Predictive modeling of beta-carotene accumulation by Dunaliella salina as a function of pH, NaCI, and irradiance

Predictive modeling of beta-carotene accumulation by Dunaliella salina as a function of NaCI, pH, and irradiance was studied. Modified Logistic, Gompertz, Schnute, Richards, and Stannard models were fitted to describe beta-carotene accumulation by the alga under various environmental conditions. Lag time (lambda, days), maximum accumulation (A, pg/cell), and the maximum production rate (mu, 1/day) for beta-carotene accumulation were calculated by modified Logistic and Gompertz models. Values of lambda, A, and mu for beta-carotene accumulation varied between 0.26 and 20.14 days, 57.48 to 198.76 pg beta-carotene/cell, and 1.80 to 3.68 1/day, respectively. Results revealed that Logistic and Gompertz models could be used to describe the accumulation of beta-carotene by D. salina as a function of salt concentrations, pH, and irradiance. The highest asymptotic value was predicted from Logistic and Gompertz models at pH 9.0, 48 kerg/(cm(2) s) light intensity, and 20% NaCl concentration.