A rapid and complete colonization of lignocellulosic biomass by white-rot fungi is a prerequisite for an efficient and contamination free delignification. To improve the colonization, mycelium growth and delignification by Ceriporiopsis subvermispora and Lentinula edodes of wheat straw, with addition of 2, 4, 6 and 10% of wheat bran for 0, 2, 4, 8 and 12 weeks, was evaluated. The ergosterol content, chemical composition and in vitro gas production (IVGP) by ruminal microorganisms were determined. The fungal biomass and starch amount was significantly (P < 0.001) affected by the inclusion level of wheat bran and incubation time. An increase in added wheat bran increased the fungal biomass with different effects observed for the two fungi. The added starch from the wheat bran was degraded by C. subvermispora, mainly during the first two weeks (up to 44%), whereas, L. edodes degraded starch during 12 weeks up to 83%. The supplementation of wheat bran, however, did not affect (P > 0.05) the amount of hemicellulose and lignin at the end of the incubation. There was no significant effect of wheat bran addition on the IVGP for the two fungal treatments. Supplementation of wheat straw with wheat bran resulted in a quicker fungal colonization, which is useful for C. subvermispora, a fungus that forms only thin mycelium and is more prone to contamination than L. edodes.