Online Monitoring of Chip-Based Microscale Perfusion Fermentations

As part of established biomanufacturing development, screening and early phase bioprocess development occurs at bench scale (microplates and shake flasks) whereby conventional offline sampling can only provide limited feedback on fermentation bioprocess parameters including strain productivity. To address these limitations, a new sensitive and selective online analytical platform consisting entirely of commercially available components with a small footprint (valves, 2DLC hardware, LC separation, and online tandem mass spectrometry) was developed for online monitoring of chip-based microbioreactors. Fermentations of microbial cell factories (Saccharomyces cerevisiae) were cultivated in 20 μL bioreactors, requiring perfusion of cell culture media at low μL/min rates delivered by syringe pump modules, operated in a multiplexed configuration with a flow-through stream selection valve, and monitored with a 2DLC-MS/MS system adapted for microscale operation. This allows uninterrupted multiplexed microperfusions to be monitored with online measurements of metabolites from parallel fermentations without the occurrence of blockages or cross-contamination between independent fermentations. Fermentations of lactic-acid-producing strains ofS. cerevisiaewere continuously monitored over 5–24 h, demonstrating the suitability of the platform for online monitoring of product quantity and key metabolites for fermentation biotechnology. Offering minimal consumption of biological material and using <1.5 mL of cell culture media over 24 h per experiment, this new platform can be used for monitoring a broad range of biomolecules, rapid strain selection, and screening of microenvironmental factors and is adaptable for targeting other key biotechnology products.