title: Relatively high-substrate consistency hydrolysis of steam-pretreated sweet sorghum bagasse at relatively low cellulase loading.
abstract: Sweet sorghum bagasse (SSB) was steam pretreated in the conditions of 190 °C for 5 min to assess its amenability to the pretreatment and enzymatic hydrolysis. Results showed that pretreatment conditions were robust enough to pretreat SSB with maximum of 87% glucan and 72% xylan recovery. Subsequent enzymatic hydrolysis showed that the pretreated SSB at 2% substrate consistency resulted in maximum of 70% glucan-glucose conversion. Increasing substrate consistency from 2% to 16% led to a significant reduction in glucan conversion. However, the decrease ratio of glucan-glucose conversion was the minimum when the consistency increased from 2% to 12%. When the pretreated SSB consistency of 12% was applied for hydrolysis, increase in cellulase loading from 7.5 up to 20 filter paper units (FPU)/g glucan resulted only in 14% increase in glucan-glucose conversion compared to 20% increase with cellulase loading varying from 2.5 to 7.5 FPU/g glucan. More than 10 cellobiase units (CBU)/g glucan β-glucosidase supplementation had no noticeable improvement on glucan-glucose conversion. Additionally, supplementation of xylanase was found to significantly increase glucan-glucose conversion from 50% to 80% with the substrate consistency of 12%, when the cellulase and β-glucosidase loadings were at relatively low enzyme loadings (7.5 FPU/g and 10 CBU/g glucan). It appeared that residual xylan played a critical role in hindering the ease of hydrolysis of SSB. A proper xylanase addition was suggested to achieve a high hydrolysis yield at relatively high substrate consistency with relatively low enzyme loadings.
authors: College of Resource and Environment, Sichuan Agricultural University, Chengdu Campus, 211 Huimin Road, Chengdu, 611130 Sichuan, China. fishensjtu@gmail.com
authors: Fei
authors: F
authors: Shen
authors: Yuehua
authors: Y
authors: Zhong
authors: Jack N
authors: JN
authors: Saddler
authors: Ronghou
authors: R
authors: Liu
mesh_terms: D001709:Biotechnology / Q000379:methods*; D001711:Biotransformation; D002480:Cellulase / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism; D005936:Glucans / Q000378:metabolism*; D005947:Glucose / Q000096:biosynthesis*; D006868:Hydrolysis; D045868:Sorghum / Q000378:metabolism*; D013227:Steam; D013458:Sulfur Dioxide / Q000378:metabolism; D014990:Xylans / Q000378:metabolism*; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D005936:Glucans; D013227:Steam; D014990:Xylans; D013458:Sulfur Dioxide; D002482:Cellulose; C027433:bagasse; D001617:beta-Glucosidase; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases; D005947:Glucose