We tested the efficacy of PreSens SensorPlugs for monitoring bacterial cultures in microfluidic bioreactors (MBs), which is important in the context of monitoring potential contamination in the culture meat bioprocess. Escherichia coli (ATCC® 25922™) was cultivated inside a custom-made MB with integrated SensorPlugs. The optical measurements showed the characteristic course of E. coli growth, and allowed precise assessment of current culture status at all times.