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Technical University of Munich

Population heterogeneity in industrial scale bioprocesses

Dr. Anna-Lena Heins, Junior research group leader at the Technical University of Munich, 2017-2023

Population heterogeneity is eminently present in industrial scale bioprocesses and defined as the unequal behaviour of cells of an isogenic population. Due to insufficient mixing in technical bioreactors, gradients arise, so that cells encounter various microenvironments at different locations in the reactor. Since not all of the cells follow the same path and can react differently, a heterogeneous cell population emerges as function of process time. Consequently, lowered yields and increased by-product formation can be found in comparison to (ideally mixed) laboratory scale cultivations.

To characterize population heterogeneities, inhomogeneities were created experimentally on a laboratory scale and the formation of subpopulations was recorded analytically using Escherichia coli as an example. In order to be able to follow the emergence and time course of population heterogeneity in vivo, various cellular reporter proteins were used. For this purpose, the expression of differently fluorescent reporter proteins was linked to selected cellular properties so that, for example, the growth rates of individual cells could be detected as a fluorescence distribution using flow cytometry.

Publications
  • Hoang MD, Polte I, Frantzmann L, von den Eichen N, Heins AL, Weuster-Botz D (2023): Impact of mixing insufficiencies on L-phenylalanine production with an Escherichia coli reporter strain in a novel two-compartment bioreactor. Microb Cell Fact 22: 153.
  • Hoang MD, Riessner S, Oropeza Vargas JE, von den Eichen N, Heins AL (2023): Influence of varying pre-culture conditions on the level of population heterogeneity in batch cultures with an Escherichia coli triple reporter strain. Microorganisms 11: 1763.
  • Arulrajah P, Heins A-L (2023): Versteckte Vielfalt: Diversität von Zellen im industriellen Bioprozess. BIOspektrum 29: 241-244.
  • Hoang MD, Doan DT, Schmidt M, Kranz H, Kremling A, Heins A-L (2023): Application of an Escherichia coli triple reporter strain for at-line monitoring of single-cell physiology during L-phenylalanine production. Eng Life Sci 23: e2100162.
  • Doan DT, Hoang MD, Heins A-L, Kremling A (2022): Applications of coarse-grained models in metabolic engineering. Front Mol Biosc DOI: 9: 806213.
  • Heins A-L, Hoang MD, Weuster-Botz D (2022): Advances in automated real-time flow cytometry for monitoring of bioreactor processes. Eng Life Sci, 22: 260-278.
  • Heins A-L, Reyelt J, Schmidt M, Kranz H, Weuster-Botz D (2020): Development and characterization of Escherichia coli triple reporter strains for investigation of population heterogeneity in bioprocesses. Microb Cell Fact 19:14.
  • Heins A-L, Lundin L, Nunes I, Gernaey KV, Sørensen SJ, Lantz AE (2019): The effect of acetate on population heterogeneity in different cellular characteristics of Escherichia coli in aerobic batch cultures. Biotechnol Prog 35: e2796.
  • Heins AL, Weuster-Botz D (2018): Population heterogeneity in bioprocesses: origin, analysis, mechanisms, and the future perspectives. Bioproc Biosys Eng 41: 889-916.
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