Characterization and adaptation of Caldicellulosiruptor strains to higher sugar concentrations, targeting enhanced hydrogen production from lignocellulosic hydrolysates
(2021) In Biotechnology for Biofuels 14.- Abstract
- The members of the genus Caldicellulosiruptor have the potential for future integration into a biorefinery system due to their capacity to generate hydrogen close to the theoretical limit of 4 mol H2/mol hexose, use a wide range of sugars and can grow on numerous lignocellulose hydrolysates. However, members of this genus are unable to survive in high sugar concentrations, limiting their ability to grow on more concentrated hydrolysates, thus impeding their industrial applicability. In this study five members of this genus, C. owensensis, C. kronotskyensis, C. bescii, C. acetigenus and C. kristjanssonii, were developed to tolerate higher sugar concentrations through an adaptive laboratory evolution... (More)
- The members of the genus Caldicellulosiruptor have the potential for future integration into a biorefinery system due to their capacity to generate hydrogen close to the theoretical limit of 4 mol H2/mol hexose, use a wide range of sugars and can grow on numerous lignocellulose hydrolysates. However, members of this genus are unable to survive in high sugar concentrations, limiting their ability to grow on more concentrated hydrolysates, thus impeding their industrial applicability. In this study five members of this genus, C. owensensis, C. kronotskyensis, C. bescii, C. acetigenus and C. kristjanssonii, were developed to tolerate higher sugar concentrations through an adaptive laboratory evolution (ALE) process. The developed mixed population C. owensensis CO80 was further studied and accompanied by the development of a kinetic model based on Monod kinetics to quantitatively compare it with the parental strain.
Results
Mixed populations of Caldicellulosiruptor tolerant to higher glucose concentrations were obtained with C. owensensis adapted to grow up to 80 g/L glucose; other strains in particular C. kristjanssonii demonstrated a greater restriction to adaptation. The C. owensensis CO80 mixed population was further studied and demonstrated the ability to grow in glucose concentrations up to 80 g/L glucose, but with reduced volumetric hydrogen productivities (QH2) and incomplete sugar conversion at elevated glucose concentrations. In addition, the carbon yield decreased with elevated concentrations of glucose. The ability of the mixed population C. owensensis CO80 to grow in high glucose concentrations was further described with a kinetic growth model, which revealed that the critical sugar concentration of the cells increased fourfold when cultivated at higher concentrations. When co-cultured with the adapted C. saccharolyticus G5 mixed culture at a hydraulic retention time (HRT) of 20 h, C. owensensis constituted only 0.09–1.58% of the population in suspension.
Conclusions
The adaptation of members of the Caldicellulosiruptor genus to higher sugar concentrations established that the ability to develop improved strains via ALE is species dependent, with C. owensensis adapted to grow on 80 g/L, whereas C. kristjanssonii could only be adapted to 30 g/L glucose. Although C. owensensis CO80 was adapted to a higher sugar concentration, this mixed population demonstrated reduced QH2 with elevated glucose concentrations. This would indicate that while ALE permits adaptation to elevated sugar concentrations, this approach does not result in improved fermentation performances at these higher sugar concentrations. Moreover, the observation that planktonic mixed culture of CO80 was outcompeted by an adapted C. saccharolyticus, when co-cultivated in continuous mode, indicates that the robustness of CO80 mixed culture should be improved for industrial application. (Less)
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https://lup.lub.lu.se/record/c4cc608d-3f2b-4ac5-9962-5c3e29c57a62
- author
- Byrne, Eoin LU ; Björkmalm, Johanna LU ; Bostick, James P. ; Sreenivas, Krishnan LU ; Willquist, Karin LU and van Niel, Ed W. J. LU
- organization
- publishing date
- 2021-10-30
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Osmolarity, Caldicellulosiruptor, Biohydrogen, Kinetic model, Adaptive laboratory evolution
- in
- Biotechnology for Biofuels
- volume
- 14
- article number
- 210
- pages
- 14 pages
- publisher
- BioMed Central (BMC)
- external identifiers
-
- scopus:85118261833
- pmid:34717729
- ISSN
- 1754-6834
- DOI
- 10.1186/s13068-021-02058-x
- language
- English
- LU publication?
