Quantity and Quality of Light on Growth and Pigment Content of <em>Dunaliella</em> sp. and <em>Anabaena</em> sp. Cultures and the Use of Their Absorption Spectra as a Proxy Method for Assessment

Abstract

(1) Background: Microalgae cultures are greatly facilitated if growers can easily and economically ascertain the quantitative and qualitative status of the culture continuously with satisfactory ac-curacy. (2) Methods: The locally isolated microalgae Dunaliella sp. and Anabaena sp. were cultured in small volumes with 2 intensities of white light (2000 and 8000 lux) and with green, blue and red light and the increase of their biomass and pigments was studied. Pigment analyses, continuous recordings of absorption spectra and calibration curves were performed. (3) Results: The intensity of 8000 lux white light yielded the highest increase in biomass, chlorophylls and carotenoids in Dunaliella sp. while 2000 lux and green light caused the greatest increase in biomass and phy-cocyanin in Anabaena sp. From the examination of the absorption spectra, the evolution of the pigment content can be estimated and both pigments and biomass are correlated very satisfactorily with the wavelength of 750 nm. (4) Conclusions: The use of absorption spectra as an easy, fast and economical method can be a useful tool for a good approximation of the state of the microalgae culture. This is clearly shown when the spectra of the culture under different lighting colors are compared which have a catalytic effect on the level of the pigments leading to the increase in carotenoids and phycocyanin of the green light.