The lack of degradability of polymeric materials has resulted in high levels of environmental contamination and numerous health hazards. The latest UN Environment 2018 report observed that the estimated annual consumption of plastics worldwide is 5 billion, where approximately 10 million are per minute. If this pattern continues, it is expected that by 2030 the planet will produce 619 million t of plastic per year, such as expanded polystyrene (United Nations Organization (UN); United Nations Environment Program, 2018). Different strategies have been developed to obtain biomaterials considering Pleurotus ostreatus as mycelium, adapting mixtures of substrates for its preparation. This work evaluates the methodology to obtain a biomaterial that replaces expanded polystyrene through mycelium using wheat bran and malt bran as substrates. An experimental design is proposed, observing that the best results corresponded to the mixture of 75 % malt bran and 25 % wheat bran obtained in 15 days of colonization at 30 °C. After this, the biodegradation was qualitatively by observing its partial decomposition for 48 h, evidencing the degradation of the size of the piece. These results promote the recovery of agro-industrial waste and the circular economy.