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Xiao F, Zhang Y, Zhang L, Li S, Chen W, Shi G, Li Y. Advancing Bacillus licheniformis as a Superior Expression Platform through Promoter Engineering. Microorganisms 2024; 12:1693. [PMID: 39203534 PMCID: PMC11356801 DOI: 10.3390/microorganisms12081693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Revised: 08/14/2024] [Accepted: 08/15/2024] [Indexed: 09/03/2024] Open
Abstract
Bacillus licheniformis is recognised as an exceptional expression platform in biomanufacturing due to its ability to produce high-value products. Consequently, metabolic engineering of B. licheniformis is increasingly pursued to enhance its utility as a biomanufacturing vehicle. Effective B. licheniformis cell factories require promoters that enable regulated expression of target genes. This review discusses recent advancements in the characterisation, synthesis, and engineering of B. licheniformis promoters. We highlight the application of constitutive promoters, quorum sensing promoters, and inducible promoters in protein and chemical synthesis. Additionally, we summarise efforts to expand the promoter toolbox through hybrid promoter engineering, transcription factor-based inducible promoter engineering, and ribosome binding site (RBS) engineering.
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Affiliation(s)
- Fengxu Xiao
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (F.X.); (Y.Z.); (L.Z.); (S.L.); (G.S.)
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
- Jiangsu Provincial Engineering Research Center for Bioactive Product Processing, Jiangnan University, Wuxi 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China;
| | - Yupeng Zhang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (F.X.); (Y.Z.); (L.Z.); (S.L.); (G.S.)
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
- Jiangsu Provincial Engineering Research Center for Bioactive Product Processing, Jiangnan University, Wuxi 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China;
| | - Lihuan Zhang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (F.X.); (Y.Z.); (L.Z.); (S.L.); (G.S.)
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
- Jiangsu Provincial Engineering Research Center for Bioactive Product Processing, Jiangnan University, Wuxi 214122, China
| | - Siyu Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (F.X.); (Y.Z.); (L.Z.); (S.L.); (G.S.)
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
- Jiangsu Provincial Engineering Research Center for Bioactive Product Processing, Jiangnan University, Wuxi 214122, China
| | - Wei Chen
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China;
| | - Guiyang Shi
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (F.X.); (Y.Z.); (L.Z.); (S.L.); (G.S.)
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
- Jiangsu Provincial Engineering Research Center for Bioactive Product Processing, Jiangnan University, Wuxi 214122, China
| | - Youran Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (F.X.); (Y.Z.); (L.Z.); (S.L.); (G.S.)
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
- Jiangsu Provincial Engineering Research Center for Bioactive Product Processing, Jiangnan University, Wuxi 214122, China
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Li M, Yang R, Guo J, Liu M, Yang J. Optimization of IspS ib stability through directed evolution to improve isoprene production. Appl Environ Microbiol 2023; 89:e0121823. [PMID: 37815338 PMCID: PMC10617563 DOI: 10.1128/aem.01218-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 08/11/2023] [Indexed: 10/11/2023] Open
Abstract
Enzyme stability is often a limiting factor in the microbial production of high-value-added chemicals and commercial enzymes. A previous study by our research group revealed that the unstable isoprene synthase from Ipomoea batatas (IspSib) critically limits isoprene production in engineered Escherichia coli. Directed evolution was, therefore, performed in the present study to improve the thermostability of IspSib. First, a tripartite protein folding system designated as lac'-IspSib-'lac, which could couple the stability of IspSib to antibiotic ampicillin resistance, was successfully constructed for the high-throughput screening of variants. Directed evolution of IspSib was then performed through two rounds of random mutation and site-saturation mutation, which produced three variants with higher stability: IspSibN397V A476V, IspSibN397V A476T, and IspSibN397V A476C. The subsequent in vitro thermostability test confirmed the increased protein stability. The melting temperatures of the screened variants IspSibN397V A476V, IspSibN397V A476T, and IspSibN397V A476C were 45.1 ± 0.9°C, 46.1 ± 0.7°C, and 47.2 ± 0.3°C, respectively, each of which was higher than the melting temperature of wild-type IspSib (41.5 ± 0.4°C). The production of isoprene at the shake-flask fermentation level was increased by 1.94-folds, to 1,335 mg/L, when using IspSibN397V A476T. These findings provide insights into the optimization of the thermostability of terpene synthases, which are key enzymes for isoprenoid production in engineered microorganisms. In addition, the present study would serve as a successful example of improving enzyme stability without requiring detailed structural information or catalytic reaction mechanisms.IMPORTANCEThe poor thermostability of IspSib critically limits isoprene production in engineered Escherichia coli. A tripartite protein folding system designated as lac'-IspSib-'lac, which could couple the stability of IspSib to antibiotic ampicillin resistance, was successfully constructed for the first time. In order to improve the enzyme stability of IspSib, the directed evolution of IspSib was performed through error-PCR, and high-throughput screening was realized using the lac'-IspSib-'lac system. Three positive variants with increased thermostability were obtained. The thermostability test and the melting temperature analysis confirmed the increased stability of the enzyme. The production of isoprene was increased by 1.94-folds, to 1,335 mg/L, using IspSibN397V A476T. The directed evolution process reported here is also applicable to other terpene synthases key to isoprenoid production.
