkKphaGC1 via transcription level optimization, which was regulated by an inducible strong promoter with its regulator, XylR-PxylA, from the xylose catabolic gene cluster of the A514 genome. This study reveals genetic features of genes involved in PHA synthesis from a lignin derivative and provides a novel strategy for rational engineering of these two traits, laying the foundation for lignin-consolidated bioprocessing.IMPORTANCE With the recent advances in processing carbohydrates in lignocellulosics for bioproducts, almost all biological conversion platforms result in the formation of a significant amount of lignin by-products, representing the second most abundant feedstock on earth. However, this resource is greatly underutilized due to its heterogeneity and recalcitrant chemical structure. Thus, exploiting lignin valorization routes would achieve the complete utilization of lignocellulosic biomass and improve cost-effectiveness. The culture conditions that encourage cell growth and polyhydroxyalkanoate (PHA) accumulation are different. Such an inconsistency represents a major hurdle in lignin-to-PHA bioconversion. In this study, we traced and compared transcription levels of key genes involved in PHA biosynthesis pathways in Pseudomonas putida A514 under different nitrogen concentrations to unveil the unusual features of PHA synthesis. Furthermore, an inducible strong promoter was identified. Thus, the molecular features and new genetic tools reveal a strategy to coenhance PHA production and cell growth from a lignin derivative.
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Drejer EB, Hakvåg S, Irla M, Brautaset T. Genetic Tools and Techniques for Recombinant Expression in Thermophilic Bacillaceae. Microorganisms 2018; 6:microorganisms6020042. [PMID: 29748477 PMCID: PMC6027425 DOI: 10.3390/microorganisms6020042] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 05/02/2018] [Accepted: 05/03/2018] [Indexed: 01/17/2023] Open
Abstract
Although Escherichia coli and Bacillus subtilis are the most prominent bacterial hosts for recombinant protein production by far, additional species are being explored as alternatives for production of difficult-to-express proteins. In particular, for thermostable proteins, there is a need for hosts able to properly synthesize, fold, and excrete these in high yields, and thermophilic Bacillaceae represent one potentially interesting group of microorganisms for such purposes. A number of thermophilic Bacillaceae including B.methanolicus, B.coagulans, B.smithii, B.licheniformis, Geobacillus thermoglucosidasius, G. kaustophilus, and G. stearothermophilus are investigated concerning physiology, genomics, genetic tools, and technologies, altogether paving the way for their utilization as hosts for recombinant production of thermostable and other difficult-to-express proteins. Moreover, recent successful deployments of CRISPR/Cas9 in several of these species have accelerated the progress in their metabolic engineering, which should increase their attractiveness for future industrial-scale production of proteins. This review describes the biology of thermophilic Bacillaceae and in particular focuses on genetic tools and methods enabling use of these organisms as hosts for recombinant protein production.
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Affiliation(s)
- Eivind B Drejer
- Department of Biotechnology and Food Science, NTNU: Norwegian University of Science and Technology, 7491 Trondheim, Norway.
| | - Sigrid Hakvåg
- Department of Biotechnology and Food Science, NTNU: Norwegian University of Science and Technology, 7491 Trondheim, Norway.
| | - Marta Irla
- Department of Biotechnology and Food Science, NTNU: Norwegian University of Science and Technology, 7491 Trondheim, Norway.
| | - Trygve Brautaset
- Department of Biotechnology and Food Science, NTNU: Norwegian University of Science and Technology, 7491 Trondheim, Norway.
