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Lazuka A, Auer L, O’Donohue M, Hernandez-Raquet G. Anaerobic lignocellulolytic microbial consortium derived from termite gut: enrichment, lignocellulose degradation and community dynamics. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:284. [PMID: 30356893 PMCID: PMC6191919 DOI: 10.1186/s13068-018-1282-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/06/2018] [Indexed: 05/25/2023]
Abstract
BACKGROUND Lignocellulose is the most abundant renewable carbon resource that can be used for biofuels and commodity chemicals production. The ability of complex microbial communities present in natural environments that are specialized in biomass deconstruction can be exploited to develop lignocellulose bioconversion processes. Termites are among the most abundant insects on earth and play an important role in lignocellulose decomposition. Although their digestive microbiome is recognized as a potential reservoir of microorganisms producing lignocellulolytic enzymes, the potential to enrich and maintain the lignocellulolytic activity of microbial consortia derived from termite gut useful for lignocellulose biorefinery has not been assessed. Here, we assessed the possibility of enriching a microbial consortium from termite gut and maintaining its lignocellulose degradation ability in controlled anaerobic bioreactors. RESULTS We enriched a termite gut-derived consortium able to transform lignocellulose into carboxylates under anaerobic conditions. To assess the impact of substrate natural microbiome on the enrichment and the maintenance of termite gut microbiome, the enrichment process was performed using both sterilized and non-sterilized straw. The enrichment process was carried out in bioreactors operating under industrially relevant aseptic conditions. Two termite gut-derived microbial consortia were obtained from Nasutitermes ephratae by sequential batch culture on raw wheat straw as the sole carbon source. Analysis of substrate loss, carboxylate production and microbial diversity showed that regardless of the substrate sterility, the diversity of communities selected by the enrichment process strongly changed compared to that observed in the termite gut. Nevertheless, the community obtained on sterile straw displayed higher lignocellulose degradation capacity; it showed a high xylanase activity and an initial preference for hemicellulose. CONCLUSIONS This study demonstrates that it is possible to enrich and maintain a microbial consortium derived from termite gut microbiome in controlled anaerobic bioreactors, producing useful carboxylates from raw biomass. Our results suggest that the microbial community is shaped both by the substrate and the conditions that prevail during enrichment. However, when aseptic conditions are applied, it is also affected by the biotic pressure exerted by microorganisms naturally present in the substrate and in the surrounding environment. Besides the efficient lignocellulolytic consortium enriched in this study, our results revealed high levels of xylanase activity that can now be further explored for enzyme identification and overexpression for biorefinery purposes.
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Affiliation(s)
- Adèle Lazuka
- Laboratoire d’Ingénierie des Systèmes Biologiques et des Procédés - LISBP, UMR5504, UMR792, CNRS, INRA, INSA, Université de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex 04, France
| | - Lucas Auer
- Laboratoire d’Ingénierie des Systèmes Biologiques et des Procédés - LISBP, UMR5504, UMR792, CNRS, INRA, INSA, Université de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex 04, France
| | - Michael O’Donohue
- Laboratoire d’Ingénierie des Systèmes Biologiques et des Procédés - LISBP, UMR5504, UMR792, CNRS, INRA, INSA, Université de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex 04, France
| | - Guillermina Hernandez-Raquet
- Laboratoire d’Ingénierie des Systèmes Biologiques et des Procédés - LISBP, UMR5504, UMR792, CNRS, INRA, INSA, Université de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex 04, France
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Auer L, Lazuka A, Sillam-Dussès D, Miambi E, O'Donohue M, Hernandez-Raquet G. Uncovering the Potential of Termite Gut Microbiome for Lignocellulose Bioconversion in Anaerobic Batch Bioreactors. Front Microbiol 2017; 8:2623. [PMID: 29312279 PMCID: PMC5744482 DOI: 10.3389/fmicb.2017.02623] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 12/15/2017] [Indexed: 11/16/2022] Open
Abstract
