On the enzymatic hydrolysis of the corn cob for xylose production

This paper intends to introduce our newly developed method to make com cob release totally its xylose by enzymatic hydrolysis. For this purpose, we have adopted 4 pretreatment methods shown as follows: (1) Put the corn cob autoclaving at 120 ℃ for 2 h;(2) The steam explosion treatment is done at 1.01×10~6 Pa (dry powder) , at 2.02×10~6 Pa (dry powder mass:H_2O volume = 1 g:2 mL), and at 20 atm (dry powder:0.1 % sulfuric acid = 1 g:2 mL). Till now, all the pretreated corn cobs were incubated with different enzymes (4 IU/mg, taking xylanase as a standard) at 40 ℃ for 24 h and the xylose released at intervals can then be determined.The results of our experiments have shown that the maximum xylose yield was 33% , which was obtained with the steam explosion pretreatment at 1.01×10~6 Pa (dry powder) by Penicillium decumbens 6.Yet as the xylanase from Penicillium decumbens 6 had a low activity, a large amount of Penicillium decumbens 6 was needed.As for the autoclaving of the pretreated corn cob, the xylanase from Aspergillus niger 2107 has achieved the xylose yield of 19.5%.While the xylanase from Aspergillus niger 30197 showed a better hydrolysis result on the corn cobs after the steam explosion pretreatment than the autoclaving pretreatment, with the xylose yields going up to 26.7 % , 27.7 % , and 29.6% respectively to the steam explosion pretreatment at 1.01 ×10~6 Pa (dry power), at 2.02×10~6 Pa (dry powd er mass:H_2O volume = 1 g:2 mL), and at 2.02×10~6 Pa (dry powder mass:0.1% sulfuric acid volume = 1 g:2 mL).The hydrolysates were assayed by thin-layer chromatography and xylose was found to be the major end product.Investigations of enzyme components of different xylanases prove to account for their different hydrolysis results.