Have you ever dreamed of a device that can determine K_La/OTR without requiring physical contact with your bioreactor and the need for manual calculations afterward? I’m sure you have. However, this isn’t a robot from sci-fi movies, so even after purchasing the device, some lab work is still necessary. Nevertheless, it will undoubtedly make your life easier. If you are a highly skilled fermentation expert with many years of experience, and you have previously worked with premium bioreactors, you may have encountered something similar.

When using other bioreactors, you can only measure at one point, for example, 1000 rpm and 200 smL/min, and will get one result dedicated to these setpoint, but with this one you can program limitless scenarios for example stirring from 100-1000 at 100 smL/min and it will run independently so end of the experiment you will get K_La values for each setpoints.

In this example, Zarrouk culture medium was used, and the temperature was set to 30°C. The airflow was fixed at 100 mL/min, and the stirring speed was increased from 100 to 1000 rpm step by step. When the temperature stabilized, the experiment started. In the first scenario, the dissolved oxygen (DO) never dropped below 20 and never rose above 80, where the slope calculation should take place. In the next measurement, the timeframe was extended to 1 hour of nitrogen stream followed by 1 hour of an air stream. In this case, the experiment was successful, and the system calculated K_La values for each stirring speed.

The first value is an artifact, so we have 10 valuable data points which belong to each individual stirring speed: 100, 200, 300, …, 1000 rpm.