Behavior of the extremophile green alga Coccomyxa melkonianii SCCA 048 in terms of lipids production and morphology at different pH values

The extremophile green alga Coccomyxa melkonianii SCCA 048 was investigated to evaluate its ability to grow in culture media with different pH. Specifically, Coccomyxa melkonianii was sampled in the Rio Irvi river (Sardinia, Italy) which is severely polluted by heavy metals as a result of abandoned mining activities. In this study, the strain was cultivated in growth media where the pH was kept fixed at the values of 4.0, 6.8 and 8.0, respectively. During the investigation, a significant phenotypic plasticity of this strain was observed. The strain grew well in the pH range 4.0–8.0, while the optimal value for its growth was 6.8. Furthermore, maximum lipid contents of about 24 and 22 %wt were achieved at the end of cultivation when using pH 4.0 and 8.0, respectively. Finally, the analysis of fatty acid methyl esters (FAMEs) highlights the presence of suitable amounts of compounds which can be profitably exploited in the food, nutraceutical, and cosmetic industry. This aspect, coupled with the possibility of cultivating Coccomyxa melkonianii under extreme pH conditions in economic open ponds, makes this strain an interesting candidate for several biotechnological applications.