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Affiliation(s)
- Meijie Li
- Energy-rich Compound Production by Photosynthetic Carbon Fixation Research Center, Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, China
| | - Rumeng Yang
- Energy-rich Compound Production by Photosynthetic Carbon Fixation Research Center, Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, China
| | - Jing Guo
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, China
- Shandong Energy Institute, Qingdao, Shandong, China
- Qingdao New Energy Shandong Laboratory, Qingdao, Shandong, China
| | - Min Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, Shandong, China
| | - Jianming Yang
- Energy-rich Compound Production by Photosynthetic Carbon Fixation Research Center, Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, Shandong, China
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3
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Development of a novel functional yogurt rich in lycopene by Bacillus subtilis. Food Chem 2023; 407:135142. [PMID: 36493487 DOI: 10.1016/j.foodchem.2022.135142] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/24/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Functional lycopene-rich yogurt displays attractive nutritious and health-promoting benefits among existing functional dairy products, owing to supplement with lycopene which could enhance immunity, prevent cancer, and cardiovascular diseases. Due to poor stability and fat-solubility of lycopene, its incorporation into yogurt is challengeable. In this study, carotenoid genes for lycopene synthesis were co-introduced into probiotic Bacillus subtilis for efficient lycopene production. Further engineered B. subtilis was applied as adjunct starter culture for achieving lycopene-rich yogurt. Developed yogurt exhibited desirable physiochemical characteristics compared with plain yogurt. Moreover, lycopene-rich yogurt was endowed with significantly high antioxidant capacity. More importantly, this functionalized yogurt had attractive sensorial attributes for quality-assured food to facilitate consumer acceptance. As the first report of fortifying yogurt of lycopene using B. subtilis with improved functional properties, this study offers a new and facile clue to enrich bioactive lycopene and probiotic B. subtilis in yogurt for healthy and nutritional food development.
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Dive A, Singhal R, Srivastava S, Shukre K, James D, Shetty S. Isolation and functional characterization of novel isoprene synthase from Artocarpus heterophyllus (jackfruit). 3 Biotech 2023; 13:24. [PMID: 36573156 PMCID: PMC9789294 DOI: 10.1007/s13205-022-03441-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
Isoprene, a Natural Volatile Organic Compound (NVOC) is one of the chief by-products of plant metabolism with important applications in the synthesis of rubber and pharmaceuticals as a platform molecule. Isoprene was obtained earlier from petroleum sources; however, to synthesise it new fermentation-based strategies are being adopted. Bioinformatics tools were utilised to isolate the Isoprene Synthase (IspS) gene which converts the precursors Isopentenyl Diphosphate (IPP) and Dimethylallyl Diphosphate (DMAPP) into isoprene. Metabolic engineering strategies were to synthesise an isoprene-producing recombinant clone derived from Artocarpus heterophyllus (jackfruit). The functional characterization was done using the overexpression of the isoprene synthase gene in an Escherichia coli BL21 host. The recombinant clone, ISPS_GBL_001 (submitted to GenBank, National Centre for Biotechnology Information or NCBI) was used for fermentation in the batch and fed-batch mode to produce isoprene. Isoprene productivity of 0.08 g/g dextrose was obtained via the fed-batch mode maintaining the process parameters at optimum. The quantification and confirmation of isoprene was done using gas chromatography (GC) and GC-mass spectrometry (GC-MS) of the extracted sample, respectively. This study makes significant contribution to the ongoing research on bio-isoprene synthesis by highlighting a novel plant source of the IspS gene followed by, its successful expression in a recombinant host, validated by fermentation. Supplementary Information The online version contains supplementary material available at 10.1007/s13205-022-03441-7.
