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Use of microbial biosensors to detect substrate heterogeneities at the single cell level and assess microbial viability: Validation of a mini-bioreactor platform
Brognaux, Alison; Neubauer, Peter; Twizere, Jean-Claude et al.
20122nd BioProScale "Inhomogeneities in large scale bioprocess: system biology and process dynamics"
 

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Keywords :
scale-down; stress responses; mini-bioreactors
Abstract :
[en] The basic principle adopted in our studies is to use substrate limitation responsive biosensors in order to detect spatial glucose heterogeneities inside industrial bioreactors (whole-cell biosensor). Indeed, such heterogeneities cause a lowering of the biomass yield and an increase of by-products concentration. In this work, we have used these biosensors for the elaboration of a mini-bioreactor platform that can be used as a scale-down tool. Three green fluorescent protein (GFP) transcriptional reporters have been chosen in Escherichia coli, i.e. uspA::gfp, csiE::gfp and yciG::gfp. Our previous studies have shown that these kinds of promoters are induced in response of substrate limitation and exhibit a strong fluorescence attenuation when cultivated in heterogeneous bioreactors. This sensitivity to substrate limitation has been confirmed in the case of the csiE and yciG biosensors. A mini scale-down platform has been proposed as a high throughput tool to investigate rapidly the usefulness of a given microbial biosensor. This platform is composed of shake flask able to operate in fed-batch mode either by using the slow release or the intermittent feeding principle. The first system is based on a commercial package (Enbase) based on the enzymatic release of glucose in the medium. The Enbase system allows the generation of a very smooth glucose profile without any perturbations. For comparison purpose, we have also used an intermittent feeding that induces strong fluctuation at the level of the glucose and the dissolved oxygen concentration. Local heterogeneities have thus been reproduced at the level of these mini-bioreactors and these one have caused a decrease of GFP expression, as in conventional scale-down reactor. The presence of GFP in supernatants has also been noticed and seems to be correlated with the substrate limitation signal for the three cultivation systems considered in this work (i.e., chemostat, conventional and mini-bioreactors) and with the membrane permeability.
Disciplines :
Biotechnology
Author, co-author :
Brognaux, Alison ;  Université de Liège - ULiège > Département des sciences de la vie > Biochimie et microbiologie industrielles
Neubauer, Peter
Twizere, Jean-Claude  ;  Université de Liège - ULiège > Chimie et bio-industries > Biologie cell. et moléc.
Thonart, Philippe ;  Université de Liège - ULiège > Département des sciences de la vie > Biochimie et microbiologie industrielles
Delvigne, Frank  ;  Université de Liège - ULiège > Chimie et bio-industries > Bio-industries
Language :
English
Title :
Use of microbial biosensors to detect substrate heterogeneities at the single cell level and assess microbial viability: Validation of a mini-bioreactor platform
Publication date :
15 March 2012
Event name :
2nd BioProScale "Inhomogeneities in large scale bioprocess: system biology and process dynamics"
Event date :
du 14 au 16 mars 2012
Audience :
International
Funders :
FRIA - Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture [BE]
Available on ORBi :
since 23 February 2012

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