Bio-valorising Paddy Straw as an Inducer-Substrate for Ethanol Production using Fungal Secretome of Penicillium mallochii.

In order to improve the process feasibility and cost function of bioethanol production, higher titres of biomass saccharifying cellulases need to be produced on commercial scale. Diverse lignocellulosic substrates including abundantly accessible paddy straw can be utilized as carbonaceous substrates for the production of cellulose hydrolysing enzymes. This study aims to meliorate milled and sequential acid/alkali pre-treated paddy straw as inducer-substrates for the synthesis of fungal secretomes from Penicillium mallochii repertoires under solid state and liquid shake flask fermentation (SSF and LSF, respectively). The analysis of enzymatic activities of the respective secretomes reinforced the cellulolytic potential of P. mallochii where the maximum cellulase production (Filter paper cellulase: 76.43, Carboxymethyl cellulase: 130.29, Avicelase: 18.6 and β-glucosidase: 83.59 U L⁻¹) was exhibited under LSF conditions using pre-treated paddy straw as the inducer. The disorganisation of the cellulosic structure via hydrogen bond disruption, as indicated by FTIR analysis, after acid/alkali pretreatment allowed a better establishment of fungus on the substrate, thereby facilitating higher cellulase production. A maximum ethanol content of 11.63 g L⁻¹ was obtained at 48 h of simultaneous saccharification and fermentation using pre-hydrolysed paddy straw at 10% (w/v) solid loading and a cellulase dosage of 25 FPU gds⁻¹. These results affirm the utilization of paddy straw for cellulase and ethanol production in an integrated bioprocess that can further be explored and optimized for scale-up studies to cater industrial applications. [ABSTRACT FROM AUTHOR]