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Kumar A, Sharma S, Dindhoria K, Thakur A, Kumar R. Insight into physico-chemical properties and microbial community structure of biogas slurry from household biogas plants of sub-Himalaya for its implications in improved biogas production. Int Microbiol 2024:10.1007/s10123-024-00530-w. [PMID: 38760649 DOI: 10.1007/s10123-024-00530-w] [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: 03/05/2024] [Revised: 04/21/2024] [Accepted: 05/07/2024] [Indexed: 05/19/2024]
Abstract
Numerous metagenomics studies, conducted in both full-scale anaerobic digesters and household biogas plants, have shed light on the composition and activity of microbial flora essential for optimizing the performance of biogas reactors, underscoring the significance of microbial community composition in biogas plant efficiency. Although the efficiency of household biogas plants in the sub-Himalayan region has been reported, there is no literature evidence on the microbial community structure of such household biogas plants in the sub-Himalayan region. The current study evaluated the physico-chemical properties and bacterial community structure from the slurry samples of household biogas plants prevalent in the sub-Himalayan region. The slurry samples were observed to be rich in nutrients; however, their carbon and nitrogen contents were higher than the recommended standard values of liquid-fermented organic manure. The species richness and diversity indices (Chao1, Shannon, and Simpson) of household biogas plants were quite similar to the advanced biogas reactors operating at mesophilic conditions. 16S rRNA gene amplicon sequencing reveals microbial diversity, showing a higher abundance of Firmicutes (70.9%) and Euryarchaeota (9.52%) in advanced biogas reactors compared to household biogas plants. Microbial analysis shows a lack of beneficial microbes for anaerobic digestion, which might be the reason for inefficient biogas production in household biogas plants of the sub-Himalayan region. The lack of efficient bacterial biomass may also be attributed to the digester design, feedstock, and ambient temperatures. This study emphasized the establishment of efficient microbial consortia for enhanced degradation rates that may increase the methane yield in biogas plants.
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Affiliation(s)
- Aman Kumar
- Department of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, 176061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Sonia Sharma
- Department of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, 176061, India
| | - Kiran Dindhoria
- Department of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, 176061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Aman Thakur
- Department of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, 176061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Rakshak Kumar
- Department of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, 176061, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
- Department of Molecular Biology & Bioinformatics, Tripura University (A Central University), Suryamaninagar, Tripura, 799022, India.
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Akram F, Fatima T, Ibrar R, Shabbir I, Shah FI, Haq IU. Trends in the development and current perspective of thermostable bacterial hemicellulases with their industrial endeavors: A review. Int J Biol Macromol 2024; 265:130993. [PMID: 38508567 DOI: 10.1016/j.ijbiomac.2024.130993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 03/12/2024] [Accepted: 03/17/2024] [Indexed: 03/22/2024]
Abstract
Hemicellulases are enzymes that hydrolyze hemicelluloses, common polysaccharides in nature. Thermophilic hemicellulases, derived from microbial strains, are extensively studied as natural biofuel sources due to the complex structure of hemicelluloses. Recent research aims to elucidate the catalytic principles, mechanisms and specificity of hemicellulases through investigations into their high-temperature stability and structural features, which have applications in biotechnology and industry. This review article targets to serve as a comprehensive resource, highlighting the significant progress in the field and emphasizing the vital role of thermophilic hemicellulases in eco-friendly catalysis. The primary goal is to improve the reliability of hemicellulase enzymes obtained from thermophilic bacterial strains. Additionally, with their ability to break down lignocellulosic materials, hemicellulases hold immense potential for biofuel production. Despite their potential, the commercial viability is hindered by their high enzyme costs, necessitating the development of efficient bioprocesses involving waste pretreatment with microbial consortia to overcome this challenge.
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Affiliation(s)
- Fatima Akram
- Institute of Industrial Biotechnology, Government College University, Lahore 54000, Pakistan.
| | - Taseer Fatima
- Institute of Industrial Biotechnology, Government College University, Lahore 54000, Pakistan
| | - Ramesha Ibrar
- Institute of Industrial Biotechnology, Government College University, Lahore 54000, Pakistan
| | - Ifrah Shabbir
- Institute of Industrial Biotechnology, Government College University, Lahore 54000, Pakistan
| | | | - Ikram Ul Haq
- Institute of Industrial Biotechnology, Government College University, Lahore 54000, Pakistan; Pakistan Academy of Sciences, Islamabad, Pakistan
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3
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Xiao Y, Dong S, Liu YJ, You C, Feng Y, Cui Q. Key roles of β-glucosidase BglA for the catabolism of both laminaribiose and cellobiose in the lignocellulolytic bacterium Clostridium thermocellum. Int J Biol Macromol 2023; 250:126226. [PMID: 37558019 DOI: 10.1016/j.ijbiomac.2023.126226] [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: 04/05/2023] [Revised: 07/31/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023]
Abstract
The thermophilic bacterium Clostridium thermocellum efficiently degrades polysaccharides into oligosaccharides. The metabolism of β-1,4-linked cello-oligosaccharides is initiated by three enzymes, i.e., the cellodextrin phosphorylase (Cdp), the cellobiose phosphorylase (Cbp), and the β-glucosidase A (BglA), in C. thermocellum. In comparison, how the oligosaccharides containing other kinds of linkage are utilized is rarely understood. In this study, we found that BglA could hydrolyze the β-1,3-disaccharide laminaribiose with much higher activity than that against the β-1,4-disaccharide cellobiose. The structural basis of the substrate specificity was analyzed by crystal structure determination and molecular docking. Genetic deletions of BglA and Cbp, respectively, and enzymatic analysis of cell extracts demonstrated that BglA is the key enzyme responsible for laminaribiose metabolism. Furthermore, the deletion of BglA can suppress the expression of Cbp and the deletion of Cbp can up-regulate the expression of BglA, indicating that BglA and Cbp have cross-regulation and BglA is also critical for cellobiose metabolism. These insights pave the way for both a fundamental understanding of metabolism and regulation in C. thermocellum and emphasize the importance of the degradation and utilization of polysaccharides containing β-1,3-linked glycosidic bonds in lignocellulose biorefinery.
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Affiliation(s)
- Yan Xiao
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Sheng Dong
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Ya-Jun Liu
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Chun You
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China.
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4
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Chai G, Wang D, Zhang Y, Wang H, Li J, Jing X, Meng H, Wang Z, Guo Y, Jiang C, Li H, Lin Y. Effects of organic substrates on sulfate-reducing microcosms treating acid mine drainage: Performance dynamics and microbial community comparison. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 330:117148. [PMID: 36584458 DOI: 10.1016/j.jenvman.2022.117148] [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: 09/30/2022] [Revised: 12/22/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
Bioremediation techniques utilizing sulfate-reducing bacteria (SRB) for acid mine drainage (AMD) treatment have attracted growing attention in recent years, yet substrate bioavailability for SRB is a key factor influencing treatment effectiveness and long-term stability. This study investigated the effects of external organic substrates, including four complex organic wastes (i.e., sugarcane bagasse, straw compost, shrimp shell (SS), and crab shell (CS)) and a small-molecule organic acid (i.e., propionate), on AMD removal performance and associated microbial communities during the 30-day operation of sulfate-reducing microcosms. The results showed that the pH values increased in all five microcosms, while CS exhibited the highest neutralization ability and a maximum alkalinity generation of 1507 mg/L (as CaCO3). Sulfate reduction was more effective in SS and CS microcosms, with sulfate removal efficiencies of 95.6% and 86.0%, respectively. All sulfate-reducing microcosms could remove heavy metals to different degrees, with the highest removal rate of >99.0% observed for aluminum. The removal efficiency of manganese, the most recalcitrant metal, was the highest (96%) in the CS microcosm. Correspondingly, SRB was more abundant in the CS and SS microcosms as revealed by sequencing analysis, while Desulfotomaculum was the dominant SRB in the CS microcosm, accounting for 10.8% of total effective bacterial sequences. Higher abundances of functional genes involved in fermentation and sulfur cycle were identified in CS and SS microcosms. This study suggests that complex organic wastes such as CS and SS could create and maintain preferable micro-environments for active growth and metabolism of functional microorganisms, thus offering a cost-efficient, stable, and environmental-friendly solution for AMD treatment and management.
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Affiliation(s)
- Guodong Chai
- State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China; Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China
| | - Dongqi Wang
- State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China; Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China; Shaanxi Key Laboratory of Water Resources and Environment, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China
| | - Yitong Zhang
- Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China
| | - Hui Wang
- Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China
| | - Jiake Li
- State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China; Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China
| | - Xiaosheng Jing
- Zhongsheng Environmental Technology Development Co., Ltd., Xi'an, Shaanxi, 710054, China
| | - Haiyu Meng
- Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China
| | - Zhe Wang
- State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China; Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China
| | - Yuan Guo
- Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China
| | - Chunbo Jiang
- Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China
| | - Huaien Li
- State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China; Department of Municipal and Environmental Engineering, School of Water Resources and Hydro-Electric Engineering, Xi'an University of Technology, Xi'an, Shaanxi, 710048, China.
| | - Yishan Lin
- Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, College of Urban and Environmental Sciences, Northwest University, Xi'an, 710127, China.
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5
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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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6
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de Camargo BR, Steindorff AS, da Silva LA, de Oliveira AS, Hamann PRV, Noronha EF. Expression profiling of Clostridium thermocellum B8 during the deconstruction of sugarcane bagasse and straw. World J Microbiol Biotechnol 2023; 39:105. [PMID: 36840776 DOI: 10.1007/s11274-023-03546-y] [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: 11/14/2022] [Accepted: 02/10/2023] [Indexed: 02/26/2023]
Abstract
The gram-positive bacterium Clostridium thermocellum contains a set of carbohydrate-active enzymes that can potentially be employed to generate high-value-added products from lignocellulose. In this study, the gene expression profiling of C. thermocellum B8 was provided during growth in the presence of sugarcane bagasse and straw as a carbon source in comparison to growth using microcrystalline cellulose. A total of 625 and 509 genes were up-regulated for growth in the presence of bagasse and straw, respectively. These genes were mainly grouped into carbohydrate-active enzymes (CAZymes), cell motility, chemotaxis, quorum sensing pathway and expression control of glycoside hydrolases. These results show that type of carbon source modulates the gene expression profiling of carbohydrate-active enzymes. In addition, highlight the importance of cell motility, attachment to the substrate and communication in deconstructing complex substrates. This present work may contribute to the development of enzymatic cocktails and industrial strains for biorefineries based on sugarcane residues as feedstock.
