Combinations of mild physical or chemical pretreatment with biological pretreatment for enzymatic hydrolysis of rice hull

Lignocellulosic carbohydrates, i.e. cellulose and hemicellulose, have abundant potential as feedstock for production of biofuels and chemicals. However, these carbohydrates are generally infiltrated by lignin. Breakdown of the lignin barrier will alter lignocelluloses structures and make the carbohydrates accessible for more efficient bioconversion. White-rot fungi produce ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase) and efficiently mineralise lignin into CO2 and H2O. Biological pretreatment of lignocelluloses using white-rot fungi has been used for decades for ruminant feed, enzymatic hydrolysis, and biopulping. Application of white-rot fungi capabilities can offer environmentally friendly processes for utilising lignocelluloses over physical or chemical pretreatment. This paper reviews white-rot fungi, ligninolytic enzymes, the effect of biological pretreatment on biomass characteristics, and factors affecting biological pretreatment. Application of biological pretreatment for enzymatic hydrolysis, biofuels (bioethanol, biogas and pyrolysis), biopulping, biobleaching, animal feed, and enzymes production are also discussed.

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Fermentasi etanol menggunakan bakteri Zymonas mobilis dari glukosa hasil hidrolisa enzimatik bagas

Jurnal Teknik Kimia Indonesia ◽

10.5614/jtki.2007.6.2.3 ◽

2018 ◽

Vol 6 (2) ◽

pp. 609

Author(s):

S Saraswati

Keyword(s):

Renewable Energy ◽

Enzymatic Hydrolysis ◽

Zymomonas Mobilis ◽

Alternative Energy ◽

Fermentation Process ◽

Raw Material ◽

Second Step ◽

Chemical Pretreatment ◽

Cellulase Enzyme ◽

Hydrolysis Of

The resources and reserves of oil which is a non renewable energy are very limited, while the oil consumption is increasing continuously. It is necessary to look for alternative energy. Etanol, a liquid energy, is a renewable alternative energy. Glucose can be used as raw material for etanol production. Glucose can be obtained by enzymatic hydrolysis of bagasse which is a solid waste of sugar canefactory. The objective of this research was to get the optimum condition of etanol production using bagasse as raw material. The experimental research consisted of 2 steps. First step : enzymatic hydrolysis of bagasse with chemical pretreatment process, and the second step was fermentation process using Zymomonas mobilis bacteria. Variables of thefirst step were the NaOH concentration (5%, 7% and 9%) as a pretreatment agent, and cellulase enzyme used (30, 40 and 50 cellulase enzyme units/gram bagasse). For the second step, the variables were glucose concentration (I2.5%, 15%, 20%, 22.5%, and 25%) and the fermentation time (20, 24, 28, 32, 36, 40 and 48 hours). The experiment showed that the best result of the enzymatic hydrolysis could be obtained by NaOH 7% as chemical pretreatment agent and using 50 units of cellulase enzyme/gram bagasse. The cellulose conversion of bagasse was 87% within 42 hours period time. The highest etanol concentration of the fermentation process was 9.238% (weight %) and the yield was 0.4912 grams etanol/gram glucose. It was reached by using 22.5% glucose during 48 hours fermentation time.Keywords: etanol; fermentation; Zymomonas mobilis; glucose; hydrolysis; cellulase enzyme; pretreatment;bagasse AbstrakCadangan minyak bumi yang merupakan non renewable energy (energi tak terbarukan) sangat terbatas, sedang konsumsinya terus meningkat. Untuk itu perlu dicari energi alternatif. Etanol merupakan salah satu energi cair alternatif yang terbarukan (renewable). Bahan baku etanol antara lain adalah glukosa. Glukosa dapat diperoleh dari hidrolisa enzimatik bagas yang merupakan limbah pabrik gula. Penelitian ini bertujuan untuk mendapatkan kondisi yang optimum dari pembuatan etanol dengan bahan baku bagas. Penelitian experimental meliputi dua tahap. Tahap I : proses hidrolisa enzimatik dari bagas dengan perlakuan pendahuluan (pretreatment), dan tahap II adalah proses fermentasi dengan bakteri Zymomonas mobilis. Variabel pada tahap I adalah konsentrasi NaOH sebagai pretreatment agent sebesar 5%, 7% dan 9% serta pemakaian enzim selulase : 30, 40 dan 50 unit enzim selulase/gram bagas. Variabel untuk tahap II adalah konsentrasi glukosa: 12.5%, 15%, 20%, 22.5% dan 25% dan waktu fermentasi 20, 24, 28, 32, 36, 40 dan 48 jam. Hasil penelitian menunjukkan bahwa untuk hidrolisa enzimatik hasil yang terbaik diperoleh dengan NaOH 7% dan 50 unit enzim selulase/gram bagas dengan konversi selulosa 87% dan waktu 42 jam. Untuk fermentasi kadar etanol tertinggi diperoleh pada konsentrasi glukosa 22.5% yaitu sebesar 9.238%, waktu 48 jam dan yield 0.4912 gram etanollgram glukosa.Kata Kunci: etanol; fennentasi; Zymomonas mobilis; glukosa; hidrolisa ; enzim selulase; pretreatment; bagas.

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