The first uranium mine that had its deposit explored in Brazil is located in the region of the Poços de Caldas Plateau (Minas Gerais) and currently, mining activities no longer take place there. Still, a serious environmental problem occurs at the site: acid mine drainage. An alternative to monitor such environments is through the analysis of the microalgae community, as this can provide information about species with biotechnological potential for remediation actions. In the present study, an analysis of the composition of the microalgae community found in the UDC/INB uranium mine pit (point CM) and in the Antas Reservoir (point 14) was carried out, and a comparison was made between these points in order to identify the present species that play important roles in the biotechnology area. The expected result was to find a much lower microalgae diversity in CM than in P14. However, the results were very similar: in both sampling sites, a taxonomically diverse microalgae flora was found, dominated by the Bacillariophyceae and Chlorophyceae classes. In addition, at both sites, microalgae were recorded which are widely used in biotechnological processes of environmental remediation, removal of contaminants from wastewater, production of biofuels, pigments, medicines, among others, showing that the use of microalgae for various purposes is a very promising and environmentally sustainable path.