Trichoderma reesei LM-UC4 was co-cultured with Aspergillus phoenicis QM329 for cellulolytic enzyme production by mixed culture solid substrate fermentation of sugar cane bagasse, supplemented either with ammonium sulfate and urea or with soybean meal. Soybean meal increased biomass production and enzyme production in single cultures, but only biomass production in mixed cultures. Mixed cultures, however produced similar enzyme activities on the cheaper ammonium sulfate supplemented bagasse to those of single cultures on the more expensive soymeal supplemented bagasse. Mixed culturing apparently may overcome nutrient limitation of the substrate.