Alkaline peroxide pretreatment for efficient enzymatic saccharification of bamboo

Bamboo is an alternative feedstock for the production of fine chemicals, such as fuel ethanol and lactic acid, because bamboo has a large amount of sugars. An effective pretreatment method for enzyme saccharification is required for the efficient production of these materials. Enzyme saccharification (48 h) using a 35 atm and 5 min steam exploded bamboo produced 426 and 488 mg/(g initial dry sample) of glucose and reducing sugar, respectively. In addition, pretreatments using 20 atm and 5 min steam explosion or mechanical milling for 5 min followed by 10 wt.% sodium hydroxide treatment at 121 °C for 60 min were attempted in order to enhance the digestibility of the holocellulose component. Both of these pretreatment methods had a large positive effect on the production of sugars by subsequent enzymatic hydrolysis. In particular, the maximum value of glucose production was obtained by the 20 atm steam explosion and 10 wt.% sodium hydroxide treatment. This produced 456 mg/(g initial dry sample) of glucose and 460 mg/(g initial dry sample) of reducing sugar. In comparison, the mechanical milling and 10 wt.% sodium hydroxide treatment produced 383 and 485 mg/(g initial dry sample) of glucose and reducing sugar, respectively. From these results, it was concluded that the pretreatment with 20 atm steam explosion and 10 wt.% sodium hydroxide treatment was the most effective pretreatment method for the production of glucose from bamboo by enzyme saccharification. However, since this pretreatment method requires the severe conditions of both high pressure and temperature steam explosion and high concentration sodium hydroxide, an alkaline peroxide pretreatment without a steam explosion and high concentration sodium hydroxide was also attempted. A comparatively large amounts of glucose and reducing sugar production, i.e. 399 and 568 mg/(g initial dry sample), respectively, were obtained in 1%(v/v) hydrogen peroxide and 1 wt.% sodium hydroxide treatment at 90 °C for 60 min. Therefore, it was concluded that alkaline peroxide pretreatment is an effective and environmentally friendly method for the enzyme saccharification of bamboo.