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Affiliation(s)
- Brenda Rabello de Camargo
- Laboratory of Enzymology, Department of Cell Biology, University of Brasília, Brasilia, DF, 70910-900, Brazil
| | | | - Leonardo Assis da Silva
- Laboratory of Virology, Department of Cell Biology, University of Brasília, Brasília, DF, Brazil
| | - Athos Silva de Oliveira
- Laboratory of Virology, Department of Cell Biology, University of Brasília, Brasília, DF, Brazil
| | - Pedro Ricardo Vieira Hamann
- São Carlos Institute of Physics, University of São Paulo, Avenida Trabalhador São-Carlense,400, Parque Arnold Schimidt, São Carlos, SP, 13566-590, Brazil
| | - Eliane Ferreira Noronha
- Laboratory of Enzymology, Department of Cell Biology, University of Brasília, Brasilia, DF, 70910-900, Brazil.
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7
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Tao S, Qingbin M, Zhiling L, Caiyu S, Lixin L, Lilai L. Comparative genomics reveals cellobiose hydrolysis mechanism of Ruminiclostridium thermocellum M3, a cellulosic saccharification bacterium. Front Microbiol 2023; 13:1079279. [PMID: 36687593 PMCID: PMC9852859 DOI: 10.3389/fmicb.2022.1079279] [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: 10/25/2022] [Accepted: 12/07/2022] [Indexed: 01/08/2023] Open
Abstract
The cellulosome of Ruminiclostridium thermocellum was one of the most efficient cellulase systems in nature. However, the product of cellulose degradation by R. thermocellum is cellobiose, which leads to the feedback inhibition of cellulosome, and it limits the R. thermocellum application in the field of cellulosic biomass consolidated bioprocessing (CBP) industry. In a previous study, R. thermocellum M3, which can hydrolyze cellulosic feedstocks into monosaccharides, was isolated from horse manure. In this study, the complete genome of R. thermocellum M3 was sequenced and assembled. The genome of R. thermocellum M3 was compared with the other R. thermocellum to reveal the mechanism of cellulosic saccharification by R. thermocellum M3. In addition, we predicted the key genes for the elimination of feedback inhibition of cellobiose in R. thermocellum. The results indicated that the whole genome sequence of R. thermocellum M3 consisted of 3.6 Mb of chromosomes with a 38.9% of GC%. To be specific, eight gene islands and 271 carbohydrate-active enzyme-encoded proteins were detected. Moreover, the results of gene function annotation showed that 2,071, 2,120, and 1,246 genes were annotated into the Clusters of Orthologous Groups (COG), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, respectively, and most of the genes were involved in carbohydrate metabolism and enzymatic catalysis. Different from other R. thermocellum, strain M3 has three proteins related to β-glucosidase, and the cellobiose hydrolysis was enhanced by the synergy of gene BglA and BglX. Meanwhile, the GH42 family, CBM36 family, and AA8 family might participate in cellobiose degradation.
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Affiliation(s)
- Sheng Tao
- College of Environmental and Chemical Engineering, Heilongjiang University of Science and Technology, Harbin, China,*Correspondence: Sheng Tao,
| | - Meng Qingbin
- College of Environmental and Chemical Engineering, Heilongjiang University of Science and Technology, Harbin, China
| | - Li Zhiling
- State Key Lab of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China,Li Zhiling,
| | - Sun Caiyu
- College of Environmental and Chemical Engineering, Heilongjiang University of Science and Technology, Harbin, China
| | - Li Lixin
- College of Environmental and Chemical Engineering, Heilongjiang University of Science and Technology, Harbin, China
| | - Liu Lilai
- College of Environmental and Chemical Engineering, Heilongjiang University of Science and Technology, Harbin, China
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8
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Nongthombam GD, Sarangi PK, Singh TA, Sharma CK, Talukdar NC. Bioethanol production from Ficus fruits ( Ficus cunia) by Fusarium oxysporum through consolidated bioprocessing system. 3 Biotech 2022; 12:178. [PMID: 35865259 PMCID: PMC9294110 DOI: 10.1007/s13205-022-03234-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 06/18/2022] [Indexed: 11/01/2022] Open
Abstract
Fusarium oxysporum is among the few filamentous fungi capable of fermenting ethanol directly from lignocellulose biomass (LCB). It has the essential enzymatic toolbox to disintegrate LCB to its monosaccharides, which subsequently fermented to ethanol under anaerobic and micro-aerobic conditions. However, the structural complexity of LCB and modest performances of wild fungi are major limitations for application in local biorefineries. This study assessed the potential of the locally isolated Fusarium oxysporum for the production of bioethanol from Ficus fruits (Ficus cunia) using Consolidated Bioprocessing (CBP). The maximum ethanol concentration achieved was at 5% substrate loadings with pH 6 irrespective of temperature variance, attaining a concentration of 3.54 g/L and 3.88 g/L at 28 °C and 32 °C, respectively. The monitoring of analytes (glucose, arabinose, cellobiose, xylose, acetic acid, ethanol, furfural, and HMF) in this study suggests the utilization of an array of sugars released from Ficus fruits, irrespective of the difference in the process parameters. This study also shows that CBP of freshly grounded Ficus fruits was feasible employing a mild hydrothermal pretreatment (autoclaved at 121 °C for 30 min in 1:10 w/v) and without supplementing any extraneous enzymes. Supplementary Information The online version contains supplementary material available at 10.1007/s13205-022-03234-y.
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Affiliation(s)
| | | | | | - Chandradev K. Sharma
- Institute of Bioresources and Sustainable Development (IBSD), Takyelpat, Imphal, 795001 India
| | - Narayan C. Talukdar
- Faculty of Science, Assam Downtown University, Panikhaiti, Guwahati, 781006 India
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9
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Mahoney BJ, Takayesu A, Zhou A, Cascio D, Clubb RT. The structure of the Clostridium thermocellum RsgI9 ectodomain provides insight into the mechanism of biomass sensing. Proteins 2022; 90:1457-1467. [PMID: 35194841 PMCID: PMC9177573 DOI: 10.1002/prot.26326] [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: 10/26/2021] [Accepted: 02/10/2022] [Indexed: 01/03/2023]
Abstract
Clostridium thermocellum is actively being developed as a microbial platform to produce biofuels and chemicals from renewable plant biomass. An attractive feature of this bacterium is its ability to efficiently degrade lignocellulose using surface-displayed cellulosomes, large multi-protein complexes that house different types of cellulase enzymes. Clostridium thermocellum tailors the enzyme composition of its cellulosome using nine membrane-embedded anti-σ factors (RsgI1-9), which are thought to sense different types of extracellular carbohydrates and then elicit distinct gene expression programs via cytoplasmic σ factors. Here we show that the RsgI9 anti-σ factor interacts with cellulose via a C-terminal bi-domain unit. A 2.0 Å crystal structure reveals that the unit is constructed from S1C peptidase and NTF2-like protein domains that contain a potential binding site for cellulose. Small-angle X-ray scattering experiments of the intact ectodomain indicate that it adopts a bi-lobed, elongated conformation. In the structure, a conserved RsgI extracellular (CRE) domain is connected to the bi-domain via a proline-rich linker, which is expected to project the carbohydrate-binding unit ~160 Å from the cell surface. The CRE and proline-rich elements are conserved in several other C. thermocellum anti-σ factors, suggesting that they will also form extended structures that sense carbohydrates.
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Affiliation(s)
- Brendan J. Mahoney
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Allen Takayesu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Anqi Zhou
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Duilio Cascio
- UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Robert T. Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA.,Molecular Biology Institute, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA.,To whom correspondence should be addressed: Prof. Robert T. Clubb, Department of Chemistry and Biochemistry, University of California, Los Angeles, 602 Boyer Hall, Los Angeles, CA 90095
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10
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Dudek K, Molina-Guerrero CE, Valdez-Vazquez I. Profitability of single- and mixed-culture fermentations for the butyric acid production from a lignocellulosic substrate. Chem Eng Res Des 2022. [DOI: 10.1016/j.cherd.2022.04.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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11
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Huang JR, Chen X, Hu BB, Cheng JR, Zhu MJ. Bioaugmentation combined with biochar to enhance thermophilic hydrogen production from sugarcane bagasse. BIORESOURCE TECHNOLOGY 2022; 348:126790. [PMID: 35104653 DOI: 10.1016/j.biortech.2022.126790] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/23/2022] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
In this study, Thermoanaerobacterium thermosaccharolyticum MJ2 and biochar were used to enhance thermophilic hydrogen production from sugarcane bagasse. MJ2 bioaugmentation notably increased the hydrogen production by 95.31%, which was further significantly improved by 158.10% by adding biochar. The addition of biochar promoted the degradation of substrate, improved the activities of hydrogenase and electron transfer system, and stimulated microbial growth and metabolism. Microbial community analysis showed that the relative abundance of Thermoanaerobacterium was significantly increased by bioaugmentation and further enriched by biochar. PICRUSt analysis showed that MJ2 combined with biochar promoted metabolic pathways related to substrate degradation and microbial metabolism. This study provides a novel enhancement method for hydrogen production of the cellulolytic microbial consortium by exogenous hydrogen-producing microorganism combined with biochar and deepens the understanding of its functional mechanism.
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Affiliation(s)
- Jin-Rong Huang
- School of Biology and Biological Engineering, Guangdong Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Panyu, Guangzhou 510006, China
| | - Xiong Chen
- Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, Hubei, China
| | - Bin-Bin Hu
- Yunnan Academy of Tobacco Agricultural Sciences, Kunming 650021, China
| | - Jing-Rong Cheng
- Sericultural & Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Agricultural Products Processing, Guangzhou 510610, China
| | - Ming-Jun Zhu
- School of Biology and Biological Engineering, Guangdong Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Panyu, Guangzhou 510006, China; Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, Hubei, China; College of Life and Geographic Sciences, The Key Laboratory of Biological Resources and Ecology of Pamirs Plateau in Xinjiang Uygur Autonomous Region, The Key Laboratory of Ecology and Biological Resources in Yarkand Oasis at Colleges & Universities under the Department of Education of Xinjiang Uygur Autonomous Region, Kashi University, Kashi 844000, China.
