Biomedical Engineering Reference
In-Depth Information
TABLE 13.2
Variations in
Neochloris oleoabundans
UTCC 1185 Biomass
Light
Intensity
(μmol m
−2
s
−1
)
Biomass
Productivity
(g L
−1
d
−1
)
Temperature
(°C)
Species
Medium
Ref.
Neochloris
oleoabundans
UTCC
1185
Bristol
26-30
150
0.03-0.15
Goueveia
et al., 2009
Neochloris
oleoabundans
UTCC
1185
Erd
Schreiber
Soil extract
30
360
0.18-0.63
Li et al.,
2009
Neochloris
oleoabundans
UTCC
1185
Bold
modified
25
270
0.50-1.50
Pruvost
et al., 2009
Neochloris
oleoabundans
UTCC
1185
Bristol
modified
20
91-273
0.047-0.075
Wahal and
Viamajlal,
2010
13.5 LIPID VARIATIONS: PHYSIOLOGICAL STATE
Microalgae produce tri- and di-glycerols, phospho- and glycol-lipids, and hydrocar-
bons (Chisti, 2007). Although claims regarding yield per acre are often exaggerated,
third-generation microalgal biomass could yield 58,700 L biodiesel ha
−1
y
−1
, or even
90,000 L ha
−1
y
−1
, comparable to 53,200 L ha
−1
y
−1
(Weyer et al., 2010), an order of
magnitude greater than the yields from first-generation biofuel crops (Chisti, 2007).
The mode of cultivation of algae is reflected in biomass and lipid yield (Table 13.3).
Lipids as a percent of dry cell weight ranged between 1.9 and 75, and
Botryococcus
braunii
yielded the highest percent (Malcata, 2010). Pienkos et al. (2011) summarized
lipids (% of DW) in the range of 9.8% in cyanobacteria, 22.7% to 37.8% in diatoms,
25.5% to 45.7% in green microalgae, and 27.1% to 44.6% in other eukaryotic algae.
Lipid production in autotrophic algae ranged from 0 to 2500 mg L
−1
d
−1
, and the high-
est was in
Chlorella protothecoides
(Chen et al., 2011). Areal production ranged from
0.57 to 38 g m
−2
d
−1
, and
Dunaliella salina
was the most productive (Mata et al., 2010).
Heterotrophy promotes faster growth and lipid accumulation. Compared to pho-
totrophic cultures, cultures of
Chlorella protothecoides
grown heterotrophically
had higher values of biomass productivity (1.7 to 7.4 g L
−1
d
−1
) and lipid productiv-
ity (732.7 to 3,701.1 mg L
−1
d
−1
), with lipid as percent dry cell weight ranging from
43% to 57.8% DW.
C. protothecoides
, when grown under heterotrophic conditions,
yielded 55% lipid per cell dry weight (Xu et al., 2006). In mixotrophic cultures of
C.
protothecoides
using glucose/acetate, higher levels of biomass (4.76 ± 1.50 g L
−1
d
−1
),
biomass productivity (1.59 ± 0.50 g L
−1
d
−1
), and lipid productivity (0.25 g L
−1
d
−1
)
were obtained; but because the cost of the raw materials was unacceptable, glycerol
and acetate were used as carbon sources (Heredia-Arroyo et al., 2010). With glyc-
erol, the corresponding values were 3.97, 0.93, and 0.19 g L
−1
d
−1
(Heredia-Arroyo
et al., 2010). However, in phototrophic cultures of
C. protothecoides,
corresponding
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