Patricia González

Some Aspects of Gibberella fujikuroi Culture Concerning Gibberellic Acid Production

Gibberellic acid (GA 3 ) is a plant growth regulator produced by Gibberella fujikuroi in submerged fermentation. Studies concerning the effects of several carbon and nitrogen sources on GA 3 production were carried out. Sucrose-starch mixture was found to be the best carbon source. No significant differences between the nitrogen sources tested were observedTwo methods were compared for estimating µ of Gibberella fujikuroi grown in different proportions of glucose and starch. The specific growth rate of Gibberella fujikuroi estimated by an image processing technique (measuring tip extension and mean hyphal length in a Petri dish) was in close agreement with measurements performed in a stirred fermentor. In addition, submerged culture was found to be better than solid-state culture for the strain under study. 1 vvm and 700 rpm were found to be the conditions leading to the highest GA 3 production. Application of cell-free, HPLC characterized fermented broth in cuban “Tangor Ortanique ”orchard resulted in a yield increase.

Kinetics of the Demineralization Reaction of Deproteinized Lobster Shells Using CO2

The demineralization kinetics of deproteinized lobster shells using CO2 were studied. Demineralization reaction proceeds until the concentration of Ca+2 in solution reaches an equilibrium value. The introduction of a cation exchange resin (cationite), in an open system for CO2, allows replacement of the solution Ca 2+ ions by Na+ ions, whereby the equilibrium shifts and an effective dissolution of the exoskeletons’ calcite is achieved. The mathematical relationships between the conductivity of the solution and the concentrations of major ions, the rate constants and kinetic parameters of the reaction in the absence and presence of the resin were obtained. It was found that the reaction follows pseudo-fi rst-order kinetics, and the experimental results were in good agreement with the proposed mathematical model.