Microbial nar-GFP cell sensors reveal oxygen limitations in highly agitated and aerated laboratory-scale fermentors

Abstract

Background: Small-scale microbial fermentations are often assumed to be homogeneous, and oxygen limitation due to inadequate micromixing is often overlooked as a potential problem. To assess the relative degree of micromixing, and hence propensity for oxygen limitation, a new cellular oxygen sensor has been developed. The oxygen responsive E. coli nitrate reductase (nar) promoter was used to construct an oxygen reporter plasmid (pNar-GFPuv) which allows cellbased reporting of oxygen limitation. Because there are greater than 10 9 cells in a fermentor, one can outfit a vessel with more than 10 9 sensors. Our concept was tested in high density, lab-scale (5 L), fed-batch, E. coli fermentations operated with varied mixing efficiency -one verses four impellers.

Programmable bacteria detect and record an environmental signal in the mammalian gut

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Genetically-encoded biosensors for monitoring cellular stress in bioprocessing

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