Development and characterization of stable anaerobic thermophilic methanogenic microbiomes fermenting switchgrass at decreasing residence times
Abstract Background Anaerobic fermentation of lignocellulose occurs in both natural and managed environments, and is an essential part of the carbon cycle as well as a promising route to sustainable production of fuels and chemicals. Lignocellulose solubilization by mixed microbiomes is important in...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2018-09-01
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| Series: | Biotechnology for Biofuels |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13068-018-1238-1 |
| _version_ | 1818265404413313024 |
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| author | Xiaoyu Liang Jason M. Whitham Evert K. Holwerda Xiongjun Shao Liang Tian Yu-Wei Wu Vincent Lombard Bernard Henrissat Dawn M. Klingeman Zamin K. Yang Mircea Podar Tom L. Richard James G. Elkins Steven D. Brown Lee R. Lynd |
| author_facet | Xiaoyu Liang Jason M. Whitham Evert K. Holwerda Xiongjun Shao Liang Tian Yu-Wei Wu Vincent Lombard Bernard Henrissat Dawn M. Klingeman Zamin K. Yang Mircea Podar Tom L. Richard James G. Elkins Steven D. Brown Lee R. Lynd |
| author_sort | Xiaoyu Liang |
| collection | DOAJ |
| description | Abstract Background Anaerobic fermentation of lignocellulose occurs in both natural and managed environments, and is an essential part of the carbon cycle as well as a promising route to sustainable production of fuels and chemicals. Lignocellulose solubilization by mixed microbiomes is important in these contexts. Results Here, we report the development of stable switchgrass-fermenting enrichment cultures maintained at various residence times and moderately high (55 °C) temperatures. Anaerobic microbiomes derived from a digester inoculum were incubated at 55 °C and fed semi-continuously with medium containing 30 g/L mid-season harvested switchgrass to achieve residence times (RT) of 20, 10, 5, and 3.3 days. Stable, time-invariant cellulolytic methanogenic cultures with minimal accumulation of organic acids were achieved for all RTs. Fractional carbohydrate solubilization was 0.711, 0.654, 0.581 and 0.538 at RT = 20, 10, 5 and 3.3 days, respectively, and glucan solubilization was proportional to xylan solubilization at all RTs. The rate of solubilization was described well by the equation r = k(C − C 0 f r), where C represents the concentration of unutilized carbohydrate, C 0 is the concentration of carbohydrate (cellulose and hemicellulose) entering the bioreactor and f r is the extrapolated fraction of entering carbohydrate that is recalcitrant at infinite residence time. The 3.3 day RT is among the shortest RT reported for stable thermophilic, methanogenic digestion of a lignocellulosic feedstock. 16S rDNA phylotyping and metagenomic analyses were conducted to characterize the effect of RT on community dynamics and to infer functional roles in the switchgrass to biogas conversion to the various microbial taxa. Firmicutes were the dominant phylum, increasing in relative abundance from 54 to 96% as RT decreased. A Clostridium clariflavum strain with genetic markers for xylose metabolism was the most abundant lignocellulose-solubilizing bacterium. A Thermotogae (Defluviitoga tunisiensis) was the most abundant bacterium in switchgrass digesters at RT = 20 days but decreased in abundance at lower RTs as did multiple Chloroflexi. Synergistetes and Euryarchaeota were present at roughly constant levels over the range of RTs examined. Conclusions A system was developed in which stable methanogenic steady-states were readily obtained with a particulate biomass feedstock, mid-season switchgrass, at laboratory (1 L) scale. Characterization of the extent and rate of carbohydrate solubilization in combination with 16S rDNA and metagenomic sequencing provides a multi-dimensional view of performance, species composition, glycoside hydrolases, and metabolic function with varying residence time. These results provide a point of reference and guidance for future studies and organism development efforts involving defined cultures. |
| first_indexed | 2024-12-12T19:50:16Z |
| format | Article |
| id | doaj.art-20b5c86c857a444393423d6b74b53fab |
| institution | Directory Open Access Journal |
| issn | 1754-6834 |
| language | English |
| last_indexed | 2024-12-12T19:50:16Z |
| publishDate | 2018-09-01 |
| publisher | BMC |
| record_format | Article |
| series | Biotechnology for Biofuels |
