Fed batch enzymatic saccharification of newspaper cellulosics improves the sugar content in the hydrolysates and eventually the ethanol fermentation by Saccharomyces cerevisiae
Introduction
Presently most of the bioethanol is produced using corn kernel or sugarcane molasses but lignocellulosics, the second generation biofuel substrate and the least explored renewable resource is yet to be tapped. Lignocellulosics are the most abundant biomass available on earth, comprising mainly of cellulose and hemicellulose [1], [2]. Among various lignocellulosics, the recycled books, magazines and newspaper could have value addition via deinking and reuse of fiber either in manufacturing of new paper or in ethanol production.
An efficient conversion of newspaper to ethanol depends mainly on the extent of carbohydrate saccharification, however, the enzymatic conversion of newspaper is majorly hindered by toner’s ink, which forms a physical barrier, restricting the hydrolysable sites as well as release fermentation inhibitory heavy metal ions [3], [4]. Among various enzymes tested to deink the newspaper pulp [5], only cellulases were found to be the most effective [6]. The deinked paper pulp can be saccharified using either acid [7], [8] or enzymes [9], [10], [11], however, enzymes are preferred over acid because enzymatic hydrolysates are free from any fermentation inhibitory products. The enzymes such as cellulases have been found to be the most effective for this purpose [12]. It is well known that combined action of cellulase and hemicellulase results in a higher sugar production as compared to cellulase alone [13]. Despite the high extent of saccharification efficiency, the lower substrate consistency in the enzymatic suspension resulted into lower sugar concentration during the enzymatic hydrolysis. Raising the substrate concentration in batch hydrolysis helps to obtain higher sugar concentration, but also causes mixing and heat transfer problem due to rheological properties of dense fibrous suspension [14]. While in fed batch hydrolysis, such problem could be avoided by adding the substrate gradually to maintain the low level of viscosity [15]. In the present study, the optimization of enzymatic saccharification using both cellulase and xylanase was carried out to improve the hydrolysis of the newspaper. In order to increase the sugar concentration in enzymatic hydrolysate, the fed batch enzymatic hydrolysis of deinked newspaper was carried out. Thereafter, the enzymatic hydrolysates comprising both the hexose and pentose sugars were fermented to ethanol using Saccharomyces cerevisiae.
Section snippets
Raw material and chemicals
The newspaper procured locally was shredded mechanically into small pieces and the processed substrate was dried in an oven at 80 °C until constant weight was obtained.
Commercial cellulase from Trichoderma reesei (ATCC 26921), β-glucosidase from Aspergillus niger (Novozyme 188), xylanase from Thermomyces languinosus, 1-hydroxylbenzotriazole (HOBT) and 3,5-di nitro salicylic acid (DNS) were purchased from Sigma (St. Louis, Missouri, U.S.A.). Ethanol was purchased from Merck (Darmstadt, Germany).
Compositional analysis of newspaper
Newspaper was found to contain (w w−1), α-cellulose (51.0%), pentosans (19.0%), lignin (16.0%), moisture (8.0%) and ash (2.0%). The high carbohydrate content (holocellulose, 70.0% w w−1) in the newspaper made it a substrate of choice for bioethanol production. The results obtained here were similar to earlier studies, where lignin, holocellulose and moisture content in newspaper were found to be 16–22%, 60–75% and 7–10%, respectively [7], [8].
Deinking of newspaper cellulosics
The dyes fixed on the repeating units of cellulose
Conclusion
The reuse of newspaper for the production of bioethanol seems feasible approach for energy conservation and waste minimization. The fed batch enzymatic hydrolysis of newspaper cellulosics improved the release of sugars (pentose and hexose) and subsequently the ethanol yield. However, the yeast did not utilized pentose sugars from the hydrolysates and non-utilization of pentose sugars limits the economization of ethanol production from cellulosics. Therefore, in order to improve the ethanol
Acknowledgement
The authors are thankful to Dr. Y. P. Khasa for his help during the preparation of this manuscript. The financial support from University of Delhi, Delhi, India is highly acknowledged.
References (39)
- et al.
Enzymatic deinking of laser printed office waste papers: some governing parameters on deinking efficiency
Bioresour Technol
(2007) - et al.