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18
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de Camargo BR, Claassens NJ, Quirino BF, Noronha EF, Kengen SW. Heterologous expression and characterization of a putative glycoside hydrolase family 43 arabinofuranosidase from Clostridium thermocellum B8. Enzyme Microb Technol 2018; 109:74-83. [DOI: 10.1016/j.enzmictec.2017.09.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 09/28/2017] [Accepted: 09/30/2017] [Indexed: 11/30/2022]
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19
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Cordova LT, Cipolla RM, Swarup A, Long CP, Antoniewicz MR. 13C metabolic flux analysis of three divergent extremely thermophilic bacteria: Geobacillus sp. LC300, Thermus thermophilus HB8, and Rhodothermus marinus DSM 4252. Metab Eng 2017; 44:182-190. [PMID: 29037779 PMCID: PMC5845442 DOI: 10.1016/j.ymben.2017.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/09/2017] [Accepted: 10/11/2017] [Indexed: 01/26/2023]
Abstract
Thermophilic organisms are being increasingly investigated and applied in metabolic engineering and biotechnology. The distinct metabolic and physiological characteristics of thermophiles, including broad substrate range and high uptake rates, coupled with recent advances in genetic tool development, present unique opportunities for strain engineering. However, poor understanding of the cellular physiology and metabolism of thermophiles has limited the application of systems biology and metabolic engineering tools to these organisms. To address this concern, we applied high resolution 13C metabolic flux analysis to quantify fluxes for three divergent extremely thermophilic bacteria from separate phyla: Geobacillus sp. LC300, Thermus thermophilus HB8, and Rhodothermus marinus DSM 4252. We performed 18 parallel labeling experiments, using all singly labeled glucose tracers for each strain, reconstructed and validated metabolic network models, measured biomass composition, and quantified precise metabolic fluxes for each organism. In the process, we resolved many uncertainties regarding gaps in pathway reconstructions and elucidated how these organisms maintain redox balance and generate energy. Overall, we found that the metabolisms of the three thermophiles were highly distinct, suggesting that adaptation to growth at high temperatures did not favor any particular set of metabolic pathways. All three strains relied heavily on glycolysis and TCA cycle to generate key cellular precursors and cofactors. None of the investigated organisms utilized the Entner-Doudoroff pathway and only one strain had an active oxidative pentose phosphate pathway. Taken together, the results from this study provide a solid foundation for future model building and engineering efforts with these and related thermophiles.
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Affiliation(s)
- Lauren T Cordova
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Robert M Cipolla
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Adti Swarup
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Christopher P Long
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Maciek R Antoniewicz
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA.
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20
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Figueiredo AS, Kouril T, Esser D, Haferkamp P, Wieloch P, Schomburg D, Ruoff P, Siebers B, Schaber J. Systems biology of the modified branched Entner-Doudoroff pathway in Sulfolobus solfataricus. PLoS One 2017; 12:e0180331. [PMID: 28692669 PMCID: PMC5503249 DOI: 10.1371/journal.pone.0180331] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 06/14/2017] [Indexed: 01/31/2023] Open
Abstract
Sulfolobus solfataricus is a thermoacidophilic Archaeon that thrives in terrestrial hot springs (solfatares) with optimal growth at 80°C and pH 2–4. It catabolizes specific carbon sources, such as D-glucose, to pyruvate via the modified Entner-Doudoroff (ED) pathway. This pathway has two parallel branches, the semi-phosphorylative and the non-phosphorylative. However, the strategy of S.solfataricus to endure in such an extreme environment in terms of robustness and adaptation is not yet completely understood. Here, we present the first dynamic mathematical model of the ED pathway parameterized with quantitative experimental data. These data consist of enzyme activities of the branched pathway at 70°C and 80°C and of metabolomics data at the same temperatures for the wild type and for a metabolic engineered knockout of the semi-phosphorylative branch. We use the validated model to address two questions: 1. Is this system more robust to perturbations at its optimal growth temperature? 2. Is the ED robust to deletion and perturbations? We employed a systems biology approach to answer these questions and to gain further knowledge on the emergent properties of this biological system. Specifically, we applied deterministic and stochastic approaches to study the sensitivity and robustness of the system, respectively. The mathematical model we present here, shows that: 1. Steady state metabolite concentrations of the ED pathway are consistently more robust to stochastic internal perturbations at 80°C than at 70°C; 2. These metabolite concentrations are highly robust when faced with the knockout of either branch. Connected with this observation, these two branches show different properties at the level of metabolite production and flux control. These new results reveal how enzyme kinetics and metabolomics synergizes with mathematical modelling to unveil new systemic properties of the ED pathway in S.solfataricus in terms of its adaptation and robustness.
