The alga Bracteacoccus bullatus (Chlorophyceae) isolated from snow, as a source of oil comprising essential unsaturated fatty acids and carotenoids
Abstrakt
A unicellular alga isolated from snow in the Sierra Nevada Mountains (Spain) was characterised using a polyphasic approach. Comparative analysis of ITS2 rDNA secondary structures identified the new culture (CCALA 1120 Cepák and Lukavský Nova Hedwigia 94:163-173, 2012) as being conspecific with Bracteacoccus bullatus (Chlorophyceae).
For the first time this study documented sexual reproduction as the pairing of gametes and also an-isogamy. Strain CCALA 1120 had a temperature optimum of growth about 21 degrees C and an irradiance optimum above 160 mu mol photons m(-2) s(-1).
It was cultivated in pilot-plant scale, using an open thin-layer photobioreactor in a greenhouse with only partial temperature control. After harvest, a high proportion of fatty acids was found (15.3% of dry mass) with linoleic (18:2 omega-6) 18.3% and alpha-linolenic acids (18:3 omega-3) 17.4% being the most abundant.
Monounsaturated fatty acids accounted for about 30% with oleic (18:1 omega-9) and vaccenic acids (18:1 omega-7) as the most prominent. The ratio of PUFA omega-6/omega-3 was 1:1.16, i.e. near to the ideal ratio of 1:1, as recommended by the World Health Organization.
Biomass production was 2.67 g m(-2) day(-1) of dry weight, i.e. 0.2 g L-1 day(-1). At the end of growth phase, total carotenoids made up 10.1 mg L-1.
These results indicate that B. bullatus is suitable for production of a vegetable oil at lower temperatures (12-18 degrees C) and comprising a high content of unsaturated fatty acids.