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A non-linear model of hydrogen production by Caldicellulosiruptor saccharolyticus for diauxic-like consumption of lignocellulosic sugar mixtures

Björkmalm, Johanna LU ; Byrne, Eoin LU ; van Niel, Ed LU and Willquist, Karin (2018) In Biotechnology for Biofuels 11(1). p.1-15
Abstract
Background: Caldicellulosiruptor saccharolyticus is an attractive hydrogen producer suitable for growth on various lignocellulosic substrates. The aim of this study was to quantify uptake of pentose and hexose monosaccharides in an
industrial substrate and to present a kinetic growth model of C. saccharolyticus that includes sugar uptake on defined and industrial media. The model is based on Monod and Hill kinetics extended with gas-to-liquid mass transfer and a
cybernetic approach to describe diauxic-like growth.
Results: Mathematical expressions were developed to describe hydrogen production by C. saccharolyticus consuming glucose, xylose, and arabinose. The model parameters were calibrated against batch fermentation data.... (More)
Background: Caldicellulosiruptor saccharolyticus is an attractive hydrogen producer suitable for growth on various lignocellulosic substrates. The aim of this study was to quantify uptake of pentose and hexose monosaccharides in an
industrial substrate and to present a kinetic growth model of C. saccharolyticus that includes sugar uptake on defined and industrial media. The model is based on Monod and Hill kinetics extended with gas-to-liquid mass transfer and a
cybernetic approach to describe diauxic-like growth.
Results: Mathematical expressions were developed to describe hydrogen production by C. saccharolyticus consuming glucose, xylose, and arabinose. The model parameters were calibrated against batch fermentation data. The
experimental data included four different cases: glucose, xylose, sugar mixture, and wheat straw hydrolysate (WSH) fermentations. The fermentations were performed without yeast extract. The substrate uptake rate of C. saccharolyticus
on single sugar-defined media was higher on glucose compared to xylose. In contrast, in the defined sugar mixture and WSH, the pentoses were consumed faster than glucose. Subsequently, the cultures entered a lag phase
when all pentoses were consumed after which glucose uptake rate increased. This phenomenon suggested a diauxic-like behavior as was deduced from the successive appearance of two peaks in the hydrogen and carbon dioxide
productivity. The observation could be described with a modified diauxic model including a second enzyme system with a higher affinity for glucose being expressed when pentose saccharides are consumed. This behavior was more
pronounced when WSH was used as substrate.
Conclusions: The previously observed co-consumption of glucose and pentoses with a preference for the latter was herein confirmed. However, once all pentoses were consumed, C. saccharolyticus most probably expressed another
uptake system to account for the observed increased glucose uptake rate. This phenomenon could be quantitatively captured in a kinetic model of the entire diauxic-like growth process. Moreover, the observation indicates a regulation
system that has fundamental research relevance, since pentose and glucose uptake in C. saccharolyticus has only been described with ABC transporters, whereas previously reported diauxic growth phenomena have been correlated
mainly to PTS systems for sugar uptake. (Less)
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author
organization
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Contribution to journal
publication status
published
subject
keywords
Caldicellulosiruptor saccharolyticus, Hydrogen, Kinetic growth model, Glucose uptake, Xylose uptake,
in
Biotechnology for Biofuels
volume
11
issue
1
pages
15 pages
publisher
BioMed Central
external identifiers
  • scopus:85049011727
ISSN
1754-6834
DOI
10.1186/s13068-018-1171-3
language
English
LU publication?
yes
id
6dbb926e-e154-4892-bf5c-d7e352ff2c9f
date added to LUP
2018-06-25 10:02:14
date last changed
2018-07-08 04:32:20
@article{6dbb926e-e154-4892-bf5c-d7e352ff2c9f,
  abstract     = {Background: Caldicellulosiruptor saccharolyticus is an attractive hydrogen producer suitable for growth on various lignocellulosic substrates. The aim of this study was to quantify uptake of pentose and hexose monosaccharides in an<br/>industrial substrate and to present a kinetic growth model of C. saccharolyticus that includes sugar uptake on defined and industrial media. The model is based on Monod and Hill kinetics extended with gas-to-liquid mass transfer and a<br/>cybernetic approach to describe diauxic-like growth.<br/>Results: Mathematical expressions were developed to describe hydrogen production by C. saccharolyticus consuming glucose, xylose, and arabinose. The model parameters were calibrated against batch fermentation data. The<br/>experimental data included four different cases: glucose, xylose, sugar mixture, and wheat straw hydrolysate (WSH) fermentations. The fermentations were performed without yeast extract. The substrate uptake rate of C. saccharolyticus<br/>on single sugar-defined media was higher on glucose compared to xylose. In contrast, in the defined sugar mixture and WSH, the pentoses were consumed faster than glucose. Subsequently, the cultures entered a lag phase<br/>when all pentoses were consumed after which glucose uptake rate increased. This phenomenon suggested a diauxic-like behavior as was deduced from the successive appearance of two peaks in the hydrogen and carbon dioxide<br/>productivity. The observation could be described with a modified diauxic model including a second enzyme system with a higher affinity for glucose being expressed when pentose saccharides are consumed. This behavior was more<br/>pronounced when WSH was used as substrate.<br/>Conclusions: The previously observed co-consumption of glucose and pentoses with a preference for the latter was herein confirmed. However, once all pentoses were consumed, C. saccharolyticus most probably expressed another<br/>uptake system to account for the observed increased glucose uptake rate. This phenomenon could be quantitatively captured in a kinetic model of the entire diauxic-like growth process. Moreover, the observation indicates a regulation<br/>system that has fundamental research relevance, since pentose and glucose uptake in C. saccharolyticus has only been described with ABC transporters, whereas previously reported diauxic growth phenomena have been correlated<br/>mainly to PTS systems for sugar uptake.},
  articleno    = {175},
  author       = {Björkmalm, Johanna and Byrne, Eoin and van Niel, Ed and Willquist, Karin},
  issn         = {1754-6834},
  keyword      = {Caldicellulosiruptor saccharolyticus, Hydrogen, Kinetic growth model, Glucose uptake, Xylose uptake,},
  language     = {eng},
  month        = {06},
  number       = {1},
  pages        = {1--15},
  publisher    = {BioMed Central},
  series       = {Biotechnology for Biofuels},
  title        = {A non-linear model of hydrogen production by Caldicellulosiruptor saccharolyticus for diauxic-like consumption of lignocellulosic sugar mixtures},
  url          = {http://dx.doi.org/10.1186/s13068-018-1171-3},
  volume       = {11},
  year         = {2018},
}