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Affiliation(s)
- Ana Sofia Figueiredo
- Institute for Experimental Internal Medicine, Medical Faculty Otto von Guericke University, Magdeburg, Germany
- * E-mail:
| | - Theresa Kouril
- Molecular Enzyme Technology and Biochemistry (MEB), Biofilm Centre, Centre for Water and Environmental Research (CWE), Faculty of Chemistry, University of Duisburg-Essen, Essen, Germany
| | - Dominik Esser
- Molecular Enzyme Technology and Biochemistry (MEB), Biofilm Centre, Centre for Water and Environmental Research (CWE), Faculty of Chemistry, University of Duisburg-Essen, Essen, Germany
| | - Patrick Haferkamp
- Molecular Enzyme Technology and Biochemistry (MEB), Biofilm Centre, Centre for Water and Environmental Research (CWE), Faculty of Chemistry, University of Duisburg-Essen, Essen, Germany
| | - Patricia Wieloch
- Bioinformatics & Biochemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Dietmar Schomburg
- Bioinformatics & Biochemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Peter Ruoff
- Center for Organelle Research (CORE), University of Stavanger, Stavanger, Norway
| | - Bettina Siebers
- Molecular Enzyme Technology and Biochemistry (MEB), Biofilm Centre, Centre for Water and Environmental Research (CWE), Faculty of Chemistry, University of Duisburg-Essen, Essen, Germany
| | - Jörg Schaber
- Institute for Experimental Internal Medicine, Medical Faculty Otto von Guericke University, Magdeburg, Germany
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21
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Mougiakos I, Bosma EF, Weenink K, Vossen E, Goijvaerts K, van der Oost J, van Kranenburg R. Efficient Genome Editing of a Facultative Thermophile Using Mesophilic spCas9. ACS Synth Biol 2017; 6:849-861. [PMID: 28146359 PMCID: PMC5440800 DOI: 10.1021/acssynbio.6b00339] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Well-developed genetic tools for thermophilic microorganisms are scarce, despite their industrial and scientific relevance. Whereas highly efficient CRISPR/Cas9-based genome editing is on the rise in prokaryotes, it has never been employed in a thermophile. Here, we apply Streptococcus pyogenes Cas9 (spCas9)-based genome editing to a moderate thermophile, i.e., Bacillus smithii, including a gene deletion, gene knockout via insertion of premature stop codons, and gene insertion. We show that spCas9 is inactive in vivo above 42 °C, and we employ the wide temperature growth range of B. smithii as an induction system for spCas9 expression. Homologous recombination with plasmid-borne editing templates is performed at 45-55 °C, when spCas9 is inactive. Subsequent transfer to 37 °C allows for counterselection through production of active spCas9, which introduces lethal double-stranded DNA breaks to the nonedited cells. The developed method takes 4 days with 90, 100, and 20% efficiencies for gene deletion, knockout, and insertion, respectively. The major advantage of our system is the limited requirement for genetic parts: only one plasmid, one selectable marker, and a promoter are needed, and the promoter does not need to be inducible or well-characterized. Hence, it can be easily applied for genome editing purposes in both mesophilic and thermophilic nonmodel organisms with a limited genetic toolbox and ability to grow at, or tolerate, temperatures of 37 and at or above 42 °C.
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Affiliation(s)
- Ioannis Mougiakos
- Laboratory
of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Elleke F. Bosma
- Laboratory
of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Koen Weenink
- Laboratory
of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Eric Vossen
- Laboratory
of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Kirsten Goijvaerts
- Laboratory
of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - John van der Oost
- Laboratory
of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Richard van Kranenburg
- Laboratory
of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Corbion, Arkelsedijk
46, 4206 AC Gorinchem, The Netherlands
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22
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Bosma EF, Forster J, Nielsen AT. Lactobacilli and pediococci as versatile cell factories - Evaluation of strain properties and genetic tools. Biotechnol Adv 2017; 35:419-442. [PMID: 28396124 DOI: 10.1016/j.biotechadv.2017.04.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/29/2017] [Accepted: 04/03/2017] [Indexed: 12/14/2022]
Abstract
This review discusses opportunities and bottlenecks for cell factory development of Lactic Acid Bacteria (LAB), with an emphasis on lactobacilli and pediococci, their metabolism and genetic tools. In order to enable economically feasible bio-based production of chemicals and fuels in a biorefinery, the choice of product, substrate and production organism is important. Currently, the most frequently used production hosts include Escherichia coli and Saccharomyces cerevisiae, but promising examples are available of alternative hosts such as LAB. Particularly lactobacilli and pediococci can offer benefits such as thermotolerance, an extended substrate range and increased tolerance to stresses such as low pH or high alcohol concentrations. This review will evaluate the properties and metabolism of these organisms, and provide an overview of their current biotechnological applications and metabolic engineering. We substantiate the review by including experimental results from screening various lactobacilli and pediococci for transformability, growth temperature range and ability to grow under biotechnologically relevant stress conditions. Since availability of efficient genetic engineering tools is a crucial prerequisite for industrial strain development, genetic tool development is extensively discussed. A range of genetic tools exist for Lactococcus lactis, but for other species of LAB like lactobacilli and pediococci such tools are less well developed. Whereas lactobacilli and pediococci have a long history of use in food and beverage fermentation, their use as platform organisms for production purposes is rather new. By harnessing their properties such as thermotolerance and stress resistance, and by using emerging high-throughput genetic tools, these organisms are very promising as versatile cell factories for biorefinery applications.
