Abstract
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.
Highlights
The high cost of nutrient medium for the cultivation of recombinant Pichia pastoris in the production of recombinant proteins is a major factor that needs to be considered and optimized for large scale production (Yadav et al, 2011)
The EGs act on the amorphous regions of cellulose, and EGII is one of the most abundant EGs produced by T. reesei and has the highest catalytic efficiency (Qin et al, 2008; Zhang et al, 2012)
The aim of this study was to determine the suitability of crude glycerol, obtained as the by-product of biodiesel production, and soybean meal and rice bran as a substitute for high purity commercial glycerol, peptone and yeast extract, respectively, in the formation of a low cost culture medium for the growth of, and recombinant (r)EGII production by, P. pastoris
Summary
The high cost of nutrient medium for the cultivation of recombinant Pichia pastoris in the production of recombinant proteins is a major factor that needs to be considered and optimized for large scale production (Yadav et al, 2011). The development of a suitable culture medium using low cost raw materials is of interest. The growth and recombinant protein production level in recombinant P. pastoris depends on various conditions and on the composition of the culture medium (Batista et al, 2013). The improvement of individual cellulase enzymes from Trichoderma reesei has been attempted by genetic engineering in P. pastoris in order to enhance their cellulose degradation ability (Boonvitthya et al., 2013). Cellulases, which degrade cellulose, consist of endoglucanases (EGs), cellobiohydrolases and betaglucosidases. The EGs act on the amorphous regions of cellulose, and EGII is one of the most abundant EGs produced by T. reesei and has the highest catalytic efficiency (Qin et al, 2008; Zhang et al, 2012)
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