Termites are xylophages, being able to digest a wide variety of lignocellulosic biomass including wood with high lignin content. This ability to feed on recalcitrant plant material is the result of complex symbiotic relationships, which involve termite-specific gut microbiomes. Therefore, these represent a potential source of microorganisms for the bioconversion of lignocellulose in bioprocesses targeting the production of carboxylates. In this study, gut microbiomes of four termite species were studied for their capacity to degrade wheat straw and produce carboxylates in controlled bioreactors. All of the gut microbiomes successfully degraded lignocellulose and up to 45% w/w of wheat straw degradation was observed, with the Nasutitermes ephratae gut-microbiome displaying the highest levels of wheat straw degradation, carboxylate production and enzymatic activity. Comparing the 16S rRNA gene diversity of the initial gut inocula to the bacterial communities in lignocellulose degradation bioreactors revealed important changes in community diversity. In particular, taxa such as Spirochaetes and Fibrobacteres that were highly abundant in the initial gut inocula were replaced by Firmicutes and Proteobacteria at the end of incubation in wheat straw bioreactors. Overall, this study demonstrates that termite-gut microbiomes constitute a reservoir of lignocellulose-degrading bacteria that can be harnessed in artificial conditions for biomass conversion processes that lead to the production of useful molecules.
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Affiliation(s)
- Lucas Auer
- Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés, Université de Toulouse, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, INSA, Toulouse, France
| | - Adèle Lazuka
- Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés, Université de Toulouse, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, INSA, Toulouse, France
| | - David Sillam-Dussès
- Laboratoire d'Éthologie Expérimentale et Comparée, Université Paris 13 - Sorbonne Paris Cité, Villetaneuse, France
- Institut d'Ecologie et des Sciences de l'Environnement de Paris, Institut de Recherche Pour le Développement – Sorbonne Universités, Bondy, France
| | - Edouard Miambi
- Institut d'Ecologie et des Sciences de l'Environnement de Paris, Université Paris-Est Créteil, Créteil, France
| | - Michael O'Donohue
- Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés, Université de Toulouse, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, INSA, Toulouse, France
| | - Guillermina Hernandez-Raquet
- Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés, Université de Toulouse, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, INSA, Toulouse, France
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Ceballos SJ, Yu C, Claypool JT, Singer SW, Simmons BA, Thelen MP, Simmons CW, VanderGheynst JS. Development and characterization of a thermophilic, lignin degrading microbiota. Process Biochem 2017. [DOI: 10.1016/j.procbio.2017.08.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Abstract
The purpose of this review is to delineate means of decontaminating soil. This information might be used to mitigate soil-associated risks of foodborne pathogens. The majority of the research in the published literature involves inactivation of plant pathogens in soil, i.e., those pathogens harmful to fruit and vegetable production and ornamental plants. Very little has been published regarding the inactivation of foodborne human pathogens in crop soil. Nevertheless, because decontamination techniques for plant pathogens might also be useful methods for eliminating foodborne pathogens, this review also includes inactivation of plant pathogens, with appropriate discussion and comparisons, in the hopes that these methods may one day be validated against foodborne pathogens. Some of the major soil decontamination methods that have been investigated and are covered include chemical decontamination (chemigation), solarization, steaming, biofumigation, bacterial competitive exclusion, torch flaming, microwave treatment, and amendment with biochar. Other innovative means of inactivating foodborne pathogens in soils may be discovered and explored in the future, provided that these techniques are economically feasible in terms of chemicals, equipment, and labor. Food microbiology and food safety researchers should reach out to soil scientists and plant pathologists to create links where they do not currently exist and strengthen relationships where they do exist to take advantage of multidisciplinary skills. In time, agricultural output and the demand for fresh produce will increase. With advances in the sensitivity of pathogen testing and epidemiological tracebacks, the need to mitigate preharvest bacterial contamination of fresh produce will become paramount. Hence, soil decontamination technologies may become more economically feasible and practical in light of increasing the microbial safety of fresh produce.
