The effect of heavy metals on the viability of AC16-MESO and an evaluation of the potential use of this microalga in bioremediation.

The use of microalgae in biotechnological processes has received much attention worldwide. This is primarily due to the fact that they are inexpensive to grow, requiring only sunlight and CO, whilst lending themselves to a range of uses, such as to reduce CO levels, as fish feed, in biofuel production, for the generation of secondary metabolites of interest, and in bioremediation. These features mean that microalgae are excellent candidates for the implementation of a range of eco-friendly technologies. Here, we investigated the behavior and feasibility of the use of the microalgal strain AC16-MESO against heavy metal contamination focused on potential use in bioremediation. The following key parameters were recorded: (i) the sedimentation efficiency, which reached 95.6% after five hours of decantation; (ii) the ion tolerance (Ca, Co, Cu, Fe, Mn and Ni) at concentrations of 0.1, 1.0, 5.0, 10.0 and 20.0 mgL and (iii) ion removal efficiency (Cu, Fe and Mn). Our results indicated a higher tolerance for iron and calcium (20 ± 1.10 mgL; 100 ± 8.10 mgL), partial to nickel, manganese and copper (4.4 ± 0.10 mgL; 4.4 ± 0.15 mgL; 5 ± 1.25 mgL) and less for cobalt (0.1 ± 0.20 mgL). Moreover, removal efficiency of 40-90% for Cu, 100% for Fe, and 20-50% for Mn over a 72 hours period, for ion concentrations of 1.0 and 5.0 mgL.