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Biofilm formation by designed co-cultures of Caldicellulosiruptor species as a means to improve hydrogen productivity

Pawar, Sudhanshu LU ; Vongkumpeang, Thitiwut; Grey, Carl LU and van Niel, Ed LU (2015) In Biotechnology for Biofuels 8.
Abstract
Background: Caldicellulosiruptor species have gained a reputation as being among the best microorganisms to

produce hydrogen (H2) due to possession of a combination of appropriate features. However, due to their low

volumetric H2 productivities (QH2), Caldicellulosiruptor species cannot be considered for any viable biohydrogen

production process yet. In this study, we evaluate biofilm forming potential of pure and co-cultures of

Caldicellulosiruptor saccharolyticus and Caldicellulosiruptor owensensis in continuously stirred tank reactors (CSTR)

and up-flow anaerobic (UA) reactors. We also evaluate biofilms as a means to retain biomass in the reactor and

its influence on QH2. Moreover,... (More)
Background: Caldicellulosiruptor species have gained a reputation as being among the best microorganisms to

produce hydrogen (H2) due to possession of a combination of appropriate features. However, due to their low

volumetric H2 productivities (QH2), Caldicellulosiruptor species cannot be considered for any viable biohydrogen

production process yet. In this study, we evaluate biofilm forming potential of pure and co-cultures of

Caldicellulosiruptor saccharolyticus and Caldicellulosiruptor owensensis in continuously stirred tank reactors (CSTR)

and up-flow anaerobic (UA) reactors. We also evaluate biofilms as a means to retain biomass in the reactor and

its influence on QH2. Moreover, we explore the factors influencing the formation of biofilm.

Results: Co-cultures of C. saccharolyticus and C. owensensis form substantially more biofilm than formed by C.

owensensis alone. Biofilms improved substrate conversion in both of the reactor systems, but improved the QH2

only in the UA reactor. When grown in the presence of each other’s culture supernatant, both C. saccharolyticus

and C. owensensis were positively influenced on their individual growth and H2 production. Unlike the CSTR, UA

reactors allowed retention of C. saccharolyticus and C. owensensis when subjected to very high substrate loading

rates. In the UA reactor, maximum QH2 (approximately 20 mmol · L−1 · h−1) was obtained only with granular sludge

as the carrier material. In the CSTR, stirring negatively affected biofilm formation. Whereas, a clear correlation was

observed between elevated (>40 μM) intracellular levels of the secondary messenger bis-(3′-5′)-cyclic dimeric

guanosine monophosphate (c-di-GMP) and biofilm formation.

Conclusions: In co-cultures C. saccharolyticus fortified the trade of biofilm formation by C. owensensis, which was

mediated by elevated levels of c-di-GMP in C. owensensis. These biofilms were effective in retaining biomass of both

species in the reactor and improving QH2 in a UA reactor using granular sludge as the carrier material. This concept

forms a basis for further optimizing the QH2 at laboratory scale and beyond. (Less)
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organization
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type
Contribution to journal
publication status
published
subject
keywords
Caldicellulosiruptor saccharolyticus, Caldicellulosiruptor owensensis, Biohydrogen, Co-culture, c-di-GMP, UA reactor, CSTR, Volumetric H2 productivity
in
Biotechnology for Biofuels
volume
8
publisher
BioMed Central
external identifiers
  • pmid:25722741
  • wos:000350161100002
  • scopus:84928687254
ISSN
1754-6834
DOI
10.1186/s13068-015-0201-7
language
English
LU publication?
yes
id
5a0acad3-8bc2-4644-ae01-619196e8dae3 (old id 5154256)
date added to LUP
2015-03-24 22:41:26
date last changed
2017-09-17 05:47:10
@article{5a0acad3-8bc2-4644-ae01-619196e8dae3,
  abstract     = {Background: Caldicellulosiruptor species have gained a reputation as being among the best microorganisms to<br/><br>
produce hydrogen (H2) due to possession of a combination of appropriate features. However, due to their low<br/><br>
volumetric H2 productivities (QH2), Caldicellulosiruptor species cannot be considered for any viable biohydrogen<br/><br>
production process yet. In this study, we evaluate biofilm forming potential of pure and co-cultures of<br/><br>
Caldicellulosiruptor saccharolyticus and Caldicellulosiruptor owensensis in continuously stirred tank reactors (CSTR)<br/><br>
and up-flow anaerobic (UA) reactors. We also evaluate biofilms as a means to retain biomass in the reactor and<br/><br>
its influence on QH2. Moreover, we explore the factors influencing the formation of biofilm.<br/><br>
Results: Co-cultures of C. saccharolyticus and C. owensensis form substantially more biofilm than formed by C.<br/><br>
owensensis alone. Biofilms improved substrate conversion in both of the reactor systems, but improved the QH2<br/><br>
only in the UA reactor. When grown in the presence of each other’s culture supernatant, both C. saccharolyticus<br/><br>
and C. owensensis were positively influenced on their individual growth and H2 production. Unlike the CSTR, UA<br/><br>
reactors allowed retention of C. saccharolyticus and C. owensensis when subjected to very high substrate loading<br/><br>
rates. In the UA reactor, maximum QH2 (approximately 20 mmol · L−1 · h−1) was obtained only with granular sludge<br/><br>
as the carrier material. In the CSTR, stirring negatively affected biofilm formation. Whereas, a clear correlation was<br/><br>
observed between elevated (&gt;40 μM) intracellular levels of the secondary messenger bis-(3′-5′)-cyclic dimeric<br/><br>
guanosine monophosphate (c-di-GMP) and biofilm formation.<br/><br>
Conclusions: In co-cultures C. saccharolyticus fortified the trade of biofilm formation by C. owensensis, which was<br/><br>
mediated by elevated levels of c-di-GMP in C. owensensis. These biofilms were effective in retaining biomass of both<br/><br>
species in the reactor and improving QH2 in a UA reactor using granular sludge as the carrier material. This concept<br/><br>
forms a basis for further optimizing the QH2 at laboratory scale and beyond.},
  articleno    = {19},
  author       = {Pawar, Sudhanshu and Vongkumpeang, Thitiwut and Grey, Carl and van Niel, Ed},
  issn         = {1754-6834},
  keyword      = {Caldicellulosiruptor saccharolyticus,Caldicellulosiruptor owensensis,Biohydrogen,Co-culture,c-di-GMP,UA reactor,CSTR,Volumetric H2 productivity},
  language     = {eng},
  publisher    = {BioMed Central},
  series       = {Biotechnology for Biofuels},
  title        = {Biofilm formation by designed co-cultures of Caldicellulosiruptor species as a means to improve hydrogen productivity},
  url          = {http://dx.doi.org/10.1186/s13068-015-0201-7},
  volume       = {8},
  year         = {2015},
}