PAT for upstream bioprocess monitoring and control in real time: information, opportunity, and reality

Process analytical technology (PAT) for monitoring and controlling nutrients and metabolites throughout bioprocesses is central to achieving consistent product and high yields.  Upstream processes are, by their very nature, complex multicomponent environments that are continuously changing throughout the growth and expression phases.  The ability to quantitate key chemicals in real time is essential to the continuous control and optimization of these dynamic processes.  Critical criteria for such real-time, on-line monitoring have been documented and include simultaneous multi-analyte quantitation, non-destructive automated and continuous operation for extended time periods, robust and repeatable performance across multiple batches, ease of operation with little operator time required, and insensitivity to normal operating conditions (agitation rates, pH changes, etc.).  Data from such a robust on-line bioprocess monitor is presented for industrial processes using yeast-based expression platforms as well as mammalian cell cultures.  Bioprocess monitor performance across multiple batches conducted over months of industrial operation will be shown.  Results from protein expression using the yeast Pichia pastoris demonstrate the reliable, accurate measurement of glycerol and methanol during more than a year of operation in bioprocess development.  Critical performance criteria will also be shown for CHO cell cultures where glucose and lactate concentrations are quantitated in real time for runs in excess of 400 hours.  The unique and high value-add information that real-time, continuous monitoring provides will be highlighted.