3.1 Fungal strain

In order for the white-rot fungi to be used in the pretreatment process, screening of a large number of fungal isolates is important in order to have the right isolates for the process. Screening step allows the selection of isolates with the highest ligninolytic enzymes production and activity as well as high lignin degradation on the specific substrates. In order to limit matter losses, selective delignification is crucial and high fermentable sugar losses must be avoided. White-rot fungi strains should therefore be carefully selected based on these important parameters. Table 4 summarizes some of white-rot fungi species that have been studied for several lignocellulosic biomass pretreatment.

## 3.2 Inoculum concentration

Inoculum concentration is an important factor in biological pretreatment. Sufficient amounts of inoculum must be defined to ensure good fungal growth and substrate colonization. The time required for the colonization of the substrate is affected by the type and amount of inoculums [31]. Higher concentration of inoculum will lead to shorter time of colonization of the substrate [49].
