-Carotene, a tetraterpenoid containing eight isoprene units, is
a known precursor of vitamin A and has been used as a supplement
in food and feed products. In addition, it is used as an antioxidant
to reduce cellular or tissue damage and as a coloring agent
for food products (e.g., margarine, soft drinks and baked goods)
[1]. Carotenoids are widely distributed in microorganisms including
the bacteria Sphingomonas sp. [2], the algae Dunaliella bardawil
[3], the fungus Blakeslea trispora [4] and yeasts of the genera Phaffia
and Rhodotorula [5,6]. Commercial production of carotenoids
using microorganisms is highly efficient because they are easily
adapted for different processing schemes [7]. Several studies have
been conducted on carotenoid synthesis by wild type microorganisms,
including the screening of wild strains [2], optimization of
the medium and environmental conditions [8], addition of stimulators
[9] and application of oxidative stress [10].