Abstract
Sunn hemp as a non-woody fiber crop was selected to determine the effect of ultrasound-assisted alkali pretreatment on enzymatic hydrolysis. We hypothesized that ultrasound-assisted alkali pretreatment (US-NaOH) was more efficient than alkali pretreatment alone; maximum fermentable sugars were released in US-NaOH-pretreated biomass by enzymatic hydrolysis. In this study, sunn hemp was pretreated with NaOH and US-NaOH at 121 °C. A higher cellulose content of 67% was obtained in US-NaOH-pretreated biomass (1% NaOH, 10-min sonication, 121 °C) as compared with that of the alkali-pretreated biomass. After ultrasound-assisted alkaline pretreatment, the crystallinity index of cellulose and the solubilization of pentose and lignin increased from 39 to 53%, leading to a significant increase in enzyme accessibility to cellulose to release reducing sugars. Scanning electron microscopy showed that the biomass underwent erosion after ultrasound pretreatment. Response surface methodology was chosen to study the individual effects of variables on enzymatic hydrolysis and their inter-dependence. The quantity of reducing sugars released was optimized using a response surface methodology, and the experimental results with optimized process variables gave 5.17 mg/mL glucose and 2.08 mg/mL xylose.
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Abbreviations
- US-NaOH:
-
Ultrasound-assisted alkaline pretreatment
- NaOH:
-
Sodium hydroxide
- XRD:
-
X-ray diffraction
- SEM:
-
Scanning electron microscope
- NDF:
-
Neutral detergent fiber
- ADF:
-
Acid detergent fiber
- ADL:
-
Acid detergent lignin
- HPLC:
-
High-performance liquid chromatography
- DNS:
-
3,5-Dinitrosalicylic acid
- CrI:
-
Crystallinity index
- ANOVA:
-
Analysis of variance
References
Agbor VB, Cicek N, Sparling R, Berlin A, Levin DB (2011) Biomass pretreatment: fundamentals toward application. Biotechnol Adv 29(6):675–685
Villa-Vélez HA, Váquiro HA, Telis-Romero J (2015) The effect of power-ultrasound on the pretreatment of acidified aqueous solutions of banana flower-stalk: structural, chemical and statistical analysis. Ind Crop Prod 66:52–61
Rehman MSU, Kim I, Chisti Y, Han JI (2013) Use of ultrasound in the production of bioethanol from lignocellulosic biomass. Energy Educ Sci Technol A: Energy Sci Res 30(2):1391–1410
Yunus R, Salleh SF, Abdullah N, Biak DRA (2010) Effect of ultrasonic pre-treatment on low temperature acid hydrolysis of oil palm empty fruit bunch. Bioresour Technol 101(24):9792–9796
Subhedar PB, Ray P, Gogate PR (2018) Intensification of delignification and subsequent hydrolysis for the fermentable sugar production from lignocellulosic biomass using ultrasonic irradiation. Ultrason Sonochem 40:140–150
Velmurugan R, Muthukumar K (2012) Ultrasound-assisted alkaline pretreatment of sugarcane bagasse for fermentable sugar production: optimization through response surface methodology. Bioresour Technol 112:293–299
Nakashima K, Ebi Y, Kubo M, Shibasaki-Kitakawa N, Yonemoto T (2016) Pretreatment combining ultrasound and sodium percarbonate under mild conditions for efficient degradation of corn stover. Ultrason Sonochem 29:455–460
Singh S, Bharadwaja S, Yadav PK, Moholkar VS, Goyal A (2014) Mechanistic investigation in ultrasound-assisted (alkaline) delignification of Parthenium hysterophorus biomass. Ind Eng Chem Res 53(37):14241–14252
Dinh Vu N, Thi Tran H, Bui ND, Duc Vu C, Viet Nguyen H (2017) Lignin and cellulose extraction from Vietnam’s rice straw using ultrasound-assisted alkaline treatment method. International Journal of Polymer Science 2017:8. https://doi.org/10.1155/2017/1063695
de Oliveira Vargas T, Diniz ER, Pacheco ALV, Santos RHS, Urquiaga S (2017) Green manure-15N absorbed by broccoli and zucchini in sequential cropping. Sci Hortic 214:209–213
Online article by United States Department of Agriculture, AgResearch magazine (2012). https://agresearchmag.ars.usda.gov/2012/jan/crop
Natural Resources Conservation Service (1999) Sunn hemp: a cover crop for southern and tropical farming systems. Soil Qual. Instit Tech. Note 10 [Online]. Available at http://soils.usda.gov/sqi/files/10d3.pdf. (accessed 23 June 2004; verified 4 Oct. 2004). USDA NRCS, Soil Quality Inst., Auburn, AL
Cantrell KB, Bauer PJ, Ro KS (2010) Utilization of summer legumes as bioenergy feedstocks. Biomass Bioenergy 34(12):1961–1967
