Biosurfactants are an alternative to petrochemical derivatives, and filamentous fungi are a promising source of these molecules. This work identified 33 strains of filamentous fungi in agroindustrial wastes. This is important because these results open the opportunity of finding new biosurfactants (hydrophobins) with unique properties. We propose the evaluation of surface tension in the supernatant as a quantitative screening to determine the production of biosurfactants from the strains of fungi.