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Affiliation(s)
- Joshua B Gurtler
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Food Safety and Intervention Technologies Research Unit, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038-8551, USA
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Jain A, Pelle HS, Baughman WH, Henson JM. Conversion of ammonia-pretreated switchgrass to biofuel precursors by bacterial-fungal consortia under solid-state and submerged-state cultivation. J Appl Microbiol 2017; 122:953-963. [PMID: 27626760 DOI: 10.1111/jam.13295] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 08/22/2016] [Accepted: 08/25/2016] [Indexed: 11/27/2022]
Abstract
AIM The aim of this study was to develop and evaluate bacterial-fungal communities to deconstruct switchgrass to biofuel precursors. METHODS AND RESULTS Bacterial-fungal consortia, mesophilic (25°C) and thermophilic (50°C), were enriched from switchgrass bales from which enzyme mixtures were used to deconstruct delignified switchgrass (DSG). The bacterial-fungal consortia were able to produce enzymes including endoglucanase, exoglucanase, β-glucosidase, xylanase, xylosidase and pectinase to convert DSG to soluble carbohydrates. 454 pyrosequencing revealed that Paenibacillus and Streptomyces were the dominant bacteria in the mesophilic and thermophilic consortia respectively. Penicillium and Acremonium were the dominant fungi in the mesophilic consortia, whereas Aspergillus and Penicillium were the dominant fungi present in the thermophilic consortia. CONCLUSIONS The results show that the state of cultivation, solid-state or submerged-state, affects the community structure as well as enzyme activities produced by these bacterial-fungal consortia. The enzyme mixture produced by the bacterial-fungal consortia released a higher amount of xylose than glucose during saccharification of DSG. SIGNIFICANCE AND IMPACT OF THE STUDY The study provides a novel approach to produce enzymes for conversion of lignocellulolytic feedstocks to soluble sugars which can be used to produce biofuel precursors.
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Affiliation(s)
- A Jain
- Biotechnology Institute, University of Minnesota, Twin Cities, Falcon Heights, MN, USA
| | - H S Pelle
- Department of Biology, Sacred Heart University, Fairfield, CT, USA
| | - W H Baughman
- University of South Carolina School of Law, Columbia, SC, USA
| | - J M Henson
- Department of Biological Sciences, Clemson University, Clemson, SC, USA
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Yu C, Harrold DR, Claypool JT, Simmons BA, Singer SW, Simmons CW, VanderGheynst JS. Nitrogen amendment of green waste impacts microbial community, enzyme secretion and potential for lignocellulose decomposition. Process Biochem 2017. [DOI: 10.1016/j.procbio.2016.11.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis. mSystems 2016; 1:mSystems00120-16. [PMID: 27981239 PMCID: PMC5155067 DOI: 10.1128/msystems.00120-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/15/2016] [Indexed: 01/12/2023] Open
Abstract
Pretreatment using ionic liquids (IL) is a promising approach for the conversion of lignocellulose to biofuels. Because IL can be inhibitory to enzymes and microorganisms involved in downstream hydrolysis and fermentation steps, discovery of IL-tolerant organisms and enzymes is critical for advancing this technology. Employing metatranscriptomics in the analysis of IL-enriched cultures facilitated tracking of dynamic changes in a complex microbial community at the level of gene transcription and doing so with genome resolution. Specific organisms were discovered that could simultaneously tolerate a moderate IL concentration and transcribe a diverse array of cellulolytic enzymes. Gene sequences of cellulolytic enzymes and efflux pumps from those same organisms were also identified, providing important resources for future research on engineering IL-tolerant organisms and enzymes. Ionic liquid (IL) pretreatment is a promising approach for the conversion of lignocellulose to biofuels. The toxicity of residual IL, however, negatively impacts the performance of industrial enzymes and microorganisms in hydrolysis and fermentation. In this