Twenty different strains of filamentous fungi were initially selected for evaluation of cellulolytic activity using a single test in a simple mineral salts culture medium with filter payer as the only carbon source. Those fungi strains that were capable of completely breaking the filter paper strip within 4-8 d were assayed also for antimicrobial action, using Staphyloccocus aureus ATCC 6538r according to the so-called agar piece method. We screened three different strains with both capacities: the production of cellulolytic activity and antibiotic action. The experimental results suggest that the fungi Penicillium sp. F0PC01, Asperigillus sp. F0Q001, and Cephalosporium sp. F03800 have both capabilities because they grew rapidly on cellulose as the only carbon source and were able to produce an area of growth inhibition in S. aureus of approx 2.04, 1.57, and 2.39 cm, respectively, on agar plates using the agar piece method. Subsequently, the antibiotic production obtained with those cellulolytic strains was evaluated by submerged fermentation at the flask level, in a simple culture medium containing lactose without biosynthesis precursor, obtaining 3670, 2830, and 4060 antibiotic units/mL, referred to as penicillin G, whereas for cellulolytic activity, the results were 1.34, 1.81 and 0.57 FrU/mL, respectively.