Application of metabolic flux analysis to the heterologous production of a polygalacturonase from Aspergillus kawachii 4th International Congress on Bioprocess in Food Industries

ORTIZ GE; ROJAS NL; GRAMISCI B; CHESINI M; CAVALITTO SF

Curitiba

Congreso; 4th International Congress on Bioprocess in Food Industries; 2010

A metabolic model for cell growth and overproduction in Saccharomyces  cerevisiae of a recombinant acid polygalacturonase (PG1) was developed. The expression of the recombinant PG1 induced by galactose caused a severe retardation in cell growth rate, increase in O2 consumption and biomass and ethanol yields reduction. The metabolic flux analysis of this transition in growth condition show that cells shift the usage of the available substrate from anabolic to catabolic pathways to increase their ability to produce energy for plasmid-encoded protein synthesis, stress protein synthesis and maintenance requirements. From this analysis, a large increase (ten times) in maintenance energy was found, indicating the great level of stress caused by the heterologous protein production (metabolic burden). From these results, it can be concluded that it is necessary a continuous adding of CES in order to improve the production of the recombinant enzyme. This condition can be achieved using a fed-batch culture system. For the system studied the pathway utilization and relative flux distributions obtained from MFA are in good agreement with reported S.cerevisiae gene expression profiles at different stages of growth and during recombinant protein overexpression.