Production of fermentable sugarsfrom oil palm trunk by aspergillus fumigatus in solid state fermentation

Abstract

Oil palm industry produces high amount of lignobiomass waste that has potential in fermentable sugar production. Oil palm trunk (OPT), which is one of abundant lignobiomass waste consist of 37.47% cellulose, 25.99% hemicellulose, and 9.93% lignin. Having a high C: N ratio content, the OPT is potentially good to act as a substrate for fermentable sugar production through solid state fermentation (SSF). In the study, OPT without chemical pre-treatment was utilized for optimization of fermentable sugar production in SSF using flask and 5L rotary drum bioreactor. Aspergillus fumigatus SK1 produce 24.40 mg/g fermentable sugar under limited nitrogen content. The application of mycelium as an inoculum gave significant impact to fermentable sugar production as compared to spore suspension. OPT particle size of 250 µm produced up to 39.46 mg/g of fermentable sugar. The optimization of fermentable sugar production using Central Composite Design (CCD) showed combination of initial pH (5.96), initial moisture (67.97%), temperature (39.77 °C), and incubation time (11 days) enhanced fermentable sugar production up to 262 mg/g, which was 9.74 fold improvement as compared to un-optimized condition (24.40 mg/g). The CCD optimized condition was applied to 5 L rotary drum bioreactor with agitation of 2 rpm/day and aeration of 2 L/min increased fermentable sugar production to 270.83 mg/g which is 10.09 fold as compared to unoptimized condition in flask. The findings of this project demonstrated the potential used of OPT as an alternative substrate for fermentable sugar production through green biorefinery processing.