Abstract
Knallgas bacteria, including Cupriavidus necator H16, are promising cell factories for converting CO(2) into high-value compounds under autotrophic conditions. C. necator H16 synthesizes polyhydroxyalkanoates (PHA), a class of biodegradable plastics. However, the trade-off between cell proliferation and PHA production often limits productivity as a result of competition for cellular resources. Real-time monitoring of both processes is crucial for optimizing this balance. However, optical density (OD), a conventional metric for monitoring proliferation, is unreliable in organisms that accumulate intracellular products such as PHA. Traditional methods such as chromatography require complex sample preparation and are not suitable for real-time analysis. This study demonstrated that the cell counts and volume measured using a Coulter counter are reliable indicators of proliferation and PHA production. This approach enables rapid and accurate monitoring and supports the optimization of material production through microbial fermentation.