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12
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Biswal AK, Hengge NN, Black IM, Atmodjo MA, Mohanty SS, Ryno D, Himmel ME, Azadi P, Bomble YJ, Mohnen D. Composition and yield of non-cellulosic and cellulosic sugars in soluble and particulate fractions during consolidated bioprocessing of poplar biomass by Clostridium thermocellum. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:23. [PMID: 35227303 PMCID: PMC8887089 DOI: 10.1186/s13068-022-02119-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 02/10/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Terrestrial plant biomass is the primary renewable carbon feedstock for enabling transition to a sustainable bioeconomy. Consolidated bioprocessing (CBP) by the cellulolytic thermophile Clostridium thermocellum offers a single step microbial platform for production of biofuels and biochemicals via simultaneous solubilization of carbohydrates from lignocellulosic biomass and conversion to products. Here, solubilization of cell wall cellulosic, hemicellulosic, and pectic polysaccharides in the liquor and solid residues generated during CBP of poplar biomass by C. thermocellum was analyzed. RESULTS The total amount of biomass solubilized in the C. thermocellum DSM1313 fermentation platform was 5.8, 10.3, and 13.7% of milled non-pretreated poplar after 24, 48, and 120 h, respectively. These results demonstrate solubilization of 24% cellulose and 17% non-cellulosic sugars after 120 h, consistent with prior reports. The net solubilization of non-cellulosic sugars by C. thermocellum (after correcting for the uninoculated control fermentations) was 13 to 36% of arabinose (Ara), xylose (Xyl), galactose (Gal), mannose (Man), and glucose (Glc); and 15% and 3% of fucose and glucuronic acid, respectively. No rhamnose was solubilized and 71% of the galacturonic acid (GalA) was solubilized. These results indicate that C. thermocellum may be selective for the types and/or rate of solubilization of the non-cellulosic wall polymers. Xyl, Man, and Glc were found to accumulate in the fermentation liquor at levels greater than in uninoculated control fermentations, whereas Ara and Gal did not accumulate, suggesting that C. thermocellum solubilizes both hemicelluloses and pectins but utilizes them differently. After five days of fermentation, the relative amount of Rha in the solid residues increased 21% indicating that the Rha-containing polymer rhamnogalacturonan I (RG-I) was not effectively solubilized by C. thermocellum CBP, a result confirmed by immunoassays. Comparison of the sugars in the liquor versus solid residue showed that C. thermocellum solubilized hemicellulosic xylan and mannan, but did not fully utilize them, solubilized and appeared to utilize pectic homogalacturonan, and did not solubilize RG-I. CONCLUSIONS The significant relative increase in RG-I in poplar solid residues following CBP indicates that C. thermocellum did not solubilize RG-I. These results support the hypothesis that this pectic glycan may be one barrier for efficient solubilization of poplar by C. thermocellum.
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Affiliation(s)
- Ajaya K. Biswal
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602 USA
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Rd, Athens, GA 30602 USA
| | - Neal N. Hengge
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Ian M. Black
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Rd, Athens, GA 30602 USA
| | - Melani A. Atmodjo
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602 USA
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Rd, Athens, GA 30602 USA
| | - Sushree S. Mohanty
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Rd, Athens, GA 30602 USA
| | - David Ryno
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Rd, Athens, GA 30602 USA
| | - Michael E. Himmel
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Rd, Athens, GA 30602 USA
| | - Yannick J. Bomble
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Debra Mohnen
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602 USA
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Rd, Athens, GA 30602 USA
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13
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Ichikawa S, Ito D, Asaoka S, Abe R, Katsuo N, Ito T, Ito D, Karita S. The expression of alternative sigma-I7 factor induces the transcription of cellulosomal genes in the cellulolytic bacterium Clostridium thermocellum. Enzyme Microb Technol 2022; 156:110002. [DOI: 10.1016/j.enzmictec.2022.110002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 01/12/2022] [Accepted: 01/31/2022] [Indexed: 01/07/2023]
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14
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Assessing the impact of substrate-level enzyme regulations limiting ethanol titer in Clostridium thermocellum using a core kinetic model. Metab Eng 2022; 69:286-301. [PMID: 34982997 DOI: 10.1016/j.ymben.2021.12.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 12/16/2021] [Accepted: 12/29/2021] [Indexed: 11/20/2022]
Abstract
Clostridium thermocellum is a promising candidate for consolidated bioprocessing because it can directly ferment cellulose to ethanol. Despite significant efforts, achieved yields and titers fall below industrially relevant targets. This implies that there still exist unknown enzymatic, regulatory, and/or possibly thermodynamic bottlenecks that can throttle back metabolic flow. By (i) elucidating internal metabolic fluxes in wild-type C. thermocellum grown on cellobiose via 13C-metabolic flux analysis (13C-MFA), (ii) parameterizing a core kinetic model, and (iii) subsequently deploying an ensemble-docking workflow for discovering substrate-level regulations, this paper aims to reveal some of these factors and expand our knowledgebase governing C. thermocellum metabolism. Generated 13C labeling data were used with 13C-MFA to generate a wild-type flux distribution for the metabolic network. Notably, flux elucidation through MFA alluded to serine generation via the mercaptopyruvate pathway. Using the elucidated flux distributions in conjunction with batch fermentation process yield data for various mutant strains, we constructed a kinetic model of C. thermocellum core metabolism (i.e. k-ctherm138). Subsequently, we used the parameterized kinetic model to explore the effect of removing substrate-level regulations on ethanol yield and titer. Upon exploring all possible simultaneous (up to four) regulation removals we identified combinations that lead to many-fold model predicted improvement in ethanol titer. In addition, by coupling a systematic method for identifying putative competitive inhibitory mechanisms using K-FIT kinetic parameterization with the ensemble-docking workflow, we flagged 67 putative substrate-level inhibition mechanisms across central carbon metabolism supported by both kinetic formalism and docking analysis.
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15
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An Q, Lin HN, Wang YT, Deng MC, Zhu MJ. Improved saccharification of pretreated lignocellulose by Clostridium thermocellum with the addition of surfactant, low loading of cellulose. Process Biochem 2021. [DOI: 10.1016/j.procbio.2021.10.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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16
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Bioconversion of Lignocellulosic Biomass into Value Added Products under Anaerobic Conditions: Insight into Proteomic Studies. Int J Mol Sci 2021; 22:ijms222212249. [PMID: 34830131 PMCID: PMC8624197 DOI: 10.3390/ijms222212249] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/07/2021] [Accepted: 11/09/2021] [Indexed: 01/14/2023] Open
Abstract
Production of biofuels and other value-added products from lignocellulose breakdown requires the coordinated metabolic activity of varied microorganisms. The increasing global demand for biofuels encourages the development and optimization of production strategies. Optimization in turn requires a thorough understanding of the microbial mechanisms and metabolic pathways behind the formation of each product of interest. Hydrolysis of lignocellulosic biomass is a bottleneck in its industrial use and often affects yield efficiency. The accessibility of the biomass to the microorganisms is the key to the release of sugars that are then taken up as substrates and subsequently transformed into the desired products. While the effects of different metabolic intermediates in the overall production of biofuel and other relevant products have been studied, the role of proteins and their activity under anaerobic conditions has not been widely explored. Shifts in enzyme production may inform the state of the microorganisms involved; thus, acquiring insights into the protein production and enzyme activity could be an effective resource to optimize production strategies. The application of proteomic analysis is currently a promising strategy in this area. This review deals on the aspects of enzymes and proteomics of bioprocesses of biofuels production using lignocellulosic biomass as substrate.
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17
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Lee HJ, Kang TG, Kim YW, Lee HS, Kim SK. Functional expression and extracellular secretion of Clostridium thermocellum Cel48S cellulase in Escherichia coli via the signal recognition particle-dependent translocation pathway. Enzyme Microb Technol 2021; 151:109918. [PMID: 34649693 DOI: 10.1016/j.enzmictec.2021.109918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/12/2021] [Accepted: 09/12/2021] [Indexed: 11/17/2022]
Abstract
As the only glycoside hydrolase family 48 member in Clostridium thermocellum, the exoglucanase Cel48S plays a crucial role in the extremely high activity of the cellulosome against crystalline cellulose. Although the importance of Cel48S in the hydrolysis of crystalline cellulose has been widely accepted, an efficient production system has not yet been established because Cel48S is usually expressed in Escherichia coli within inactive inclusion bodies. For unstable proteins like Cel48S, translocation across the inner membrane can be more advantageous than cytoplasmic production due to the presence of folding modulators in the periplasm and the absence of cytoplasmic proteases. In this study, we evaluated whether the production of Cel48S in the periplasmic space of E. coli could enhance its functional expression. To do so, we attached the PelB signal peptide, which mediates post-translational secretion, to the N-terminal end of Cel48S (P-Cel48S). The PelB signal peptide allowed catalytically active Cel48S to be successfully produced in the culture medium. In addition, we investigated the role of an alternative co-translational pathway on the extracellular production of Cel48S, finding that co-translational secretion yielded a specific activity of recombinant Cel48S of 135.1 ± 10.0 U/mg cell in the culture medium, which was 2.2 times higher than that associated with P-Cel48S expression. Therefore, we believe that our approach has potential applications for the cost-effective conversion of lignocellulosic biomass and the industrial production of other unstable proteins.
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Affiliation(s)
- Hyun-Jae Lee
- Department of Food Science and Technology, Chung-Ang University, Anseong, Gyeonggi, 17546, Republic of Korea
| | - Tae-Gu Kang
- Department of Food Science and Technology, Chung-Ang University, Anseong, Gyeonggi, 17546, Republic of Korea
| | - Young-Woo Kim
- Department of Food Science and Technology, Chung-Ang University, Anseong, Gyeonggi, 17546, Republic of Korea
| | - Hee-Seok Lee
- Department of Food Science and Technology, Chung-Ang University, Anseong, Gyeonggi, 17546, Republic of Korea.
| | - Sun-Ki Kim
- Department of Food Science and Technology, Chung-Ang University, Anseong, Gyeonggi, 17546, Republic of Korea.
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18
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Gardner JG, Schreier HJ. Unifying themes and distinct features of carbon and nitrogen assimilation by polysaccharide-degrading bacteria: a summary of four model systems. Appl Microbiol Biotechnol 2021; 105:8109-8127. [PMID: 34611726 DOI: 10.1007/s00253-021-11614-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 11/24/2022]
Abstract
Our current understanding of enzymatic polysaccharide degradation has come from a huge number of in vitro studies with purified enzymes. While this vast body of work has been invaluable in identifying and characterizing novel mechanisms of action and engineering desirable traits into these enzymes, a comprehensive picture of how these enzymes work as part of a native in vivo system is less clear. Recently, several model bacteria have emerged with genetic systems that allow for a more nuanced study of carbohydrate active enzymes (CAZymes) and how their activity affects bacterial carbon metabolism. With these bacterial model systems, it is now possible to not only study a single nutrient system in isolation (i.e., carbohydrate degradation and carbon metabolism), but also how multiple systems are integrated. Given that most environmental polysaccharides are carbon rich but nitrogen poor (e.g., lignocellulose), the interplay between carbon and nitrogen metabolism in polysaccharide-degrading bacteria can now be studied in a physiologically relevant manner. Therefore, in this review, we have summarized what has been experimentally determined for CAZyme regulation, production, and export in relation to nitrogen metabolism for two Gram-positive (Caldicellulosiruptor bescii and Clostridium thermocellum) and two Gram-negative (Bacteroides thetaiotaomicron and Cellvibrio japonicus) polysaccharide-degrading bacteria. By comparing and contrasting these four bacteria, we have highlighted the shared and unique features of each, with a focus on in vivo studies, in regard to carbon and nitrogen assimilation. We conclude with what we believe are two important questions that can act as guideposts for future work to better understand the integration of carbon and nitrogen metabolism in polysaccharide-degrading bacteria. KEY POINTS: • Regardless of CAZyme deployment system, the generation of a local pool of oligosaccharides is a common strategy among Gram-negative and Gram-positive polysaccharide degraders as a means to maximally recoup the energy expenditure of CAZyme production and export. • Due to the nitrogen deficiency of insoluble polysaccharide-containing substrates, Gram-negative and Gram-positive polysaccharide degraders have a diverse set of strategies for supplementation and assimilation. • Future work needs to precisely characterize the energetic expenditures of CAZyme deployment and bolster our understanding of how carbon and nitrogen metabolism are integrated in both Gram-negative and Gram-positive polysaccharide-degrading bacteria, as both of these will significantly influence a given bacterium's suitability for biotechnology applications.
