Assessing the Impact of Low Level Laser Radiation on Microalgae Cultures ^†

Laser radiation (LR) is generated by an optical quantum generator. This technical device emits light in a very narrow spectral range in the form of a directed high-coherent monochromatic polarized beam in the form of highly ordered electromagnetic one-color radiation in space and time [1]. The effects of lasers on biological systems has been used in medicine, agriculture, and biotechnology [2]. Microalgae biomasses have been considered promising renewable sources of raw material for biofuel production, as well as sources of valued nutrients in livestock feeds, dietary supplements, and in cosmetology. Microalgae have the capacity to change their functional composition based on growth conditions and stress factors. To date, there has been no experimental evidence relating microalgae Nannochloris sp. biomass accumulation and biomass composition under laser stress.

In this work, microalgae Nannochloris sp. was used to investigate the effect of two lasers (650 nm and 532 nm) on cell growth, lipid accumulation, and lipid composition. Different irradiation times (1, 5, 10, 15, and 20 min) for both laser wavelengths have been studied. The greatest increase in biomass was observed when 650 nm laser radiation was applied. The biomass accumulation increased with the exposure time. The maximum increase of the biomass was 30%, compared to the blank sample, and was obtained after 20 min of irradiation.