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Jilani SB, Olson DG. Mechanism of furfural toxicity and metabolic strategies to engineer tolerance in microbial strains. Microb Cell Fact 2023; 22:221. [PMID: 37891678 PMCID: PMC10612203 DOI: 10.1186/s12934-023-02223-x] [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: 08/29/2023] [Accepted: 10/05/2023] [Indexed: 10/29/2023] Open
Abstract
Lignocellulosic biomass represents a carbon neutral cheap and versatile source of carbon which can be converted to biofuels. A pretreatment step is frequently used to make the lignocellulosic carbon bioavailable for microbial metabolism. Dilute acid pretreatment at high temperature and pressure is commonly utilized to efficiently solubilize the pentose fraction by hydrolyzing the hemicellulose fibers and the process results in formation of furans-furfural and 5-hydroxymethyl furfural-and other inhibitors which are detrimental to metabolism. The presence of inhibitors in the medium reduce productivity of microbial biocatalysts and result in increased production costs. Furfural is the key furan inhibitor which acts synergistically along with other inhibitors present in the hydrolysate. In this review, the mode of furfural toxicity on microbial metabolism and metabolic strategies to increase tolerance is discussed. Shared cellular targets between furfural and acetic acid are compared followed by discussing further strategies to engineer tolerance. Finally, the possibility to use furfural as a model inhibitor of dilute acid pretreated lignocellulosic hydrolysate is discussed. The furfural tolerant strains will harbor an efficient lignocellulosic carbon to pyruvate conversion mechanism in presence of stressors in the medium. The pyruvate can be channeled to any metabolite of interest by appropriate modulation of downstream pathway of interest. The aim of this review is to emphasize the use of hydrolysate as a carbon source for bioproduction of biofuels and other compounds of industrial importance.
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Affiliation(s)
- S Bilal Jilani
- Thayer School of Engineering, Dartmouth College, 15 Thayer Drive, Hanover, NH, 03755, USA.
| | - Daniel G Olson
- Thayer School of Engineering, Dartmouth College, 15 Thayer Drive, Hanover, NH, 03755, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
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Ran Y, Yang Q, Zeng J, Li F, Cao Y, Xu Q, Qiao D, Xu H, Cao Y. Potential xylose transporters regulated by CreA improved lipid yield and furfural tolerance in oleaginous yeast Saitozyma podzolica zwy-2-3. BIORESOURCE TECHNOLOGY 2023; 386:129413. [PMID: 37390935 DOI: 10.1016/j.biortech.2023.129413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/02/2023]
Abstract
Lignocellulose's hydrolysate, a significant renewable source, contains xylose and furfural, making it challenging for industrial production of oleaginous yeast. On xylose fermentation with furfural treatment, OE::DN7263 and OE::DN7661 increased lipid yield and furfural tolerance versus WT, while, which of OE::CreA were decreased owing to CreA regulating DN7263 and DN7661 negatively. OE::CreA generated reactive oxygen species (ROS) causing oxidative damage. OE::DN7263, OE::DN7661, and ΔCreA reduced furfural via NADH; while ΔCreA produced less ROS and OE::DN7263, and OE::DN7661 scavenged ROS quickly, minimizing oxidative damage. Overall, CreA knockout increased DN7263 and DN7661 expression to facilitate xylose assimilation, enhancing NADH generation and ROS clearance. Finally, with mixed sugar fermentation, ΔCreA and OE::DN7263's biomass and lipid yield rose without furfural addition, while that of ΔCreA remained higher than WT after furfural treatment. These findings revealed how oleaginous yeast zwy-2-3 resisted furfural stress and indicated ΔCreA and OE::DN7263 might develop into robust industrial chassis strains.
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Affiliation(s)
- Yulu Ran
- Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan Province 610065, PR China
| | - Qingzhuoma Yang
- Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan Province 610065, PR China
| | - Jie Zeng
- Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan Province 610065, PR China
| | - Fazhi Li
- Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan Province 610065, PR China
| | - Yu Cao
- Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan Province 610065, PR China
| | - Qingrui Xu
- Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan Province 610065, PR China
| | - Dairong Qiao
- Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan Province 610065, PR China
| | - Hui Xu
- Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan Province 610065, PR China.
| | - Yi Cao
- Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan Province 610065, PR China.