study, a thermophilic microbial community was cultured on switchgrass amended with various levels of the ionic liquid 1-ethyl-3-methylimidazolium acetate. Changes in the microbial community composition and transcription of genes relevant to IL tolerance and lignocellulose hydrolysis were quantified. Increasing the level of IL to 0.1% (wt) led to increased levels of relative abundance and transcription in organisms of the phylum Firmicutes. Interestingly, IL concentrations of up to 1% (wt) also resulted in greater xylanase transcription and enzyme activity as well as increased transcription of endoglucanase, beta-glucosidase, and IL tolerance genes compared to communities without IL. IL levels above 1% (wt) resulted in decreased enzyme activity and transcription of genes involved in lignocellulose hydrolysis. The results indicate that moderate levels of IL select for thermophilic microorganisms that not only tolerate IL but also effectively hydrolyze lignocellulose from switchgrass. Discovery of IL-tolerant organisms and enzymes is critical for the development of biological processes that convert IL-pretreated biomass to biofuels and chemicals. Employing metatranscriptomic analysis of enrichment cultures can facilitate the discovery of microorganisms and enzymes that may be active in the presence of toxic compounds such as ionic liquids. IMPORTANCE Pretreatment using ionic liquids (IL) is a promising approach for the conversion of lignocellulose to biofuels. Because IL can be inhibitory to enzymes and microorganisms involved in downstream hydrolysis and fermentation steps, discovery of IL-tolerant organisms and enzymes is critical for advancing this technology. Employing metatranscriptomics in the analysis of IL-enriched cultures facilitated tracking of dynamic changes in a complex microbial community at the level of gene transcription and doing so with genome resolution. Specific organisms were discovered that could simultaneously tolerate a moderate IL concentration and transcribe a diverse array of cellulolytic enzymes. Gene sequences of cellulolytic enzymes and efflux pumps from those same organisms were also identified, providing important resources for future research on engineering IL-tolerant organisms and enzymes.
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Jain A, Bediako SH, Henson JM. Correlation analysis of enzyme activities and deconstruction of ammonia-pretreated switchgrass by bacterial-fungal communities. BIORESOURCE TECHNOLOGY 2016; 218:1082-1089. [PMID: 27469088 DOI: 10.1016/j.biortech.2016.07.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 07/07/2016] [Accepted: 07/08/2016] [Indexed: 06/06/2023]
Abstract
The mixed microbial communities that occur naturally on lignocellulosic feedstocks can provide feedstock-specific enzyme mixtures to saccharify lignocelluloses. Bacterial-fungal communities were enriched from switchgrass bales to deconstruct ammonia-pretreated switchgrass (DSG). Correlation analysis was carried out to elucidate the relationship between microbial decomposition of DSG by these communities, enzymatic activities produced and enzymatic saccharification of DSG using these enzyme mixtures. Results of the analysis showed that β-glucosidase and xylosidase activities limited the extent of microbial deconstruction and enzymatic saccharification of DSG. The results also underlined the importance of ligninase activity for the enzymatic saccharification of pretreated lignocellulosic feedstock. The bacterial-fungal communities developed in this research can be used to produce enzyme mixtures to deconstruct DSG, and the results from the correlation analysis can be used to optimize these enzyme mixtures for efficient saccharification of DSG to produce second-generation biofuels.
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Affiliation(s)
- Abhiney Jain
- Biotechnology Institute, University of Minnesota, Twin Cities, 1479 Gortner Avenue, Falcon Heights, MN 55108, United States
| | - Sandra H Bediako
- Sacred Heart University, Department of Biology, 5151 Park Avenue, Fairfield, CT 06825, United States
| | - J Michael Henson
- Department of Biological Sciences, 157A Life Sciences Facility, Clemson University, Clemson, SC 29634, United States.