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Affiliation(s)
- Jeffrey G Gardner
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA.
| | - Harold J Schreier
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA.,Department of Marine Biotechnology, Institute of Marine and Environmental Technology, University of Maryland, Baltimore County, Baltimore, MD, USA
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19
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Banu JR, Kumar G, Chattopadhyay I. Management of microbial enzymes for biofuels and biogas production by using metagenomic and genome editing approaches. 3 Biotech 2021; 11:429. [PMID: 34603908 DOI: 10.1007/s13205-021-02962-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 08/04/2021] [Indexed: 12/16/2022] Open
Abstract
Non-renewable fossil fuels such as bitumen, coal, natural gas, oil shale, and petroleum are depleting over the world owing to unrestricted consumption. Biofuels such as biodiesel, biobutanol, bioethanol, and biogas are considered an eco-friendly and cost-effective alternatives of fossil fuels. For energy sustainability, the production of advanced biofuels is required. The advancement of genetic and metabolic engineering in microbial cells played a significant contribution to biofuels overproduction. Essential approaches such as next-generation sequencing technologies and CRISPR/Cas9-mediated genome editing of microbial cells are required for the mass manufacture of biofuels globally. Advanced "omics" approaches are used to construct effective microorganisms for biofuels manufacturing. A new investigation is required to augment the production of lignocellulosic-based biofuels with minimal use of energy. Advanced areas of metabolic engineering are introduced in the manufacture of biofuels by the use of engineered microbial strains. Genetically modified microorganisms are used for the production of biofuels in large quantities at a low-cost.
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Affiliation(s)
- J Rajesh Banu
- Department of Life Sciences, Central University of Tamil Nadu, Thiruvarur, Tamilnadu India
| | - Gopalakrishnan Kumar
- Faculty of Science and Technology, Institute of Chemistry, Bioscience and Environmental Engineering, University of Stavanger, Forus, Box 8600, 4036 Stavanger, Norway
| | - Indranil Chattopadhyay
- Department of Life Sciences, Central University of Tamil Nadu, Thiruvarur, Tamilnadu India
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20
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Poudel S, Cope AL, O'Dell KB, Guss AM, Seo H, Trinh CT, Hettich RL. Identification and characterization of proteins of unknown function (PUFs) in Clostridium thermocellum DSM 1313 strains as potential genetic engineering targets. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:116. [PMID: 33971924 PMCID: PMC8112048 DOI: 10.1186/s13068-021-01964-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 04/26/2021] [Indexed: 05/13/2023]
Abstract
BACKGROUND Mass spectrometry-based proteomics can identify and quantify thousands of proteins from individual microbial species, but a significant percentage of these proteins are unannotated and hence classified as proteins of unknown function (PUFs). Due to the difficulty in extracting meaningful metabolic information, PUFs are often overlooked or discarded during data analysis, even though they might be critically important in functional activities, in particular for metabolic engineering research. RESULTS We optimized and employed a pipeline integrating various "guilt-by-association" (GBA) metrics, including differential expression and co-expression analyses of high-throughput mass spectrometry proteome data and phylogenetic coevolution analysis, and sequence homology-based approaches to determine putative functions for PUFs in Clostridium thermocellum. Our various analyses provided putative functional information for over 95% of the PUFs detected by mass spectrometry in a wild-type and/or an engineered strain of C. thermocellum. In particular, we validated a predicted acyltransferase PUF (WP_003519433.1) with functional activity towards 2-phenylethyl alcohol, consistent with our GBA and sequence homology-based predictions. CONCLUSIONS This work demonstrates the value of leveraging sequence homology-based annotations with empirical evidence based on the concept of GBA to broadly predict putative functions for PUFs, opening avenues to further interrogation via targeted experiments.
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Affiliation(s)
- Suresh Poudel
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- The Center for Bioenergy Innovation at Oak Ridge National Laboratory, Oak Ridge, TN, USA
- The Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
| | - Alexander L Cope
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- The Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
| | - Kaela B O'Dell
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- The Center for Bioenergy Innovation at Oak Ridge National Laboratory, Oak Ridge, TN, USA
- The Bredesen Center, University of Tennessee, Knoxville, TN, USA
| | - Adam M Guss
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- The Bredesen Center, University of Tennessee, Knoxville, TN, USA
| | - Hyeongmin Seo
- The Center for Bioenergy Innovation at Oak Ridge National Laboratory, Oak Ridge, TN, USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA
| | - Cong T Trinh
- The Center for Bioenergy Innovation at Oak Ridge National Laboratory, Oak Ridge, TN, USA
- The Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, USA
- The Bredesen Center, University of Tennessee, Knoxville, TN, USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA
| | - Robert L Hettich
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
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21
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Ahmed J, Kumar K, Sharma K, Fontes CMGA, Goyal A. Computational and SAXS-based structure insights of pectin acetyl esterase ( CtPae12B) of family 12 carbohydrate esterase from Clostridium thermocellum ATCC 27405. J Biomol Struct Dyn 2021; 40:8437-8454. [PMID: 33860720 DOI: 10.1080/07391102.2021.1911858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Pectin is a complex form of polysaccharide and is composed of several structural components that require the concerted action of several pectinases for its complete degradation. In this study, in silico and solution structure of a pectin acetyl esterase (CtPae12B) of family 12 carbohydrate esterase (CE12) from Clostridium thermocellum was determined. The CtPae12B modelled structure, showed a new α/β hydrolase fold, similar to the fold found in the crystal structures of its nearest homologues from CE12 family, which differed from α/β hydrolase fold found in glycoside hydrolases. In the active site of CtPae12B, two loops (loop1 and loop6) play an important role in the formation of a catalytic triad Ser15-Asp187-His190, where Ser15 acts as a nucleophile. The structural stability of CtPae12B and its catalytic site was detected by performing molecular dynamic (MD) simulation which showed stable and compact conformation of the structure. Molecular docking method was employed to analyse the conformations of various suitable ligands docked at the active site of CtPae12B. The stability and structural specificity of the catalytic residues with the ligand, 4-nitrophenyl acetate (4-NPA) was confirmed by MD simulation of CtPae12B-4NPA docked complex. Moreover, it was found that the nucleophile Ser15, forms hydrophobic interaction with 4-NPA in the active site to complete covalent catalysis. Small angle X-ray scattering analysis of CtPae12B at 3 mg/mL displayed elongated, compact and monodispersed nature in solution. The ab initio derived dummy model showed that CtPae12B exists as a homotrimer at 3 mg/mL which was also confirmed by dynamic light scattering.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Jebin Ahmed
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Krishan Kumar
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Kedar Sharma
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India.,Laboratory of Small Molecules & Macro Molecular Crystallography at Department of Bioengineering, Indian Institute of Technology Gandhinagar, Gandhinagar, India
| | - Carlos M G A Fontes
- CIISA - Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, Lisbon, Portugal.,NZYTech - Genes & Enzymes, Estrada do Paço do Lumiar, Lisbon, Portugal
| | - Arun Goyal
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
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22
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New Insights into the Co-Occurrences of Glycoside Hydrolase Genes among Prokaryotic Genomes through Network Analysis. Microorganisms 2021; 9:microorganisms9020427. [PMID: 33669523 PMCID: PMC7922503 DOI: 10.3390/microorganisms9020427] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 02/06/2021] [Accepted: 02/14/2021] [Indexed: 12/21/2022] Open
Abstract
Glycoside hydrolase (GH) represents a crucial category of enzymes for carbohydrate utilization in most organisms. A series of glycoside hydrolase families (GHFs) have been classified, with relevant information deposited in the CAZy database. Statistical analysis indicated that most GHFs (134 out of 154) were prone to exist in bacteria rather than archaea, in terms of both occurrence frequencies and average gene numbers. Co-occurrence analysis suggested the existence of strong or moderate-strong correlations among 63 GHFs. A combination of network analysis by Gephi and functional classification among these GHFs demonstrated the presence of 12 functional categories (from group A to L), with which the corresponding microbial collections were subsequently labeled, respectively. Interestingly, a progressive enrichment of particular GHFs was found among several types of microbes, and type-L as well as type-E microbes were deemed as functional intensified species which formed during the microbial evolution process toward efficient decomposition of lignocellulose as well as pectin, respectively. Overall, integrating network analysis and enzymatic functional classification, we were able to provide a new angle of view for GHs from known prokaryotic genomes, and thus this study is likely to guide the selection of GHs and microbes for efficient biomass utilization.
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23
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Tingley JP, Low KE, Xing X, Abbott DW. Combined whole cell wall analysis and streamlined in silico carbohydrate-active enzyme discovery to improve biocatalytic conversion of agricultural crop residues. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:16. [PMID: 33422151 PMCID: PMC7797155 DOI: 10.1186/s13068-020-01869-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 12/24/2020] [Indexed: 05/08/2023]
Abstract
The production of biofuels as an efficient source of renewable energy has received considerable attention due to increasing energy demands and regulatory incentives to reduce greenhouse gas emissions. Second-generation biofuel feedstocks, including agricultural crop residues generated on-farm during annual harvests, are abundant, inexpensive, and sustainable. Unlike first-generation feedstocks, which are enriched in easily fermentable carbohydrates, crop residue cell walls are highly resistant to saccharification, fermentation, and valorization. Crop residues contain recalcitrant polysaccharides, including cellulose, hemicelluloses, pectins, and lignin and lignin-carbohydrate complexes. In addition, their cell walls can vary in linkage structure and monosaccharide composition between plant sources. Characterization of total cell wall structure, including high-resolution analyses of saccharide composition, linkage, and complex structures using chromatography-based methods, nuclear magnetic resonance, -omics, and antibody glycome profiling, provides critical insight into the fine chemistry of feedstock cell walls. Furthermore, improving both the catalytic potential of microbial communities that populate biodigester reactors and the efficiency of pre-treatments used in bioethanol production may improve bioconversion rates and yields. Toward this end, knowledge and characterization of carbohydrate-active enzymes (CAZymes) involved in dynamic biomass deconstruction is pivotal. Here we overview the use of common "-omics"-based methods for the study of lignocellulose-metabolizing communities and microorganisms, as well as methods for annotation and discovery of CAZymes, and accurate prediction of CAZyme function. Emerging approaches for analysis of large datasets, including metagenome-assembled genomes, are also discussed. Using complementary glycomic and meta-omic methods to characterize agricultural residues and the microbial communities that digest them provides promising streams of research to maximize value and energy extraction from crop waste streams.
