Optimizing bamboo biomass for sustainable isobutanol production using genetically engineered Escherichia coli

Abstract

Researchers are finding sustainable fuel alternatives due to the growing costs and environmental issues related to fossil energy. Isobutanol is an attractive biofuel with a higher energy content than ethanol and the potential to replace gasoline. Bamboo emerges as a promising and cost-effective feedstock for isobutanol production due to its fast growth and high holocellulosic content. By using response surface methodology, this study optimized glucose recovery from bamboo biomass by varying pretreatment temperature (30–70°C), reaction time (0.5–6 h), and NaOH concentration (0.5–3 %). The maximum glucose recovery was achieved using 1 % NaOH at 68°C for 6 hours, resulting in improved cellulose and reduced hemicellulose and lignin content in bamboo. This process released 31.01 mg/mL glucose, representing 65 % of available sugars. Structural modifications of the untreated and alkali-treated bamboo biomass were confirmed through Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Isobutanol fermentation with the engineered E. coli strain JCL260 produced 2.28 g/L of isobutanol from enzymatic hydrolysate, achieving 22.86 % of the theoretical maximum. This study determines that cellulose from bamboo has been efficiently transformed into isobutanol through fermentation, although at a lower concentration associated with pure glucose.