Immobilization of Kluyveromyces marxianus K21 via coaxial electrospinning of PVA and sugarcane bagasse composite for bioethanol production

Abstract

The study employed coaxial electrospinning technology to design an immobilization system for ethanol production from a sugarcane bagasse (SCB) and polyvinyl alcohol (PVA) composite. Using response surface methodology (RSM), the most suitable pretreatment conditions were 1.84 N H2SO4 at 70.85 °C for 30 min which resulted in 4.73 mg polysaccharide per 1 mL of SCB being extracted, comparing to the theoretical value of 4.51 mg. According to physical characterization analyses, both PVA/SCB and yeast-embedded PVA/SCB composites had superior strength and ductility compared to PVA-only sample. With 36.5 g/L of sugar consumption, a total of 18.01 g/L ethanol was produced after 10 h of cultivation from PVA/SCB/K21 which was higher than that from the freely suspended culture (15.31 g/L at 12 h), resulting in a 15% increase in yield. Furthermore, the PVA/SCB/K21 system was able to maintain constant ethanol production even after 21 days of storage, and could be reused in fermentation for at least 8 cycles. The findings showed that the PVA/SCB/K21 nanothreads is an ideal system for repeated bioethanol production while upcycling sugarcane bagasse biomass waste.