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Affiliation(s)
- Jeffrey P Tingley
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB, T1J 4B1, Canada
- Department of Biochemistry, University of Lethbridge, Lethbridge, AB, T1K 6T5, Canada
| | - Kristin E Low
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB, T1J 4B1, Canada
| | - Xiaohui Xing
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB, T1J 4B1, Canada
| | - D Wade Abbott
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB, T1J 4B1, Canada.
- Department of Biochemistry, University of Lethbridge, Lethbridge, AB, T1K 6T5, Canada.
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24
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Kosek D, Hickman AB, Ghirlando R, He S, Dyda F. Structures of ISCth4 transpososomes reveal the role of asymmetry in copy-out/paste-in DNA transposition. EMBO J 2021; 40:e105666. [PMID: 33006208 PMCID: PMC7780238 DOI: 10.15252/embj.2020105666] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/07/2020] [Accepted: 09/10/2020] [Indexed: 01/23/2023] Open
Abstract
Copy-out/paste-in transposition is a major bacterial DNA mobility pathway. It contributes significantly to the emergence of antibiotic resistance, often by upregulating expression of downstream genes upon integration. Unlike other transposition pathways, it requires both asymmetric and symmetric strand transfer steps. Here, we report the first structural study of a copy-out/paste-in transposase and demonstrate its ability to catalyze all pathway steps in vitro. X-ray structures of ISCth4 transposase, a member of the IS256 family of insertion sequences, bound to DNA substrates corresponding to three sequential steps in the reaction reveal an unusual asymmetric dimeric transpososome. During transposition, an array of N-terminal domains binds a single transposon end while the catalytic domain moves to accommodate the varying substrates. These conformational changes control the path of DNA flanking the transposon end and the generation of DNA-binding sites. Our results explain the asymmetric outcome of the initial strand transfer and show how DNA binding is modulated by the asymmetric transposase to allow the capture of a second transposon end and to integrate a circular intermediate.
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Affiliation(s)
- Dalibor Kosek
- Laboratory of Molecular BiologyNational Institute of Diabetes and Digestive and Kidney DiseasesNational Institutes of HealthBethesdaMDUSA
| | - Alison B Hickman
- Laboratory of Molecular BiologyNational Institute of Diabetes and Digestive and Kidney DiseasesNational Institutes of HealthBethesdaMDUSA
| | - Rodolfo Ghirlando
- Laboratory of Molecular BiologyNational Institute of Diabetes and Digestive and Kidney DiseasesNational Institutes of HealthBethesdaMDUSA
| | - Susu He
- Laboratory of Molecular BiologyNational Institute of Diabetes and Digestive and Kidney DiseasesNational Institutes of HealthBethesdaMDUSA
- Present address:
State Key Laboratory of Pharmaceutical BiotechnologyMedical School of Nanjing UniversityNanjingJiangsuChina
| | - Fred Dyda
- Laboratory of Molecular BiologyNational Institute of Diabetes and Digestive and Kidney DiseasesNational Institutes of HealthBethesdaMDUSA
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25
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Froese AG, Sparling R. Cross-feeding and wheat straw extractives enhance growth of Clostridium thermocellum-containing co-cultures for consolidated bioprocessing. Bioprocess Biosyst Eng 2021; 44:819-830. [PMID: 33392746 DOI: 10.1007/s00449-020-02490-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 11/24/2020] [Indexed: 01/19/2023]
Abstract
Co-cultures consisting of three thermophilic and lignocellulolytic bacteria, namely Clostridium thermocellum, C. stercorarium, and Thermoanaerobacter thermohydrosulfuricus, degrade lignocellulosic material in a synergistic manner. When cultured in a defined minimal medium two of the members appeared to be auxotrophic and unable to grow, but the growth of all species was observed in all co-culture combinations, indicating cross-feeding of unidentified growth factors between the members. Growth factors also appeared to be present in water-soluble extractives obtained from wheat straw, allowing for the growth of the auxotrophic monocultures in the defined minimal medium. Cell enumeration during growth on wheat straw in this medium revealed different growth profiles of the members that varied between the co-cultures. End-product profiles also varied substantially between the cultures, with significantly higher ethanol production in all co-cultures compared to the mono-cultures. Understanding interactions between co-culture members, and the additional nutrients provided by lignocellulosic substrates, will aid us in consolidated bioprocessing design.
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Affiliation(s)
- Alan G Froese
- Department of Microbiology, University of Manitoba, 213 Buller Building, Winnipeg, MB, R3T 2N2, Canada
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, 213 Buller Building, Winnipeg, MB, R3T 2N2, Canada.
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26
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Walls LE, Rios-Solis L. Sustainable Production of Microbial Isoprenoid Derived Advanced Biojet Fuels Using Different Generation Feedstocks: A Review. Front Bioeng Biotechnol 2020; 8:599560. [PMID: 33195174 PMCID: PMC7661957 DOI: 10.3389/fbioe.2020.599560] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/09/2020] [Indexed: 01/17/2023] Open
Abstract
As the fastest mode of transport, the aircraft is a major driver for globalization and economic growth. The development of alternative advanced liquid fuels is critical to sustainable development within the sector. Such fuels should be compatible with existing infrastructure and derived from second generation feedstocks to avoid competition with food markets. With properties similar to petroleum based fuels, isoprenoid derived compounds such as limonene, bisabolane, farnesane, and pinene dimers are of increasing interest as "drop-in" replacement jet fuels. In this review potential isoprenoid derived jet fuels and progress toward their microbial production was discussed in detail. Although substantial advancements have been achieved, the use of first generation feedstocks remains ubiquitous. Lignocellulosic biomass is the most abundant raw material available for biofuel production, however, technological constraints associated with its pretreatment and saccharification hinder its economic feasibility for low-value commodity production. Non-conventional microbes with novel characteristics including cellulolytic bacteria and fungi capable of highly efficient lignocellulose degradation and xylose fermenting oleaginous yeast with enhanced lignin-associated inhibitor tolerance were investigated as alternatives to traditional model hosts. Finally, innovative bioprocessing methods including consolidated bioprocessing and sequential bioreactor approaches, with potential to capitalize on such unique natural capabilities were considered.
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Affiliation(s)
- Laura Ellen Walls
- Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, United Kingdom
- Centre for Synthetic and Systems Biology (SynthSys), The University of Edinburgh, Edinburgh, United Kingdom
| | - Leonardo Rios-Solis
- Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, United Kingdom
- Centre for Synthetic and Systems Biology (SynthSys), The University of Edinburgh, Edinburgh, United Kingdom
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27
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Transcriptomic analysis of a Clostridium thermocellum strain engineered to utilize xylose: responses to xylose versus cellobiose feeding. Sci Rep 2020; 10:14517. [PMID: 32884054 PMCID: PMC7471329 DOI: 10.1038/s41598-020-71428-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 08/10/2020] [Indexed: 12/20/2022] Open
Abstract
Clostridium (Ruminiclostridium) thermocellum is recognized for its ability to ferment cellulosic biomass directly, but it cannot naturally grow on xylose. Recently, C. thermocellum (KJC335) was engineered to utilize xylose through expressing a heterologous xylose catabolizing pathway. Here, we compared KJC335′s transcriptomic responses to xylose versus cellobiose as the primary carbon source and assessed how the bacteria adapted to utilize xylose. Our analyses revealed 417 differentially expressed genes (DEGs) with log2 fold change (FC) >|1| and 106 highly DEGs (log2 FC >|2|). Among the DEGs, two putative sugar transporters, cbpC and cbpD, were up-regulated, suggesting their contribution to xylose transport and assimilation. Moreover, the up-regulation of specific transketolase genes (tktAB) suggests the importance of this enzyme for xylose metabolism. Results also showed remarkable up-regulation of chemotaxis and motility associated genes responding to xylose feeding, as well as widely varying gene expression in those encoding cellulosomal enzymes. For the down-regulated genes, several were categorized in gene ontology terms oxidation–reduction processes, ATP binding and ATPase activity, and integral components of the membrane. This study informs potentially critical, enabling mechanisms to realize the conceptually attractive Next-Generation Consolidated BioProcessing approach where a single species is sufficient for the co-fermentation of cellulose and hemicellulose.
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28
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Thakur CJ, Saini S, Notra A, Chauhan B, Arya S, Gupta R, Thakur J, Kumar V. Deciphering the functional role of hypothetical proteins from Chloroflexus aurantiacs J-10-f1 using bioinformatics approach. MOLECULAR BIOLOGY RESEARCH COMMUNICATIONS 2020; 9:129-139. [PMID: 33313333 PMCID: PMC7727763 DOI: 10.22099/mbrc.2020.36894.1495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Chloroflexus aurantiacus J-10-f1 is an anoxygenic, photosynthetic, facultative autotrophic gram negative bacterium found from hot spring at a temperature range of 50-60°C. It can sustain itself in dark only if oxygen is available thereby exhibiting a dark orange color, however display a dark green color when grown in sunlight. Genome of the organism contains total of 3853 proteins out of which 785 (~20%) proteins are uncharacterised or hypothetical proteins (HPs). Therefore in this work we have characterized the 785 hypothetical proteins of Chloroflexus aurantiacus J-10-f1 using bioinformatics tools and databases. HPs annotated by more than five domain prediction tools were filtered and named high confidence-hypothetical proteins (HC-HPs). These HC-HPs were further annotated by calculating their physiochemical properties, homologous, subcellular locations, signal peptides and transmembrane regions. We found most of the HC-HPs were involved in photosynthesis, carbohydrate metabolism, biofuel production and cellulose synthesis processes. Furthermore, few of these HC-HPs could provide resistance to bacteria at high temperature due to their thermophilic nature. Hence these HC-HPs have the potential to be used in industrial as well as in biomedical needs. To conclude, the bioinformatics approach used in this study provides an insight to better understand the nature and role of Chloroflexus aurantiacus J-10-f1 hypothetical proteins.
