Environmental Engineering Reference
In-Depth Information
Ueda 1997, 1999; Polle et al. 2003). Recently, Mussgnug et al. (2007) used RNA interference (RNAi)
to downregulate the expression of light harvesting antenna complex proteins of
C. reinhardtii
with
the recombinant strain showing higher resistance to photodamage and increased light penetration
in the culture.
Alternatively, genetic engineering may be used to enhance key parts of the pathway
of lipid synthesis. For example, the acetyl-CoA carboxylase (ACC) gene from
Cyclotella
cryptica
has been transformed into the diatoms
C. cryptica
and
Navicula saprophila
, resulting
in overexpression of the ACC gene,
acc
1, enhancing enzyme activity 2- to 3-fold. However,
there was no significant increase in lipid accumulation in the transgenic diatoms (Roessler
et al. 1994; Dunahay et al. 1995, 1996), suggesting that there is a secondary limiting step in
the TAG pathway. As an alternative approach, Courchesne et al. (2009) proposed to enhance
lipid overproduction by overexpressing transcription factors regulating the metabolic pathways
involved in the production of lipids.
These potential improvements in the efficiency of light use and metabolic redirection to lipid
synthesis, coupled with essential improvements in culture and harvesting systems, will contribute
to the development of commercially viable and environmentally sustainable production of biofuels
from algae.
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