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Enrichment of microbial communities tolerant to the ionic liquids tetrabutylphosphonium chloride and tributylethylphosphonium diethylphosphate. Appl Microbiol Biotechnol 2016; 100:5639-52. [DOI: 10.1007/s00253-016-7525-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 03/21/2016] [Accepted: 04/05/2016] [Indexed: 10/21/2022]
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Yu C, Reddy AP, Simmons CW, Simmons BA, Singer SW, VanderGheynst JS. Preservation of microbial communities enriched on lignocellulose under thermophilic and high-solid conditions. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:206. [PMID: 26633993 PMCID: PMC4667496 DOI: 10.1186/s13068-015-0392-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Accepted: 11/17/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND Microbial communities enriched from diverse environments have shown considerable promise for the targeted discovery of microorganisms and enzymes for bioconversion of lignocellulose to liquid fuels. While preservation of microbial communities is important for commercialization and research, few studies have examined storage conditions ideal for preservation. The goal of this study was to evaluate the impact of preservation method on composition of microbial communities enriched on switchgrass before and after storage. The enrichments were completed in a high-solid and aerobic environment at 55 °C. Community composition was examined for each enrichment to determine when a stable community was achieved. Preservation methods included cryopreservation with the cryoprotective agents DMSO and glycerol, and cryopreservation without cryoprotective agents. Revived communities were examined for their ability to decompose switchgrass under high-solid and thermophilic conditions. RESULTS High-throughput 16S rRNA gene sequencing of DNA extracted from enrichment samples showed that the majority of the shift in composition of the switchgrass-degrading community occurred during the initial three 2-week enrichments. Shifts in community structure upon storage occurred in all cryopreserved samples. Storage in liquid nitrogen in the absence of cryoprotectant resulted in variable preservation of dominant microorganisms in enriched samples. Cryopreservation with either DMSO or glycerol provided consistent and equivalent preservation of dominant organisms. CONCLUSIONS A stable switchgrass-degrading microbial community was achieved after three 2-week enrichments. Dominant microorganisms were preserved equally well with DMSO and glycerol. DMSO-preserved communities required more incubation time upon revival to achieve pre-storage activity levels during high-solid thermophilic cultivation on switchgrass. Despite shifts in the community with storage, the samples were active upon revival under thermophilic and high-solid conditions. The results suggest that the presence of microorganisms may be more important than their relative abundance in retaining an active microbial community.
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Affiliation(s)
- Chaowei Yu
- />Department of Biological and Agricultural Engineering, University of California, One Shields Ave, Davis, CA 95616 USA
| | - Amitha P. Reddy
- />Department of Biological and Agricultural Engineering, University of California, One Shields Ave, Davis, CA 95616 USA
- />Joint BioEnergy Institute, Emeryville, CA 94608 USA
| | - Christopher W. Simmons
- />Joint BioEnergy Institute, Emeryville, CA 94608 USA
- />Department of Food Science and Technology, University of California, Davis, CA 95616 USA
| | - Blake A. Simmons
- />Joint BioEnergy Institute, Emeryville, CA 94608 USA
- />Biological and Materials Science Center, Sandia National Laboratories, Livermore, CA 94551 USA
| | - Steven W. Singer
- />Joint BioEnergy Institute, Emeryville, CA 94608 USA
- />Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Jean S. VanderGheynst
- />Department of Biological and Agricultural Engineering, University of California, One Shields Ave, Davis, CA 95616 USA
- />Joint BioEnergy Institute, Emeryville, CA 94608 USA
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Lazuka A, Auer L, Bozonnet S, Morgavi DP, O'Donohue M, Hernandez-Raquet G. Efficient anaerobic transformation of raw wheat straw by a robust cow rumen-derived microbial consortium. BIORESOURCE TECHNOLOGY 2015; 196:241-9. [PMID: 26247975 DOI: 10.1016/j.biortech.2015.07.084] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 07/23/2015] [Accepted: 07/24/2015] [Indexed: 05/15/2023]
Abstract
A rumen-derived microbial consortium was enriched on raw wheat straw as sole carbon source in a sequential batch-reactor (SBR) process under strict mesophilic anaerobic conditions. After five cycles of enrichment the procedure enabled to select a stable and efficient lignocellulolytic microbial consortium, mainly constituted by members of Firmicutes and Bacteroidetes phyla. The enriched community, designed rumen-wheat straw-derived consortium (RWS) efficiently hydrolyzed lignocellulosic biomass, degrading 55.5% w/w of raw wheat straw over 15days at 35°C and accumulating carboxylates as main products. Cellulolytic and hemicellulolytic activities, mainly detected on the cell bound fraction, were produced in the earlier steps of degradation, their production being correlated with the maximal lignocellulose degradation rates. Overall, these results demonstrate the potential of RWS to convert unpretreated lignocellulosic substrates into useful chemicals.
