@article{OehlenschlaegerVolkmarStiefelmaieretal.2024,
  author    = {Oehlenschl{\"a}ger, Katharina and Volkmar, Marianne and Stiefelmaier, Judith and Langsdorf, Alexander and Holtmann, Dirk and Tippk{\"o}tter, Nils and Ulber, Roland},
  title     = {New insights into the influence of pre-culture on robust solvent production of C. acetobutylicum},
  series = {Applied Microbiology and Biotechnology},
  volume    = {108},
  journal   = {Applied Microbiology and Biotechnology},
  publisher = {Springer},
  address   = {Berlin, Heidelberg},
  issn      = {1432-0614},
  doi       = {10.1007/s00253-023-12981-8},
  pages     = {10 Seiten},
  year      = {2024},
  abstract  = {Clostridia are known for their solvent production, especially the production of butanol. Concerning the projected depletion of fossil fuels, this is of great interest. The cultivation of clostridia is known to be challenging, and it is difficult to achieve reproducible results and robust processes. However, existing publications usually concentrate on the cultivation conditions of the main culture. In this paper, the influence of cryo-conservation and pre-culture on growth and solvent production in the resulting main cultivation are examined. A protocol was developed that leads to reproducible cultivations of Clostridium acetobutylicum. Detailed investigation of the cell conservation in cryo-cultures ensured reliable cell growth in the pre-culture. Moreover, a reason for the acid crash in the main culture was found, based on the cultivation conditions of the pre-culture. The critical parameter to avoid the acid crash and accomplish the shift to the solventogenesis of clostridia is the metabolic phase in which the cells of the pre-culture were at the time of inoculation of the main culture; this depends on the cultivation time of the pre-culture. Using cells from the exponential growth phase to inoculate the main culture leads to an acid crash. To achieve the solventogenic phase with butanol production, the inoculum should consist of older cells which are in the stationary growth phase. Considering these parameters, which affect the entire cultivation process, reproducible results and reliable solvent production are ensured.},
  language  = {en}
}
@article{HengsbachEngelCwienczeketal.2023,
  author    = {Hengsbach, Jan-Niklas and Engel, Mareike and Cwienczek, Marcel and Stiefelmaier, Judith and Tippk{\"o}tter, Nils and Ulber, Roland},
  title     = {Scalable unseparated bioelectrochemical reactors by using a carbon fiber brush as stirrer and working electrode},
  series = {ChemElectroChem},
  volume    = {10},
  journal   = {ChemElectroChem},
  number    = {21},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {2196-0216},
  doi       = {10.1002/celc.202300440},
  pages     = {9 Seiten},
  year      = {2023},
  abstract  = {The concept of energy conversion into platform chemicals using bioelectrochemical systems (BES) has gained increasing attention in recent years, as the technology simultaneously provides an opportunity for sustainable chemical production and tackles the challenge of Power-to-X technologies. There are many approaches to realize the industrial scale of BES. One concept is to equip standard bioreactors with static electrodes. However, large installations resulted in a negative influence on various reactor parameters. In this study, we present a new single-chamber BES based on a stirred tank reactor in which the stirrer was replaced by a carbon fiber brush, performing the functions of the working electrode and the stirrer. The reactor is characterized in abiotic studies and electro-fermentations with Clostridium acetobutylicum. Compared to standard reactors an increase in butanol production of 20.14±3.66 \% shows that the new BES can be efficiently used for bioelectrochemical processes.},
  language  = {en}
}