Modification of sterol concentration in marine microalgae

Semicontinuous cultures of the marine microalgae Phaeodactylum tricornutum and Tetraselmis suecica were carried but with renewal rates (RR) of 10, 20, 30, 40 and 50%. The concentration of (24S)-24-methylcholesta-5,22E-dien-3 beta-ol in P. tricornutum followed a progressive fall from a maximum of 29.1 fg cell(-1), in the culture with the 10% RR, to a minimum of 20 fg cell(-1) in the culture with the 50% RR. In Tetraselmis suecica, 24-methylcholest-5-en-3 beta-ol ranged from 137 fg cell(-1) with a 10% RR to 40 fg cell(-1) with a 40% RR and 24-methylcholesta-5,24(28)-dien-3 beta-ol ranged from 403 fg cell(-1) with a 10% RR to 80 fg cell(-1) with a renewal rate of 50%. Renewal rate is a good tool to modify the sterol concentration in marine microalgae. (C) 1997 Elsevier Science Ltd.