Publisher DOI: 10.1002/bit.26963
Title: Enhanced electron transfer of different mediators for strictly opposite shifting of metabolism in Clostridium pasteurianum grown on glycerol in a new electrochemical bioreactor
Language: English
Authors: Utesch, Tyll 
Sabra, Wael Ahmed 
Prescher, Christin 
Baur, Julian 
Arbter, Philipp 
Zeng, An-Ping 
Issue Date: Jul-2019
Source: Biotechnology and Bioengineering 7 (116): 1627-1643 (2019-07)
Journal or Series Name: Biotechnology and Bioengineering 
Abstract (english): Microbial electrosynthesis or electro-fermentation in bioelectrochemical systems (BES) have recently received much attention. Here, we demonstrate with the glycerol metabolism by Clostridium pasteurianum that H 2 from in situ water electrolysis, especially in combination with a redox mediator, provides a simple and flexible way for shifting product selectivity and enhancing product yield in the fermentation process. In particular, we report and quantify for the first time strictly different effects of Neutral Red (NR) and the barely studied redox mediator Brilliant Blue (BB) on the growth and product formation of C. pasteurianum grown on glycerol in a newly developed BES. We were able to switch the product formation pattern of C. pasteurianum with a concentration-dependent addition of NR and BB under varied iron availability. Interestingly, NR and BB influenced the glycerol metabolism in a strictly opposite manner concerning the formation of the major products 1,3-propanediol (1,3-PDO) and n-butanol (BuOH). Whereas, NR and iron generally enhance the formation of BuOH, BB favors the formation of 1,3-PDO. In BES the metabolic shifts were enhanced, leading to a further increased yield by as high as 33% for BuOH in NR fermentations and 21% for 1,3-PDO in BB fermentations compared with the respective controls. For the first time, the electron transfer mediated by these mediators and their recycle (recharge) were unambiguously quantified by excluding the overlapping effect of iron. BB has a higher capacity than NR and iron. The extra electron transfer by BB can account for as high as 30–75% of the total NAD + regeneration under certain conditions, contributing significantly to the product formation.
URI: http://hdl.handle.net/11420/2749
ISSN: 0006-3592
Institute: Bioprozess- und Biosystemtechnik V-1 
Type: (wissenschaftlicher) Artikel
Funded by: This work was supported by a project in the Hamburg Landesforschungsförderung LFF FV 43.
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