Spirulina (Arthrospira) platensis biomass has a wide range of applications in several industries. One of the key issues for its production is the reduction of the culture medium cost. Here we have shown the possibility of a single recycling (repeated usage) of the modified Zarrouk nutrient medium (MZM; which contains 8.4 g/l of NaHCO3and 0.1 g/l of NaOH instead of 16.8 g/l of NaHCO3) for spirulina cultivation without altering culture productivity, photosynthetic pigments and protein contents in its biomass  given that technological approach consisting in application of a mixture of a freshly prepared and once recycled modified Zarrouk medium in a ratio of 1:1 by volume is used. The obtained results can be applied for further reduction of costs of spirulina biomass production compared to methods described in previous studies.

No abstract

The effect of NaCl (25, 50, 100, 200 and 300 mM) on the productivity of the Haematococcus pluvialis strain IBCE H-17 on such parameters as dry biomass, content of protein, photosynthetic pigments, as well as astaxanthin and reactive oxygen species (ROS) was studied. It was found that NaCl at low and medium concentrations (25, 50 and 100 mM) in the culture medium stimulated the accumulation of dry biomass during the first 7 days of cultivation on average 1,3 times as compared to the control (Rudik’s standard medium). After 12 days of incubation, stimulation averaged 33 % using 25 and 50 mM salt. The protein content on a dry weight basis fell, averaging 70 % of the control on the 7th day of incubation with 50–300 mM salt and 55 % on the 12th day for a salt concentration of 100–300 mM. When the algae was grown for 7 days on solutions containing NaCl, the total content of photosynthetic pigments – chlorophylls (Chl) a and b as well as the carotenoids neoxanthine, violaxanthin, lutein and β-carotene decreased. Chl b was more resistant to salinity than Chl a. Of all the pigments, NaCl exerts the greatest negative effect on β-carotene. Stress conditions created by NaCl led to the generation of ROS, in particular, after 7 days of cultivation the total ROS content in the “NaCl-100” variant was 1.7 times higher than that in the control culture and 3.0 times higher than the control in the 12-day culture. A significant positive effect of salinity on the content of astaxanthin was noted. The maximum effect was observed with 100 mM NaCl. After 7 days of incubation, the content of astaxanthin exceeded the control indices by 2.8 times, and after 12 days – by 20.5 times. The number of algae cells after 7 days of incubation in the “NaCl-100” variant decreased on average by 33 %, while the cell diameter increased by 29 %.