BMP assay medium (Wang et al., 1994) was used. Experiments were performed according to the procedure published by Wang et al. (1994) and were carried out in triplicate in 125 ml sterile glass serum bottles. 0.5 g of filter paper, as cellulosic substrate, or 0.5 g of mechanically treated paper paste (composition: 53% of holocellulose, 32% of lignin and 15% of others compounds), as lignocellulosic substrate, were introduced into bottles containing 45 ml of BMP medium, and 5 ml of inocula. Two inocula were compared. One consisted of only AMN107 sludge and the other was a mix 50:50 of anaerobic sludge and isolated cellulolytic consortium. pH was adjusted with a 0.5 M KOH solution to achieve an initial pH of 7.3 in each sample, and a maximum variation during the culture period of pH ± 1 was maintained. The sample bottles were capped tightly with rubber septa and sealed with aluminum seals. To generate the anaerobic conditions, headspace of bottles, tightly capped with rubber septa and sealed with aluminum caps, was flushed with carbon dioxide and with oxygen-free nitrogen gas in a second step. Bottles were incubated at 55 °C.