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Affiliation(s)
- Chander Jyoti Thakur
- Department of Bioinformatics, GGDSD College, Sector 32-C, 160030, Chandigarh, India,Corresponding Author: Department of Bioinformatics, GGDSD College, Chandigarh, India. Tel: +91 8699776533 ; Fax: +91 172 2661077, E. mail:
| | - Sandeep Saini
- Department of Bioinformatics, GGDSD College, Sector 32-C, 160030, Chandigarh, India,Department of Biophysics, Panjab University, Sector 25, 160014, Chandigarh, India
| | - Aayushi Notra
- Department of Bioinformatics, GGDSD College, Sector 32-C, 160030, Chandigarh, India
| | - Bhavanshu Chauhan
- Department of Bioinformatics, GGDSD College, Sector 32-C, 160030, Chandigarh, India
| | - Sarthak Arya
- Department of Bioinformatics, GGDSD College, Sector 32-C, 160030, Chandigarh, India
| | - Rishabh Gupta
- Department of Bioinformatics, GGDSD College, Sector 32-C, 160030, Chandigarh, India
| | - Jyotsna Thakur
- Department of Bioinformatics, GGDSD College, Sector 32-C, 160030, Chandigarh, India
| | - Varinder Kumar
- Department of Bioinformatics, GGDSD College, Sector 32-C, 160030, Chandigarh, India
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29
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Garcia S, Thompson RA, Giannone RJ, Dash S, Maranas CD, Trinh CT. Development of a Genome-Scale Metabolic Model of Clostridium thermocellum and Its Applications for Integration of Multi-Omics Datasets and Computational Strain Design. Front Bioeng Biotechnol 2020; 8:772. [PMID: 32974289 PMCID: PMC7471609 DOI: 10.3389/fbioe.2020.00772] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 06/18/2020] [Indexed: 01/29/2023] Open
Abstract
Solving environmental and social challenges such as climate change requires a shift from our current non-renewable manufacturing model to a sustainable bioeconomy. To lower carbon emissions in the production of fuels and chemicals, plant biomass feedstocks can replace petroleum using microorganisms as biocatalysts. The anaerobic thermophile Clostridium thermocellum is a promising bacterium for bioconversion due to its capability to efficiently degrade lignocellulosic biomass. However, the complex metabolism of C. thermocellum is not fully understood, hindering metabolic engineering to achieve high titers, rates, and yields of targeted molecules. In this study, we developed an updated genome-scale metabolic model of C. thermocellum that accounts for recent metabolic findings, has improved prediction accuracy, and is standard-conformant to ensure easy reproducibility. We illustrated two applications of the developed model. We first formulated a multi-omics integration protocol and used it to understand redox metabolism and potential bottlenecks in biofuel (e.g., ethanol) production in C. thermocellum. Second, we used the metabolic model to design modular cells for efficient production of alcohols and esters with broad applications as flavors, fragrances, solvents, and fuels. The proposed designs not only feature intuitive push-and-pull metabolic engineering strategies, but also present novel manipulations around important central metabolic branch-points. We anticipate the developed genome-scale metabolic model will provide a useful tool for system analysis of C. thermocellum metabolism to fundamentally understand its physiology and guide metabolic engineering strategies to rapidly generate modular production strains for effective biosynthesis of biofuels and biochemicals from lignocellulosic biomass.
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Affiliation(s)
- Sergio Garcia
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, United States.,Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - R Adam Thompson
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, United States.,Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Richard J Giannone
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Satyakam Dash
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States
| | - Costas D Maranas
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, United States.,Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, United States.,Oak Ridge National Laboratory, Oak Ridge, TN, United States
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30
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Harnvoravongchai P, Singwisut R, Ounjai P, Aroonnual A, Kosiyachinda P, Janvilisri T, Chankhamhaengdecha S. Isolation and characterization of thermophilic cellulose and hemicellulose degrading bacterium, Thermoanaerobacterium sp. R63 from tropical dry deciduous forest soil. PLoS One 2020; 15:e0236518. [PMID: 32702033 PMCID: PMC7377481 DOI: 10.1371/journal.pone.0236518] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/07/2020] [Indexed: 12/31/2022] Open
Abstract
Thermophilic microorganisms and their enzymes have been utilized in various industrial applications. In this work, we isolated and characterized thermophilic anaerobic bacteria with the cellulose and hemicellulose degrading activities from a tropical dry deciduous forest in northern Thailand. Out of 502 isolated thermophilic anaerobic soil bacteria, 6 isolates, identified as Thermoanaerobacterium sp., displayed an ability to utilize a wide range of oligosaccharides and lignocellulosic substrates. The isolates exhibited significant cellulase and xylanase activities at high temperature (65°C). Among all isolates, Thermoanaerobacterium sp. strain R63 exhibited remarkable hydrolytic properties with the highest cellulase and xylanase activities at 1.15 U/mg and 6.17 U/mg, respectively. Extracellular extract of Thermoanaerobacterium sp. strain R63 was thermostable with an optimal temperature at 65°C and could exhibit enzymatic activities on pH range 5.0-9.0. Our findings suggest promising applications of these thermoanaerobic bacteria and their potent enzymes for industrial purposes.
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Affiliation(s)
| | - Ratiyakorn Singwisut
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Puey Ounjai
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Amornrat Aroonnual
- Department of Tropical Nutrition and Food Science, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Pahol Kosiyachinda
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Tavan Janvilisri
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
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31
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Althuri A, Venkata Mohan S. Sequential and consolidated bioprocessing of biogenic municipal solid waste: A strategic pairing of thermophilic anaerobe and mesophilic microaerobe for ethanol production. BIORESOURCE TECHNOLOGY 2020; 308:123260. [PMID: 32251860 DOI: 10.1016/j.biortech.2020.123260] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/23/2020] [Accepted: 03/24/2020] [Indexed: 06/11/2023]
Abstract
Feedstock availability and its pretreatment, high process economics and insufficient ethanol (HEt) titres necessitated the bioprocesses that are sustainable. The advanced consolidated bioprocessing (CBPSeq) strategy presently considered for improved HEt production involves, sequential coupling of CBP thermophile, Clostridium thermocellum ATCC-27405 with mesophilic microaerobe, Pichia stipitis NCIM-3498. Biogenic municipal solid waste (BMSW) pretreated with 0.5% NaOH (CSPBMSW) served as the sole carbon source. CBPSeq (23.99 g/L) fared better than CBP standalone (18.10 g/L) wherein 1.32-folds improvement in HEt titre was recorded. Considering insufficient xylanase titre in cellulosome complex of C. thermocellum, CBPSeq was performed employing exogenous xylanases (CBPSeqE) to improve xylan digestibility and HEt yield. CBPSeqE-II biosystem at pH 5 showed maximum HEt titre of 36.90 g/L which corresponds to yield of 0.26 g HEt/ g CSPBMSW. This study substantiates efficacy of CBPSeqE-II biosystem in sustainable bioethanol production from BMSW in a single reactor without laborious steps.
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Affiliation(s)
- Avanthi Althuri
- Bioengineering and Environmental Sciences Lab, Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500007, Telangana, India.
| | - S Venkata Mohan
- Bioengineering and Environmental Sciences Lab, Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500007, Telangana, India
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32
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Seo H, Nicely PN, Trinh CT. Endogenous carbohydrate esterases of Clostridium thermocellum are identified and disrupted for enhanced isobutyl acetate production from cellulose. Biotechnol Bioeng 2020; 117:2223-2236. [PMID: 32333614 DOI: 10.1002/bit.27360] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/12/2020] [Accepted: 04/22/2020] [Indexed: 12/18/2022]
Abstract
Medium-chain esters are versatile chemicals with broad applications as flavors, fragrances, solvents, and potential drop-in biofuels. Currently, these esters are largely produced by the conventional chemical process that uses harsh operating conditions and requires high energy input. Alternatively, the microbial conversion route has recently emerged as a promising platform for sustainable and renewable ester production. The ester biosynthesis pathways can utilize either lipases or alcohol acyltransferase (AAT), but the AAT-dependent pathway is more thermodynamically favorable in an aqueous fermentation environment. Even though a cellulolytic thermophile Clostridium thermocellum harboring an AAT-dependent pathway has recently been engineered for direct conversion of lignocellulosic biomass into esters, the production is not efficient. One potential bottleneck is the ester degradation caused by the endogenous carbohydrate esterases (CEs) whose functional roles are poorly understood. The challenge is to identify and disrupt CEs that can alleviate ester degradation while not negatively affecting the efficient and robust capability of C. thermocellum for lignocellulosic biomass deconstruction. In this study, by using bioinformatics, comparative genomics, and enzymatic analysis to screen a library of CEs, we identified and disrupted the two most critical CEs, Clo1313_0613 and Clo1313_0693, that significantly contribute to isobutyl acetate degradation in C. thermocellum. We demonstrated that an engineered esterase-deficient C. thermocellum strain not only reduced ester hydrolysis but also improved isobutyl acetate production while maintaining effective cellulose assimilation.
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Affiliation(s)
- Hyeongmin Seo
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, Tennessee.,Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Preston N Nicely
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, Tennessee
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, Tennessee.,Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee
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33
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Wen Z, Ledesma‐Amaro R, Lu M, Jiang Y, Gao S, Jin M, Yang S. Combined evolutionary engineering and genetic manipulation improve low pH tolerance and butanol production in a synthetic microbial
Clostridium
community. Biotechnol Bioeng 2020; 117:2008-2022. [DOI: 10.1002/bit.27333] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/14/2020] [Accepted: 03/12/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Zhiqiang Wen
- School of Environmental and Biological Engineering, Nanjing University of Science & Technology Nanjing China
| | | | - Minrui Lu
- School of Environmental and Biological Engineering, Nanjing University of Science & Technology Nanjing China
| | - Yu Jiang
- Huzhou Center of Industrial Biotechnology, Shanghai Institutes of Biological SciencesChinese Academy of Sciences Zhejiang China
- Shanghai TaoYuSheng Biotechnology Co., Ltd. Shanghai China
| | - Shuliang Gao
- Zhejiang Huarui Biotechnology Co., Ltd. Zhejiang China
| | - Mingjie Jin
- School of Environmental and Biological Engineering, Nanjing University of Science & Technology Nanjing China
| | - Sheng Yang
- Huzhou Center of Industrial Biotechnology, Shanghai Institutes of Biological SciencesChinese Academy of Sciences Zhejiang China
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of Sciences Shanghai China
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34
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Ganguly J, Martin‐Pascual M, van Kranenburg R. CRISPR interference (CRISPRi) as transcriptional repression tool for Hungateiclostridium thermocellum DSM 1313. Microb Biotechnol 2020; 13:339-349. [PMID: 31802632 PMCID: PMC7017836 DOI: 10.1111/1751-7915.13516] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/06/2019] [Accepted: 11/12/2019] [Indexed: 01/13/2023] Open
Abstract
Hungateiclostridium thermocellum DSM 1313 has biotechnological potential as a whole-cell biocatalyst for ethanol production using lignocellulosic renewable sources. The full exploitation of H. thermocellum has been hampered due to the lack of simple and high-throughput genome engineering tools. Recently in our research group, a thermophilic bacterial CRISPR-Cas9-based system has been developed as a transcriptional suppression tool for regulation of gene expression. We applied ThermoCas9-based CRISPR interference (CRISPRi) to repress the H. thermocellum central metabolic lactate dehydrogenase (ldh) and phosphotransacetylase (pta) genes. The effects of repression on target genes were studied based on transcriptional expression and product formation. Single-guide RNA (sgRNA) under the control of native intergenic 16S/23S rRNA promoter from H. thermocellum directing the ThermodCas9 to the promoter region of both pta and ldh silencing transformants reduced expression up to 67% and 62% respectively. This resulted in 24% and 17% decrease in lactate and acetate production, correspondingly. Hence, the CRISPRi approach for H. thermocellum to downregulate metabolic genes can be used for remodelling of metabolic pathways without the requisite for genome engineering. These data established for the first time the feasibility of employing CRISPRi-mediated gene repression of metabolic genes in H. thermocellum DSM 1313.
