Sunday, April 29, 2007

Bleach boosting effects of microbial xylanases on organosolv sugarcane straw pulp

Regina Yanako Moriya1, Adilson Roberto Gonçalves2, and Adriane Milagres1. (1) Biotechnology, Escola de Engenharia de Lorena EEL/USP, Estrada Municipal do Campinho, s/n, Lorena, 12600-970, Brazil, (2) Biotechnology, Escola de Engenharia de Lorena, Universidade de São Paulo, Estrada Municipal do Campinho, s/n, Lorena, 12600-970, Brazil

Agricultural wastes can be used to produce pulp and paper.  Sugarcane straw pulps were obtained through  organosolv pulping process. Xylanase pretreatment has been reported to lower bleaching chemical consumption and to result in a higher final pulp brightness. Three different microbial xylanases were evaluated for prebleaching of acetosolv sugarcane straw pulp. Sugarcane straw pulps were treated with Bacillus pumilus, recombinant Humicola grisea var. thermoidea and Thermoascus aurantiacus xylanases with varied enzyme dosage 1 to 150 IU/g  for 2 h at 50ºC. The Humicola grisea xylanase, used at 1 IU/g, enhanced viscosity of the pulp by 1 cP over control pulp after alkaline extraction, indicating the high enzyme efficiency at low dosages. Acetosolv sugarcane straw pulps treated with 50 IU/g xylanase from Bacillus pumilus followed by alkaline extraction, increased the viscosity by 1.5 cP and only enzymatic treatment with 10 IU/g decreased the kappa number by 4 points over control pulp. 10 IU/g xylanase from Thermoascus aurantiacus  decreased kappa number by 10 points (17% decresead compared with the pulp original) and the pulp treated with xylanase followed by alkaline extraction presented kappa number 29 (26% decresed kappa number over control pulp). Bacillus pumilus xylanase increased the viscosity of the acetosolv sugarcane straw pulp and the Thermoascus aurantiacus xylanase decresed de kappa number of the pulp.

Acknowledgements: CNPq, FAPESP and CAPES: Brazilian agencies