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Seo H, Singh P, Wyman CE, Cai CM, Trinh CT. Rewiring metabolism of Clostridium thermocellum for consolidated bioprocessing of lignocellulosic biomass poplar to produce short-chain esters. BIORESOURCE TECHNOLOGY 2023:129263. [PMID: 37271458 DOI: 10.1016/j.biortech.2023.129263] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/06/2023]
Abstract
Consolidated bioprocessing (CBP) of lignocellulosic biomass uses cellulolytic microorganisms to enable enzyme production, saccharification, and fermentation to produce biofuels, biochemicals, and biomaterials in a single step. However, understanding and redirecting metabolisms of these microorganisms compatible with CBP are limited. Here, a cellulolytic thermophile Clostridium thermocellum was engineered and demonstrated to be compatible with CBP integrated with a Co-solvent Enhanced Lignocellulosic Fractionation (CELF) pretreatment for conversion of hardwood poplar into short-chain esters with industrial use as solvents, flavors, fragrances, and biofuels. The recombinant C. thermocellum engineered with deletion of carbohydrate esterases and stable overexpression of alcohol acetyltransferases improved ester production without compromised deacetylation activities. These esterases were discovered to exhibit promiscuous thioesterase activities and their deletion enhanced ester production by rerouting the electron and carbon metabolism. Ester production was further improved up to 80-fold and ester composition could be modulated by deleting lactate biosynthesis and using poplar with different pretreatment severity.
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Affiliation(s)
- Hyeongmin Seo
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Priyanka Singh
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Chemical and Environmental Engineering Department, University of California, Riverside, CA 92521, USA
| | - Charles E Wyman
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Chemical and Environmental Engineering Department, University of California, Riverside, CA 92521, USA
| | - Charles M Cai
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Chemical and Environmental Engineering Department, University of California, Riverside, CA 92521, USA
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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Kim SK, Bomble YJ, Westpheling J. Simultaneous expression of an endogenous spermidine synthase and a butanol dehydrogenase from Thermoanaerobacter pseudethanolicus in Clostridium thermocellum results in increased resistance to acetic acid and furans, increased ethanol production and an increase in thermotolerance. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:46. [PMID: 36918887 PMCID: PMC10012442 DOI: 10.1186/s13068-023-02291-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 02/28/2023] [Indexed: 03/16/2023]
Abstract
BACKGROUND Sensitivity to inhibitors derived from the pretreatment of plant biomass is a barrier to the consolidated bioprocessing of these complex substrates to fuels and chemicals by microbes. Spermidine is a low molecular weight aliphatic nitrogen compound ubiquitous in microorganisms, plants, and animals and is often associated with tolerance to stress. We recently showed that overexpression of the endogenous spermidine synthase enhanced tolerance of the Gram-positive bacterium, Clostridium thermocellum to the furan derivatives furfural and HMF. RESULTS Here we show that co-expression with an NADPH-dependent heat-stable butanol dehydrogenase from Thermoanaerobacter pseudethanolicus further enhanced tolerance to furans and acetic acid and most strikingly resulted in an increase in thermotolerance at 65 °C. CONCLUSIONS Tolerance to fermentation inhibitors will facilitate the use of plant biomass substrates by thermophiles in general and this organism in particular. The ability to grow C. thermocellum at 65 °C has profound implications for metabolic engineering.
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Affiliation(s)
- Sun-Ki Kim
- Department of Genetics, University of Georgia, Athens, GA, 30602, USA.,Oak Ridge National Laboratory, The BioEnergy Science Center and The Center for Bioenergy Innovation, Oak Ridge, TN, 37831, USA.,Department of Food Science and Technology, Chung-Ang University, Anseong, Gyeonggi, 17546, Republic of Korea
| | - Yannick J Bomble
- Oak Ridge National Laboratory, The BioEnergy Science Center and The Center for Bioenergy Innovation, Oak Ridge, TN, 37831, USA.,Biosciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Janet Westpheling
- Department of Genetics, University of Georgia, Athens, GA, 30602, USA. .,Oak Ridge National Laboratory, The BioEnergy Science Center and The Center for Bioenergy Innovation, Oak Ridge, TN, 37831, USA.
