Experimental study of the temporal scaling characteristics of growth-dependent radiative properties of Spirulina platensis

The interaction of a cell with light is described by electromagnetic theory through parameters such as absorption cross-section, scattering cross-section and scattering phase function, which are essential radiative properties in radiative transfer theory for analysis of light transport in dispersed media. The radiative properties of microalgae vary with time due to the growth process of cell division and metabolism. In this paper, the growth-dependent radiative properties of Spirulina platensis (a microalgae with filamentous helix structure) was experimentally investigated in batch cultivation. The microalgae was cultivated in a flat-plate photobioreactor under dark and light cycle 12 h and 12 h with irradiance of 2000-2500 lx. The absorption and scattering cross-sections of Spirulina platensis were measured in the spectral region 380-850 nm at different growth time. The experimental results showed temporal scaling behavior of the radiative properties of this filamentous microalgae, which confirms the temporal scaling law of radiative properties of microalgae reported recently, namely, the temporal scaling function (TSF) defined as the ratio of spectral absorption or scattering cross-sections at different growth time to that at stationary phase is nearly wavelength independent. This paper is the first work on the temporal scaling behavior of radiative properties of Spirulina platensis, and also provides additional experimental evidence on the general validity of the temporal scaling law of radiative properties of microalgae cells.