On-site produced and commercially available alkali-active xylanases compared for xylan extraction from sugarcane bagasse

• Published in: Biocatalysis and agricultural biotechnology Vol. 18; p. 101081
• Main Authors: Santos, Maiara P., Reinoso, Felipe A.M., Távilla, Verônica, Ferraz, André, Milagres, Adriane M.F.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2019
• Subjects: Bacillus pumilus; Luminase; Sugarcane bagasse; Xylan extraction; Xylanase; Xylooligosaccharides; Bacillus pumilus; Xylan extraction; Xylanase; Xylooligosaccharides; Luminase; Sugarcane bagasse
• ISSN: 1878-8181; 1878-8181
• DOI: 10.1016/j.bcab.2019.101081

The purpose of this work was to investigate the enzymatic extraction of xylan using xylanases active in alkaline conditions. One on-site produced and three commercial xylanases designed to boost bleaching of pulped wood were characterized for their optimal pH, temperature and stability to compare their effects on xylan extraction from pretreated sugarcane bagasse. On-site produced xylanase was prepared from cultures of the alkaliphilic Bacillus pumilus CBMAI 0008 strain. The optimal temperatures and pH levels for all commercial xylanases were 60 °C and 6, whereas for B. pumilus xylanase, they were 50 °C and 8, respectively. B. pumilus was active up to pH 10, but it had low thermal stability. Five sugarcane substrates were prepared to contain decreasing lignin content based on alkaline-sulfite pretreatment or acid-chlorite delignification. Xylanase doses (5–100 IU/g substrate) were applied to these substrates at pH 8.0, 50 °C and a 24-h reaction. Xylan extraction yields were strongly dependent on the lignin content of the substrates. Maximal xylan extraction yields were obtained in acid-chlorite delignified substrates, reaching values of 64% and 45% for Luminase and B. pumilus xylanases, respectively. Residual (non-extractable) xylans seemed occluded by and/or complexed with residual lignin of the substrates.