title: Parallel online multi-wavelength (2D) fluorescence spectroscopy in each well of a continuously shaken microtiter plate.
abstract: Small-scale high-throughput screening devices are becoming increasingly important in bioprocess development. Conventional dipping probes for process monitoring are often too large to be used in these devices. Thus, optical measurements are often the method of choice. Even some parameters that cannot directly be measured by fluorescence become accessible via sensitive fluorescence dyes. However, not all compounds of interest are measurable by this technique. Recent studies applying multi-wavelength (2D) fluorescence spectroscopy in combination with chemometrics have shown that information on numerous analytes is obscured by the fluorescence data. Hitherto, this measurement technique has only been available on the scale of stirred tank fermenters. This work introduces a new device for multi-wavelength (2D) fluorescence spectroscopy in each well of a continuously shaken microtiter plate. Using a combination of spectrograph and CCD detector, the required time per measurement cycle in a 48-well microtiter plate was 0.5 h. Cultures of Hansenula polymorpha and Escherichia coli are monitored. The concentrations of glycerol, glucose and acetate as well as pH are determined using partial least square (PLS) models. Because a pH-sensitive fluorescence dye was not required, no dependency of the pKaof a fluorescence dye exists, and measurements in the low pH range can be obtained.
authors.affiliation: AVT - Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Ladner
authors.affiliation: AVT - Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Beckers
authors.affiliation: Universität Hohenheim, Fachgebiet Prozessanalytik & Getreidetechnologie, Stuttgart, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Hitzmann
authors.affiliation: AVT - Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Büchs
mesh_terms: D000085:Acetates / Q000032:analysis / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism; D005947:Glucose / Q000032:analysis / Q000378:metabolism; D005990:Glycerol / Q000032:analysis / Q000378:metabolism; D057166:High-Throughput Screening Assays / Q000295:instrumentation / Q000379:methods; D006863:Hydrogen-Ion Concentration; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D010843:Pichia / Q000254:growth & development / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000295:instrumentation* / Q000379:methods*
chemical_list: D000085:Acetates; D001426:Bacterial Proteins; D008164:Luminescent Proteins; C054562:yellow fluorescent protein, Bacteria; D005947:Glucose; D005990:Glycerol
keywords: (2D) Fluorescence spectroscopy; Chemometrics; High-throughput system; Microtiter plate; Multi-wavelength; Online monitoring