Evaluation of sugar cane hemicellulose hydrolyzate for cultivation of yeasts and filamentous fungi.

Sugar cane bagasse hemicellulosic fraction submitted to hydrolytic treatment with 100 mg of sulfuric acid per gram of dry mass, at 140 degrees C for 20 min, was employed as a substrate for microbial protein production. Among the 22 species of microorganisms evaluated, Candida tropicalis IZ 1824 showed TRS consumption rate of 89.8%, net cell mass of 11.8 g L-1 and yield coefficient (Yx/s) of 0.50 g g-1. The hydrolyzate supplemented with rice bran (20.0 g L-1), P2O5 (2.0 g L-1) and urea (2.0 g L-1) provided a TRS consumption rate of 86.3% and a cell mass of 8.4 g L-1. At pH 4.0 cellular metabolism was inhibited, whereas at pH 6.0 the highest yield was obtained. The presence of furfural (2.0 g L-1) hydroxymethylfurfural (0.08 g L-1) and acetic acid (3.7 g L-1) in the hydrolyzate did not interfere with cultivation at pH 6.0.