Culture of Penicillium ulaiense in batch-reactor. Stoichiometric studies.

V.B. RAJAL; C.M. CUEVAS

WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY

SPRINGER

Año: 2008 vol. 24 p. 1081 - 1090

0959-3993

Penicillium ulaiense is a pathogenic, slowgrowing, fungus that affects citrus fruits post-harvest. Thisis the first study on the growth of this fungus with differentcarbon sources. The linear relations between the netconversion rates were used to make the first approach tosimulate the system. To accomplish this, P. ulaiense wascultured in a bioreactor using three carbon sources: glucose,sucrose, and lactose. The mass balance for C wasclosed. A black box model was adopted to describe thesystem, represented by two macrochemical reactions: (1)formation of biomass and (2) combustion of the C-source.The experimental yield coefficient and the elemental andcharge balances were used to determine the linear relationsbetween the net conversion rates of the relevant substancesinvolved and the stoichiometric coefficients. The reactionrates were determined as a function of the independentconversion rates. The energy balance was based on thedescription of three redox half-reactions: production ofbiomass, utilization of substrate, and electron transfer. Theapplication of the second law of thermodynamics allowedthe calculation of the maximal theoretical yield coefficient.The dissipated energy, the theoretical yield coefficient, themaintenance energies and the thermodynamic efficiencieswere also calculated.