Lutein production by coccomyxa sp. SCCA048 isolated from a heavy metal-polluted river in Sardinia (Italy)

The unicellular green alga, Coccomyxa sp. SCCA048 was previously isolated scraping the ferrous material deposited on the rocks along the heavy metals-contaminated river 'Rio Irvi' (Arburese mining district, Sardinia, Italy). The kinetics of autotrophic growth and pigment production of the strain in stressing (continuous light) and control cultures (12: 12 light-dark photoperiod) was described. Time course of both cultures reflected typical microbial growth curves. The maximum cell densities (3.1 × 107 and 1.1 × 107 cell/ml, for continuous light and control cultures, respectively) were found at the end of log phase (day 40). However, continuous light conditions accounted for ≅ 280% higher density than control cultures. The specific growth rate (μ) of the microalga during exponential phase in continuous light was 1.5 times higher than that recorded for the control. The pigment profile, characterised by HPLC, was particularly rich in carotenoids, especially lutein (up to 80% of total carotenoids). The algal strain, cultivated in continuous light, showed high intracellular contents of lutein (0.34 pg/cell) at the beginning of the exponential phase. In addition, lutein cell content, at maximum growth, was higher than those reported in literature for others carotenogenic strains of Coccomyxa. Pigment production by control cultures was always much lower. These data suggested that the microalga cultivated under conditions of stressing light might have potential for the large-scale production of antioxidant carotenoids.