The application of an on-line optical sensor to measure biomass of a filamentous bioprocess

Abstract

Monitoring of all critical process parameters in bioprocess engineering is essential. Sensors have been previously developed for specific parameters such as on-line temperature, pH or stirring control and data logging. However, biomass monitoring needs further development. All current non-invasive technology, such as Near Infra-Red, is limited on biomass measurement of animal and insect cells. Biomass monitoring of industrial bioprocesses of filamentous microorganisms still requires sample removal from the vessel, which could potentially compromise sterility. This study has focused on the application of a non-invasive optical sensor in the on-line monitoring of the biomass of the filamentous microorganism Streptomyces coelicolor A3 (2). Raw output data from the biomass monitor were directly compared to data from the sensors measuring dissolved oxygen levels and off gas evolution and the results successfully demonstrate that the optical sensor is sensitive in identifying different levels of biomass. Therefore, it is possible to use the simple output data to provide real time information on biomass levels of filamentous microorganisms, a very powerful tool in bioprocess engineering.