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Performance and population analysis of a non‐sterile trickle bed reactor inoculated with Caldicellulosiruptor saccharolyticus , a thermophilic hydrogen producer
Author(s) -
van Groenestijn J.W.,
Geelhoed J.S.,
Goorissen H.P.,
Meesters K.P.M.,
Stams A.J.M.,
Claassen P.A.M.
Publication year - 2008
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.22185
Subject(s) - fermentation , chemistry , food science , sucrose , population , bioreactor , thermophile , chromatography , biochemistry , organic chemistry , enzyme , demography , sociology
Non‐axenic operation of a 400 L trickle bed reactor inoculated with the thermophile Caldicellulosiruptor saccharolyticus , yielded 2.8 mol H 2 /mol hexose converted. The reactor was fed with a complex medium with sucrose as the main substrate, continuously flushed with nitrogen gas, and operated at 73°C. The volumetric productivity was 22 mmol H 2 /(L filterbed h). Acetic acid and lactic acid were the main by‐products in the liquid phase. Production of lactic acid occurred when hydrogen partial pressure was elevated above 2% and during suboptimal fermentation conditions that also resulted in the presence of mono‐ and disaccharides in the effluent. Methane production was negligible. The microbial community was analyzed at two different time points during operation. Initially, other species related to members of the genera Thermoanaerobacterium and Caldicellulosiruptor were present in the reactor. However, these were out‐competed by C. saccharolyticus during a period when sucrose was completely used and no saccharides were discharged with the effluent. In general, the use of pure cultures in non‐sterile industrial applications is known to be less useful because of contamination. However, our results show that the applied fermentation conditions resulted in a culture of a single dominant organism with excellent hydrogen production characteristics. Biotechnol. Bioeng. 2009;102: 1361–1367. © 2008 Wiley Periodicals, Inc.