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Affiliation(s)
- Adèle Lazuka
- Université de Toulouse, INSA, UPS, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse Cedex 4, France; INRA, UMR792, Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France; CNRS, UMR5504, F-31400 Toulouse, France
| | - Lucas Auer
- Université de Toulouse, INSA, UPS, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse Cedex 4, France; INRA, UMR792, Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France; CNRS, UMR5504, F-31400 Toulouse, France
| | - Sophie Bozonnet
- Université de Toulouse, INSA, UPS, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse Cedex 4, France; INRA, UMR792, Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France; CNRS, UMR5504, F-31400 Toulouse, France
| | - Diego P Morgavi
- INRA, UR1213 Herbivores, Centre de Theix, F-63122 St-Genès-Champanelle, France
| | - Michael O'Donohue
- Université de Toulouse, INSA, UPS, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse Cedex 4, France; INRA, UMR792, Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France; CNRS, UMR5504, F-31400 Toulouse, France
| | - Guillermina Hernandez-Raquet
- Université de Toulouse, INSA, UPS, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse Cedex 4, France; INRA, UMR792, Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France; CNRS, UMR5504, F-31400 Toulouse, France.
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Vishnivetskaya TA, Hamilton-Brehm SD, Podar M, Mosher JJ, Palumbo AV, Phelps TJ, Keller M, Elkins JG. Community analysis of plant biomass-degrading microorganisms from Obsidian Pool, Yellowstone National Park. MICROBIAL ECOLOGY 2015; 69:333-345. [PMID: 25319238 DOI: 10.1007/s00248-014-0500-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 09/16/2014] [Indexed: 06/04/2023]
Abstract
The conversion of lignocellulosic biomass into biofuels can potentially be improved by employing robust microorganisms and enzymes that efficiently deconstruct plant polysaccharides at elevated temperatures. Many of the geothermal features of Yellowstone National Park (YNP) are surrounded by vegetation providing a source of allochthonic material to support heterotrophic microbial communities adapted to utilize plant biomass as a primary carbon and energy source. In this study, a well-known hot spring environment, Obsidian Pool (OBP), was examined for potential biomass-active microorganisms using cultivation-independent and enrichment techniques. Analysis of 33,684 archaeal and 43,784 bacterial quality-filtered 16S rRNA gene pyrosequences revealed that archaeal diversity in the main pool was higher than bacterial; however, in the vegetated area, overall bacterial diversity was significantly higher. Of notable interest was a flooded depression adjacent to OBP supporting a stand of Juncus tweedyi, a heat-tolerant rush commonly found growing near geothermal features in YNP. The microbial community from heated sediments surrounding the plants was enriched in members of the Firmicutes including potentially (hemi)cellulolytic bacteria from the genera Clostridium, Anaerobacter, Caloramator, Caldicellulosiruptor, and Thermoanaerobacter. Enrichment cultures containing model and real biomass substrates were established at a wide range of temperatures (55-85 °C). Microbial activity was observed up to 80 °C on all substrates including Avicel, xylan, switchgrass, and Populus sp. Independent of substrate, Caloramator was enriched at lower (<65 °C) temperatures while highly active cellulolytic bacteria Caldicellulosiruptor were dominant at high (>65 °C) temperatures.
