Fig. 6. The differentiation of lobed structures in mycelium from CBEL⁺ and CBEL^- P.p.n. strains in contact with cellulosic substrates. The mycelium was grown on a cellophane membrane (A,B) or on flax cellulose fibres dispersed onto a cellophane membrane (C,D) placed on top of V-8 agar medium. After 7 days of culture, the cellophane sheet was removed from the medium underneath and processed for scanning electron microscopy. (A,C) Aggregates of intricate ramified hyphae (arrows) were observed in the EX11-1 CBEL⁺ strain grown on cellophane or flax fibres. (B,D) The EX11-4 CBEL^- strain formed only smooth hyphae that rarely branched on either substrate. Asterisks indicate the flax cellulose fibres. Bars, 40 µm.