Variations in structure and saccharification efficiency of biomass of different sorghum varieties subjected to aqueous ammonia and glycerol pretreatments

Abstract

Sorghum biomass is a potential feedstock for lignocellulosic bioethanol production. The selection of suitable sorghum variety is essential to obtain high ethanol yield. In this paper we screened sorghum varieties belonging to sweet sorghum, post rainy sorghum, and hybrid sorghum. These varieties were screened based on their agronomic traits, amenability to pretreatment methods, and enzymatic digestibility. The sorghum biomass was pretreated using glycerol (60 %) at 190 ̊C for 60 min and aqueous ammonia (15 %) at 120 ̊C for 60 min. The digestibility of the pretreated biomass was determined using commercial cellulase (Cellic CTec2) at 10U/g loading, and the structural changes in the pretreated biomass were analyzed by spectroscopy and scanning electron microscopy. Sweet sorghum varieties showed significant variations in phenotypic traits such as fresh stalk yield, dry fodder yield, and juice yield. The cellulose digestibility among the sorghum varieties after the pretreatment also differed significantly. The cellulose digestibility levels of glycerol range from 64 % to 89 % and ammonia pretreated sorghum from 63 % to 81 %. The total sugar yields varied from 227 mg/g to 356 mg/g and 209 mg/g to 313 mg/g for sorghum pretreated with ammonia and glycerol, respectively. Although the delignification of sorghum varieties was higher (31%-65%) after ammonia pretreatment than glycerol pretreatment, the cellulose digestibility was higher for the glycerol pretreated biomass. These results indicated that effect of delignification on cellulose digestibility is trivial. This study explores factors affecting pretreatment and cellulose digestibility of sorghum varieties for maximum sugar yield in the cellulosic ethanol process.

Succession changes of fermentation parameters, nutrient components and bacterial community of sorghum stalk silage

“…Sorghum is one kind of gramineous annual herb C4 plant, characterized as great resistance of drought, waterlogging, soil salinity and acidity, infertility, and commonly distributed in tropical, subtropical and temperate regions ( Ibeto et al, 2011 ; Joy et al, 2021 ). Nowadays, sorghum grows as one of top five cereal crops with an annually global planting area and yield of 40 million hectares and 59 million tons, and China is one of the main sorghum producers (∼3.6 million tons per year) and consumers with an annual consumption around 8.4 million tons in 2020 ( FAOSTAT, 2022 ).…”

Characteristic comparison of lignocellulose nanofibrils from wheat straw having different mechanical pretreatments

“…In contrast, the hemicellulose of LCNF samples is removed more than cellulose and lignin content. It illustrates that the process of glycerol swelling, acid catalysis, and mechanical treatment would cause a mass removal of hemicellulose 34,40 . Notably, the hemicellulose and lignin content of S‐LCNFs is lower than C‐LCNFs and B‐LCNFs, while the cellulose content of S‐LC is higher than C‐LCNFs and B‐LCNFs.…”

“…It illustrates that the process of glycerol swelling, acid catalysis, and mechanical treatment would cause a mass removal of hemicellulose. 34,40 Notably, the hemicellulose and lignin content of S-LCNFs is lower than C-LCNFs and B-LCNFs, while the cellulose content of S-LC is higher than C-LCNFs and B-LCNFs. These results further prove the disintegration of the cell wall and high-efficient fibrillation of samples by screw extrusion combined with glycerol swelling, acid catalysis, and mechanical milling.…”

Comparative study of single stage and two-stage pretreatments on corn stover: A kinetic assessment

“…In order to improve the efficient utilization of corn stover by microorganisms, disruption of the cellulose and hemicellulose polymeric chains into monosaccharides via pretreatment is needed. Former researchers have investigated many pretreatment methods, such as dilute acid (Mafe et al 2015;Zang et al 2015;Saha et al 2016;Sivagurunathan et al 2017;Morais et al 2020), alkali (Nargotra et al 2018;Yang et al 2019), steam explosion (Kataria et al 2016;Theuretzbacher et al 2016), ammonia (Sakuragi et al 2017;Joy et al 2020), enzymatic pretreatment (Yeo-Myeong et al 2014;Bhushan et al 2021), and other methods (Zakaria et al 2015;Zhang et al 2016;Fu et al 2021;Rana and Prajapati 2021;Yiin et al 2021). However, these pretreatments still have several problems, such as low efficiency, high cost, and environmental pollution (Liu et al 2009).…”