Modeling Growth Of Microalgae Dunaliella Salina Under Different Nutritional Conditions

American Journal of Biochemistry and Biotechnology 6 (4): 279-283, 2010 ISSN 1553-3468 © 2010 Science Publications

Modeling Growth of Microalgae Dunaliella Salina under Different Nutritional Conditions
Sergio Santos Jesus and Rubens Maciel Filho Department of Chemical Process, Laboratory of Optimization, Design and Advanced Control, School of Chemical Engineering, University of Campinas,Unicamp Cidade Universitária Zeferino Vaz, CP 6066, Campinas, SP, Brazil
Abstract: 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 withagitation 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 describingthe 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. Key words: β-carotene, culture medium, Dunaliella salina, kinetic model, initial concentration, biologicalfunctions, natural pigments, salinity decreases, cellular concentration, synergistic effect, microalgal species INTRODUCTION Carotenoids are natural pigments with much diversified structure-yet similar in their general chemical structure-and widely spread in nature, where they fulfill their essential biological functions. Carotenoids, some of which are provitamin A, have a range of diverse biologicalfunctions and actions, especially regarding human health. The carotene’s pigment is of international importance because of its dual function as vitamin and colorant in the food industry to pigment salmon, trout and poultry meat, or to intensify the color of egg yolk (Martelli et al., 1992; Johnson and Schroeder, 1995). The β-carotene also present other physiological effects as inhibitor of cancer andsome diseases concerning photosensible skin. It also increases immunological response to certain types of infection (Mayne, 1996). Dunaliella salina, unicellular green microalgae, halophylic with free wall, is scientifically interesting for its capacity of producing β-carotene and glycerol. D. salina can accumulate a very high concentration, (up to 14% ) of cell dry weight of β-carotene underconditions of high light, high salinity and nutrient deprivation and it is recognized as the best biological source of this carotenoid (Borowitzka and Borowitzka, 1990; Markovits et al., 1993; Lee, 2001). Severe conditions such as high salinity, low nutrient levels, high irradiance and high temperature have been claimed to induce β-carotene production in the cell but, at the same time, decrease thenumber of cells per culture volume by affecting cell division (Tafreshi and Shariati, 2006). Ben-Amotz and Avron (1983) showed that the salinity and irradiance have an additive or synergistic effect on carotenogensis in D. salina.

Corresponding Author: Sergio S. Jesus, Department of Chemical Process, Laboratory of Optimization, Design and Advanced Control,

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