title: Whole-cell Escherichia coli lactate biosensor for monitoring mammalian cell cultures during biopharmaceutical production.
abstract: Many high-value added recombinant proteins, such as therapeutic glycoproteins, are produced using mammalian cell cultures. In order to optimize the productivity of these cultures it is important to monitor cellular metabolism, for example the utilization of nutrients and the accumulation of metabolic waste products. One metabolic waste product of interest is lactic acid (lactate), overaccumulation of which can decrease cellular growth and protein production. Current methods for the detection of lactate are limited in terms of cost, sensitivity, and robustness. Therefore, we developed a whole-cell Escherichia coli lactate biosensor based on the lldPRD operon and successfully used it to monitor lactate concentration in mammalian cell cultures. Using real samples and analytical validation we demonstrate that our biosensor can be used for absolute quantification of metabolites in complex samples with high accuracy, sensitivity, and robustness. Importantly, our whole-cell biosensor was able to detect lactate at concentrations more than two orders of magnitude lower than the industry standard method, making it useful for monitoring lactate concentrations in early phase culture. Given the importance of lactate in a variety of both industrial and clinical contexts we anticipate that our whole-cell biosensor can be used to address a range of interesting biological questions. It also serves as a blueprint for how to capitalize on the wealth of genetic operons for metabolite sensing available in nature for the development of other whole-cell biosensors. Biotechnol. Bioeng. 2017;114: 1290-1300. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.
authors.affiliation: Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK.|Centre for Synthetic Biology and Innovation, Imperial College London, London, UK.
authors.forename: Lisa
authors.initials: L
authors.lastname: Goers
authors.affiliation: Centre for Synthetic Biology and Innovation, Imperial College London, London, UK.|Department of Bioengineering, Imperial College London, London, UK.
authors.forename: Catherine
authors.initials: C
authors.lastname: Ainsworth
authors.affiliation: Department of Chemical Engineering, Imperial College London, London, UK.
authors.forename: Cher Hui
authors.initials: CH
authors.lastname: Goey
authors.affiliation: Centre for Synthetic Biology and Innovation, Imperial College London, London, UK.|Department of Chemical Engineering, Imperial College London, London, UK.
authors.forename: Cleo
authors.initials: C
authors.lastname: Kontoravdi
authors.affiliation: Centre for Synthetic Biology and Innovation, Imperial College London, London, UK.|Department of Medicine, Imperial College London, London, UK.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Freemont
authors.affiliation: Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK.|Centre for Synthetic Biology and Innovation, Imperial College London, London, UK.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Polizzi
mesh_terms: D001681:Biological Assay / Q000295:instrumentation*; D001688:Biological Products / Q000302:isolation & purification / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology; D015374:Biosensing Techniques / Q000295:instrumentation*; D004353:Drug Evaluation, Preclinical / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004926:Escherichia coli / Q000187:drug effects*; D019344:Lactic Acid / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001688:Biological Products; D019344:Lactic Acid
keywords:  LldPRD operon;  lactate / lactic acid; biopharmaceutical processing; synthetic biology; whole-cell bacterial biosensor