4]. These processes are advantageous compared to conventional
methods, since they use waste materials generated by
various industries as feedstock. Moreover, microbial lipid
can be produced in close proximity to biodiesel industrial
plants and it is easy to scale up their production [5].
Different bacteria, yeasts, algae, and fungi have the
ability to convert carbohydrates and other substrates into
intracellular lipid. When a microorganism’s intracellular
lipid accumulation levels are greater than 20% of cell dry
weight (CDW), it is labeled an “oleaginous microorganism”.
Oleaginous microorganisms include yeast species,
such as Rhodosporidium sp., Rhodotorula sp., Lipomyces
sp., and Yarrowia lipolytica, whose intracellular lipid
accumulation levels can reach 80% of CDW [6–8]. The
main components of the accumulated lipid are triacylglycerols
composed of long-chain fatty acids (16–18 carbon
atoms in the chain) [6–8].
There are many ways of increasing intracellular lipid
accumulation. Some involve metabolically engineering