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Olorunsogbon T, Adesanya Y, Atiyeh HK, Okonkwo CC, Ujor VC, Ezeji TC. Effects of Clostridium beijerinckii and Medium Modifications on Acetone–Butanol–Ethanol Production From Switchgrass. Front Bioeng Biotechnol 2022; 10:942701. [PMID: 35992339 PMCID: PMC9382077 DOI: 10.3389/fbioe.2022.942701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 06/20/2022] [Indexed: 11/29/2022] Open
Abstract
The presence of lignocellulose-derived microbial inhibitory compounds (LDMICs) in lignocellulosic biomass (LB) hydrolysates is a barrier to efficient conversion of LB hydrolysates to fuels and chemicals by fermenting microorganisms. Results from this study provide convincing evidence regarding the effectiveness of metabolically engineered C. beijerinckii NCIMB 8052 for the fermentation of LB-derived hydrolysates to acetone–butanol–ethanol (ABE). The engineered microbial strain (C. beijerinckii_SDR) was produced by the integration of an additional copy of a short-chain dehydrogenase/reductase (SDR) gene (Cbei_3904) into the chromosome of C. beijerinckii NCIMB 8052 wildtype, where it is controlled by the constitutive thiolase promoter. The C. beijerinckii_SDR and C. beijerinckii NCIMB 8052 wildtype were used for comparative fermentation of non-detoxified and detoxified hydrothermolysis-pretreated switchgrass hydrolysates (SHs) with and without (NH4)2CO3 supplementation. In the absence of (NH4)2CO3, fermentation of non-detoxified SH with C. beijerinckii_SDR resulted in the production of 3.13- and 2.25-fold greater quantities of butanol (11.21 g/L) and total ABE (20.24 g/L), respectively, than the 3.58 g/L butanol and 8.98 g/L ABE produced by C. beijerinckii_wildtype. When the non-detoxified SH was supplemented with (NH4)2CO3, concentrations were similar for butanol (9.5 compared with 9.2 g/L) and ABE (14.2 compared with 13.5 g/L) produced by C. beijerinckii_SDR and C. beijerinckii_wildtype, respectively. Furthermore, when C. beijerinckii_SDR and C. beijerinckii_wildtype were cultured in detoxified SH medium, C. beijerinckii_SDR produced 1.11- and 1.18-fold greater quantities of butanol and ABE, respectively, than when there was culturing with C. beijerinckii_wildtype. When the combined results of the present study are considered, conclusions are that the microbial strain and medium modifications of the fermentation milieu resulted in greater production of fuels and chemicals from non-detoxified LB hydrolysates.
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Affiliation(s)
- Tinuola Olorunsogbon
- Department of Animal Science, The Ohio State University, Wooster, OH, United States
| | - Yinka Adesanya
- Biosystems and Agricultural Engineering, Oklahoma State University, Stillwater, OK, United States
| | - Hasan K. Atiyeh
- Biosystems and Agricultural Engineering, Oklahoma State University, Stillwater, OK, United States
| | - Christopher Chukwudi Okonkwo
- Biotechnology Program, College of Science, The Roux Institute, Northeastern University, Portland, ME, United States
| | - Victor Chinomso Ujor
- Department of Food Science, University of Wisconsin-Madison, Maddison, WI, United States
| | - Thaddeus Chukwuemeka Ezeji
- Department of Animal Science, The Ohio State University, Wooster, OH, United States
- *Correspondence: Thaddeus Chukwuemeka Ezeji,
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Merchel Piovesan Pereira B, Adil Salim M, Rai N, Tagkopoulos I. Tolerance to Glutaraldehyde in Escherichia coli Mediated by Overexpression of the Aldehyde Reductase YqhD by YqhC. Front Microbiol 2021; 12:680553. [PMID: 34248896 PMCID: PMC8262776 DOI: 10.3389/fmicb.2021.680553] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 05/27/2021] [Indexed: 11/13/2022] Open
Abstract
Glutaraldehyde is a widely used biocide on the market for about 50 years. Despite its broad application, several reports on the emergence of bacterial resistance, and occasional outbreaks caused by poorly disinfection, there is a gap of knowledge on the bacterial adaptation, tolerance, and resistance mechanisms to glutaraldehyde. Here, we analyze the effects of the independent selection of mutations in the transcriptional regulator yqhC for biological replicates of Escherichia coli cells subjected to adaptive laboratory evolution (ALE) in the presence of glutaraldehyde. The evolved strains showed improved survival in the biocide (11-26% increase in fitness) as a result of mutations in the activator yqhC, which led to the overexpression of the yqhD aldehyde reductase gene by 8 to over 30-fold (3.1-5.2 log2FC range). The protective effect was exclusive to yqhD as other aldehyde reductase genes of E. coli, such as yahK, ybbO, yghA, and ahr did not offer protection against the biocide. We describe a novel mechanism of tolerance to glutaraldehyde based on the activation of the aldehyde reductase YqhD by YqhC and bring attention to the potential for the selection of such tolerance mechanism outside the laboratory, given the existence of YqhD homologs in various pathogenic and opportunistic bacterial species.
