PROCESS OPTIMIZATION OF SIMULTANEOUS SACCHARIFICATION AND FERMENTATION SYSTEM FOR BIOETHANOL PRODUCTION FROM PEARL MILLET STALK

S. SRIRAMAJAYAM¹*, T. PADHI², D. RAMESH³, J. GITANJALI⁴, V. PALANISELVAM^5
1Department of Renewable Energy Engineering, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, 641003, India
²Department of Renewable Energy Engineering, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, 641003, India
³Department of Renewable Energy Engineering, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, 641003, India
⁴Department of Renewable Energy Engineering, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, 641003, India
⁵Agricultural College & Research Institute, Killikulam, Vallanadu, 628 252, Tamil Nadu Agricultural University, Coimbatore, 641003, Tamil Nadu, India
* Corresponding Author : ramajayam@gmail.com

Received : 02-06-2022     Accepted : 27-06-2022     Published : 30-06-2022
Volume : 14     Issue : 6       Pages : 11381 - 11385
Int J Agr Sci 14.6 (2022):11381-11385

Keywords : Bioethanol, Pearl millet stalk, S.cerevisiae, Pretreatment, Simultaneous Saccharification and Fermentation
Academic Editor : Dr D. S. Perke
Conflict of Interest : None declared
Acknowledgements/Funding : Authors are thankful to Department of Renewable Energy Engineering, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, 641003, Tamil Nadu, India
Author Contribution : All authors equally contributed

Bioethanol can be produced from sugar and starch crops, but lignocellulosic biomass can also be utilized for bioethanol production. The physicochemical analysis pearl millet stalk was carried out. Pretreatment process optimization of the selected biomass was done with 7.5, 10 and 12.5 % of total solid loadings for all the biomass with the ortho-phosphoric acid concentration of 5, 7.5 and 10 % at 100?C and 121?C for 1, 2 and 3 h of time interval. With 12.5 % of total solid loading and 7.5 % of ortho-phosphoric acid at 121?C the sugar release and lignin reduction were highest after 3 h of pretreatment. Hence, it was selected as the optimized conditions for ortho-phosphoric acid pretreatment. Pearl millet stalk released about 38.96 g l-1 of total sugar while the lignin content was 9 % at the optimized condition. The lab scale Simultaneous Saccharification and Fermentation (SSF) experiment was done with the hydrolysate alone, hydrolysate with artificial sugar (total sugar concentration of 60 g l-1), hydrolysate with 10 % (w/v) of yeast extract. The two types of enzymes cellulase of 40 FPU g-1 and xylanase of 25 U ml-1 was used in all the treatments for saccharification. The two types of yeasts (S.cerevisiae and P.stipitis) were used for the optimization of fermentation. The ethanol yield was calculated as 32.13 g l-1 from pearl millet stalk after 96 h of fermentation with S.cerevisiae from the hydrolysate with added artificial sugar (total sugar concentration of 60 g l-1). The sugar consumption was highest in pearl millet (58.48 g l-1) in the condition 2 with S.cerevisiae. Hence, the hydrolysate with added artificial sugar with S.cerevisiae was selected for fermentation up to 96 h for all the biomass samples. The process parameters for SSF viz., temperature and agitation speed were optimized with the above treatment. The SSF experiment in the above optimized treatment with S.cerevisiae was done at 25, 30 and 35?C. The three different agitation speed were used such as 75, 100 and 125 rpm for optimization. The highest ethanol concentration of was achieved from pearl millet stalk (44.24 g l-1) at 30?C with 100 rpm at 96 h compared to other temperatures and agitation speed. Hence, the optimized temperature and agitation speed selected were 30?C and 100 rpm respectively for bioethanol production from pearl millet stalk

1. Putro J.N., Soetaredjo F.E., Lin S.Y., Yi-Hsu Ju and Ismadji S. (2016) RSC Advances, 6, 46834-46852.
2. Madadi M., Tu Y. and Abbas A. (2017) Int J Appl Sci Biotech., 5, 1-11.
3. Joginder S., Meenakshi, S and Anil D. (2015) Carbohydrate Polymers, 624, 631.
4. Fernando S., Paulo E., Humbertode Q. and Fernando G. (2020) Sugarcane Biorefinery, Technology and Perspectives, 195-228.
5. Wang T. and Lu X. (2021) Advances in 2nd Generation of Bioethanol Production, 137-159.
6. Deepthi H. and Ramachandra V. (2022) Handbook of Biofuels, 295-312.
7. Goering H.K. and Soest P.J.V. (1975) Agr. Res. Ser. Handbook, 369, 12-17.
8. Mosier N., Hendrickson R., Ho N., Sedlak M. and Ladisch M. (2005) Bioresource Technol., 96, 1986-1993.
9. Miller G.L. (1959) Analyt. Chem., 31, 426-428.
10. Krishna H.S., Prabhakar Y. and Rao R.J. (1997) Indian J. Pharma. Sci., 59, 39-42.
11. Karagoz P. and Ozkan M. (2013) Journal of Biochemistry, 38(4), 457-467.
12. Kadar Z., Szengyel Z. and Reczecy K. (2004) Ind Crop prod., 20, 103-110.
13. Mc Kendry P. (2002) Bioresource Technology, 83, 37-46.
14. Hendriks A.T. and Zeeman G. (2009) Bioresource Technol., 100(1), 10-18.
15. Jorgensen H., Vibe-Pedersen J., Larsen J. and Felby C. (2007) Biotechnol. Bioeng., 96, 862-870.