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Affiliation(s)
- Amol Dive
- Institute of Chemical Technology, Matunga, Mumbai, India
- Godavari Biorefineries Ltd., Mahape, Navi Mumbai, India
| | - Rekha Singhal
- Institute of Chemical Technology, Matunga, Mumbai, India
| | | | - Kedar Shukre
- Godavari Biorefineries Ltd., Mahape, Navi Mumbai, India
| | - Deepak James
- Godavari Biorefineries Ltd., Mahape, Navi Mumbai, India
| | - Sneha Shetty
- Godavari Biorefineries Ltd., Mahape, Navi Mumbai, India
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Isar J, Jain D, Joshi H, Dhoot S, Rangaswamy V. MICROBIAL isoprene production: an overview. World J Microbiol Biotechnol 2022; 38:122. [PMID: 35637362 DOI: 10.1007/s11274-022-03306-4] [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: 03/16/2022] [Accepted: 05/09/2022] [Indexed: 11/28/2022]
Abstract
Isoprene, a volatile C5 hydrocarbon, is a precursor of synthetic rubber and an important building block for a variety of natural products, solely being produced by petrochemical routes. To mitigate the ever-increasing contribution of petrochemical industry to global warming through significant carbon (CO2) evolution, bio-based process for isoprene production using microbial cell factories have been explored. Highly efficient fermentation-based processes have been studied for little over a decade now with extensive research on the rational strain development for creating robust strains for commercial isoprene production. Most of these studies involved sugars as feedstocks and using naturally occurring isoprene pathways viz., mevalonate and methyl erythritol pathway in E. coli. Recent advances, driven by efforts in reducing environmental pollution, have focused on utilization of inorganic CO2 by cyanobacteria or syngas from waste gases by acetogens for isoprene production. This review endeavors to capture the latest relevant progress made in rational strain development, metabolic engineering and synthetic biology strategies used, challenges in fermentation process development at lab and commercial scale production of isoprene along with a future perspective pertaining to this area of research.
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Affiliation(s)
- Jasmine Isar
- High Value Chemicals, Reliance Industries Limited, Reliance Corporate Park, Ghansoli, Navi Mumbai, 400701, India
| | - Dharmendra Jain
- High Value Chemicals, Reliance Industries Limited, Reliance Corporate Park, Ghansoli, Navi Mumbai, 400701, India
| | - Harshvardhan Joshi
- High Value Chemicals, Reliance Industries Limited, Reliance Corporate Park, Ghansoli, Navi Mumbai, 400701, India
| | - Shrikant Dhoot
- High Value Chemicals, Reliance Industries Limited, Reliance Corporate Park, Ghansoli, Navi Mumbai, 400701, India
| | - Vidhya Rangaswamy
- High Value Chemicals, Reliance Industries Limited, Reliance Corporate Park, Ghansoli, Navi Mumbai, 400701, India.
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Song Y, He S, Abdallah II, Jopkiewicz A, Setroikromo R, van Merkerk R, Tepper PG, Quax WJ. Engineering of Multiple Modules to Improve Amorphadiene Production in Bacillus subtilis Using CRISPR-Cas9. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:4785-4794. [PMID: 33877851 PMCID: PMC8154554 DOI: 10.1021/acs.jafc.1c00498] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/06/2021] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
Engineering strategies to improve terpenoids' production in Bacillus subtilis mainly focus on 2C-methyl-d-erythritol-4-phosphate (MEP) pathway overexpression. To systematically engineer the chassis strain for higher amorphadiene (precursor of artemisinin) production, a clustered regularly interspaced short palindromic repeat-Cas9 (CRISPR-Cas9) system was established in B. subtilis to facilitate precise and efficient genome editing. Then, this system was employed to engineer three more modules to improve amorphadiene production, including the terpene synthase module, the branch pathway module, and the central metabolic pathway module. Finally, our combination of all of the useful strategies within one strain significantly increased extracellular amorphadiene production from 81 to 116 mg/L after 48 h flask fermentation without medium optimization. For the first time, we attenuated the FPP-derived competing pathway to improve amorphadiene biosynthesis and investigated how the TCA cycle affects amorphadiene production in B. subtilis. Overall, this study provides a universal strategy for further increasing terpenoids' production in B. subtilis by comprehensive and systematic metabolic engineering.
