Figure 1 : Effects of increasing concentrations of fermentor used medium on P.tricornutum growth.
This means that metabolites only, either degraded hydrocarbons or tensioactive substances, are implicated in the stimulation- inhibition effects of the used medium on the
algae growth. These metabolites might act either separately or through any combination.
However, the role of the concentration factor seems to be preponderant.
Comparative effects of the total used medium, the lipid free used medium and the lipid
extract on P. tricornutum and P. micans growth at concentration 10%.
Both the lipid extract and the lipid free used medium stimulate the algae growth during
the first days of the cultures (Fig. 2 and Fig. 3).
Lipid extract general effect is to depress the cultures growth (after 48 h for P. tricornutum
and 5 days for P. micans). However, P. micans is more sensitive to the lipid extract.
The lipid free used medium which contains carbohydrates, amino acids and vitamins has
no effect on the exponential growth of the algae.
The general pattern of growth inhibition due to the total used medium (10 %) and to the
lipid extract ( 10 %) is not similar for the two algae. The total used medium inhibits much
more P. tricornutum growth than the lipid extract does, whereas it is the opposite
concerning P. micans. Moreover, some of the lipids present in the used medium (22 %),
acting on the algae growth, are denaturated by the extraction process. Thus their effects
cannot be evaluated at the present stage of the study.
624
This means that metabolites only, either degraded hydrocarbons or tensioactive substances, are implicated in the stimulation- inhibition effects of the used medium on the
algae growth. These metabolites might act either separately or through any combination.
However, the role of the concentration factor seems to be preponderant.
Comparative effects of the total used medium, the lipid free used medium and the lipid
extract on P. tricornutum and P. micans growth at concentration 10%.
Both the lipid extract and the lipid free used medium stimulate the algae growth during
the first days of the cultures (Fig. 2 and Fig. 3).
Lipid extract general effect is to depress the cultures growth (after 48 h for P. tricornutum
and 5 days for P. micans). However, P. micans is more sensitive to the lipid extract.
The lipid free used medium which contains carbohydrates, amino acids and vitamins has
no effect on the exponential growth of the algae.
The general pattern of growth inhibition due to the total used medium (10 %) and to the
lipid extract ( 10 %) is not similar for the two algae. The total used medium inhibits much
more P. tricornutum growth than the lipid extract does, whereas it is the opposite
concerning P. micans. Moreover, some of the lipids present in the used medium (22 %),
acting on the algae growth, are denaturated by the extraction process. Thus their effects
cannot be evaluated at the present stage of the study.
624