Determination of hydrolyzing and ethanolic potential of cellulolytic bacteria isolated from fruit waste

Abstract

Fruit wastes containing cellulose can be made valuable by cellulolytic bacteria in biofuel production. This study aimed to assess the potential of isolated cellulolytic bacteria to produce bioethanol and its fermentation efficiency. Seven out of 16 bacterial isolates were selected on the basis of their cellulose-degrading potential by providing cellulose as the only carbon source. Their potential to degrade cellulose was determined by different biochemical tests. All strains produced bubbles as indicators of carbon dioxide production in Durham tubes. The maximum hallow on Congo red staining was shown by CA2, CG2, as 54, 40 mm with cellulolytic index 16.3 and 19. Cellulose degradation was evaluated as light pink to maroon color in triphenyl tetrazolium in all strains except CA4 and CB1. Cellulose (2%) added medium was provided to the isolated strains for the period of 10 days to allow fermentation. CG2 and CA2 yielded maximum ethanol as 0.42±0.005 and 0.43±0.011 (g of ethanol/ g of reducing sugar consumed), respectively. Their percent fermentation efficiency was observed as 79.71±0.059% and 75.58±0.011% correspondingly. All strains showed cellulose activity, and the maximum was seen in CA2 and CG2 as 0.265±0.05, 0.27±0.011 μmol/min/L. Molecular characterization suggested that the CA2 and CG2 strains were Bacillus manliponesis CA2 and Bacillus sp. CG2 (Accession Nos. ON324120 and OM974175). This study elaborates on the capability of bacteria to produce bioethanol by degrading cellulose.