Quantitative assessment of the impact of the typeof inoculum on the kinetics of cell growth,substrate consumption and pigment productivityby Penicillium purpurogenum GH2 in liquid culturewith an integrated stochastic approach


Morales-Oyervides1, J.C. Oliveira1, M.J. Sousa-Gallagher1, A. Méndez-Zavala2, J.C. Montañez2*

1School of Engineering, University College Cork, Cork, Ireland

2Department of Chemical Engineering, Universidad Autónoma de Coahuila, Saltillo, COAH, Mexico


Natural ingredients are in demand and microbial processes to produce biocolourings arethus being developed. Penicillium spp. is particularly interesting for food applications. Whilemicrobial growth would be enhanced by using mycelium as inoculum, studies aimed atoptimising pigments yields produced by Penicillium spp. have used spores as inoculum. Aquantitative comparison of the pre-culture method for producing pigments by P. purpuro-genum GH2 is provided in this work. Data analysis showed that simple growth models donot provide a suitable description of the fermentation process with mycelium as inocu-lum, which requires accounting for the effect of cell death. Probability density functionswere applied to describe cell growth, substrate consumption and pigment production jointlyand accurately. Specific production was 51% higher using mycelium as inoculum instead ofspores, reaching a highest production of pigments with 10% (v/v) initial concentration beingoptimal (10.60 ± 0.40 units of Optical Density at 500 nm). Productivity of pigments per hourwas 55% higher using mycelium as inoculum compared to spores. Three stochastic dis-tributions provided equally good quantifications of all data (normal, gamma and Weibull).The three variables could be described by a same distribution function, with biomass beingrelated to both live cells and accumulated dead residue.

Food and Bioproducts processing 2015