Biofilm formation and lipid accumulation of attached culture of Botryococcus braunii.

The microorganisms in biofilms live in a self-produced matrix of hydrated extracellular polymeric substances (EPS) that forms their immediate environment. The objective of this paper was to investigate the relationships between culture conditions, EPS, microalgal biofilms growth and lipid accumulation. Fresh water alga Botryococcus braunii was attached culture in multi-layers photobioreactors with different culture media and substrates. The results indicated that the production of EPS was affected by culture period, nutrient, and substrate. Increasing the production of EPS may enhance the biofilm growth. However, the EPS components, namely proteins and polysaccharide had a more profound effect on biofilm formation compared to total EPS, with protein being more significant than polysaccharide. Nitrogen-free and EPS strategies were conducted to increase the lipid content of B. braunii biofilm from 11.6 to 42.3 % and 51.3 %, respectively. Compared to suspended culture, the lipid quality was enhanced. The dominant component of hexadecanoic acid (16:0) was enhanced from 21.78 to 48.17 % and 55.44 %, respectively.