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Affiliation(s)
- Elleke F Bosma
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet B220, 2800 Kgs. Lyngby, Denmark
| | - Jochen Forster
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet B220, 2800 Kgs. Lyngby, Denmark
| | - Alex Toftgaard Nielsen
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet B220, 2800 Kgs. Lyngby, Denmark.
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23
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Complete Genome Sequence of Geobacillus thermoglucosidasius NCIMB 11955, the Progenitor of a Bioethanol Production Strain. GENOME ANNOUNCEMENTS 2016; 4:4/5/e01065-16. [PMID: 27688322 PMCID: PMC5043570 DOI: 10.1128/genomea.01065-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The industrially important thermophile Geobacillus thermoglucosidasius has the potential to produce chemicals and fuels from biomass-derived sugar feedstocks. Here, we present the genome sequence of strain NCIMB 11955, the progenitor of an ethanologenic industrial strain, revealing 11 single-nucleotide polymorphisms and 2 indels compared to strain DSM 2542 and two novel plasmids.
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24
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Gao L, Liu Y, Sun H, Li C, Zhao Z, Liu G. Advances in mechanisms and modifications for rendering yeast thermotolerance. J Biosci Bioeng 2016; 121:599-606. [DOI: 10.1016/j.jbiosc.2015.11.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 11/05/2015] [Accepted: 11/08/2015] [Indexed: 10/22/2022]
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25
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Cordova LT, Lu J, Cipolla RM, Sandoval NR, Long CP, Antoniewicz MR. Co-utilization of glucose and xylose by evolved Thermus thermophilus LC113 strain elucidated by (13)C metabolic flux analysis and whole genome sequencing. Metab Eng 2016; 37:63-71. [PMID: 27164561 DOI: 10.1016/j.ymben.2016.05.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 04/04/2016] [Accepted: 05/05/2016] [Indexed: 01/20/2023]
Abstract
We evolved Thermus thermophilus to efficiently co-utilize glucose and xylose, the two most abundant sugars in lignocellulosic biomass, at high temperatures without carbon catabolite repression. To generate the strain, T. thermophilus HB8 was first evolved on glucose to improve its growth characteristics, followed by evolution on xylose. The resulting strain, T. thermophilus LC113, was characterized in growth studies, by whole genome sequencing, and (13)C-metabolic flux analysis ((13)C-MFA) with [1,6-(13)C]glucose, [5-(13)C]xylose, and [1,6-(13)C]glucose+[5-(13)C]xylose as isotopic tracers. Compared to the starting strain, the evolved strain had an increased growth rate (~2-fold), increased biomass yield, increased tolerance to high temperatures up to 90°C, and gained the ability to grow on xylose in minimal medium. At the optimal growth temperature of 81°C, the maximum growth rate on glucose and xylose was 0.44 and 0.46h(-1), respectively. In medium containing glucose and xylose the strain efficiently co-utilized the two sugars. (13)C-MFA results provided insights into the metabolism of T. thermophilus LC113 that allows efficient co-utilization of glucose and xylose. Specifically, (13)C-MFA revealed that metabolic fluxes in the upper part of metabolism adjust flexibly to sugar availability, while fluxes in the lower part of metabolism remain relatively constant. Whole genome sequence analysis revealed two large structural changes that can help explain the physiology of the evolved strain: a duplication of a chromosome region that contains many sugar transporters, and a 5x multiplication of a region on the pVV8 plasmid that contains xylose isomerase and xylulokinase genes, the first two enzymes of xylose catabolism. Taken together, (13)C-MFA and genome sequence analysis provided complementary insights into the physiology of the evolved strain.
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Affiliation(s)
- Lauren T Cordova
- Department of Chemical & Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Jing Lu
- Department of Chemical & Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Robert M Cipolla
- Department of Chemical & Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Nicholas R Sandoval
- Department of Chemical & Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Christopher P Long
- Department of Chemical & Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA
| | - Maciek R Antoniewicz
- Department of Chemical & Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark, DE 19716, USA.
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26
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Draft Genome Sequence of Caloranaerobacter sp. TR13, an Anaerobic Thermophilic Bacterium Isolated from a Deep-Sea Hydrothermal Vent. GENOME ANNOUNCEMENTS 2015; 3:3/6/e01491-15. [PMID: 26679595 PMCID: PMC4683240 DOI: 10.1128/genomea.01491-15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Here, we report the draft 2,261,881-bp genome sequence of Caloranaerobacter sp. TR13, isolated from a deep-sea hydrothermal vent on the East Pacific Rise. The sequence will be helpful for understanding the genetic and metabolic features, as well as potential biotechnological application in the genus Caloranaerobacter.