Modeling of countercurrent shrinking-bed reactor in dilute-acid hydrolysis of lignocellulosic biomass
Bioresour Technol
(2000) Biological conversion of lignocellulosic biomass to ethanol
J Biotechnol
(1997)- et al.
Enzymatic saccharification of wheat straw for bioethanol production by a combined cellulase, xylanase and feruloyl esterase treatment
Enz Microb Technol
(2006) - et al.
A comparison between batch and fed batch simultaneous saccharification and fermentation of straw pretreated spruce
Enz Microb Technol
(2005) - et al.
Enzymatic hydrolysis of corncob and ethanol production from cellulosic hydrolysate
Int J Biodet Biodeg
(2007) - et al.
Separate hydrolysis and fermentation (SHF) of Prosopis juliflora, a woody substrate, for the production of cellulosic ethanol by Saccharomyces cerevisiae and Pichia stipitis-NCIM 3498
Bioresour Technol
(2009) - et al.
Cost-effective xylanase production from free and immobilized Bacillus pumilus strain MK001 and its application in saccharification of Prosopis juliflora
Biochem Engg J
(2008) - et al.
Effect of amino acids and vitamins on laccase production by the birds nest fungus Cyathus bulleri
Bioresour Technol
(2002) - et al.
Structural changes in lignin during the deinking of old newsprint with lacase-violuric acid system
Enz Microb Technol
(2006)
Biodeinking of mixed office waste paper by alkaline active cellulase from alkalotolerant Fusarium sp
Enz Microb Technol
Enzymatic upgrade of old paperboard containers
Enz Microb Technol
Effect of endoglucanases and hemicellulases in magnetic and flotation deinking of xerographic and laser-printed papers
J Biotechnol
Conversion of recycled paper sludge to ethanol by SHF and SSF using Pichia stipitis
Biomass Bioenergy
Mechanism of surfactant effect in enzymatic hydrolysis of lignocellulose
Enz Microb Technol
Purification and Characterization of a bifunctional enzyme with chitosanase and cellulase activity from commercial cellulase
Biochem Engg J
Fermentation of lignocellulose hydrolysate with yeasts and xylose isomerase
Enz Microb Technol
How did Saccharomyces evolve to become a good brewer?
Trends Genet
Microorganisms and enzyme involved in the degradation of plant fiber cell wall
Adv Biochem Engg Biotechnol
Cited by (102)
Pretreatment and acid hydrolysis of Omani Prosopis Juliflora wood
2023, Journal of King Saud University - Engineering SciencesCitation Excerpt :All the efforts were directed towards producing biofuel from non-edible plants, waste biomass especially when the latter is considered as an environmental burden. Therefore, utilization of plant waste such as seaweed wastes (Ge et al., 2011), sago waste (Lee et al., 2014), whatmann filter paper (Hubbell and Ragauskas, 2010), sugarcane bagasse (Asem et al., 2021), Pentose Sugar (Kuhad et al., 2011), Lantana Camara (Kuhad et al., 2010), newspaper cellulose (Chander Kuhad et al., 2010), Wheat bran (Kumar et al., 2012; (Tsegaye et al., 2019), cassava (Awoyale and Lokhat, 2019), rice husk (Nwakaire et al., 2013), napiegrass (Yasuda et al., 2014) would be a promising approach. Prosopis juliflora is one of the fast growing trees that may have the potential for bioethanol production (Chander Kuhad et al., 2010; Kumar et al., 2012; Tsegaye et al., 2019; Awoyale and Lokhat, 2019).
The role of microbes and enzymes for bioelectricity generation: a belief toward global sustainability
2023, Biotechnology of Microbial Enzymes: Production, Biocatalysis, and Industrial Applications, Second EditionA comprehensive review on strategic study of cellulase producing marine actinobacteria for biofuel applications
2022, Environmental ResearchSustainability of biomass-based insulation materials in buildings: Current status in France, end-of-life projections and energy recovery potentials
2022, Renewable and Sustainable Energy ReviewsImproved enzymatic hydrolysis of lignocellulosic waste biomass: most essential stage to develop cost-effective second-generation biofuel production
2022, Biofuels and Bioenergy: A Techno-Economic ApproachFungal lignocellulolytic enzymes and lignocellulose: A critical review on their contribution to multiproduct biorefinery and global biofuel research
2021, International Journal of Biological Macromolecules