Edwin J. Barbosa-Hernández

The yeast Kluyveromyces marxianus has shown the potential to produce $\beta$-fructofuranosidases, which are enzymes capable of hydrolyzing $\beta$-fructofuranosides links of fructans to obtain fructooligosaccharides. The thriving market for fructose syrup and the quality standards imposed by food and pharmaceutical industries have generated an increased search for improved, monitored, and controlled production processes. Monitoring $\beta$-fructofuranosidase activity in a bioprocess requires the use of adequate sensors and the processing of information using efficient software algorithms; nevertheless, currently, such a sensor does not exist for this purpose. In this contribution, a sequential injection analysis system (SIA) developed in our laboratory was adapted to monitor at-line $\beta$-fructofuranosidase activity produced by the yeast K. marxianus. Samples were taken out automatically from the bioreactor and analyzed using 3,5-dinitrosalicylic (DNS). An algorithm was designed to operate the overall components of the lab-made SIA system. The enzymatic activity error obtained with the automatic SIA compared to the off-line laboratory determinations varied from 0.07% at high enzyme concentrations to 20.39% at low $\beta$-fructofuranosidase activity. Further development is required to improve the performance of the lab-made SIA system; nevertheless, such a device must be considered as a potential method for monitoring $\beta$-fructofuranosidase activity in real time.