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Monitoring Cell Concentration and Activity by Multiple Excitation Fluorometry
Author(s) -
Li J.K.,
Asali E. C.,
Humphrey A. E.,
Horvath J. J.
Publication year - 1991
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp00007a004
Subject(s) - yeast , fermentation , fluorescence , tryptophan , biochemistry , fluorescence spectroscopy , saccharomyces cerevisiae , nad+ kinase , chemistry , pyridoxine , ethanol fermentation , chromatography , enzyme , amino acid , physics , quantum mechanics
Four key cellular metabolic fluorophores‐tryptophan, pyridoxine, NAD(P)H, and riboflavin‐were monitored on‐line by a multiple excitation fluorometric system (MEFS) and a modified SLM 8000C scanning spectrofluorometer in three model yeast fermentation systems‐bakers' yeast growing on glucose, Candida utilis growing on ethanol, and Saccharomyces cerevisiae RTY110/pRB58 growing on glucose. The measured fluorescence signals were compared with cell concentration, protein concentration, and cellular activity. The results indicate that the behavior and fluorescence intensity of various fluorophores differ in the various fermentation systems. Tryptophan fluorescence is the best signal for the monitoring of cell concentration in bakers' yeast and C. utilis fermentations. Pyridoxine fluorescence is the best signal for the monitoring of cell concentration in the S. cerevisiae RTY110/pRB58 fermentation. In bakers' yeast fermentations the pyridoxine fluorescence signal can be used to monitor cellular activity. The NAD(P)H fluorescence signal is a good indicator of cellular activity in the C. utilis fermentation. For this fermentation NAD(P)H fluorescence can be used to control ethanol feeding in a fed‐batch process.