Abstract
Bicarbonate ions are the primary source of inorganic carbon for autotrophic organisms living in aquatic environments. In the present study, we evaluated the short-term (hours) effects of sodium bicarbonate (NaHCO3) addition on the growth and photosynthetic efficiency of the green algae Chlorella sorokiniana (211/8k). Bicarbonate was added to nonaxenic cultures at concentrations of 1, 2, and 3 g L−1 leading to a significant increase in biomass especially at the highest salt concentration (3 g L−1) and also showing a bactericidal and bacteriostatic effect that helped to keep a reduced microbial load in the algal culture. Furthermore, bicarbonate stimulated the increase in cellular content of chlorophyll a, improving the photosynthetic performance of cells. Since microalgae of genus Chlorella spp. show great industrial potential for the production of biofuels, nutraceuticals, cosmetics, health, and dietary supplements and the use of bicarbonate as a source of inorganic carbon led to short-term responses in Chlorella sorokiniana, this method represents a valid alternative not only to the insufflation of carbon dioxide for the intensive cultures but also for the production of potentially bioactive compounds in a short period.
Highlights
Research studies on microalgae have increased in the last decades due to the wide range of applications associated with these photosynthetic microorganisms that can be utilized as sources of biofuels, pharmaceuticals, cosmetics, health, and dietary supplements [1,2,3,4,5,6]
The biological carbon pump is a major component of the global carbon cycle, which regulates atmospheric CO2 levels and transfers both organic and inorganic carbon fixed by primary producers in terrestrial and aquatic ecosystems [9]
The growth of Chlorella sorokiniana was monitored for 72 h as changes in optical density (OD800 ), cell number, and cellular size
Summary
Research studies on microalgae have increased in the last decades due to the wide range of applications associated with these photosynthetic microorganisms that can be utilized as sources of biofuels, pharmaceuticals, cosmetics, health, and dietary supplements [1,2,3,4,5,6]. Microalgal photosynthesis is similar to that of higher plants, characterized by a higher yield compared to terrestrial crops as it is more efficient in converting solar into chemical energy [7]. Due to their high growth rate, these organisms can be cultured in closed bioreactor systems reaching high biomass yields [4,8]. While terrestrial photosynthetic organisms utilize the atmospheric carbon dioxide (CO2 ) as a source of inorganic carbon (Ci) into Calvin-Benson cycle directly [10], aquatic photosynthetic organisms are The biological carbon pump is a major component of the global carbon cycle, which regulates atmospheric CO2 levels and transfers both organic and inorganic carbon fixed by primary producers in terrestrial and aquatic ecosystems [9].
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