Kinetic Study of Biohydrogen Production Improvement via Dark Fermentation of Sugarcane Molasses by Escherichia marmotae

Abstract

H YDROGEN (H 2 ) is expected to become the most sustainable and promising clean alternative fuel in the future. This study evaluated the potential of a new facultative anaerobic bacterium isolated from cow rumen to produce H 2 from sugarcane molasses. The bacterial isolate RM122 produced 451.67 ±12.14 and 387.67 ±19.23mL/L H 2 on 6% glucose and 6% molasses sugar, respectively. RM122 was characterized phenotypically, identified genotypically by 16S rRNA sequence analysis as Escherichia marmotae, and deposited in NCBI GenBank database with the accession number OP345936. H 2 production was improved to 1670.00 ±40.41mL/L by application of optimization experiments design and kinetic study. Sugarcane molasses was used as a fermentation substrate and the optimum sugar concentration was 4%, The recorded maximum hydrogen production (H max ) was 560.00±25.98mL/L with R max (maximum hydrogen production rate) of 31.43 ±2.14mL/L/h, R max (MGM) of 30.73 mL/ L/h and λ (lag phase) of 15.19h for 52.43 fermentation time. H max of 646.67 ±23.33mL/L with R max (Exp) of 35.28 ±2.65mL/L/h, R max (MGM) of 31.90mL/L/h, λ of 13.92h and R 2 of 0.9999 were obtained at the optimum pH 8. At the optimum fermentation temperature (35°C), λ of 4.12h was achieved to maximize hydrogen production to 828.33 ±21.67mL/L with R max (MGM) of 27.98mL/L/h, and R 2 of 0.9594. At the optimum inoculum size (10%, v/v), the recorded H max was 1670.00 ±40.41mL/L with R max (Exp) of 60.00 ±2.04mL/L/h and λ of 13.50h. These findings suggest using E. marmotae RM122 as a prospective biohydrogen producer from cheap agro-industrial wastes.