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Affiliation(s)
| | - Maria Martin‐Pascual
- Laboratory of MicrobiologyWageningen UniversityStippeneng 46708WE WageningenThe Netherlands
| | - Richard van Kranenburg
- CorbionArkelsedijk 464206AC GorinchemThe Netherlands
- Laboratory of MicrobiologyWageningen UniversityStippeneng 46708WE WageningenThe Netherlands
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35
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Lee JW, Trinh CT. Towards renewable flavors, fragrances, and beyond. Curr Opin Biotechnol 2020; 61:168-180. [PMID: 31986468 DOI: 10.1016/j.copbio.2019.12.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 12/01/2019] [Accepted: 12/17/2019] [Indexed: 02/08/2023]
Abstract
Esters constitute a large space of unique molecules with broad range of applications as flavors, fragrances, pharmaceuticals, cosmetics, green solvents, and advanced biofuels. Global demand of natural esters in food, household cleaner, personal care, and perfume industries is increasing while the ester supply from natural sources has been limited. Development of novel microbial cell factories for ester production from renewable feedstocks can potentially provide an alternative and sustainable source of natural esters and hence help fulfill growing demand. Here, we highlight recent advances in microbial production of esters and provide perspectives for improving its economic feasibility. As the field matures, microbial ester production platforms will enable renewable and sustainable production of flavors and fragrances, and open new market opportunities beyond what nature can offer.
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Affiliation(s)
- Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Cong T Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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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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Ozbayram EG, Kleinsteuber S, Nikolausz M. Biotechnological utilization of animal gut microbiota for valorization of lignocellulosic biomass. Appl Microbiol Biotechnol 2019; 104:489-508. [DOI: 10.1007/s00253-019-10239-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 10/25/2019] [Accepted: 11/04/2019] [Indexed: 10/25/2022]
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Okonkwo O, Escudie R, Bernet N, Mangayil R, Lakaniemi AM, Trably E. Bioaugmentation enhances dark fermentative hydrogen production in cultures exposed to short-term temperature fluctuations. Appl Microbiol Biotechnol 2019; 104:439-449. [PMID: 31754763 PMCID: PMC6942602 DOI: 10.1007/s00253-019-10203-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/27/2019] [Accepted: 10/19/2019] [Indexed: 01/20/2023]
Abstract
Hydrogen-producing mixed cultures were subjected to a 48-h downward or upward temperature fluctuation from 55 to 35 or 75 °C. Hydrogen production was monitored during the fluctuations and for three consecutive batch cultivations at 55 °C to evaluate the impact of temperature fluctuations and bioaugmentation with synthetic mixed culture of known H2 producers either during or after the fluctuation. Without augmentation, H2 production was significantly reduced during the downward temperature fluctuation and no H2 was produced during the upward fluctuation. H2 production improved significantly during temperature fluctuation when bioaugmentation was applied to cultures exposed to downward or upward temperatures. However, when bioaugmentation was applied after the fluctuation, i.e., when the cultures were returned to 55 °C, the H2 yields obtained were between 1.6 and 5% higher than when bioaugmentation was applied during the fluctuation. Thus, the results indicate the usefulness of bioaugmentation in process recovery, especially if bioaugmentation time is optimised.
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Affiliation(s)
| | | | | | - Rahul Mangayil
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
| | - Aino-Maija Lakaniemi
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
| | - Eric Trably
- LBE, Univ Montpellier, INRA, Narbonne, France
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Banerjee S, Mishra G, Roy A. Metabolic Engineering of Bacteria for Renewable Bioethanol Production from Cellulosic Biomass. BIOTECHNOL BIOPROC E 2019. [DOI: 10.1007/s12257-019-0134-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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40
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Influence of substrate loadings on the consolidated bioprocessing of rice straw and sugarcane bagasse biomass using Ruminiclostridium thermocellum. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.biteb.2019.01.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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41
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Bashir Z, Sheng L, Anil A, Lali A, Minton NP, Zhang Y. Engineering Geobacillus thermoglucosidasius for direct utilisation of holocellulose from wheat straw. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:199. [PMID: 31452680 PMCID: PMC6701081 DOI: 10.1186/s13068-019-1540-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 08/06/2019] [Indexed: 05/29/2023]
Abstract
BACKGROUND A consolidated bioprocessing (CBP), where lignocellulose is converted into the desired product(s) in a single fermentative step without the addition of expensive degradative enzymes, represents the ideal solution of renewable routes to chemicals and fuels. Members of the genus Geobacillus are able to grow at elevated temperatures and are able to utilise a wide range of oligosaccharides derived from lignocellulose. This makes them ideally suited to the development of CBP. RESULTS In this study, we engineered Geobacillus thermoglucosidasius NCIMB 11955 to utilise lignocellulosic biomass, in the form of nitric acid/ammonia treated wheat straw to which expensive hydrolytic enzymes had not been added. Two different strains, BZ9 and BZ10, were generated by integrating the cglT (β-1,4-glucosidase) gene from Thermoanaerobacter brockii into the genome, and localising genes encoding different cellulolytic enzymes on autonomous plasmids. The plasmid of strain BZ10 carried a synthetic cellulosomal operon comprising the celA (Endoglucanase A) gene from Clostridium thermocellum and cel6B (Exoglucanase) from Thermobifida fusca; whereas, strain BZ9 contained a plasmid encoding the celA (multidomain cellulase) gene from Caldicellulosiruptor bescii. All of the genes were successfully expressed, and their encoded products secreted in a functionally active form, as evidenced by their detection in culture supernatants by Western blotting and enzymatic assay. In the case of the C. bescii CelA enzyme, this is one of the first times that the heterologous production of this multi-functional enzyme has been achieved in a heterologous host. Both strains (BZ9 and BZ10) exhibited improved growth on pre-treated wheat straw, achieving a higher final OD600 and producing greater numbers of viable cells. To demonstrate that cellulosic ethanol can be produced directly from lignocellulosic biomass by a single organism, we established our consortium of hydrolytic enzymes in a previously engineered ethanologenic G. thermoglucosidasius strain, LS242. We observed approximately twofold and 1.6-fold increase in ethanol production in the recombinant G. thermoglucosidasius equivalent to BZ9 and BZ10, respectively, compared to G. thermoglucosidasius LS242 strain at 24 h of growth. CONCLUSION We engineered G. thermoglucosidasius to utilise a real-world lignocellulosic biomass substrate and demonstrated that cellulosic ethanol can be produced directly from lignocellulosic biomass in one step. Direct conversion of biomass into desired products represents a new paradigm for CBP, offering the potential for carbon neutral, cost-effective production of sustainable chemicals and fuels.
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Affiliation(s)
- Zeenat Bashir
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD UK
| | - Lili Sheng
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD UK
| | - Annamma Anil
- DBT-ICT Centre for Energy Biosciences, Institute of Chemical Technology, Nathalal Parikh Marg, Mumbai, 400019 India
| | - Arvind Lali
- DBT-ICT Centre for Energy Biosciences, Institute of Chemical Technology, Nathalal Parikh Marg, Mumbai, 400019 India
| | - Nigel P. Minton
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD UK
| | - Ying Zhang
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD UK
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Rational development of transformation in Clostridium thermocellum ATCC 27405 via complete methylome analysis and evasion of native restriction-modification systems. J Ind Microbiol Biotechnol 2019; 46:1435-1443. [PMID: 31342224 PMCID: PMC6791906 DOI: 10.1007/s10295-019-02218-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 07/11/2019] [Indexed: 12/13/2022]
Abstract
A major barrier to both metabolic engineering and fundamental biological studies is the lack of genetic tools in most microorganisms. One example is Clostridium thermocellum ATCC 27405T, where genetic tools are not available to help validate decades of hypotheses. A significant barrier to DNA transformation is restriction–modification systems, which defend against foreign DNA methylated differently than the host. To determine the active restriction–modification systems in this strain, we performed complete methylome analysis via single-molecule, real-time sequencing to detect 6-methyladenine and 4-methylcytosine and the rarely used whole-genome bisulfite sequencing to detect 5-methylcytosine. Multiple active systems were identified, and corresponding DNA methyltransferases were expressed from the Escherichia coli chromosome to mimic the C. thermocellum methylome. Plasmid methylation was experimentally validated and successfully electroporated into C. thermocellum ATCC 27405. This combined approach enabled genetic modification of the C. thermocellum-type strain and acts as a blueprint for transformation of other non-model microorganisms.
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43
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Soares LA, Silva Rabelo CAB, Sakamoto IK, Silva EL, Varesche MBA. Screening and Bioprospecting of Anaerobic Consortia for Biofuel Production Enhancement from Sugarcane Bagasse. Appl Biochem Biotechnol 2019; 190:232-251. [PMID: 31332677 DOI: 10.1007/s12010-019-03074-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/05/2019] [Indexed: 01/21/2023]
Abstract
The genera Dysgonomonas, Coprococcus, Sporomusa, Bacteroides, Sedimentibacter, Pseudomonas, Ruminococcus, and Clostridium predominate in compost residue, and vadimCA02, Anaerobaculum, Tatlockia, Caloramator, and Syntrophus prevail in soil used as inoculum in batch rectors. This mixed consortium was used as inoculum for biogas production using different concentrations of sugarcane bagasse (SCB) (from 1.58 to 4.42 g/L) and yeast extract (YE) (from 0.58 to 3.42 g/L) according to a composite central design. The maximum ethanol production (20.11 mg L-1) was observed using 2.0 and 3.0 g L-1 of YE and SCB, respectively (C6). Likewise, the highest hydrogen production (0.60 mmol L-1) was observed using 3.0 and 4.0 g L-1 of YE and SCB, respectively (C1). Methane was also observed, reaching the maximum production (1.44 mmol L-1) using 1.0 and 4.0 g L-1 of YE and SCB, respectively (C2). The archaeal similarity between these conditions was above 90%; however, the richness and diversity were higher in the C2 (12 and 2.42, respectively) than in C1 (5 and 1.43, respectively) and C6 (11 and 2.29, respectively). Equally, the bacterial similarity between C1 and C6 was 60% while richness of 24 and 17 and diversity of 3.13 and 2.81 were observed in C1 and C6, respectively.
