Avaliação da produção de amilase pela Galdieria sulphuraria

Abstract

Microalgae are microorganisms with biotechnological potential, offering various applications using their biomass, such as biodiesel production, pigments, and wastewater treatment. However, there are limitations to the use of these microorganisms, including low yield and difficulty in scaling up the process, which increases production costs and makes many microalgae-derived products less viable. Some strategies to reduce costs and make microalgae industrially feasible include the use of extremophile microorganisms that prevent contamination losses, exhibit greater resistance to scale-up, and produce more stable molecules. Among the extremophiles, the microalga Galdieria sulphuraria stands out as a potential candidate for industrial applications, generating products such as pigments and more stable enzymes. Among these enzymes, amylases are notable for their wide range of uses, including in bleaching, detergents, and bioremediation. However, extracellular and/or intracellular amylase production by G. sulphuraria has not been described in the literature. Therefore, the aim of this study is to identify the production and release of amylolytic enzymes and to determine the type of enzyme using a simple methodology based on the reaction between iodine and starch, which produces a color read in the UV-Vis spectrum. Two calibration curves were prepared: one for starch and another for reducing sugars. The enzymatic reaction was carried out using the supernatant from the cultures, followed by the addition of iodine and reading of starch degradation and sugar production using the DNS method. It was found that starch consumption by G. sulphuraria occurs, with an approximate 40% reduction in starch. Furthermore, it was observed that despite the acidic cultivation conditions, starch is minimally degraded, with the microalga being the main cause of the reduction. Despite promising preliminary results, it was not possible to identify significant enzymatic activity or the production of reducing sugars, which prevented the identification of the type of amylase. It is concluded that amylases are produced; however, it is believed that this enzyme is not released in the conventional manner (i.e., secreted). It is argued that the enzyme is released accidentally into the medium, due to cell lysis of the mother cell during the release of its endospores.