2-22: Validation of a high through-put analysis for enzymatic hydrolysis of diluted acid pre-treated poplar for bio-ethanol production

The aim of this study was to validate a methodology for optimizing pretreatment conditions for bio-ethanol production using poplar (Populus Spp) as lignocellulosic raw material. The assays were carried out using small stirred reactors and high throughput enzymatic hydrolysis. Best conditions were afterward assayed at higher working volumes (up to 4 L) followed by a high consistency enzymatic hydrolysis (up to 20 % w/w).

Preliminary assays included poplar samples at a 10% (w/w) of solid to liquid ratio were subjected to two-step processes:

-Diluted acid hydrolysis pre-treatment in 50 ml stirred-reactors considering: acid concentration, time, pressure and temperature.

-High-throughput microplate enzymatic hydrolysis process (0.75 ml working volume). This methodology was validated through an enzymatic hydrolysis carried out with a shigher working volume (up to 100 ml) in erlenmeyer flasks.

Once the optimized conditions had been selected, the pretreatment step was carried out in a 4 L stirred- reactor at a solid to liquid ratio of 10% (w/w) followed by an enzymatic hydrolysis at 20 % w/w of solid content.

Inhibitors (furfural, HMF, organic acids) generated during the pretreatment step and Saccharification yields were measured by HPLC-RID technique.

This high throughput analysis methodology shows advantages against usual procedures carried out in erlenemeyers or in fermentors:

-Reduces the amount of raw material, working time and costs.

-Allows optimize among different parameters conditions both for the pretreatment step and for the enzymatic hydrolysis step.

-Able to use a solid to liquid ratio of 10% (w/w) along the whole process and useful for other lignocellulosic materials.