Microbial population heterogeneity versus bioreactor heterogeneity: evaluation of Redox Sensor Green as an exogenous metabolic biosensor

Abstract

Microbial heterogeneity in metabolic performances has attracted a lot of attention,considering its potential impact on industrial bioprocesses. However, little is knownabout the impact of extracellular perturbations (i.e. bioreactor heterogeneity) oncell-to-cell variability in metabolic performances (i.e. microbial population hetero-geneity). In this work, we have evaluated the relevance of Redox Sensor Green (RSG)as an exogenous biosensor of metabolic activity at the sing le-cell level. RSG sig-nal is proportional to the activity of the electron t ransport chain and its signal isstrongly affected by metabolic burden, availability of electron final acceptor, and sidemetabolisms (i.e. overflow and mixed acid fermentation). RSG can also be used forthe estimation of the impact of scale-down conditions on microbial metabolic ro-bustness. The relationship linking averaged RSG ac tivity and its cell-to-cell variability(noise) has been highlighted but seems unaffected by environmental perturbations.