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27
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Cordova LT, Long CP, Venkataramanan KP, Antoniewicz MR. Complete genome sequence, metabolic model construction and phenotypic characterization of Geobacillus LC300, an extremely thermophilic, fast growing, xylose-utilizing bacterium. Metab Eng 2015; 32:74-81. [PMID: 26391740 DOI: 10.1016/j.ymben.2015.09.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 08/26/2015] [Accepted: 09/11/2015] [Indexed: 02/07/2023]
Abstract
We have isolated a new extremely thermophilic fast-growing Geobacillus strain that can efficiently utilize xylose, glucose, mannose and galactose for cell growth. When grown aerobically at 72 °C, Geobacillus LC300 has a growth rate of 2.15 h(-1) on glucose and 1.52 h(-1) on xylose (doubling time less than 30 min). The corresponding specific glucose and xylose utilization rates are 5.55 g/g/h and 5.24 g/g/h, respectively. As such, Geobacillus LC300 grows 3-times faster than E. coli on glucose and xylose, and has a specific xylose utilization rate that is 3-times higher than the best metabolically engineered organism to date. To gain more insight into the metabolism of Geobacillus LC300 its genome was sequenced using PacBio's RS II single-molecule real-time (SMRT) sequencing platform and annotated using the RAST server. Based on the genome annotation and the measured biomass composition a core metabolic network model was constructed. To further demonstrate the biotechnological potential of this organism, Geobacillus LC300 was grown to high cell-densities in a fed-batch culture, where cells maintained a high xylose utilization rate under low dissolved oxygen concentrations. All of these characteristics make Geobacillus LC300 an attractive host for future metabolic engineering and biotechnology applications.
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Affiliation(s)
- Lauren T Cordova
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, 150 Academy St, Newark, DE 19716, USA
| | - Christopher P Long
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, 150 Academy St, Newark, DE 19716, USA
| | - Keerthi P Venkataramanan
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, 150 Academy St, Newark, DE 19716, USA
| | - Maciek R Antoniewicz
- Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, 150 Academy St, Newark, DE 19716, USA.
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28
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Urbieta MS, Donati ER, Chan KG, Shahar S, Sin LL, Goh KM. Thermophiles in the genomic era: Biodiversity, science, and applications. Biotechnol Adv 2015; 33:633-47. [PMID: 25911946 DOI: 10.1016/j.biotechadv.2015.04.007] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/18/2014] [Accepted: 04/14/2015] [Indexed: 01/30/2023]
Abstract
Thermophiles and hyperthermophiles are present in various regions of the Earth, including volcanic environments, hot springs, mud pots, fumaroles, geysers, coastal thermal springs, and even deep-sea hydrothermal vents. They are also found in man-made environments, such as heated compost facilities, reactors, and spray dryers. Thermophiles, hyperthermophiles, and their bioproducts facilitate various industrial, agricultural, and medicinal applications and offer potential solutions to environmental damages and the demand for biofuels. Intensified efforts to sequence the entire genome of hyperthermophiles and thermophiles are increasing rapidly, as evidenced by the fact that over 120 complete genome sequences of the hyperthermophiles Aquificae, Thermotogae, Crenarchaeota, and Euryarchaeota are now available. In this review, we summarise the major current applications of thermophiles and thermozymes. In addition, emphasis is placed on recent progress in understanding the biodiversity, genomes, transcriptomes, metagenomes, and single-cell sequencing of thermophiles in the genomic era.
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Affiliation(s)
- M Sofía Urbieta
- CINDEFI (CCT La Plata-CONICET, UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calle 47 y 115, 1900 La Plata, Argentina
| | - Edgardo R Donati
- CINDEFI (CCT La Plata-CONICET, UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calle 47 y 115, 1900 La Plata, Argentina
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Saleha Shahar
- Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia
| | - Lee Li Sin
- Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia
| | - Kian Mau Goh
- Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia.
