Comparative Hydrolytic Approaches Using Bacterial Cellulases for Valorization of Pomegranate Peels Waste

Abstract

The sustainable management of fruit waste offers both economic and environmental benefits, particularly in addressing the global energy crisis. This study explores the conversion of pomegranate peel waste (PPW) into bioethanol through acidic, enzymatic, and combined (acidic + enzymatic) hydrolysis followed by fermentation. Cellulolytic bacterial isolates Bacillus sp. CG2 and Bacillus manliponensis CA2 were used to perform enzymatic and combined hydrolysis of the PPW with cellulolytic potential of 0.27±0.011 and 0.265±0.05 IU, respectively. Enzymatic hydrolysis was performed at 50 °C with PPW, enzyme dosage, and acetate buffer for different time intervals while optimum conditions for acidic saccharified PPW were 6% H₂SO₄, 50 °C, 60 min. The combined hydrolysis approach used a 1:1 ratio of acidic and enzymatic hydrolysates, yielding maximum reducing and total sugar concentrations of 85.77±1.21 g/L and 179.18±3.42 g/L, respectively, after 96 h. Saccharomyces cerevisiae K7 and Metschnikowia cibodasensis Y34, was employed to ferment treated PPW hydrolysates. M. cibodasensis Y34 in combined hydrolysate produced the highest ethanol concentration (16.05 ± 0.66 g/L), with a fermentation efficiency of 83.8% and ethanol yield of 0.41 g/g. These findings highlighted the potential of integrated hydrolysis techniques for efficient bioethanol production from fruit waste.