Fed-Batch cultivations of rhodospirillum rubrum under multiple nutrient-limited growth conditions on syngas as a novel option to produce poly(3-hydroxybutyrate) (PHB)

Karmann, Stephanie (School of Engineering, HES-SO Valais-Wallis, HEI, HES-SO // University of Applied Sciences Western Switzerland ; Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland) ; Panke, Sven (Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland) ; Zinn, Manfred (School of Engineering, HES-SO Valais-Wallis, HEI, HES-SO // University of Applied Sciences Western Switzerland)

Syngas from gasified organic waste materials is a promising feedstock for the biotechnological synthesis of the bioplastic poly([R]-3-hydroxybutyrate) (PHB) with Rhodospirillum rubrum. In a first approach, growth studies were carried out with this strain in gas-tight serum vials. When syngas (40% CO, 40% H2, 10% CO2, and 10% N2 v/v) was diluted with N2 to 60%, a 4-fold higher biomass production was detected compared to samples grown on 100% syngas, thus indicating a growth inhibitory effect. The best performing syngas-mixture was then used for C-, C,N-, and C,P-limited fed-batch fermentations in a bioreactor with continuous syngas and acetate supply. It was found that C,P-limited PHB productivity was 5 times higher than for only C-limited growth and reached a maximal PHB content of 30% w/w. Surprisingly, growth and PHB production stopped when N, as a second nutrient, became growth-limiting. Finally, it was concluded that a minimal supply of 0.2 g CO g−1 biomass h−1 has to be guaranteed in order to cover the cellular maintenance energy.


Keywords:
Article Type:
scientifique
Faculty:
Ingénierie et Architecture
School:
HEI-VS
Institute:
Institut Technologies du vivant
Date:
2019-04
Pagination:
11 p.
Published in:
Frontiers in Bioengineering and Biotechnology
Numeration (vol. no.):
2019, vol. 7, article no. 59
DOI:
ISSN:
2296-4185
Appears in Collection:



 Record created 2020-01-24, last modified 2020-01-24

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