Evaluation of the interaction of temperature and light intensity on the growth of Phaeodactylum tricornutum: Kinetic modeling and optimization

In this study, the effects of two highly variable factors, temperature ranging from 10-35 degrees C and light intensity from 98-1289 mu mol m(-2) s(-1), on the specific growth rate, mu, of a diatom, Phaeodactylum tricornutum, at a constant aeration rate of 3000 cm(3) min(-1) were elucidated. The choice of the adequate kinetic models describing the growth related to temperature and light intensity resulted in rapid determination of optimum growth conditions. Ratkowsky's square root model and Monod-type model were assessed as the most suitable expressions among the three temperature- and eight light intensity-dependent models, respectively, presenting the highest adjusted R-2 and smallest average relative deviation (ARD) values by means of nonlinear least squares method. Also, among the kinetic model approaches utilized to verify the combined effects of temperature and light intensity, the temperature-dependent Ratkowsky model in conjunction with the Monod-type expression with the smallest ARD value (4.19 %) and a high adjusted R-2 (0.9775) exhibited the best surface fit. The optimum cultivation temperature and light intensity conditions for the achieving maximum specific growth rate of P. tricornutum were determined as 21 degrees C and 496 mu mol m(-2)s(-1), respectively, by the help of the Central Composite Design (CCD) of the Response Surface Methodology (RSM).