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Trumbo JL, Zhang B, Stewart CN. Manipulating microRNAs for improved biomass and biofuels from plant feedstocks. PLANT BIOTECHNOLOGY JOURNAL 2015; 13:337-54. [PMID: 25707745 DOI: 10.1111/pbi.12319] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 11/25/2014] [Accepted: 11/29/2014] [Indexed: 05/22/2023]
Abstract
Petroleum-based fuels are nonrenewable and unsustainable. Renewable sources of energy, such as lignocellulosic biofuels and plant metabolite-based drop-in fuels, can offset fossil fuel use and reverse environmental degradation through carbon sequestration. Despite these benefits, the lignocellulosic biofuels industry still faces many challenges, including the availability of economically viable crop plants. Cell wall recalcitrance is a major economic barrier for lignocellulosic biofuels production from biomass crops. Sustainability and biomass yield are two additional, yet interrelated, foci for biomass crop improvement. Many scientists are searching for solutions to these problems within biomass crop genomes. MicroRNAs (miRNAs) are involved in almost all biological and metabolic process in plants including plant development, cell wall biosynthesis and plant stress responses. Because of the broad functions of their targets (e.g. auxin response factors), the alteration of plant miRNA expression often results in pleiotropic effects. A specific miRNA usually regulates a biologically relevant bioenergy trait. For example, relatively low miR156 overexpression leads to a transgenic feedstock with enhanced biomass and decreased recalcitrance. miRNAs have been overexpressed in dedicated bioenergy feedstocks such as poplar and switchgrass yielding promising results for lignin reduction, increased plant biomass, the timing of flowering and response to harsh environments. In this review, we present the status of miRNA-related research in several major biofuel crops and relevant model plants. We critically assess published research and suggest next steps for miRNA manipulation in feedstocks for increased biomass and sustainability for biofuels and bioproducts.
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Affiliation(s)
- Jennifer Lynn Trumbo
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN, USA; Department of Plant Sciences, University of Tennessee, Knoxville, TN, USA
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Kananavičiūtė R, Čitavičius D. Genetic engineering of Geobacillus spp. J Microbiol Methods 2015; 111:31-9. [DOI: 10.1016/j.mimet.2015.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 02/02/2015] [Accepted: 02/02/2015] [Indexed: 11/15/2022]
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Olson DG, Sparling R, Lynd LR. Ethanol production by engineered thermophiles. Curr Opin Biotechnol 2015; 33:130-41. [PMID: 25745810 DOI: 10.1016/j.copbio.2015.02.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/11/2015] [Accepted: 02/13/2015] [Indexed: 12/17/2022]
Abstract
We compare a number of different strategies that have been pursued to engineer thermophilic microorganisms for increased ethanol production. Ethanol production from pyruvate can proceed via one of four pathways, which are named by the key pyruvate dissimilating enzyme: pyruvate decarboxylase (PDC), pyruvate dehydrogenase (PDH), pyruvate formate lyase (PFL), and pyruvate ferredoxin oxidoreductase (PFOR). For each of these pathways except PFL, we see examples where ethanol production has been engineered with a yield of >90% of the theoretical maximum. In each of these cases, this engineering was achieved mainly by modulating expression of native genes. We have not found an example where a thermophilic ethanol production pathway has been transferred to a non-ethanol-producing organism to produce ethanol at high yield. A key reason for the lack of transferability of ethanol production pathways is the current lack of understanding of the enzymes involved.
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Affiliation(s)
- Daniel G Olson
- Thayer School of Engineering at Dartmouth College, Hanover, NH 03755, United States; BioEnergy Science Center, Oak Ridge, TN 37830, United States
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada R3T 5V6
| | - Lee R Lynd
- Thayer School of Engineering at Dartmouth College, Hanover, NH 03755, United States; BioEnergy Science Center, Oak Ridge, TN 37830, United States.
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Hwang HJ, Choi SP, Lee SY, Choi JI, Han SJ, Lee PC. Dynamics of membrane fatty acid composition of succinic acid-producing Anaerobiospirillum succiniciproducens. J Biotechnol 2015; 193:130-3. [DOI: 10.1016/j.jbiotec.2014.11.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 11/08/2014] [Accepted: 11/26/2014] [Indexed: 11/17/2022]
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Liu Y, Zhang G, Sun H, Sun X, Jiang N, Rasool A, Lin Z, Li C. Enhanced pathway efficiency of Saccharomyces cerevisiae by introducing thermo-tolerant devices. BIORESOURCE TECHNOLOGY 2014; 170:38-44. [PMID: 25118151 DOI: 10.1016/j.biortech.2014.07.063] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/15/2014] [Accepted: 07/16/2014] [Indexed: 06/03/2023]
Abstract
In this study, thermo-tolerant devices consisting of heat shock genes from thermophiles were designed and introduced into Saccharomyces cerevisiae for improving its thermo-tolerance. Among ten engineered thermo-tolerant yeasts, T.te-TTE2469, T.te-GroS2 and T.te-IbpA displayed over 25% increased cell density and 1.5-4-fold cell viability compared with the control. Physiological characteristics of thermo-tolerant strains revealed that better cell wall integrity, higher trehalose content and enhanced metabolic energy were preserved by thermo-tolerant devices. Engineered thermo-tolerant strain was used to investigate the impact of thermo-tolerant device on pathway efficiency by introducing β-amyrin synthesis pathway, showed 28.1% increased β-amyrin titer, 28-35°C broadened growth temperature range and 72h shortened fermentation period. The results indicated that implanting heat shock proteins from thermophiles to S. cerevisiae would be an efficient approach to improve its thermo-tolerance.
