Colormetric system for monitoring the growth of microalgae Dunaliella salina under laboratory conditions

The brackish microalgae Dunaliella salina, being an extremophilic halophyte, is a promising object for biotechnological production. The aim of this work is to develop a methodology for non-destructive control of the development of a microalgae culture under conditions of balanced growth during periodic cultivation on plates. Before the start of the experiment, the microalgae culture was synchronized. The quantitative content of chlorophylls a and b, as well as carotenoids, was determined spectrophotometrically in alcohol extracts. During cultivation, time-lapse images were recorded on a smartphone camera. The basis of the colorimetric evaluation is the analysis of the time series of images in the RGB color model. It is shown that the ratio of colors correlates to a high degree with the content of the determined main plant pigments – chlorophylls and carotenoids, and with the data of spectrophotometric measurements of live suspensions. The changes in the blue channel are the most pronounced, the least being in the green channel. The logarithm of color intensity is linearly dependent on the degree of dilution of the culture. The developed method for real-time monitoring of the development dynamics of the D. salina microalgae culture makes it possible to build growth curves and solve multiparametric problems to optimize the cultivation of microalgae, including when working with large arrays of samples.