Co-fermentation of forest pine needle waste biomass hydrolysate into bioethanol

Pine needle waste biomass is a troublesome forest biomass from the mid Himalayan region. Every year, it causes number of forest fire incidents causing a significant damage to the Himalayan ecology and environment. However, this forest waste biomass may be utilized to produce various value-added products, including biofuels. Pine needle waste biomass (PNWB) obtained from the Himalayan forests was chopped, ground, and subjected to physico-chemical pre-treatments (1.0% NaOH + Microwave (900 W for 12 min) that resulted in 72.58 ± 0.46% wt/v lignin removal. Saccharification of the resultant lignin-free PNWB with xylanase from Bacillus pumilus XRL5 and cellulase from Bacillus subtilis CPS-66 enzymes (2:4 U/g of pine needles) for 48 h at 45 °C produced 25.64 ± 2.36 mg/ml of fermentable sugars. Subsequent 1.5 l co-fermentation of PNWB fermentable sugars with Schizosaccharomyces sp. EF-3 and Kluyveromyces marxianus MTCC 1498 produced 17.65 g/l ethanol with 86.6% purity and 91.22% fermentation efficiency. Findings of the present study suggest that pine needle waste biomass from the forest could be utilized as an important bioresource for bioethanol production, which will not only help in protecting the Chir-Pine forests from devastating forest fires but will also help in protecting the biodiversity and environment.