Modeling growth of microalgae Dunaliella salina under different nutritional conditions

Problem statement: The aim of this study was to find the empirical model that describes the growth kinetics of Dunaliella salina, with low production cost and to estimate parameters of this model. Approach: In this study the strain of D. salina UTEX 200 was cultivated in seawater (0.5 M NaCl) at room temperature with agitation of 150 rpm and luminous intensity of 60 mmols.m-2.s-1. The synthetic medium AS100 (0.2 M NaCl) was used in this study for comparison purposes and in order to determine the optimal growth of the microalgae. Kinetics of growth and β-carotene production was determined in a period of 15 days. Results: After the analysis of the behavior graphic, an unstructured model was used for describing the cell growth (logistic model). It was observed that the model was well adjusted to experimental data for the two conditions of analysis. It was observed that alga produces carotenoids under conditions of stress, in which the cell division are retarded. In the case of cells grown in seawater (higher salt concentration), the cell growth was lower but the concentration of β-carotene was higher. Conclusion: In general, these results suggest that D. salina presents higher potential for β-carotene accumulation and that high salinity decreases cellular concentration (measured by the parameter Xm of the kinetic model proposed); however there is an increase in β-carotene production. © 2010 Science Publications.