Selection of actinomycetes for degradation lignocellulosic biomass.

Abstract

Lignocellulose is the major structural component of woody plants and nonwoody plants which represents a major source of renewable organic matter. The structural component lignocelluloses consist of 40% to 50% cellulose, 20% to 30% hemicellulose, 10% to 25% lignin and extractable components. The component of lignocellulose biomass can potentially be converted into various different valuable products including biofuels, organic chemicals, cheap energy sources for fermentation, and improving animal feeds and human nutrients. Lignocellulose components are difficult to hydrolyze because cellulose is associated with hemicellulose, their fiber surrounded by a lignin seal and much of it has a crystalline structure, giving it a highly ordered, tightly packed structure. Delignification should be done for increasing the surface area of cellulose by removing the lignin seal, solubilizing hemicellulose, disrupting crystallinity, and increasing pore volume. This study aims to obtain isolates of actinomycetes that produce lignin peroxidase enzyme and applied it for delignification agricultural biomass such as sugarcane bagasse, corn cobs, oil palm empty fruit bunch (OPEFB), and sawdust. The study was conducted into three main steps as the following: selection of actinomycet isolate that produce lignin peroxidase, characterization of selected isolate, and applied it for delignification agricultural biomass. Qualitative observations using congo red and fuchsin were conducted as the initial screening. Screening by congo red revealed 11 isolates that produce clear zone, while only one isolate (isolate 42) obtained Fuchsin screening. This isolate secreted lignin peroxidase enzymes with the highest activities after 8 days as 24.46 U/mg, and xylanase enzyme after 10 days as 0.055 U/ml. Actinomycetes isolate 42 can grow on all lignocelullose substrates, and degraded all components in the substrates. After 6 weeks cultivation, degradation caused 2.14-13.8% lossed weight, with the highest weight loss from sugar cane substrate. Isolate 42 has highest delignification capability (7.45%) and cellulose degradation (10.69%) on corncobs and, highest hemicelullose solubilization capability on OPEFB (9.93%)