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Affiliation(s)
- Beatriz Merchel Piovesan Pereira
- Microbiology Graduate Group, University of California, Davis, Davis, CA, United States
- Genome Center, University of California, Davis, Davis, CA, United States
| | - Muhammad Adil Salim
- Microbiology Graduate Group, University of California, Davis, Davis, CA, United States
- Genome Center, University of California, Davis, Davis, CA, United States
| | - Navneet Rai
- Genome Center, University of California, Davis, Davis, CA, United States
- Department of Computer Science, University of California, Davis, Davis, CA, United States
| | - Ilias Tagkopoulos
- Genome Center, University of California, Davis, Davis, CA, United States
- Department of Computer Science, University of California, Davis, Davis, CA, United States
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Rodríguez M A, Rache LY, Brijaldo MH, Romanelli GP, Luque R, Martinez JJ. Biocatalytic transformation of furfural into furfuryl alcohol using resting cells of Bacillus cereus. Catal Today 2021. [DOI: 10.1016/j.cattod.2021.01.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Mazzoli R, Olson D. Clostridium thermocellum: A microbial platform for high-value chemical production from lignocellulose. ADVANCES IN APPLIED MICROBIOLOGY 2020; 113:111-161. [PMID: 32948265 DOI: 10.1016/bs.aambs.2020.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Second generation biorefining, namely fermentation processes based on lignocellulosic feedstocks, has attracted tremendous interest (owing to the large availability and low cost of this biomass) as a strategy to produce biofuels and commodity chemicals that is an alternative to oil refining. However, the innate recalcitrance of lignocellulose has slowed progress toward economically viable processes. Consolidated bioprocessing (CBP), i.e., single-step fermentation of lignocellulose may dramatically reduce the current costs of 2nd generation biorefining. Metabolic engineering has been used as a tool to develop improved microbial strains supporting CBP. Clostridium thermocellum is among the most efficient cellulose degraders isolated so far and one of the most promising host organisms for application of CBP. The development of efficient and reliable genetic tools has allowed significant progress in metabolic engineering of this strain aimed at expanding the panel of growth substrates and improving the production of a number of commodity chemicals of industrial interest such as ethanol, butanol, isobutanol, isobutyl acetate and lactic acid. The present review aims to summarize recent developments in metabolic engineering of this organism which currently represents a reference model for the development of biocatalysts for 2nd generation biorefining.
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Suo Y, Liao Z, Qu C, Fu H, Wang J. Metabolic engineering of Clostridium tyrobutyricum for enhanced butyric acid production from undetoxified corncob acid hydrolysate. BIORESOURCE TECHNOLOGY 2019; 271:266-273. [PMID: 30278351 DOI: 10.1016/j.biortech.2018.09.095] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 09/15/2018] [Accepted: 09/17/2018] [Indexed: 06/08/2023]
Abstract
Resistance to furan derivatives and phenolic compounds plays an important role in the use of lignocellulosic biomass for biological production of chemicals and fuels. This study confirmed that expression of short-chain dehydrogenase/reductase (SDR) from Clostridium beijerinckii NCIMB 8052 significantly improved the tolerance of C. tyrobutyricum to furfural due to the enhanced activity for furfural reduction. And on this basis, co-expression of SDR and heat shock chaperones GroESL could simultaneously enhance the tolerance of C. tyrobutyricum to furan derivatives and phenolic compounds, which were the main inhibitors presented in dilute-acid lignocellulosic hydrolysates. Consequently, the recombinant strain ATCC 25755/sdr+groESL exhibited good performance in butyric acid production with corncob acid hydrolysate as the substrate. Batch fermentation in bioreactor showed that the butyrate produced by ATCC 25755/sdr+groESL was 32.8 g/L, increased by 28.1% as compared with the wild-type strain. Meanwhile, the butyrate productivity increased from 0.19 g/L·h to 0.29 g/L·h.
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Affiliation(s)
- Yukai Suo
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China; School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Zhengping Liao
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Chunyun Qu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Hongxin Fu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China.
| | - Jufang Wang
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China; School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China.
