Efeitos ecotóxicos do biossurfactante produzido por Rhodotorula mucilaginosa em espécie de cladócero de água doce

Abstract

Biosurfactants are one of the main classes of metabolites produced by microorganisms, with high surface and emulsifying activity, low toxicity, and good environmental compatibility, and are applied in various segments such as industrial and oil sectors, for bioremediation of oil spillage. Therefore, there’s a rising interest in the industrial production of biosurfactants due to their advantages over the production of chemical surfactants. Biosurfactants make the use of renewable substrates possible, such as agro-industrial waste and by-products, generating lower production costs. These biomolecules are biodegradable and less toxic than their synthetic counterparts, but there is still a need of being studied in terms of their environmental toxicity. Hence, the aim of the present study was to assess the ecotoxicity of the biosurfactant produced by the yeast Rhodotorula mucilaginosa, isolated from Antarctic seaweed, on the model organism Daphnia magna. The biomolecule was produced by submerged fermentation of the yeast using pineapple (Ananas comosus) waste as the carbon source. The cold acetone method was used to extract the biomolecule. The compound demonstrated a total concentration of 30 g/L, which was verified applying a gravimetric method. The in vivo ecotoxic effects of five different concentrations of the extracted biomolecule were assessed (15 g/L, 10 g/L, 7,5 g/L, 5 g/L e 3,75 g/L). The immobilization rate and abnormal behavior of neonate daphnids were observed after 24 hours and 48 hours. The concentration equivalent to the Maximal Concentration Effect at 50% (EC50) obtained after 24 hours was 6 g/L while the value obtained after 48 hours was 2 g/L. These data suggest the low environmental toxicity of the compound studied.