Transient initial phase in
continuous culture of Isochrysis galbana affinis Tahiti
G. Bougaran, L. Le Dιan, E. Lukomska, R. Kaas, R.
Baron-2003
Aquatic Living Resources, 16(4): 389-394
Abstract
Starting microalgae continuous culture generally
includes a preliminary batch culture to obtain sufficient cell density. It
is possible to apply continuous regime from the beginning of the culture (IC
mode) rather than to begin by an initial batch (IB mode). It is our purpose
to check that both initial modes lead to identical steady-state cell
characteristics. The microalga Isochrysis galbana affinis Tahiti
was used for this comparative study. With an initial cell density of 5 Χ
105 cell ml1 and a dilution rate of about 1.0 d1,
both IB and IC modes led to identical cell density once steady-state is
reached between 6 and 8 d after inoculation in the two cases. Cell
concentration of chlorophyll a and pheopigment a were found to
be similar for IB and IC modes at steady-state. Initial culture conditions
did not influence saturation irradiance and oxygen consumption rate, which
were found to be 650 ± 143 ΅mol phot m2 s1
and 1.54 Χ 103 ± 105 ΅mol O2
ml1 min1, respectively. At steady-state,
nutrient cell uptakes were ρN = 83.3 ± 2.0 fmol
N cell1 d1 for NO3 and ρP = 5.5 ± 0.4 fmol
P cell1 d1 for H2PO4
and did not exhibit significant differences between IB and IC modes. Under
the prevailing experimental conditions, results show that IC mode involved
very similar steady-state cell characteristics when compared to IB mode
subsequent steady-state. IC mode could be an attractive alternative
especially for experimental laboratory studies, as it should lead to higher
flexibility in starting continuous cultures.
(IFREMER,
rue de l'Ile d'Yeu, 44311, Nantes cedex 3, France, e-mail: gael.bougaran@ifremer.fr)