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Affiliation(s)
- Tatiana A Vishnivetskaya
- BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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Simmons CW, Reddy AP, VanderGheynst JS, Simmons BA, Singer SW. Bacillus coagulanstolerance to 1-ethyl-3-methylimidazolium-based ionic liquids in aqueous and solid-state thermophilic culture. Biotechnol Prog 2014; 30:311-6. [DOI: 10.1002/btpr.1859] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 09/01/2013] [Accepted: 11/28/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Christopher W. Simmons
- Joint BioEnergy Inst., Deconstruction Division; Emeryville CA
- Biological and Agricultural Engineering; University of California-Davis; Davis CA
- Food Science and Technology; University of California-Davis; Davis CA
| | - Amitha P. Reddy
- Joint BioEnergy Inst., Deconstruction Division; Emeryville CA
- Biological and Agricultural Engineering; University of California-Davis; Davis CA
| | - Jean S. VanderGheynst
- Joint BioEnergy Inst., Deconstruction Division; Emeryville CA
- Biological and Agricultural Engineering; University of California-Davis; Davis CA
| | - Blake A. Simmons
- Joint BioEnergy Inst., Deconstruction Division; Emeryville CA
- Physical and Life Sciences Directorate; Lawrence Livermore National Laboratory; Livermore CA
| | - Steven W. Singer
- Joint BioEnergy Inst., Deconstruction Division; Emeryville CA
- Dept. of Biomass Science and Conversion Technology; Sandia National Laboratories; Livermore CA
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Reddy AP, Simmons CW, D’haeseleer P, Khudyakov J, Burd H, Hadi M, Simmons BA, Singer SW, Thelen MP, VanderGheynst JS. Discovery of microorganisms and enzymes involved in high-solids decomposition of rice straw using metagenomic analyses. PLoS One 2013; 8:e77985. [PMID: 24205054 PMCID: PMC3808287 DOI: 10.1371/journal.pone.0077985] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/16/2013] [Indexed: 02/01/2023] Open
Abstract
High-solids incubations were performed to enrich for microbial communities and enzymes that decompose rice straw under mesophilic (35°C) and thermophilic (55°C) conditions. Thermophilic enrichments yielded a community that was 7.5 times more metabolically active on rice straw than mesophilic enrichments. Extracted xylanase and endoglucanse activities were also 2.6 and 13.4 times greater, respectively, for thermophilic enrichments. Metagenome sequencing was performed on enriched communities to determine community composition and mine for genes encoding lignocellulolytic enzymes. Proteobacteria were found to dominate the mesophilic community while Actinobacteria were most abundant in the thermophilic community. Analysis of protein family representation in each metagenome indicated that cellobiohydrolases containing carbohydrate binding module 2 (CBM2) were significantly overrepresented in the thermophilic community. Micromonospora, a member of Actinobacteria, primarily housed these genes in the thermophilic community. In light of these findings, Micromonospora and other closely related Actinobacteria genera appear to be promising sources of thermophilic lignocellulolytic enzymes for rice straw deconstruction under high-solids conditions. Furthermore, these discoveries warrant future research to determine if exoglucanases with CBM2 represent thermostable enzymes tolerant to the process conditions expected to be encountered during industrial biofuel production.
