For the first time, Polyporus brumalis BRFM985 was cultivated on wheat straw to investigate the simultaneous effects of pretreatment parameters on anaerobic digestion: these include initial substrate humidity, temperature, duration, and metal supplementation. Surface response methodology was applied to quantify the importance of each parameter, as well as the synergistic effects between them. Firstly, metal addition and secondly, pretreatment duration, both resulted in a positive impact. According to calculations, the highest methane production (182 dm(3) of methane per kilogram of initial Total Solids) is associated to pretreatment with metal addition during 20 days. In comparison with the least optimal conditions (118 dm(3).kg(-1) without metal addition, during 15 days), this result implies a 52% increase.