Strain Selection for Biodiesel Production - Biotechnological Applications of Microalgae - page 30

TABLE 3.5 ( Continued )
Advantages and Disadvantages of Microalgal Purification Techniques

Purification
Technique Advantages Disadvantages Ref.

Flow cytometry • Precise and rapid

method
• Simultaneous
measurements of
individual particle
volume,
fluorescence and
light scatter
properties
• Highly suitable for
separating bacteria
from algae to
establish axenic
algal cultures
• Can be used
directly in natural
samples
• Useful for small
and delicate taxa

• Requires
considerable costs
for equipment and its
operation
• Requires multi-user
or central facilities
• Axenic cultures are
difficult to obtain
from algae to which
bacteria are
physically attached

Sensen et al., 1993

Ultrasonication • Useful for

separating attached
bacteria from algal
cell walls or
mucilage

• Not a stand-alone
method
• Should be coupled
subsequent to cell
sorting

Steup and Melkonian,
1981

Immunological
methods

• High speciicity
• Highly selective

• High cost
• May cause cell
damage

Han and Frazier,
2005; Takahashi
et al., 2004

Source: Adapted from Mutanda et al. (2011).

into the growth medium. Some of these could prove valuable as co-products, and
new approaches are needed to develop screening methods for extracellular mate-
rials. For mass culture of a given algal strain, it is also important to consider the
strain's robustness, which includes parameters such as culture consistency, resil-
ience, community stability, and susceptibility to predators present in a given envi-
ronment. Previous studies revealed that algal strains tested in the laboratory do not
always perform similarly in outdoor mass cultures (Sheehan et al., 1998). Therefore,
to determine a strain's robustness, small-scale simulations of mass culture conditions
must be performed.
At this time, the bottleneck in screening large numbers of algae stems from a
lack of high-throughput methodologies that would allow simultaneous screening
of multiple phenotypes, such as growth rate and metabolite productivity. Solvent