Real-time VOC profiling for controlling the Crabtree effect in Saccharomyces cerevisiae

The Crabtree effect enables ethanol production in aerobic environments with high glucose concentrations. This metabolic shift produces a characteristic VOCs profile. Its mechanism is not fully understood for different reasons, including differences in growing conditions, low temporal resolution monitoring, and loss of molecular information due to saturation or high selectivity. Using a portable mass spectrometer (MoBiMS) connected directly to a bioreactor headspace, we developed a method for continuous VOC monitoring that overcomes limitations of traditional techniques regarding specificity, saturation, and temporal resolution. This approach improves resolution from hours to seconds. We used these VOC profiles to train a model to classify metabolic states as Crabtree-positive or Crabtree-negative in seconds. Furthermore, signal processing of the kinetic data reveals stimulus timing and periodicity. Our findings demonstrate the viability of in situ online VOC monitoring in bioprocesses, enabling detection of Crabtree effect induction and analysis of metabolic responses to glucose addition stimuli. • Direct and real-time VOCs monitoring for fast determination of Crabtree-positive or Crabtree-negative fermentations. • Signal treatment of VOCs dynamics reveals the moment when a glucose stimulus was applied and its periodicity. • Direct VOCs monitoring from bioreactor headspace with a low-cost mass spectrometer using a 3D-printed adaptor.