Basic HTML Version
International Journal of Marine Science 2013, Vol.3, No.17, 135-144
http://ijms.sophiapublisher.com
140
(2009); Chen et al (2008) and Westerhoff et al (2010)
found that the optimal cultivation temperature for the
specific growth rate of
Nannochloropsis oculata
and
Nitzschia laevis
, was 20
℃
and 23
℃
, respectively. In
Westerhoff et al.’s study showed that the exponential
growth rate constant (l = 0.03 h1) did not vary
between 27
℃
and 39
℃
of
Scenedesmus
and
Chlorella
, but at 42
℃
the microalgae could not grow.
Chlorophyll
a
concentration of three microalgal
cultured showed a similar pattern in respond to
temperature stress and nutrient limitation (Figure 2).
Three microalgal cultured exhibited two times higher
chl
a
concentration. Chl
a
concentration in
Dunaliella
tertiolecta
ranged from 8.56×10
-7
to 7.67×10
-6
pg
cell
-1
and decreased with time at both temperature and
nutrient conditions (Figure 2A). No significant
different of chl
a
concentration in relation to culture
time (0, 2, 4, 6, 8 and 10 day) for the temperature and
nutrient condition (p<0.05). Chl
a
concentration
expressed per cell at the end the cultivation period
ranged from 8.15×10
-7
to 1.68×10
-6
pg cell
-1
. Chl
a
concentration at
Dunaliella tertiolecta
in this experiment
was lower than other
Dunaliella
species, such as
Dunaliella salina
and
D. viridis
that reported by
Garcia et al (2007). Photosynthetic limit to
temperature was affected by different in size and
morphological feature between these species (Coles
and John, 2000). Temperature cultivation condition
showed a slightly affect to chl a concentration at
Dunaliella tertiolecta
. This result supported by
previous study of Garcia et al (2007) at different
Dunaliella species. However, nutrient depletion
showed a significant effect to chl a concentration of
Dunaliella tertiolecta.
Chl
a
concentration trend over cultivation period of
Scenedesmus
sp. was similar with
Dunaliella tertiolecta
(Figure 2B). There was two peak of chl
a
per cell,
which were initial and day 4 of cultivation. Chl a
concentration in
Scenedesmus
sp. ranged from
4.55×10
-9
to 2.76×10
-6
pg cell
-1
. Chl
a
concentration at
25
℃
temperature cultivation and replete nutrient
condition was higher than at 18
℃
. Statistically, there
was a significant different of chl
a
concentration between
25
℃
and 18
℃
and between nutrient treatment (p<0.05).
Chl
a
concentration of
Nannochloropsis
sp. over
cultivation period was showed at Figure 2C. Peak of
Figure 2 Chlorophyll
a
concentration per cell in response to
varying nutrient and temperature condition. Chl
a
per cell of (A)
Dunaliella tertiolecta
, (B)
Scenedesmus
sp. and (C)
Nannochloropsis
sp.
chl a concentration per cell was occurred at initial and
day 4 of cultivation for 18
℃
and 25
℃
, respectively.
The range of chl
a
concentration was 4.94×10
-9
to
3.24×10
-6
pg cell
-1
. There was a significant different of
chl
a
concentration at day 4 of cultivation between 18
℃
and 25
℃
(p<0.05). The result of chl
a
concentration in
Nannochloropsis
sp. was consistent with previous
study by Sukenik et al (1993) that showed the highest
chlorophyll
a
content was recorded in cultures grown
at 25
℃
, whereas the lowest value was measured in
cultures grown at 18
℃
.
3.2 Effect of temperature and nutrient depletion on
the lipid content
The cell growth and lipid accumulation were closely