Optimisation of T-ISO
biomass production rich in essential fatty acids
I. Effect of different light
regimes on growth and biomass production
I.
Tzovenis, N. De Pauw, P. Sorgeloos-2003
Aquaculture, 216(1-4): 203-222
Abstract:
T-ISO is a microalgal strain widely used in
aquaculture for its favourable lipid composition. In this study, we report
on the results of an optimisation scheme for maximal biomass production
under three different photoperiods (24:0, 16:08 and 12:12-h L/D) combined
with three photon flux densities (PFD, 120, 220 and 460 µmol photons m-2
s-1) at 25°C. Sampling for growth took place in both the
exponential and post-exponential (light-limited only) phase. Results showed
that specific growth rate of T-ISO maximised with an increase of the total
PFD supplied per day. Under continuous light, cell size of T-ISO (both cell
dry weight (CDW) and cell volume) correlated positively to PFD with a
further increase when the cells were transiently light-limited in the
post-exponential phase. In contrast, cell dry weight under discontinuous
light increased only at subsaturating PFD with a significant decrease in the
post-exponential phase. Cell size, as volume, did not correlate to CDW under
discontinuous light, revealing an intracellular density change particularly
for the 16:08-h L/D regimes. As a result, biomass yield and productivity had
different patterns for continuous and discontinuous light whereas cell yield
and productivity were simply a function of total PFD per day. Biomass
productivity under continuous light was inferior than under discontinuous
light, although the final yield was maximal compared to those under
discontinuous light.
(Department of Ecology and Systematics, Faculty of
Biology, University of Athens, Panepistimioupolis, Zografou 15784, Greece.
Tel.: +30-1-7274042; fax: +30-1-7274885; email: itzoveni@eexi.gr)