T Taufikurahman
Department of Bioengineering, School of Life Sciences and Technology, Bandung Institute of Technology

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A Comparison of Alkali and Biological Pretreatment Methods in Napier Grass (Pennisetum purpureum Scumach.) for Reducing Lignin Content in the Bioethanol Production Process T Taufikurahman; Wendo Obert Delimanto
3BIO: Journal of Biological Science, Technology and Management Vol. 2 No. 1 (2020)
Publisher : School of Life Sciences and Technology, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/3bio.2020.2.1.5

Abstract

Napier grass is one of lignocellulosic plants that has the potential to be converted as bioethanol due to high productivity and relatively fast harvesting time. However, the problems of processing lignocellulosic plants into bioethanol are the high lignin content and the different lignin structure of each plant. Lignin can inhibit biological agents in accessing cellulose and hemicellulose. Therefore, it is necessary to select and optimize the pretreatment process with the aim of degrading lignin and maintaining the value of the cellulose. This study was conducted to compare the effectiveness of two different pretreatments (biological and alkaline) in degrading lignin. For the alkali pretreatment, lime (Ca(OH)2) was added to the Napier grass substrate using concentrations of 0.05, 0.1, and 0.5 grams/gram, which was then incubated at 23-25 oC each within 6, 24, and 96 hours period. For biological pretreatment, Aspergillus niger spore was used as an agent, which was incubated onto the Napier grass substrate using concentrations of 106, 107, and 108 cells/mL, an optimal temperature of 35oC and within 1, 3, 5, 7, and 9 days period. As a comparison, Phanerochaete chrysosporium was also incubated using a concentration of 106 a temperature of 35 oC within 28 days period. The extracted Napier grass was then analyzed for lignocellulose content, which included hot water soluble, Hemicellulose, cellulose, lignin, and ash, using Chesson-Datta method and reducing sugar test. Comparison of biological pretreatment between Aspergillus niger and Phanerochaete chrysosporium showed that Aspergillus niger was better at degrading lignin, with a lignin-to-cellulose ratio of 24.3%, smaller than Phanerochaete chrysosporium at 30.645%. This ratio was furthermore compared with the ratio resulting from Alkali pretreatment, which showed that the former was proven to be more optimum.
Bioconversion of Napier Grass Mixed with Soybean Curd Residue Producing Bioethanol through Simultaneous Saccharification and Fermentation in a Solid State Culture T Taufikurahman; Jessica Jessica
3BIO: Journal of Biological Science, Technology and Management Vol. 2 No. 1 (2020)
Publisher : School of Life Sciences and Technology, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/3bio.2020.2.1.4

Abstract

Napier grass is a promising lignocellulosic biomass for bioethanol production because of its high cellulose content and high annual productivity. Converting a lignocellulosic biomass into a bioethanol usually takes two steps which resulted in a long processing time and sometimes includes the utilization of hazardous chemicals. Simultaneous saccharification and fermentation in a solid-state culture using single bioconversion agent, Neurospora sitophila Shear, can reduce the overall processing time and also increase the yield of the products. The research is aimed to determine the optimum aerobic and micro-aerobic conditions that yields the highest enzyme activity and bioethanol concentration from the mixture of Napier grass and soybean curd residue. The saccharification and fermentation process was conducted in the laboratory using an incubator at 33oC. The cellulase enzyme activity was calculated as FPAse. The highest activity achieved was 0.538 filter paper unit with the optimum mass ratio of Napier grass to soybean curd residue was 1:1 on the second day of cultivation period. The fermentation process was conducted aerobically for two days and then followed by six days of micro-aerobic fermentation, resulting in the highest bioethanol yield of 2.12% (w/w) at the end of the culture period. The optimum mass ratio was found to be 9:1. This study shows that Napier grass and simultaneous saccharification and fermentation method has a great potential for cellulase and bioethanol production, but further improvement on the micro-aerobic system is needed to maximize the bioethanol yield.