Low cost medium for recombinant endoglucanase II production by Pichia pastoris

The suitability of crude glycerol (75% (v/v) glycerol content) from a biodiesel production plant, and soybean meal and rice bran hydrolysates as replacements in the culture medium for commercially available glycerol, peptone and yeast extract, respectively, to form a low cost culture medium for the growth of, and recombinant endoglucanase II production by, Pichia pastoris was evaluated. The use of 1% (v/v) crude glycerol as a carbon source, and a mixture of 0.175% (v/v) soybean meal and 0.15% (v/v) rice bran hydrolysate in the presence of 0.5% (w/v) ammonium sulfate was found to be a suitable medium in the presence of 3% (v/v) methanol as the inducer. Under these conditions, the highest level of extracellular endoglucanase II activity (61.5 U/mL) was found after 120 h culture at 30°C and pH 6.0.  Key words: Biodiesel glycerol, soybean meal, rice bran, endoglucanase II, Pichia pastoris.