Cu-mediated biomass productivity enhancement and lutein enrichment of the novel microalga Coccomyxa onubensis

The influence of Cu (II) on productivity and accumulation of value carotenoids of a microalga that naturally grows at low pH, Coccomyxa onubensis, was investigated. The presence of Cu (II), added in range between 0.06 and 0.4 mM, increases both algal viability and synthesis of carotenoids, mostly lutein and β-carotene. A copper concentration of 0.2 mM was found to be as the most appropriate one to enhance productivity and lutein accumulation and was further used in semicontinuous cultures. Unlike acidophile microalgae, C. onubensis showed unusual high growth rates (0.50 d−1) when cultured semicontinuously at 0.2 mM Cu (II) and getting an average productivity of 0.42 g l−1 d−1. Lutein content in 0.2 mM Cu (II) cultures was roughly 50% higher than that obtained for control cultures. C. onubensis seems to have great potential as lutein producer when compared to known lutein accumulating microalgae. C. onubensis is able to live in highly selective environment, which confers the microalga a competitive advantage over other organisms that cannot survive at such low pH and high concentrations of heavy metals. This might make of C. onubensis a unique alga for large producer in open systems.

► Cu (II) enhances growth and carotenoid accumulation of Coccomyxa onubensis.
► Semicontinuous cultivation in Cu (II)-containing culture media leads to increased productivities of C. onubensis.
► Low pH and presence of Cu (II) determines maximal lutein productivity in cultures of C. onubensis.