Strain Selection for Biodiesel Production - Biotechnological Applications of Microalgae - page 29

TABLE 3.5
Advantages and Disadvantages of Microalgal Purification Techniques

Purification
Technique Advantages Disadvantages Ref.

Pringsheim's
micropipette
method

• Single cells can be
successively
transferred and
purified

• Laborious and
time-consuming
method requiring
considerable manual
skills
• The method often
fails with small
nonflagellate cells,
which are more
difficult to recognize
during serial
transfers
• Some delicate
flagellates are easily
damaged during
successive
micropipette
transfers

Guillard, 1973;
Melkonian, 1990

Agar plating (or
spraying)

• Relatively easy • Cannot be used with

most flagellate taxa
that fail to grow on
solid substrates

Hoshaw and
Rosowski, 1973

Serial dilution • Relatively easy • Unsuccessful when

the numerical ratio
between algae and
bacteria is
unfavorable

Brahamsha, 1996

Differential
centrifugation

• Less damaging to
sensitive cells

• Costly method Wiedeman et al.,

1964

Filtration • Less damaging to

sensitive cells and
usually gives
better separation
of algae from
bacteria than
differential
centrifugation

• It is problematical
with small algal cells
and with cells
secreting mucilage
because of bacteria
embedded in the
mucilage that may
also clog filters

Melkonian, 1990

Use of antibiotics • Relatively easy

• Low cost

• Damage the alga as
well as leads to
increased resistance
levels in
contaminating
bacteria

McDaniel et al., 1962

( Continued )