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Liu YJ, Qi K, Zhang J, Chen C, Cui Q, Feng Y. Firmicutes-enriched IS 1447 represents a group of IS 3-family insertion sequences exhibiting unique + 1 transcriptional slippage. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:300. [PMID: 30410575 PMCID: PMC6211511 DOI: 10.1186/s13068-018-1304-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/27/2018] [Indexed: 05/12/2023]
Abstract
BACKGROUND Bacterial insertion sequences (ISs) are ubiquitous mobile genetic elements that play important roles in genome plasticity, cell adaptability, and function evolution. ISs of various families and subgroups contain significantly diverse molecular features and functional mechanisms that are not fully understood. RESULTS IS1447 is a member of the widespread IS3 family and was previously detected to have transposing activity in a typical thermophilic and cellulolytic microorganism Clostridium thermocellum. Phylogenetic analysis showed that IS1447-like elements are widely distributed in Firmicutes and possess unique features in the IS3 family. Therefore, IS1447 may represent a novel subgroup of the IS3 family. Unlike other well-known IS3 subgroups performing programmed - 1 translational frameshifting for the expression of the transposase, IS1447 exhibits transcriptional slippage in both the + 1 and - 1 directions, each with a frequency of ~ 16%, and only + 1 slippage results in full-length and functional transposase. The slippage-prone region of IS1447 contains a run of nine A nucleotides following a stem-loop structure in mRNA, but mutagenesis analysis indicated that seven of them are sufficient for the observed slippage. Western blot analysis indicated that IS1447 produces three types of transposases with alternative initiations. Furthermore, the IS1447-subgroup elements are abundant in the genomes of several cellulolytic bacteria. CONCLUSION Our result indicated that IS1447 represents a new Firmicutes-enriched subgroup of the IS3 family. The characterization of the novel IS3-family member will enrich our understanding of the transposition behavior of IS elements and may provide insight into developing IS-based mutagenesis tools for thermophiles.
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Affiliation(s)
- Ya-Jun Liu
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Dalian, China
| | - Kuan Qi
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Dalian, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Jie Zhang
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Dalian, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- Present Address: Department of Biosystems Engineering, Auburn University, Auburn, AL 36849 USA
| | - Chao Chen
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Dalian, China
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Dalian, China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Dalian, China
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Engineering a spermidine biosynthetic pathway in Clostridium thermocellum results in increased resistance to furans and increased ethanol production. Metab Eng 2018; 49:267-274. [DOI: 10.1016/j.ymben.2018.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 08/27/2018] [Accepted: 09/04/2018] [Indexed: 12/29/2022]
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Groom J, Chung D, Kim SK, Guss A, Westpheling J. Deletion of the Clostridium thermocellum recA gene reveals that it is required for thermophilic plasmid replication but not plasmid integration at homologous DNA sequences. J Ind Microbiol Biotechnol 2018; 45:753-763. [PMID: 29808293 PMCID: PMC6483729 DOI: 10.1007/s10295-018-2049-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 05/19/2018] [Indexed: 12/30/2022]
Abstract
A limitation to the engineering of cellulolytic thermophiles is the availability of functional, thermostable (≥ 60 °C) replicating plasmid vectors for rapid expression and testing of genes that provide improved or novel fuel molecule production pathways. A series of plasmid vectors for genetic manipulation of the cellulolytic thermophile Caldicellulosiruptor bescii has recently been extended to Clostridium thermocellum, another cellulolytic thermophile that very efficiently solubilizes plant biomass and produces ethanol. While the C. bescii pBAS2 replicon on these plasmids is thermostable, the use of homologous promoters, signal sequences and genes led to undesired integration into the bacterial chromosome, a result also observed with less thermostable replicating vectors. In an attempt to overcome undesired plasmid integration in C. thermocellum, a deletion of recA was constructed. As expected, C. thermocellum ∆recA showed impaired growth in chemically defined medium and an increased susceptibility to UV damage. Interestingly, we also found that recA is required for replication of the C. bescii thermophilic plasmid pBAS2 in C. thermocellum, but it is not required for replication of plasmid pNW33N. In addition, the C. thermocellum recA mutant retained the ability to integrate homologous DNA into the C. thermocellum chromosome. These data indicate that recA can be required for replication of certain plasmids, and that a recA-independent mechanism exists for the integration of homologous DNA into the C. thermocellum chromosome. Understanding thermophilic plasmid replication is not only important for engineering of these cellulolytic thermophiles, but also for developing genetic systems in similar new potentially useful non-model organisms.
