Enhanced biohydrogen production from date seeds by Clostridium thermocellum ATCC 27405

Abstract

Biohydrogen production from waste lignocellulosic biomass serves the dual purpose of converting waste into valuable products and alleviates waste disposal issues. In this study, waste date seeds were valorized for biohydrogen production via consolidated bioprocessing by Clostridium thermocellum ATCC 27405. Effect of various surfactants (PEG1000, surfactin, Triton X-100) and sodium carbonate (buffering agent) on biohydrogen production from the acid pre-treated substrate was examined. Among the various surfactants, addition of Triton X-100 resulted in the maximum biohydrogen yield of 103.97 mmol/L at an optimal dosage of 0.75% w/v. Triton X-100 supplementation favoured the production of ethanol and acetate as co-metabolites than butyrate. Addition of Na2CO3 to date seed fermentation medium at a concentration of 15 mM enhanced the biohydrogen production by 33.16%. Also, Na2CO3 buffering supported the glycolytic pathway and subsequent ethanol production than acetate/butyrate formation. Combined effect of the optimal dosages of Triton X-100 and Na2CO3 resulted in high hydrogen productivity up to 72 h (0.443 mmol/g h of H2) with a total increase in hydrogen yield of 40.6% at the end of 168 h, as compared to fermentation supplemented with Triton X-100 alone. Further analysis revealed that the combined effects of the additives resulted in better substrate degradation, favourable pH window and cell growth promotion which ensured enhanced hydrogen productivity and yield. Thus, the study highlights a novel stimulatory approach for enhanced biohydrogen production from a new substrate.