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Affiliation(s)
- Amitha P. Reddy
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Biological and Agricultural Engineering, University of California Davis, Davis, California, United States of America
| | - Christopher W. Simmons
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Biological and Agricultural Engineering, University of California Davis, Davis, California, United States of America
- Food Science, University of California Davis, Davis, California, United States of America
| | - Patrik D’haeseleer
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States of America
| | - Jane Khudyakov
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States of America
| | - Helcio Burd
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Masood Hadi
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Biological and Materials Science Center, Sandia National Laboratories, Livermore, California, United States of America
| | - Blake A. Simmons
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Biological and Materials Science Center, Sandia National Laboratories, Livermore, California, United States of America
| | - Steven W. Singer
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Michael P. Thelen
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States of America
| | - Jean S. VanderGheynst
- Joint BioEnergy Institute, Emeryville, California, United States of America
- Biological and Agricultural Engineering, University of California Davis, Davis, California, United States of America
- * E-mail:
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15
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Reddy A, Simmons C, Claypool J, Jabusch L, Burd H, Hadi M, Simmons B, Singer S, VanderGheynst J. Thermophilic enrichment of microbial communities in the presence of the ionic liquid 1-ethyl-3-methylimidazolium acetate. J Appl Microbiol 2012; 113:1362-70. [DOI: 10.1111/jam.12002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 08/26/2012] [Accepted: 08/29/2012] [Indexed: 11/28/2022]
Affiliation(s)
- A.P. Reddy
- Joint BioEnergy Institute; Emeryville CA USA
- Biological and Agricultural Engineering; University of California-Davis; Davis CA USA
| | - C.W. Simmons
- Joint BioEnergy Institute; Emeryville CA USA
- Biological and Agricultural Engineering; University of California-Davis; Davis CA USA
| | - J. Claypool
- Biological and Agricultural Engineering; University of California-Davis; Davis CA USA
| | - L. Jabusch
- Biological and Agricultural Engineering; University of California-Davis; Davis CA USA
| | - H. Burd
- Joint BioEnergy Institute; Emeryville CA USA
- Earth Sciences Division; Lawrence Berkeley National Laboratory; Berkeley CA USA
| | - M.Z. Hadi
- Joint BioEnergy Institute; Emeryville CA USA
- Physical and Life Sciences Directorate; Lawrence Livermore National Laboratory; Livermore CA USA
| | - B.A. Simmons
- Joint BioEnergy Institute; Emeryville CA USA
- Physical and Life Sciences Directorate; Lawrence Livermore National Laboratory; Livermore CA USA
| | - S.W. Singer
- Joint BioEnergy Institute; Emeryville CA USA
- Department of Biomass Science and Conversion Technology; Sandia National Laboratories; Livermore CA USA
| | - J.S. VanderGheynst
- Joint BioEnergy Institute; Emeryville CA USA
- Biological and Agricultural Engineering; University of California-Davis; Davis CA USA
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16
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Global transcriptome response to ionic liquid by a tropical rain forest soil bacterium, Enterobacter lignolyticus. Proc Natl Acad Sci U S A 2012; 109:E2173-82. [PMID: 22586090 DOI: 10.1073/pnas.1112750109] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To process plant-based renewable biofuels, pretreatment of plant feedstock with ionic liquids has significant advantages over current methods for deconstruction of lignocellulosic feedstocks. However, ionic liquids are often toxic to the microorganisms used subsequently for biomass saccharification and fermentation. We previously isolated Enterobacter lignolyticus strain SCF1, a lignocellulolytic bacterium from tropical rain forest soil, and report here that it can grow in the presence of 0.5 M 1-ethyl-3-methylimidazolium chloride, a commonly used ionic liquid. We investigated molecular mechanisms of SCF1 ionic liquid tolerance using a combination of phenotypic growth assays, phospholipid fatty acid analysis, and RNA sequencing technologies. Potential modes of resistance to 1-ethyl-3-methylimidazolium chloride include an increase in cyclopropane fatty acids in the cell membrane, scavenging of compatible solutes, up-regulation of osmoprotectant transporters and drug efflux pumps, and down-regulation of membrane porins. These findings represent an important first step in understanding mechanisms of ionic liquid resistance in bacteria and provide a basis for engineering microbial tolerance.
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