Fig. 4. Degradation of lignocellulose by a microbe community producing cellulolytic and lignolytic enzymes (scenario 2).

Cellulose is initially embedded in lignin and not accessible to its enzymes. a Distribution of polymerization, noted p, in the pools of inaccessible cellulose (left), cellulose accessible to cellulolytic enzymes (center), lignin accessible to lignolytic enzymes (right). Domains of substrate accessibility to enzymes are in blue, domains of substrate accessibility to microbial uptake are in red. The black arrow between inaccessible and accessible cellulose highlights the transfer of C between the two cellulose pools. Inaccessible cellulose is progressively transferred in the accessible pool without alteration of its polymerization. The transfer is directly related to lignin depolymerization and the associated degradation of the physical barrier. b Residual amount of C in the different pools over time. The lignolytic activity induces a quick disentanglement of the cellulose from the lignocellulosic complex (from orange to green), which makes polymerized cellulose accessible to its enzymes. Depolymerized cellulose and lignin are taken up by microbes. A Supplementary Movie illustrates this scenario.