A multiwavelength fluorescence probe: is one probe capable for on-line monitoring of recombinant protein production and biomass activity?

Monitoring cell culture performance requires maximizing the number and the quality of measured parameters and in situ 2D fluorescence spectroscopy could allow intensification of simultaneous data acquisition. The use of a multiwavelength fluorescence probe is proposed for monitoring GFP-producing cultures in bioreactor. The yeast Pichia pastoris and NSO mammalian cells were studied as model systems. Tryptophan, NAD(P)H and riboflavins (riboflavin, FMN, FAD) signals were effective for on-line yeast biomass estimation during the growth phase. During the GFP production phase, in situ measurements of the GFP concentration from the fluorescence probe were well correlated with off-line analyses. Tryptophan and NAD(P)H signals diverged from that of biomass during GFP production. With NSO mammalian cells, results showed that the culture parameters have to be optimized for the use of a fluorescence probe. The use of serum and phenol-red interfered with NAD(P)H and riboflavins fluorescence signals. Nevertheless, it appears that a multiwavelength probe could be useful for culture monitoring of biomass, cell activity and recombinant protein expression in an optimized culture medium.