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Affiliation(s)
- Laís Américo Soares
- University of São Paulo, João Dagnone Avenue, 1100, São Carlos, SP, 13563-120, Brazil.
| | | | | | - Edson Luís Silva
- Federal University of São Carlos, Rod Washington Luis, Km 235, São Carlos, SP, 13565-905, Brazil
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Wang Y, Leng L, Islam MK, Liu F, Lin CSK, Leu SY. Substrate-Related Factors Affecting Cellulosome-Induced Hydrolysis for Lignocellulose Valorization. Int J Mol Sci 2019; 20:ijms20133354. [PMID: 31288425 PMCID: PMC6651384 DOI: 10.3390/ijms20133354] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 06/30/2019] [Accepted: 07/03/2019] [Indexed: 11/22/2022] Open
Abstract
Cellulosomes are an extracellular supramolecular multienzyme complex that can efficiently degrade cellulose and hemicelluloses in plant cell walls. The structural and unique subunit arrangement of cellulosomes can promote its adhesion to the insoluble substrates, thus providing individual microbial cells with a direct competence in the utilization of cellulosic biomass. Significant progress has been achieved in revealing the structures and functions of cellulosomes, but a knowledge gap still exists in understanding the interaction between cellulosome and lignocellulosic substrate for those derived from biorefinery pretreatment of agricultural crops. The cellulosomic saccharification of lignocellulose is affected by various substrate-related physical and chemical factors, including native (untreated) wood lignin content, the extent of lignin and xylan removal by pretreatment, lignin structure, substrate size, and of course substrate pore surface area or substrate accessibility to cellulose. Herein, we summarize the cellulosome structure, substrate-related factors, and regulatory mechanisms in the host cells. We discuss the latest advances in specific strategies of cellulosome-induced hydrolysis, which can function in the reaction kinetics and the overall progress of biorefineries based on lignocellulosic feedstocks.
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Affiliation(s)
- Ying Wang
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science & Technology, Guangzhou 510650, China
- Department of Civil and Environmental Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Ling Leng
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, Higashi 1-1-1, Tsukuba, Ibaraki 305-8566, Japan
| | - Md Khairul Islam
- Department of Civil and Environmental Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Fanghua Liu
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science & Technology, Guangzhou 510650, China
| | - Carol Sze Ki Lin
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China
| | - Shao-Yuan Leu
- Department of Civil and Environmental Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
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45
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Ichikawa S, Ogawa S, Nishida A, Kobayashi Y, Kurosawa T, Karita S. Cellulosomes localise on the surface of membrane vesicles from the cellulolytic bacterium Clostridium thermocellum. FEMS Microbiol Lett 2019; 366:5526221. [DOI: 10.1093/femsle/fnz145] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 06/27/2019] [Indexed: 12/21/2022] Open
Abstract
ABSTRACTMembrane vesicles released from bacteria contribute to cell–cell communication by carrying various cargos such as proteins, nucleic acids and signaling molecules. Cellulolytic bacteria have been isolated from many environments, yet the function of membrane vesicles for cellulolytic ability has been rarely described. Here, we show that a Gram-positive cellulolytic bacterium Clostridium thermocellum released membrane vesicles, each approximately 50–300 nm in diameter, into the broth. The observations with immunoelectron microscopy also revealed that cellulosomes, which are carbohydrate-active enzyme complexes that give C. thermocellum high cellulolytic activity, localized on the surface of the membrane vesicles. The membrane vesicles collected by ultracentrifugation maintained the cellulolytic activity. Supplementation with the biosurfactant surfactin or sonication treatment disrupted the membrane vesicles in the exoproteome of C. thermocellum and significantly decreased the degradation activity of the exoproteome for microcrystalline cellulose. However, these did not affect the degradation activity for soluble carboxymethyl cellulose. These results suggest a novel function of membrane vesicles: C. thermocellum releases cellulolytic enzymes on the surface of membrane vesicles to enhance the cellulolytic activity of C. thermocellum for crystalline cellulose.
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Affiliation(s)
- Shunsuke Ichikawa
- Graduate School of Education, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
| | - Satoru Ogawa
- Faculty of Medicine, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
| | - Ayami Nishida
- Graduate School of Education, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
| | - Yuzuki Kobayashi
- Faculty of Education, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
| | - Toshihito Kurosawa
- Advanced Science Research Promotion Center, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
| | - Shuichi Karita
- Graduate School of Bioresources, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan
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46
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Grinberg IR, Yaniv O, de Ora LO, Muñoz-Gutiérrez I, Hershko A, Livnah O, Bayer EA, Borovok I, Frolow F, Lamed R, Voronov-Goldman M. Distinctive ligand-binding specificities of tandem PA14 biomass-sensory elements from Clostridium thermocellum and Clostridium clariflavum. Proteins 2019; 87:917-930. [PMID: 31162722 PMCID: PMC6852018 DOI: 10.1002/prot.25753] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 05/26/2019] [Accepted: 05/30/2019] [Indexed: 11/25/2022]
Abstract
Cellulolytic clostridia use a highly efficient cellulosome system to degrade polysaccharides. To regulate genes encoding enzymes of the multi‐enzyme cellulosome complex, certain clostridia contain alternative sigma I (σI) factors that have cognate membrane‐associated anti‐σI factors (RsgIs) which act as polysaccharide sensors. In this work, we analyzed the structure‐function relationship of the extracellular sensory elements of Clostridium (Ruminiclostridium) thermocellum and Clostridium clariflavum (RsgI3 and RsgI4, respectively). These elements were selected for comparison, as each comprised two tandem PA14‐superfamily motifs. The X‐ray structures of the PA14 modular dyads from the two bacterial species were determined, both of which showed a high degree of structural and sequence similarity, although their binding preferences differed. Bioinformatic approaches indicated that the DNA sequence of promoter of sigI/rsgI operons represents a strong signature, which helps to differentiate binding specificity of the structurally similar modules. The σI4‐dependent C. clariflavum promoter sequence correlates with binding of RsgI4_PA14 to xylan and was identified in genes encoding xylanases, whereas the σI3‐dependent C. thermocellum promoter sequence correlates with RsgI3_PA14 binding to pectin and regulates pectin degradation‐related genes. Structural similarity between clostridial PA14 dyads to PA14‐containing proteins in yeast helped identify another crucial signature element: the calcium‐binding loop 2 (CBL2), which governs binding specificity. Variations in the five amino acids that constitute this loop distinguish the pectin vs xylan specificities. We propose that the first module (PA14A) is dominant in directing the binding to the ligand in both bacteria. The two X‐ray structures of the different PA14 dyads represent the first reported structures of tandem PA14 modules.
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Affiliation(s)
- Inna Rozman Grinberg
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel.,Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Oren Yaniv
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Lizett Ortiz de Ora
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel.,Department of Chemistry, University of California, Irvine, California
| | - Iván Muñoz-Gutiérrez
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel.,Outreach Research Training and Minority Science Programs, School of Biological Sciences, University of California, Irvine, California
| | - Almog Hershko
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Oded Livnah
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Wolfson Centre for Applied Structural Biology, The Hebrew University of Jerusalem, The Edmond J. Safra Campus, Jerusalem, Israel
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Ilya Borovok
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Felix Frolow
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Milana Voronov-Goldman
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
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47
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Engineering Clostridium for improved solvent production: recent progress and perspective. Appl Microbiol Biotechnol 2019; 103:5549-5566. [DOI: 10.1007/s00253-019-09916-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/15/2019] [Accepted: 05/15/2019] [Indexed: 01/07/2023]
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48
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Glucose production from cellulose through biological simultaneous enzyme production and saccharification using recombinant bacteria expressing the β-glucosidase gene. J Biosci Bioeng 2019; 127:340-344. [DOI: 10.1016/j.jbiosc.2018.08.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/16/2018] [Accepted: 08/20/2018] [Indexed: 12/18/2022]
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49
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Froese A, Schellenberg J, Sparling R. Enhanced depolymerization and utilization of raw lignocellulosic material by co-cultures of Ruminiclostridium thermocellum with hemicellulose-utilizing partners. Can J Microbiol 2019; 65:296-307. [PMID: 30608879 DOI: 10.1139/cjm-2018-0535] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Ruminiclostridium thermocellum is one of the most promising candidates for consolidated bioprocessing (CBP) of low-cost lignocellulosic materials to biofuels but it still shows poor performance in its ability to deconstruct untreated lignocellulosic substrates. One promising approach to increase R. thermocellum's rate of hydrolysis is to co-culture this cellulose-specialist with partners that possess synergistic hydrolysis enzymes and metabolic capabilities. We have created co-cultures of R. thermocellum with two hemicellulose utilizers, Ruminiclostridium stercorarium and Thermoanaerobacter thermohydrosulfuricus, both of which secrete xylanolytic enzymes and utilize the pentose oligo- and monosaccharides that inhibit R. thermocellum's hydrolysis and metabolism. When grown on milled wheat straw, the co-cultures were able to solubilize up to 58% more of the total polysaccharides than the R. thermocellum mono-culture control. Repeated passaging of the co-cultures on wheat straw yielded stable populations with reduced R. thermocellum cell numbers, indicating competition for cellodextrins released from cellulose hydrolysis, although these stabilized co-cultures were still able to outperform the mono-culture controls. Repeated passaging on Avicel cellulose also yielded stable populations. Overall, the observed synergism suggests that co-culturing R. thermocellum with other members is a viable option for increasing the rate and extent of untreated lignocellulose deconstruction by R. thermocellum for CBP purposes.
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Affiliation(s)
- Alan Froese
- Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.,Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - John Schellenberg
- Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.,Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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50
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Mejia J, He S, Yang Y, Ginder-Vogel M, Roden EE. Stability of Ferrihydrite-Humic Acid Coprecipitates under Iron-Reducing Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:13174-13183. [PMID: 30354092 PMCID: PMC8381759 DOI: 10.1021/acs.est.8b03615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Recent studies have suggested the potential for release of iron (hydr)oxide-bound organic carbon (OC) during dissimilatory iron oxide reduction (DIR). However, the stability of iron (hydr)oxide-bound OC in the presence of a natural microbial consortium capable of driving both OC metabolism and DIR has not been resolved. Pure ferrihydrite (Fhy) and Fhy-humic acid coprecipitates (Fhy-HA) were inoculated with a small quantity of freshwater sediment and incubated under anoxic conditions in the presence and absence of H2 or glucose as electron donors for DIR. H2 promoted DIR led to release of ca. 1 mM dissolved organic carbon (DOC). However, comparable amounts of DOC were released from both pure Fhy and Fhy-HA, similar to DOC levels in mineral-free, inoculum-only controls. These results suggest that the observed DOC release during H2-promoted DIR originated from OC contained in the inoculum as opposed to the much larger pool (ca. 38 mM) of OC in the Fhy-HA. Thus, DIR preferentially released sorbed OC with low aromaticity (inoculum OC) versus highly aromatic OC (HA) coprecipitated with iron oxide. Our findings provide new insight into the extent and mechanisms by which DIR is likely to influence aqueous/solid-phase OC partitioning in anoxic soils and sediments.
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Affiliation(s)
- Jacqueline Mejia
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Shaomei He
- Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Yu Yang
- Department of Civil and Environmental Engineering, University of Nevada-Reno, Reno, NV, 89557, USA
| | - Matthew Ginder-Vogel
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Eric E Roden
- Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706, USA
- Corresponding Author: Eric E. Roden. , Phone: 608-890-7024. Fax: 608-262-0693
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