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Affiliation(s)
- Joseph Groom
- Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, GA, 30602, USA
- Department of Chemical Engineering, University of Washington, Seattle, WA, 98105, USA
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA
| | - Daehwan Chung
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO, 80401, USA
- Oak Ridge National Laboratory, The BioEnergy Science Center, Oak Ridge, TN, 37831, USA
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA
| | - Sun-Ki Kim
- Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, GA, 30602, USA
- Oak Ridge National Laboratory, The BioEnergy Science Center, Oak Ridge, TN, 37831, USA
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA
| | - Adam Guss
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Oak Ridge National Laboratory, The BioEnergy Science Center, Oak Ridge, TN, 37831, USA
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA
| | - Janet Westpheling
- Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, GA, 30602, USA.
- Oak Ridge National Laboratory, The BioEnergy Science Center, Oak Ridge, TN, 37831, USA.
- Oak Ridge National Laboratory, The Center for BioEnergy Innovation, Oak Ridge, TN, 37831, USA.
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Suo Y, Fu H, Ren M, Yang X, Liao Z, Wang J. Butyric acid production from lignocellulosic biomass hydrolysates by engineered Clostridium tyrobutyricum overexpressing Class I heat shock protein GroESL. BIORESOURCE TECHNOLOGY 2018; 250:691-698. [PMID: 29220814 DOI: 10.1016/j.biortech.2017.11.059] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/17/2017] [Accepted: 11/18/2017] [Indexed: 06/07/2023]
Abstract
Lignocellulosic biomass is the most abundant and renewable substrate for biological fermentation, but the inhibitors present in the lignocellulosic hydrolysates could severely inhibit the cell growth and productivity of industrial strains. This study confirmed that overexpressing of native groESL in Clostridium tyrobutyricum could significantly improve its tolerance to lignocellulosic hydrolysate-derived inhibitors, especially for phenolic compounds. Consequently, ATCC 25755/groESL showed a better performance in butyric acid fermentation with hydrolysates of corn cob, corn straw, rice straw, wheat straw, soybean hull and soybean straw, respectively. When corn straw and rice straw hydrolysates, which showed strong toxicity to C. tyrobutyricum, were used as the substrates, 29.6 g/L and 30.1 g/L butyric acid were obtained in batch fermentation, increased by 26.5% and 19.4% as compared with the wild-type strain, respectively. And more importantly, the butyric acid productivity reached 0.31 g/L·h (vs. 0.20-0.21 g/L·h for the wild-type strain) due to the shortened lag phase.
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Affiliation(s)
- Yukai Suo
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Hongxin Fu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Mengmeng Ren
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Xitong Yang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Zhengping Liao
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Jufang Wang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China; State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China.
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Verbeke TJ, Garcia GM, Elkins JG. The effect of switchgrass loadings on feedstock solubilization and biofuel production by Clostridium thermocellum. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:233. [PMID: 29213307 PMCID: PMC5708108 DOI: 10.1186/s13068-017-0917-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/08/2017] [Indexed: 05/25/2023]
Abstract
BACKGROUND Efficient deconstruction and bioconversion of solids at high mass loadings is necessary to produce industrially relevant titers of biofuels from lignocellulosic biomass. To date, only a few studies have investigated the effect of solids loadings on microorganisms of interest for consolidated bioprocessing. Here, the effects that various switchgrass loadings have on Clostridium thermocellum solubilization and bioconversion are investigated. RESULTS Clostridium thermocellum was grown for 10 days on 10, 25, or 50 g/L switchgrass or Avicel at equivalent glucan loadings. Avicel was completely consumed at all loadings, but total cellulose solubilization decreased from 63 to 37% as switchgrass loadings increased from 10 to 50 g/L. Washed, spent switchgrass could be additionally hydrolyzed and fermented in second-round fermentations suggesting that access to fermentable substrates was not the limiting factor at higher feedstock loadings. Results from fermentations on Avicel or cellobiose using culture medium supplemented with 50% spent fermentation broth demonstrated that compounds present in the supernatants from the 25 or 50 g/L switchgrass loadings were the most inhibitory to continued fermentation. CONCLUSIONS Recalcitrance alone cannot fully account for differences in solubilization and end-product formation between switchgrass and Avicel at increased substrate loadings. Experiments aimed at separating metabolic inhibition from inhibition of hydrolysis suggest that C. thermocellum's hydrolytic machinery is more vulnerable to inhibition from switchgrass-derived compounds than its fermentative metabolism.
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Affiliation(s)
- Tobin J. Verbeke
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6038 USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6038 USA
- Present Address: Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4 Canada
| | - Gabriela M. Garcia
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6038 USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6038 USA
| | - James G. Elkins
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6038 USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6038 USA
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