Differences in the physiology of Pichia pastoris grown on glycerol/glucose using polyurethane foam slabs as solid support

BACKGROUND

Growth physiology and metabolic flux of Pichia pastoris were analyzed using glass columns containing slabs of polyurethane foam as a solid support and culture medium with glycerol or glucose as a carbon source.

RESULTS

Media with glycerol produced an average of 30.91% more biomass than media where glucose was used. However, the specific growth rate registered higher values for media with glucose than those with glycerol at low substrate concentrations: 0.46 versus 0.22 h⁻¹. Media with glycerol produced a large amount of d-arabitol, whereas ethanol and citrate were the predominant metabolites in media with glucose. Both types of culture systems generated biphasic curves in terms of the respiratory quotient value, whose inflection point coincided with the transition from aerobic metabolism to a mixed one.

CONCLUSION

Adequate oxygen transfer occurred in both culture systems; therefore, the differences found in growth physiology can be explained by the transport mechanism that internalizes glycerol, the access point to primary metabolism, and the degree of glycerol oxidation. The arrangement of cells in the polyurethane matrix allowed an attenuation of the repression phenomenon due to excess substrate for both carbon sources. This is the first work to study metabolic flux comparisons using this system. © 2024 Society of Chemical Industry (SCI).