Fermentation Monitoring

Challenge: To improve process yield and economics, through better real time process understanding and improved equipment utilisation.

Solution: Stratophase's SpectroSens technology provides a real-time process status monitoring solution capable of accurately indicating relative reaction conditions. These measurements allow process operators to make informed decisions based on the quality of the process without the need to regularly take samples for chemical analysis.

Stratophase Advantages:

• Real-time process status indication
• Profile rate of nutrient uptake, product evolution and identify key process stages
• Easy to interpret comparison of real time data against historical model
• Overview of changes in chemical composition from complex mixtures
• Insertion probe monitoring temperature compensated refractive index
• Armoured optical fibre network allowing 8 probes to connect to a single readout unit

The Challenges of Fermentation Monitoring

Fermentation is a dynamic biological process that utilises microorganisms grown in batch conditions to bulk manufacture chemical products of interest. The process is commonly used during the production of high-value-add products such as pharmaceuticals, plastics and fuels.

By its very nature, fermentation takes place in a complex chemical environment, containing multiple components the concentrations of which all vary at different rates throughout the process. The organisms involved slowly metabolise food sources while gradually generating products and other waste chemicals, altering the composition of the media.

Monitoring of the fermentation process is critical to ensuring that the reaction proceeds efficiently and without error. Historically, the procedure is assessed using a combination of in-line measurements to directly control the process, as well as off-line sampling to determine the quality of the process. Commonly used inline measurements such as pH and dissolved oxygen concentration are critical to controlling the fermentation, but are commonly not able to fully define the quality of the process or more specifically the yield. In comparison full chemical analytic techniques, such as mass spectrometry and spectroscopy, offer a greater insight into the nature of the process but at the expense of invasive sampling and a slow turnaround time. Ideally, for a process to be optimal a measurement of process quality which is fast enough to inform control is required, this is not easily available using current process control parameters or off-line analytical techniques.

The Stratophase Solution

To counter these problems, Stratophase provides the SpectroSens monitoring solution, which offers real-time, informative process profiling. Using a highly engineered microchip sensor that records optical measurements, SpectroSens technology monitors the refractive index (RI) of the media to infer changes in its chemical composition. The sensors are housed within industry standard insertion probes, which can be easily introduced into bench-top or free-standing bioreactors. Although the system cannot directly infer the absolute levels of specific products and metabolites, it can accurately depict the reaction phase and rates of change for the fermentation process in real-time. Any significant deviations from the normal process profile can be quickly identified, allowing the process to be recovered either through the use of process models to identify failure mechanisms or triggering intelligent off-line sampling regimes involving full analytical techniques. Where recovery is not possible the process can be halted thereby minimising the equipment time associated with the production of out-of-spec product. In addition, the system can be calibrated to provide information on the process, such as the point at which the maximum amount of product has been generated allowing harvesting at the optimum time — improving yield and minimising process time.

The SpectroSens optical chips are connected via armoured fibre optic cables to a control unit capable of integrating the input of up to eight independent sensors. This means that sensors can be employed to monitor multiple reactors, separated by large distances and undertaking different fermentation reactions, providing flexible multipoint capability. The control unit itself can be further networked to other Stratophase control units, or to existing process management systems, providing a fully integrated monitoring solution. By providing a modular, flexible system, the Stratophase SpectroSens technology can be easily expanded to facilitate production scale-up or to adapt to changes in the fermentation process.