White-rot Fungi Pretreatment Enhanced Dilute-acid Hydrolysis of Oil Palm Empty Fruit Bunches
Isroi, I. Kresnawati, S. Ropikoh, D. Santoso, Siswanto
Indonesian Biotechnology Research Institute for Estate Crops, Jl Taman Kencana 1, Bogor 16151, Indonesia
Poster presented in The 4th Indonesia Biotechnology Conference, IPB International Convention Center, Bogor, 5 – 7th August 2008
Oil palm empty fruit bunches (OPEFB) is lignocellulosic waste from palm oil mills. It is a potential source for second generation of bioethanol. As others lignocellulosic biomass, OPEFB has limited its accessibility to be hydrolyzed by acid or enzyme. Pretreatment of the material prior to acid hydrolysis is essential to obtain high overall yields of sugar and ethanol. This study investigated microbial pretreatment of OPEFB by solid state cultivation (SSC) using white-rot fungi. The fungi were cultivated over OPEFB by SSC for 30 days. After pretreatment 0PEFB were than milled to reduce size and remove mycelia. Dilute-acid hydrolysis was performed at 120oC, several different of acid concentrations (0, 1, 2.5, and 5 % H2SO4), substrate concentrations (10%, 20%, and 30%), and durations (15, 30, 45, and 60 min). Acid concentration affected yield of reducing sugars. The highest yield of reducing sugar was 34 g/l, which was obtained from the 2.5% H2SO4 hydrolysis. Increasing substrate concentration (10% to 30%) would increase reducing sugar yields to 25.4, 38.9, and 52. 4 g/l respectively. At the 120oC hydrolysis, the incubation time tested did not effect to the yield of reducing sugar. In addition, a hydrolysis experiment performed in a mini digester at 160oC for 60 min, 0.5% H2SO4 and 25% substrate concentration, the pretreated OPEFB indicated to produce higher yield of reducing sugar (52.8 g/l) compared to untreated control of OPEFB (37.5 g/l).
Key words: microbial pretreatment, lignocellulosic biomass, reducing sugar.