Enhancement of Carotenoids in Green Alga-Botryococcus braunii in Various Autotrophic Media under Stress Conditions.

Botryococcus braunii is a green colonial micro alga that is used mainly for the production of hydrocarbons, exopolysaccharides, and
carotenoids. Growth and carotenoid production of B. braunii culture were studied by using autotrophic media such as CHU13, Z8, BBM
and BG11 under stress conditions at high light intensity (3.5 ± 0.2 klux). The cultures were grown under low light (1.5 ± 0.2 klux)
intensity at 25 ± 1°C temperature for a period of 14 days followed by exposure to stress conditions (0.1% sodium chloride, 0.1% sodium
chloride with 0.1% sodium bicarbonate and 0.1% sodium chloride with 4 mM sodium acetate) and incubated further for a period of 21
days under high light intensity (3.5 ± 0.2 klux). Among the different autotrophic media used, BG11 and Z8 media were found to be the
best for biomass and carotenoid production. The data in the table shows 3.6 and 3.2 (g/L) biomass with a carotenoid content of 0.28 and
0.27% (w/w) in BG11 and Z8 media with 0.1% sodium chloride, respectively. Under these conditions, the carotenoid profile indicated
violaxanthin (6-9%), lutein (79-84%), astaxanthin (3-8%), zeaxanthin (0.32-0.78%), and -carotene (1.75-2.14%), which are identified by
mass spectrum. These results indicate that B. braunii culture can grow in a wide range of media and produce lutein as major carotenoid
which can be enhanced under stress conditions.