Solid state fermentation (SSF) is an alternative to submerged cultures, because it is possible to achieve high specific productivity and to apply low-cost substrates such as corncobs, wheat bran and sugarcane bagasse.

The objective of this work was to compare the production of cellulases in different substrates: wheat bran, sugarcane bagasse, and mixtures of both supplemented with either corn steep liquor (3% w/v) and yeast extract (1% w/v) or salt solution. Fermentations were perfomed by Trichoderma reesei RUT C30 in erlenmeyers flasks, and a packed-bed column, 0.3 L capacity, at 30°C. Medium had initial moisture of 60% (wet basis), was inoculated with 10⁷ spores.gdm^-1. Enzyme extraction was performed with 20 mL of a 1:1 mixture of water and citrate buffer (pH 4.8) per g of fermented medium (wet basis). FPase and CMCase activities were estimated (Table 1).

Table  SEQ Table \* ARABIC 1: Activities observed for different substrates

The highest activity was observed in the supplemented wheat bran medium (3.4 U/gdm FPase). Different culture conditions have shown that the supplementation of the medium led to a 10% increase in FPase production, in relation to the pure wheat bran culture. Addition of salts retained the FPase rate, but significantly reduced CMCase production. Mixtures of bagasse and wheat bran showed a steadier production curve than pure bagasse medium (Graph 1), resulting in about 40% higher final FPase production.

Graph 1