| spelling | doaj.art-20b5c86c857a444393423d6b74b53fab2022-12-22T00:13:59ZengBMCBiotechnology for Biofuels1754-68342018-09-0111111810.1186/s13068-018-1238-1Development and characterization of stable anaerobic thermophilic methanogenic microbiomes fermenting switchgrass at decreasing residence timesXiaoyu Liang0Jason M. Whitham1Evert K. Holwerda2Xiongjun Shao3Liang Tian4Yu-Wei Wu5Vincent Lombard6Bernard Henrissat7Dawn M. Klingeman8Zamin K. Yang9Mircea Podar10Tom L. Richard11James G. Elkins12Steven D. Brown13Lee R. Lynd14Thayer School of Engineering, Dartmouth CollegeBioEnergy Sciences CenterThayer School of Engineering, Dartmouth CollegeThayer School of Engineering, Dartmouth CollegeThayer School of Engineering, Dartmouth CollegeGraduate Institute of Biomedical Informatics, College of Medical Science and Technology, Taipei Medical UniversityCNRS, UMR 7257, Aix-Marseille UniversityCNRS, UMR 7257, Aix-Marseille UniversityBioEnergy Sciences CenterBiosciences Division, Oak Ridge National LaboratoryBiosciences Division, Oak Ridge National LaboratoryDepartment of Agricultural and Biological Engineering, The Pennsylvania State University, University ParkBioEnergy Sciences CenterBioEnergy Sciences CenterThayer School of Engineering, Dartmouth CollegeAbstract Background Anaerobic fermentation of lignocellulose occurs in both natural and managed environments, and is an essential part of the carbon cycle as well as a promising route to sustainable production of fuels and chemicals. Lignocellulose solubilization by mixed microbiomes is important in these contexts. Results Here, we report the development of stable switchgrass-fermenting enrichment cultures maintained at various residence times and moderately high (55 °C) temperatures. Anaerobic microbiomes derived from a digester inoculum were incubated at 55 °C and fed semi-continuously with medium containing 30 g/L mid-season harvested switchgrass to achieve residence times (RT) of 20, 10, 5, and 3.3 days. Stable, time-invariant cellulolytic methanogenic cultures with minimal accumulation of organic acids were achieved for all RTs. Fractional carbohydrate solubilization was 0.711, 0.654, 0.581 and 0.538 at RT = 20, 10, 5 and 3.3 days, respectively, and glucan solubilization was proportional to xylan solubilization at all RTs. The rate of solubilization was described well by the equation r = k(C − C 0 f r), where C represents the concentration of unutilized carbohydrate, C 0 is the concentration of carbohydrate (cellulose and hemicellulose) entering the bioreactor and f r is the extrapolated fraction of entering carbohydrate that is recalcitrant at infinite residence time. The 3.3 day RT is among the shortest RT reported for stable thermophilic, methanogenic digestion of a lignocellulosic feedstock. 16S rDNA phylotyping and metagenomic analyses were conducted to characterize the effect of RT on community dynamics and to infer functional roles in the switchgrass to biogas conversion to the various microbial taxa. Firmicutes were the dominant phylum, increasing in relative abundance from 54 to 96% as RT decreased. A Clostridium clariflavum strain with genetic markers for xylose metabolism was the most abundant lignocellulose-solubilizing bacterium. A Thermotogae (Defluviitoga tunisiensis) was the most abundant bacterium in switchgrass digesters at RT = 20 days but decreased in abundance at lower RTs as did multiple Chloroflexi. Synergistetes and Euryarchaeota were present at roughly constant levels over the range of RTs examined. Conclusions A system was developed in which stable methanogenic steady-states were readily obtained with a particulate biomass feedstock, mid-season switchgrass, at laboratory (1 L) scale. Characterization of the extent and rate of carbohydrate solubilization in combination with 16S rDNA and metagenomic sequencing provides a multi-dimensional view of performance, species composition, glycoside hydrolases, and metabolic function with varying residence time. These results provide a point of reference and guidance for future studies and organism development efforts involving defined cultures.http://link.springer.com/article/10.1186/s13068-018-1238-1LignocelluloseAnaerobicMethanogenicThermophilicSolubilizationMicrobial communities |
| spellingShingle | Xiaoyu Liang Jason M. Whitham Evert K. Holwerda Xiongjun Shao Liang Tian Yu-Wei Wu Vincent Lombard Bernard Henrissat Dawn M. Klingeman Zamin K. Yang Mircea Podar Tom L. Richard James G. Elkins Steven D. Brown Lee R. Lynd Development and characterization of stable anaerobic thermophilic methanogenic microbiomes fermenting switchgrass at decreasing residence times Biotechnology for Biofuels Lignocellulose Anaerobic Methanogenic Thermophilic Solubilization Microbial communities |
| title | Development and characterization of stable anaerobic thermophilic methanogenic microbiomes fermenting switchgrass at decreasing residence times |
| title_full | Development and characterization of stable anaerobic thermophilic methanogenic microbiomes fermenting switchgrass at decreasing residence times |
| title_fullStr | Development and characterization of stable anaerobic thermophilic methanogenic microbiomes fermenting switchgrass at decreasing residence times |
| title_full_unstemmed | Development and characterization of stable anaerobic thermophilic methanogenic microbiomes fermenting switchgrass at decreasing residence times |
| title_short | Development and characterization of stable anaerobic thermophilic methanogenic microbiomes fermenting switchgrass at decreasing residence times |
| title_sort | development and characterization of stable anaerobic thermophilic methanogenic microbiomes fermenting switchgrass at decreasing residence times |
| topic | Lignocellulose Anaerobic Methanogenic Thermophilic Solubilization Microbial communities |
| url | http://link.springer.com/article/10.1186/s13068-018-1238-1 |
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