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Affiliation(s)
- Yueqin Liu
- School of Chemical Engineering, Tianjin University, Tianjin 300072, China
| | - Genli Zhang
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Huan Sun
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Xiangying Sun
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Nisi Jiang
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Aamir Rasool
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | | | - Chun Li
- School of Chemical Engineering, Tianjin University, Tianjin 300072, China; School of Life Science, Beijing Institute of Technology, Beijing 100081, China.
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Elleuche S, Schröder C, Sahm K, Antranikian G. Extremozymes--biocatalysts with unique properties from extremophilic microorganisms. Curr Opin Biotechnol 2014; 29:116-23. [PMID: 24780224 DOI: 10.1016/j.copbio.2014.04.003] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 03/14/2014] [Accepted: 04/02/2014] [Indexed: 02/03/2023]
Abstract
Extremozymes are enzymes derived from extremophilic microorganisms that are able to withstand harsh conditions in industrial processes that were long thought to be destructive to proteins. Heat-stable and solvent-tolerant biocatalysts are valuable tools for processes in which for example hardly decomposable polymers need to be liquefied and degraded, while cold-active enzymes are of relevance for food and detergent industries. Extremophilic microorganisms are a rich source of naturally tailored enzymes, which are more superior over their mesophilic counterparts for applications at extreme conditions. Especially lignocellulolytic, amylolytic, and other biomass processing extremozymes with unique properties are widely distributed in thermophilic prokaryotes and are of high potential for versatile industrial processes.
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Affiliation(s)
- Skander Elleuche
- Institute of Technical Microbiology, Hamburg University of Technology (TUHH), Kasernenstr. 12, D-21073 Hamburg, Germany
| | - Carola Schröder
- Institute of Technical Microbiology, Hamburg University of Technology (TUHH), Kasernenstr. 12, D-21073 Hamburg, Germany
| | - Kerstin Sahm
- Institute of Technical Microbiology, Hamburg University of Technology (TUHH), Kasernenstr. 12, D-21073 Hamburg, Germany
| | - Garabed Antranikian
- Institute of Technical Microbiology, Hamburg University of Technology (TUHH), Kasernenstr. 12, D-21073 Hamburg, Germany.
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Abstract
The term "extremophile" was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of "extreme" environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally "hot environments" on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong to the Archaea has definitely made this area of investigation more exciting. Particularly fascinating are their structural and physiological features allowing them to withstand extremely selective environmental conditions. These properties are often due to specific biomolecules (DNA, lipids, enzymes, osmolites, etc.) that have been studied for years as novel sources for biotechnological applications. In some cases (DNA-polymerase, thermostable enzymes), the search and applications successful exceeded preliminary expectations, but certainly further exploitations are still needed.
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Young J, Chung D, Bomble YJ, Himmel ME, Westpheling J. Deletion of Caldicellulosiruptor bescii CelA reveals its crucial role in the deconstruction of lignocellulosic biomass. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:142. [PMID: 25317205 PMCID: PMC4195899 DOI: 10.1186/s13068-014-0142-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 09/17/2014] [Indexed: 05/08/2023]
Abstract
BACKGROUND Members of the bacterial genus Caldicellulosiruptor are the most thermophilic cellulolytic organisms described to date, and have the ability to grow on lignocellulosic biomass without conventional pretreatment. Different species vary in their abilities to degrade cellulose, and the presence of CelA, a bifunctional glycoside hydrolase that contains a Family 48 and a Family 9 catalytic domain, correlates well with cellulolytic ability in members of this genus. For example, C. hydrothermalis, which does not contain a CelA homolog, or a GH48 Family or GH9 Family glycoside hydrolase, is the least cellulolytic of the Caldicellulosiruptor species so far described. C. bescii, which contains CelA and expresses it constitutively, is among the most cellulolytic. In fact, CelA is the most abundant extracellular protein produced in C. bescii. The enzyme contains two catalytic units, a Family 9A-CBM3c processive endoglucanase and a Family 48 exoglucanase, joined by two Family 3b carbohydrate-binding domains. Although there are two non-reducing end-specific Family 9 and three reducing end-specific Family 48 glycoside hydrolases (producing primarily glucose and cellobiose; and cellobiose and cellotriose, respectively) in C. bescii, CelA is the only protein that combines both enzymatic activities. RESULTS A deletion of the celA gene resulted in a dramatic reduction in the microorganism's ability to grow on crystalline cellulose (Avicel) and diminished growth on lignocellulosic biomass. A comparison of the overall endoglucanase and exoglucanase activities of the mutant compared with the wild-type suggests that the loss of the endoglucanase activity provided by the GH9 family domain is perhaps compensated for by other enzymes produced by the cell. In contrast, it appears that no other enzymes in the C. bescii secretome can compensate for the loss of exoglucanase activity. The change in enzymatic activity in the celA mutant resulted in a 15-fold decrease in sugar release on Avicel compared with the parent and wild-type strains. CONCLUSIONS The exoglucanase activity of the GH48 domain of CelA plays a major role in biomass degradation within the suite of C. bescii biomass-degrading enzymes.