- yes
- id
- c4cc608d-3f2b-4ac5-9962-5c3e29c57a62
- date added to LUP
- 2021-10-31 10:39:30
- date last changed
- 2022-04-27 05:21:39
@article{c4cc608d-3f2b-4ac5-9962-5c3e29c57a62,
abstract = {{The members of the genus <i>Caldicellulosiruptor</i> have the potential for future integration into a biorefinery system due to their capacity to generate hydrogen close to the theoretical limit of 4 mol H2/mol hexose, use a wide range of sugars and can grow on numerous lignocellulose hydrolysates. However, members of this genus are unable to survive in high sugar concentrations, limiting their ability to grow on more concentrated hydrolysates, thus impeding their industrial applicability. In this study five members of this genus, <i>C. owensensis</i>, <i>C. kronotskyensis</i>, <i>C. bescii</i>, <i>C. acetigenus</i> and <i>C. kristjanssonii</i>, were developed to tolerate higher sugar concentrations through an adaptive laboratory evolution (ALE) process. The developed mixed population <i>C. owensensis</i> CO80 was further studied and accompanied by the development of a kinetic model based on Monod kinetics to quantitatively compare it with the parental strain.<br/><br/>Results<br/>Mixed populations of <i>Caldicellulosiruptor </i>tolerant to higher glucose concentrations were obtained with <i>C. owensensis</i> adapted to grow up to 80 g/L glucose; other strains in particular <i>C. kristjanssonii</i> demonstrated a greater restriction to adaptation. The <i>C. owensensis</i> CO80 mixed population was further studied and demonstrated the ability to grow in glucose concentrations up to 80 g/L glucose, but with reduced volumetric hydrogen productivities (Q<sub>H2</sub>) and incomplete sugar conversion at elevated glucose concentrations. In addition, the carbon yield decreased with elevated concentrations of glucose. The ability of the mixed population <i>C. owensensis</i> CO80 to grow in high glucose concentrations was further described with a kinetic growth model, which revealed that the critical sugar concentration of the cells increased fourfold when cultivated at higher concentrations. When co-cultured with the adapted C. saccharolyticus G5 mixed culture at a hydraulic retention time (HRT) of 20 h, C. owensensis constituted only 0.09–1.58% of the population in suspension.<br/><br/>Conclusions<br/>The adaptation of members of the <i>Caldicellulosiruptor </i>genus to higher sugar concentrations established that the ability to develop improved strains via ALE is species dependent, with <i>C. owensensis</i> adapted to grow on 80 g/L, whereas <i>C. kristjanssonii</i> could only be adapted to 30 g/L glucose. Although <i>C. owensensis</i> CO80 was adapted to a higher sugar concentration, this mixed population demonstrated reduced <i>Q</i><sub>H2</sub> with elevated glucose concentrations. This would indicate that while ALE permits adaptation to elevated sugar concentrations, this approach does not result in improved fermentation performances at these higher sugar concentrations. Moreover, the observation that planktonic mixed culture of CO80 was outcompeted by an adapted <i>C. saccharolyticus</i>, when co-cultivated in continuous mode, indicates that the robustness of CO80 mixed culture should be improved for industrial application.}},
author = {{Byrne, Eoin and Björkmalm, Johanna and Bostick, James P. and Sreenivas, Krishnan and Willquist, Karin and van Niel, Ed W. J.}},
issn = {{1754-6834}},
keywords = {{Osmolarity; Caldicellulosiruptor; Biohydrogen; Kinetic model; Adaptive laboratory evolution}},
language = {{eng}},
month = {{10}},
publisher = {{BioMed Central (BMC)}},
series = {{Biotechnology for Biofuels}},
title = {{Characterization and adaptation of <i>Caldicellulosiruptor </i>strains to higher sugar concentrations, targeting enhanced hydrogen production from lignocellulosic hydrolysates}},
url = {{https://lup.lub.lu.se/search/files/109040210/Byrne_et_al_2021_B4B_14_210.pdf}},
doi = {{10.1186/s13068-021-02058-x}},
volume = {{14}},
year = {{2021}},
}