Kamireddy SR, Li J, Abbina S, Berti M, Tucker M, Ji Y (2013) Converting forage sorghum and sunn hemp into biofuels through dilute acid pretreatment. Ind Crop Prod 49:598–609
Kalyani D, Lee K-M, Kim T-S, Li J, Dhiman SS, Kang YC, Lee J-K (2013) Microbial consortia for saccharification of woody biomass and ethanol fermentation. Fuel 107:815–822
Sindhu R, Kuttiraja M, Preeti VE, Vani S, Sukumaran RK, Binod P (2013) A novel surfactant-assisted ultrasound pretreatment of sugarcane tops for improved enzymatic release of sugars. Bioresour Technol 135:67–72
Goering HK (1970) Forage fiber analysis. Apparatus, reagents, procedures and some applications. Agric handbook 379:20
Segal L, Creely J, Martin A Jr, Conrad C (1959) An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer. Text Res J 29(10):786–794
Ninomiya K, Kamide K, Takahashi K, Shimizu N (2012) Enhanced enzymatic saccharification of kenaf powder after ultrasonic pretreatment in ionic liquids at room temperature. Bioresour Technol 103(1):259–265
De Lima CJ, Coelho LF, Contiero J (2010) The use of response surface methodology in optimization of lactic acid production: focus on medium supplementation, temperature and pH control. Food Technol Biotechnol 48(2):175–181
Asghar U, Irfan M, Iram M, Huma Z, Nelofer R, Nadeem M, Syed Q (2015) Effect of alkaline pretreatment on delignification of wheat straw. Nat Prod Res 29(2):125–131
Zhang J, Zhang H, Zhang J (2014) Effect of alkali treatment on the quality of hemp fiber. Journal of Engineered Fibers and Fabrics 9(2):19–24
Pakarinen A, Zhang J, Brock T, Maijala P, Viikari L (2012) Enzymatic accessibility of fiber hemp is enhanced by enzymatic or chemical removal of pectin. Bioresour Technol 107:275–281
Zhang Y, Fu E, Liang J (2008) Effect of ultrasonic waves on the saccharification processes of lignocellulose. Chem Eng Technol 31(10):1510–1515
Zhu S, Huang W, Huang W, Wang K, Chen Q, Wu Y (2015) Coproduction of xylose, lignosulfonate and ethanol from wheat straw. Bioresour Technol 185:234–239
Sindhu R, Binod P, Pandey A (2016) Biological pretreatment of lignocellulosic biomass—an overview. Bioresour Technol 199:76–82
Zhao XB, Wang L, Liu DH (2008) Peracetic acid pretreatment of sugarcane bagasse for enzymatic hydrolysis: a continued work. J Chem Technol Biotechnol 83(6):950–956
Subhedar PB, Gogate PR (2014) Alkaline and ultrasound assisted alkaline pretreatment for intensification of delignification process from sustainable raw-material. Ultrason Sonochem 21(1):216–225
Chen D, Guo Y, Huang R, Lu Q, Huang J (2010) Pretreatment by ultra-high pressure explosion with homogenizer facilitates cellulase digestion of sugarcane bagasses. Bioresour Technol 101(14):5592–5600
Eblaghi M, Niakousari M, Sarshar M, Mesbahi GR (2016) Combining ultrasound with mild alkaline solutions as an effective pretreatment to boost the release of sugar trapped in sugarcane bagasse for bioethanol production. J Food Process Eng 39(3):273–282
Wang S, Li F, Zhang P, Jin S, Tao X, Tang X, Ye J, Nabi M, Wang H (2017) Ultrasound assisted alkaline pretreatment to enhance enzymatic saccharification of grass clipping. Energy Convers Manag 149:409–415
Li F, Zhang P, Zhang G, Tang X, Wang S, Jin S (2017) Enhancement of corn stover hydrolysis with rumen fluid pretreatment at different solid contents: effect, structural changes and enzymes participation. Int Biodeterior Biodegrad 119:405–412
Zakaria B, Nassar H, Amr SA, El-Gendy NS (2015) Applying factorial design and response surface methodology to enhance microbial denitrogenation by Tween 80 and yeast extract. Pet Sci Technol 33(8):880–892
Preetha B, Viruthagiri T (2007) Application of response surface methodology for the biosorption of copper using Rhizopus arrhizus. J Hazard Mater 143(1):506–510
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The authors acknowledge the support provided by the Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, India.
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P, M., Saroj, P. & Korrapati, N. Ultrasound-assisted alkaline pretreatment to intensify enzymatic saccharification of Crotalaria juncea using a statistical method. Biomass Conv. Bioref. 8, 659–668 (2018). https://doi.org/10.1007/s13399-018-0324-8
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DOI: https://doi.org/10.1007/s13399-018-0324-8