Influence of magnesium concentrations on the biomass and biochemical variations in the freshwater algae, Chlorella vulgaris

The current study deals with the biological response variations on some biochemical properties of the freshwater green algae Chlorella vulgaris by exposure to different Mg2+ concentrations (5, 10, and 15) mg/L. Physiological and biochemical parameters, including growth curve, doubling time, photosynthesis pigments, total protein and carbohydrates were investigated. Moreover, enzy-matic parameters such as catalase (CAT), superoxide dismutase (SOD), and reactive oxygen species (ROS) were also examined. The maximum growth rate was 0.482/day during the 9th day with 5 mg/L Mg2+, while the minimum was 0.019/day during the 13th and 14th days with 10 mg/L Mg2+. Furthermore, doubling time ranged between 15.501 during the 13th day with 10 mg/L Mg2+, and 0.624 during the 9th day with 5 mg/L. The maximum value of chlorophyll-a was 0.157 mu g/mL during the 1st day with 10 mg/L Mg2+, while the minimum was 0.062 mu g/mL during the 14th day with 15 mg/L Mg2+. The carotenoid ranged between 0.029 mu g/mL during the 7th day with 15 mg/L Mg2+ and 0.002 mu g/mL during the 14th day. The maximum protein value was 9.620 mu g/L during the 1st day with 15 mg/L Mg2+, while the minimum was 1.772 mu g/L during the 14th day with 15 mg/L Mg2+. The carbohydrate showed a maximum value of 0.824 mu g/mL during the 1st day with 10 mg/L Mg2+, while the minimum was 0.293 mu g/mL during the 14th day with 15 mg/L. Moreover, SOD ranged between 0.884 unit/L during the 1st day with 15 mg/L Mg2+, and 0.073 unit/L as the minimum value during the 14th day with 15 mg/L Mg2+. The maximum value of ROS was 3.627 mM/mL during the 1st day with 5 and 15 mg/L Mg2+, while the mini-mum was 1.674 mM/mL during the 14th day with 10 mg/L. The results show that values of CAT ranged between 0.200 unit/mL during the 7th day with 10 mg/L Mg2+, and 0.010 unit/mL during the 14th day with 15 mg/L. Overall, 5 mg/L for biomass production and 15 mg/L for protein and carbohydrate production were optimum doses.

Automated summary

The study investigates the variations in biological response of Chlorella vulgaris to different Mg2+ concentrations. The growth curve, photosynthesis pigments, total protein, carbohydrates, and enzymatic parameters were examined. The results show that 5 mg/L Mg2+ is optimum for biomass production, while 15 mg/L Mg2+ is optimum for protein and carbohydrate production.