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Affiliation(s)
- Yafeng Song
- Department
of Chemical and Pharmaceutical Biology, Groningen Research Institute
of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Siqi He
- Department
of Chemical and Pharmaceutical Biology, Groningen Research Institute
of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Ingy I. Abdallah
- Department
of Chemical and Pharmaceutical Biology, Groningen Research Institute
of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
- Department
of Pharmacognosy, Faculty of Pharmacy, Alexandria
University, 21521 Alexandria, Egypt
| | - Anita Jopkiewicz
- Department
of Chemical and Pharmaceutical Biology, Groningen Research Institute
of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Rita Setroikromo
- Department
of Chemical and Pharmaceutical Biology, Groningen Research Institute
of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Ronald van Merkerk
- Department
of Chemical and Pharmaceutical Biology, Groningen Research Institute
of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Pieter G. Tepper
- Department
of Chemical and Pharmaceutical Biology, Groningen Research Institute
of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Wim J. Quax
- Department
of Chemical and Pharmaceutical Biology, Groningen Research Institute
of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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Pramastya H, Song Y, Elfahmi EY, Sukrasno S, Quax WJ. Positioning Bacillus subtilis as terpenoid cell factory. J Appl Microbiol 2020; 130:1839-1856. [PMID: 33098223 PMCID: PMC8247319 DOI: 10.1111/jam.14904] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/29/2020] [Accepted: 10/09/2020] [Indexed: 12/16/2022]
Abstract
Increasing demands for bioactive compounds have motivated researchers to employ micro‐organisms to produce complex natural products. Currently, Bacillus subtilis has been attracting lots of attention to be developed into terpenoids cell factories due to its generally recognized safe status and high isoprene precursor biosynthesis capacity by endogenous methylerythritol phosphate (MEP) pathway. In this review, we describe the up‐to‐date knowledge of each enzyme in MEP pathway and the subsequent steps of isomerization and condensation of C5 isoprene precursors. In addition, several representative terpene synthases expressed in B. subtilis and the engineering steps to improve corresponding terpenoids production are systematically discussed. Furthermore, the current available genetic tools are mentioned as along with promising strategies to improve terpenoids in B. subtilis, hoping to inspire future directions in metabolic engineering of B. subtilis for further terpenoid cell factory development.
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Affiliation(s)
- H Pramastya
- University of Groningen, Groningen, The Netherlands.,Pharmaceutical Biology Research Group, School of Pharmacy, Institut Teknologi Bandung, Bandung, Indonesia
| | - Y Song
- University of Groningen, Groningen, The Netherlands
| | - E Y Elfahmi
- Pharmaceutical Biology Research Group, School of Pharmacy, Institut Teknologi Bandung, Bandung, Indonesia
| | - S Sukrasno
- Pharmaceutical Biology Research Group, School of Pharmacy, Institut Teknologi Bandung, Bandung, Indonesia
| | - W J Quax
- University of Groningen, Groningen, The Netherlands
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Li M, Nian R, Xian M, Zhang H. Metabolic engineering for the production of isoprene and isopentenol by Escherichia coli. Appl Microbiol Biotechnol 2018; 102:7725-7738. [PMID: 30006784 PMCID: PMC6132537 DOI: 10.1007/s00253-018-9200-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 06/23/2018] [Accepted: 06/25/2018] [Indexed: 12/12/2022]
Abstract
The biotechnological production of isoprene and isopentenol has recently been studied. Isoprene, which is currently made mainly from petroleum, is an important platform chemical for synthesizing pesticides, medicines, oil additives, fragrances, and more and is especially important in the rubber production industry. Isopentenols, which have better combustion properties than well-known biofuels (ethanol), have recently received more attention. Supplies of petroleum, the conventional source of isoprene and isopentenols, are unsustainable, and chemical synthesis processes could cause serious environmental problems. As an alternative, the biosynthesis of isoprene and isopentenols in cell factories is more sustainable and environmentally friendly. With a number of advantages over other microorganisms, Escherichia coli is considered to be a powerful workhorse organism for producing these compounds. This review will highlight the recent advances in metabolic engineering for isoprene and isopentenol production, especially using E. coli cell factories.
