Xylitol Fermentation with different yeast strains

Technical University of Budapest uses sensors of Hamilton Bonaduz AG for successful research

(Bonaduz, 10/04/2016) – The Technical University of Budapest is highly experienced in bio-refining processes. The university has recently made remarkable research efforts to optimize microbial xylitol production by means of state-of-the-art sensors of the Hamilton Bonaduz AG.

Xylitol is a sugar alcohol that can be found in dietary fibers of many fruits and vegetables. With its anti-cariogenic and low energy characteristics it is mostly used in the food industry. The multistep production process starts with the fractionation of dietary fiber into its three core carbohydrate components. One of these components is hemicellulose which consists of arabinoxylan, arabinose-rich and xylose-rich sub-fractions. The latter is used for the microbial production of the sugar alcohol by means of Candida species.

The University of Budapest invented a two-step fermentation strategy in order to optimize the production process. It starts with low cell density propagation of the Candida yeast under aerobic conditions. After several hours the aeration is drastically reduced to micro-aerobic conditions in order to produce Xylitol without significant further cell growth. The researchers use the Hamilton sensors VisiFerm DO and Incyte for the continuous measurement of dissolved oxygen and viable cell density. The optical dissolved oxygen sensor VisiFerm DO does not need to be polarized before usage and is therefore instantly ready for operation and ensures stable measurements from the start. Incyte is based on a real-time permittivity measurement of viable cells in an alternating electrical field. The sensor provides continuous data resulting in faster optimization of feeding and harvesting strategies. In addition to that, it is not influenced by changes of the media, microcarriers, dead cells and debris. Furthermore, the EasyFerm Plus Arc sensor is used for the precise, drift-free pH measurement. Designed for hygienic applications, its pre-pressurized reference electrolyte prevents the diffusion of the sample in the sensor. The Everef-F cartridge of the sensor ensures that the Phermlyte reference electrolyte remains free of silver and precipitation. EasyFerm Plus and VisiFerm DO can both be configured and calibrated with the ArcAir App. This allows reading the measurement results easily on a mobile device as well as on the controller. For an easy integration of the sensors into an older controller, the Arc ECS pH adapter and the ECS version of VisiFerm DO were chosen.

Another test was performed by the university in order to examine the difference in the kinetic behavior of the consumption of different carbon sources. As expected by the research team, Glucose was the preferred carbon source. A significant metabolism of Xylose was only observed after the majority of Glucose was already metabolized. The research team was very pleased about the easy operation and user-friendly design of the sensors as well as the wireless connection via Bluetooth and the ArcAir App. The continuous monitoring of the cell growth provided the team important insights to ensure an optimized yield.