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Affiliation(s)
- Jenna Young
- />Department of Genetics, University of Georgia, Athens, Georgia
- />The BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Daehwan Chung
- />Department of Genetics, University of Georgia, Athens, Georgia
- />The BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Yannick J Bomble
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO USA
- />The BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Michael E Himmel
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO USA
- />The BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Janet Westpheling
- />Department of Genetics, University of Georgia, Athens, Georgia
- />The BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
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Lin L, Ji Y, Tu Q, Huang R, Teng L, Zeng X, Song H, Wang K, Zhou Q, Li Y, Cui Q, He Z, Zhou J, Xu J. Microevolution from shock to adaptation revealed strategies improving ethanol tolerance and production in Thermoanaerobacter. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:103. [PMID: 23875846 PMCID: PMC3751872 DOI: 10.1186/1754-6834-6-103] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/17/2013] [Indexed: 05/08/2023]
Abstract
INTRODUCTION The molecular links between shock-response and adaptation remain poorly understood, particularly for extremophiles. This has hindered rational engineering of solvent tolerance and correlated traits (e.g., productivity) in extremophiles. To untangle such molecular links, here we established a model that tracked the microevolution from shock to adaptation in thermophilic bacteria. METHOD Temporal dynamics of genomes and transcriptomes was tracked for Thermoanaerobacter sp. X514 which under increasing exogenous ethanol evolved from ethanol-sensitive wild-type (Strain X) to tolerance of 2%- (XI) and eventually 6%-ethanol (XII). Based on the reconstructed transcriptional network underlying stress tolerance, genetic engineering was employed to improve ethanol tolerance and production in Thermoanaerobacter. RESULTS The spontaneous genome mutation rate (μg) of Thermoanaerobacter sp. X514, calculated at 0.045, suggested a higher mutation rate in thermophile than previously thought. Transcriptomic comparison revealed that shock-response and adaptation were distinct in nature, whereas the transcriptomes of XII resembled those of the extendedly shocked X. To respond to ethanol shock, X employed fructose-specific phosphotransferase system (PTS), Arginine Deiminase (ADI) pathway, alcohol dehydrogenase (Adh) and a distinct mechanism of V-type ATPase. As an adaptation to exogenous ethanol, XI mobilized resistance-nodulation-cell division (RND) efflux system and Adh, whereas XII, which produced higher ethanol than XI, employed ECF-type ϭ24, an alcohol catabolism operon and phase-specific heat-shock proteins (Hsps), modulated hexose/pentose-transport operon structure and reinforced membrane rigidity. Exploiting these findings, we further showed that ethanol productivity and tolerance can be improved simultaneously by overexpressing adh or ϭ24 in X. CONCLUSION Our work revealed thermophilic-bacteria specific features of adaptive evolution and demonstrated a rational strategy to engineer co-evolving industrial traits. As improvements of shock-response, stress tolerance and productivity have been crucial aims in industrial applications employing thermophiles, our findings should be valuable not just to the production of ethanol but also to a wide variety of biofuels and biochemicals.
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Affiliation(s)
- Lu Lin
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Yuetong Ji
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Qichao Tu
- Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - Ranran Huang
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Lin Teng
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Xiaowei Zeng
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Houhui Song
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Kun Wang
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Qian Zhou
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Yifei Li
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Qiu Cui
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
| | - Zhili He
- Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - Jizhong Zhou
- Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - Jian Xu
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, P. R. China
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