Evaluation of Morphological Properties of Solanum chrysotrichum Cell Cultures in a Shake Flask and Fermentor and Rheological Properties of Broths

Solanum chrysotrichum cells were grown in a shake flask and a stirred tank bioreactor. Their growth kinetics and rheological and morphological behaviors were evaluated. The specific growth rate obtained in both systems was similar (0.09 day), but biomass yield achieved in shake flasks was 60 % higher than that in the fermentor. Culture broths exhibited non-Newtonian and shear-thinning characteristics, which can be simulated by the Ostwald de Waele model (power law). Results show that the pseudoplasticity of culture broths was determined by the biomass concentration and aggregate size distribution, while the aggregate roundness, measured as the elliptical form factor, was similar in both systems. Morphological analysis indicated that 100 % of the cell aggregates from the fermentor were <0.25 mm, and their size distribution remained constant during cultivation. The cultures grown in shake flasks presented a tendency to increase their aggregate size as a consequence of cell growth. The reduction of the size of S. chrysotrichum aggregates during the scale-up had an important influence on flow index behavior and consistency coefficient values.