Study of photobiosynthesis efficiency of Arthrospira (Spirulina) platensis batch culture

Abstract

The dynamics of the integral coefficient of light absorption and photobiosynthesis efficiency of dense cultures of microalgae is researched. A batch cyanoprokaryotic culture of Arthrospira (Spirulina) platensis (Nordst.) Gomont was grown under light-limiting conditions. The choice of the light-limiting region is due to the low rates of photobiosynthesis, which, from a methodological point of view, simplifies the determination of the dynamics of biomass concentration and its main biochemical components. An express method for determining the concentration of chlorophyll a from true absorption spectra compensated for scattering is proposed. The production characteristics of culture were calculated (maximum specific growth rate – 0.02 h-1, productivity 0.17 g·l-1·d-1, percentage of Chl a – 1.5%). It is shown their relationship with the surface irradiation of the. It is revealed the dependence of the integral light absorption coefficient on the surface concentration of Chl a is described with high accuracy (R2 = 0.99) by the Bouguer-Lambert-Beer law. The specific absorption rate was 0.02 m2·mg-1, which is 2 times higher than that calculated for green algae. The efficiency of light energy utilization decreased at the exponential growth phase and stabilized at the linear one at the level of 4.9%. The obtained results can be used to predict the production of biologically valuable components in laboratory and semi-industrial conditions.