Avaliação da viabilidade produtiva de meio alternativo à base de Lemna minor para o cultivo de Chlorella sp

Abstract

Currently, microalgae represent one of the most promising sources for generating bio-inputs, but the greatest difficulty faced is the high cost of culture media. Therefore, given the scarcity of studies on new formulations, the present work aims to evaluate the behavior of the microalga of the genus Chlorella in a medium enriched with the extract of the macrophyte Lemna minor, which is easily found in large quantities in the natural environment, to quantify the amount of protein generated by the microalga in an alternative medium, and to verify the effectiveness of cryopreservation of the species through the maintenance of its viability. The water sample was obtained from the Itá stream, in the Barra do Itá settlement, in Bela Vista – MS. Isolation was performed using the “streak plating” method, in which a sample of the obtained water was subjected to streaking using a platinum loop on a Petri dish containing a solid medium composed of agar (1%) and NPK agricultural fertilizer (10-10-10 1.0 g.L-1). After plating, the plates were kept on a bench under a 16-hour photoperiod until the first isolated colonies grew. To prepare the extract, 2.5% w/v of dried and crushed L. minor was added to distilled water, which was kept boiling for 15 minutes. Tests showed that the medium enriched with 1% and 2% Lemna minor was more nutritious for Chlorella sp. compared to the adapted BBM medium. Macronutrient analyses of the 2.5% Lemna minor extract show that this macrophyte has a high nutritional content, largely due to its ability to absorb large quantities of nutrients present in the culture medium. However, further academic research is needed on the use of this macrophyte as a nutrient source for other microorganisms and on other potential nutrient suppliers for new alternative media formulations. The study also demonstrated that the cryopreservation of Chlorella sp. At -80°C using 10% glycerol as a cryoprotectant, it is viable for short to medium term storage (up to 42 days), maintaining cell viability and recovery capacity after thawing.