Prospecting Parthenium sp. pretreated with Trametes hirsuta, as a potential bioethanol feedstock

Abstract

The main aim of this study was selection of the most potent white rot fungus for biological pretreatment of Parthenium sp. and to investigate the susceptibility of delignified biomass to enzymatic hydrolysis. Five white rot fungi were evaluated for lignolytic enzyme activity under submerged fermentation (SmF) with Parthenium sp. as sole carbon source. Among which Trametes hirsuta ITCC136 was found to be the most efficient strain with high lignolytic enzymatic activity (42.08 IU ml−1 laccase, 7.02 IU ml−1 manganese peroxidase and 3.58 IU ml−1 lignin peroxidase). Solid state fermentation (SSF) of Parthenium sp. using T. hirsuta revealed delignification of substrate to greater extent within 7 days with higher lignin recovery (1.92 fold) and enrichment of holocellulose content as compared to untreated (uninoculated) control. The alteration in structure and delignification was ascertained by scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The pretreated biomass yielded much higher level of sugars (485.64 mg/gds) than controls in 24 h of saccharification with Accellerase®1500. Higher availability of holocellulose (52.65%) in Parthenium sp. and selective lignin degradation by T. hirsuta in shorter incubation time makes it a prospective feedstock for bioethanol production. This study represents a first time report illustrating the suitability of biologically delignified Parthenium sp. as a feedstock for fuel ethanol production.