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Affiliation(s)
- Meijie Li
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 135 Songling Road, Qingdao, 266101, People's Republic of China.,University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Rui Nian
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 135 Songling Road, Qingdao, 266101, People's Republic of China
| | - Mo Xian
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 135 Songling Road, Qingdao, 266101, People's Republic of China.
| | - Haibo Zhang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 135 Songling Road, Qingdao, 266101, People's Republic of China.
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Wang S, Wang Z, Wang Y, Nie Q, Yi X, Ge W, Yang J, Xian M. Production of isoprene, one of the high-density fuel precursors, from peanut hull using the high-efficient lignin-removal pretreatment method. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:297. [PMID: 29234464 PMCID: PMC5721603 DOI: 10.1186/s13068-017-0988-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 12/02/2017] [Indexed: 05/12/2023]
Abstract
BACKGROUND Isoprene as the feedstock can be used to produce renewable energy fuels, providing an alternative to replace the rapidly depleting fossil fuels. However, traditional method for isoprene production could not meet the demands for low-energy consumption and environment-friendliness. Moreover, most of the previous studies focused on biofuel production out of lignocellulosic materials such as wood, rice straw, corn cob, while few studies concentrated on biofuel production using peanut hull (PH). As is known, China is the largest peanut producer in the globe with an extremely considerable amount of PH to be produced each year. Therefore, a novel, renewable, and environment-friendly pretreatment strategy to increase the enzymatic hydrolysis efficiency of cellulose and reduce the inhibitors generation was developed to convert PH into isoprene. RESULTS The optimal pretreatment conditions were 100 °C, 60 min, 10% (w/v) solid loading with a 2:8 volume ratio of phosphoric acid and of hydrogen peroxide. In comparison with the raw PH, the hemicellulose and lignin were reduced to 85.0 and 98.0%, respectively. The cellulose-glucose conversion of pretreated PH reached up to 95.0% in contrast to that of the raw PH (19.1%). Only three kinds of inhibitors including formic acid, levulinic acid, and a little furfural were formed during the pretreatment process, whose concentrations were too low to inhibit the isoprene yield for Escherichia coli fermentation. Moreover, compared with the isoprene yield of pure glucose fermentation (298 ± 9 mg/L), 249 ± 6.7 and 294 ± 8.3 mg/L of isoprene were produced using the pretreated PH as the carbon source by the engineered strain via separate hydrolysis and fermentation and simultaneous saccharification and fermentation (SSF) methods, respectively. The isoprene production via SSF had a 9.8% glucose-isoprene conversion which was equivalent to 98.8% of isoprene production via the pure glucose fermentation. CONCLUSIONS The optimized phosphoric acid/hydrogen peroxide combination pretreatment approach was proved effective to remove lignin and hemicellulose from lignocellulosic materials. Meanwhile, the pretreated PH could be converted into isoprene efficiently in the engineered Escherichia coli. It is concluded that this novel strategy of isoprene production using lignocellulosic materials pretreated by phosphoric acid/hydrogen peroxide is a promising alternative to isoprene production using traditional way which can fully utilize non-renewable fossil sources.
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Affiliation(s)
- Sumeng Wang
- Shandong Key Lab of Applied Mycology, College of Life Science, Qingdao Agricultural University, No. 700 Changcheng Road, Chengyang District, Qingdao, 266109 China
| | - Zhaobao Wang
- Shandong Key Lab of Applied Mycology, College of Life Science, Qingdao Agricultural University, No. 700 Changcheng Road, Chengyang District, Qingdao, 266109 China
| | - Yongchao Wang
- Shandong Key Lab of Applied Mycology, College of Life Science, Qingdao Agricultural University, No. 700 Changcheng Road, Chengyang District, Qingdao, 266109 China
| | - Qingjuan Nie
- Foreign Languages School, Qingdao Agricultural University, Qingdao, 266109 China
| | - Xiaohua Yi
- Shandong Key Lab of Applied Mycology, College of Life Science, Qingdao Agricultural University, No. 700 Changcheng Road, Chengyang District, Qingdao, 266109 China
| | - Wei Ge
- Shandong Key Lab of Applied Mycology, College of Life Science, Qingdao Agricultural University, No. 700 Changcheng Road, Chengyang District, Qingdao, 266109 China
| | - Jianming Yang
- Shandong Key Lab of Applied Mycology, College of Life Science, Qingdao Agricultural University, No. 700 Changcheng Road, Chengyang District, Qingdao, 266109 China
| | - Mo Xian
- CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101 China
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